Add eager and lazy freezing strategies to VACUUM.

[pgsql.git] / src / backend / access / common / reloptions.c

/*-------------------------------------------------------------------------
 *
 * reloptions.c
 *        Core support for relation options (pg_class.reloptions)
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        src/backend/access/common/reloptions.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <float.h>

#include "access/gist_private.h"
#include "access/hash.h"
#include "access/heaptoast.h"
#include "access/htup_details.h"
#include "access/nbtree.h"
#include "access/reloptions.h"
#include "access/spgist_private.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/tablespace.h"
#include "commands/view.h"
#include "nodes/makefuncs.h"
#include "postmaster/postmaster.h"
#include "utils/array.h"
#include "utils/attoptcache.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/rel.h"

/*
 * Contents of pg_class.reloptions
 *
 * To add an option:
 *
 * (i) decide on a type (integer, real, bool, string), name, default value,
 * upper and lower bounds (if applicable); for strings, consider a validation
 * routine.
 * (ii) add a record below (or use add_<type>_reloption).
 * (iii) add it to the appropriate options struct (perhaps StdRdOptions)
 * (iv) add it to the appropriate handling routine (perhaps
 * default_reloptions)
 * (v) make sure the lock level is set correctly for that operation
 * (vi) don't forget to document the option
 *
 * The default choice for any new option should be AccessExclusiveLock.
 * In some cases the lock level can be reduced from there, but the lock
 * level chosen should always conflict with itself to ensure that multiple
 * changes aren't lost when we attempt concurrent changes.
 * The choice of lock level depends completely upon how that parameter
 * is used within the server, not upon how and when you'd like to change it.
 * Safety first. Existing choices are documented here, and elsewhere in
 * backend code where the parameters are used.
 *
 * In general, anything that affects the results obtained from a SELECT must be
 * protected by AccessExclusiveLock.
 *
 * Autovacuum related parameters can be set at ShareUpdateExclusiveLock
 * since they are only used by the AV procs and don't change anything
 * currently executing.
 *
 * Fillfactor can be set because it applies only to subsequent changes made to
 * data blocks, as documented in hio.c
 *
 * n_distinct options can be set at ShareUpdateExclusiveLock because they
 * are only used during ANALYZE, which uses a ShareUpdateExclusiveLock,
 * so the ANALYZE will not be affected by in-flight changes. Changing those
 * values has no effect until the next ANALYZE, so no need for stronger lock.
 *
 * Planner-related parameters can be set with ShareUpdateExclusiveLock because
 * they only affect planning and not the correctness of the execution. Plans
 * cannot be changed in mid-flight, so changes here could not easily result in
 * new improved plans in any case. So we allow existing queries to continue
 * and existing plans to survive, a small price to pay for allowing better
 * plans to be introduced concurrently without interfering with users.
 *
 * Setting parallel_workers is safe, since it acts the same as
 * max_parallel_workers_per_gather which is a USERSET parameter that doesn't
 * affect existing plans or queries.
 *
 * vacuum_truncate can be set at ShareUpdateExclusiveLock because it
 * is only used during VACUUM, which uses a ShareUpdateExclusiveLock,
 * so the VACUUM will not be affected by in-flight changes. Changing its
 * value has no effect until the next VACUUM, so no need for stronger lock.
 */

static relopt_bool boolRelOpts[] =
{
        {
                {
                        "autosummarize",
                        "Enables automatic summarization on this BRIN index",
                        RELOPT_KIND_BRIN,
                        AccessExclusiveLock
                },
                false
        },
        {
                {
                        "autovacuum_enabled",
                        "Enables autovacuum in this relation",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                true
        },
        {
                {
                        "user_catalog_table",
                        "Declare a table as an additional catalog table, e.g. for the purpose of logical replication",
                        RELOPT_KIND_HEAP,
                        AccessExclusiveLock
                },
                false
        },
        {
                {
                        "fastupdate",
                        "Enables \"fast update\" feature for this GIN index",
                        RELOPT_KIND_GIN,
                        AccessExclusiveLock
                },
                true
        },
        {
                {
                        "security_barrier",
                        "View acts as a row security barrier",
                        RELOPT_KIND_VIEW,
                        AccessExclusiveLock
                },
                false
        },
        {
                {
                        "security_invoker",
                        "Privileges on underlying relations are checked as the invoking user, not the view owner",
                        RELOPT_KIND_VIEW,
                        AccessExclusiveLock
                },
                false
        },
        {
                {
                        "vacuum_truncate",
                        "Enables vacuum to truncate empty pages at the end of this table",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                true
        },
        {
                {
                        "deduplicate_items",
                        "Enables \"deduplicate items\" feature for this btree index",
                        RELOPT_KIND_BTREE,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                true
        },
        /* list terminator */
        {{NULL}}
};

static relopt_int intRelOpts[] =
{
        {
                {
                        "fillfactor",
                        "Packs table pages only to this percentage",
                        RELOPT_KIND_HEAP,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                HEAP_DEFAULT_FILLFACTOR, HEAP_MIN_FILLFACTOR, 100
        },
        {
                {
                        "fillfactor",
                        "Packs btree index pages only to this percentage",
                        RELOPT_KIND_BTREE,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                BTREE_DEFAULT_FILLFACTOR, BTREE_MIN_FILLFACTOR, 100
        },
        {
                {
                        "fillfactor",
                        "Packs hash index pages only to this percentage",
                        RELOPT_KIND_HASH,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                HASH_DEFAULT_FILLFACTOR, HASH_MIN_FILLFACTOR, 100
        },
        {
                {
                        "fillfactor",
                        "Packs gist index pages only to this percentage",
                        RELOPT_KIND_GIST,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                GIST_DEFAULT_FILLFACTOR, GIST_MIN_FILLFACTOR, 100
        },
        {
                {
                        "fillfactor",
                        "Packs spgist index pages only to this percentage",
                        RELOPT_KIND_SPGIST,
                        ShareUpdateExclusiveLock        /* since it applies only to later
                                                                                 * inserts */
                },
                SPGIST_DEFAULT_FILLFACTOR, SPGIST_MIN_FILLFACTOR, 100
        },
        {
                {
                        "autovacuum_vacuum_threshold",
                        "Minimum number of tuple updates or deletes prior to vacuum",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0, INT_MAX
        },
        {
                {
                        "autovacuum_vacuum_insert_threshold",
                        "Minimum number of tuple inserts prior to vacuum, or -1 to disable insert vacuums",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -2, -1, INT_MAX
        },
        {
                {
                        "autovacuum_analyze_threshold",
                        "Minimum number of tuple inserts, updates or deletes prior to analyze",
                        RELOPT_KIND_HEAP,
                        ShareUpdateExclusiveLock
                },
                -1, 0, INT_MAX
        },
        {
                {
                        "autovacuum_vacuum_cost_limit",
                        "Vacuum cost amount available before napping, for autovacuum",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 1, 10000
        },
        {
                {
                        "autovacuum_freeze_min_age",
                        "Minimum age at which VACUUM should freeze a table row, for autovacuum",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0, 1000000000
        },
        {
                {
                        "autovacuum_multixact_freeze_min_age",
                        "Minimum multixact age at which VACUUM should freeze a row multixact's, for autovacuum",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0, 1000000000
        },
        {
                {
                        "autovacuum_freeze_max_age",
                        "Age at which to autovacuum a table to prevent transaction ID wraparound",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 100000, 2000000000
        },
        {
                {
                        "autovacuum_multixact_freeze_max_age",
                        "Multixact age at which to autovacuum a table to prevent multixact wraparound",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 10000, 2000000000
        },
        {
                {
                        "autovacuum_freeze_table_age",
                        "Age at which VACUUM should perform a full table sweep to freeze row versions",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                }, -1, 0, 2000000000
        },
        {
                {
                        "autovacuum_multixact_freeze_table_age",
                        "Age of multixact at which VACUUM should perform a full table sweep to freeze row versions",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                }, -1, 0, 2000000000
        },
        {
                {
                        "autovacuum_freeze_strategy_threshold",
                        "Table size at which VACUUM freezes using eager strategy, in megabytes.",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                }, -1, 0, MAX_KILOBYTES
        },
        {
                {
                        "log_autovacuum_min_duration",
                        "Sets the minimum execution time above which autovacuum actions will be logged",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, -1, INT_MAX
        },
        {
                {
                        "toast_tuple_target",
                        "Sets the target tuple length at which external columns will be toasted",
                        RELOPT_KIND_HEAP,
                        ShareUpdateExclusiveLock
                },
                TOAST_TUPLE_TARGET, 128, TOAST_TUPLE_TARGET_MAIN
        },
        {
                {
                        "pages_per_range",
                        "Number of pages that each page range covers in a BRIN index",
                        RELOPT_KIND_BRIN,
                        AccessExclusiveLock
                }, 128, 1, 131072
        },
        {
                {
                        "gin_pending_list_limit",
                        "Maximum size of the pending list for this GIN index, in kilobytes.",
                        RELOPT_KIND_GIN,
                        AccessExclusiveLock
                },
                -1, 64, MAX_KILOBYTES
        },
        {
                {
                        "effective_io_concurrency",
                        "Number of simultaneous requests that can be handled efficiently by the disk subsystem.",
                        RELOPT_KIND_TABLESPACE,
                        ShareUpdateExclusiveLock
                },
#ifdef USE_PREFETCH
                -1, 0, MAX_IO_CONCURRENCY
#else
                0, 0, 0
#endif
        },
        {
                {
                        "maintenance_io_concurrency",
                        "Number of simultaneous requests that can be handled efficiently by the disk subsystem for maintenance work.",
                        RELOPT_KIND_TABLESPACE,
                        ShareUpdateExclusiveLock
                },
#ifdef USE_PREFETCH
                -1, 0, MAX_IO_CONCURRENCY
#else
                0, 0, 0
#endif
        },
        {
                {
                        "parallel_workers",
                        "Number of parallel processes that can be used per executor node for this relation.",
                        RELOPT_KIND_HEAP,
                        ShareUpdateExclusiveLock
                },
                -1, 0, 1024
        },

        /* list terminator */
        {{NULL}}
};

static relopt_real realRelOpts[] =
{
        {
                {
                        "autovacuum_vacuum_cost_delay",
                        "Vacuum cost delay in milliseconds, for autovacuum",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, 100.0
        },
        {
                {
                        "autovacuum_vacuum_scale_factor",
                        "Number of tuple updates or deletes prior to vacuum as a fraction of reltuples",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, 100.0
        },
        {
                {
                        "autovacuum_vacuum_insert_scale_factor",
                        "Number of tuple inserts prior to vacuum as a fraction of reltuples",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, 100.0
        },
        {
                {
                        "autovacuum_analyze_scale_factor",
                        "Number of tuple inserts, updates or deletes prior to analyze as a fraction of reltuples",
                        RELOPT_KIND_HEAP,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, 100.0
        },
        {
                {
                        "seq_page_cost",
                        "Sets the planner's estimate of the cost of a sequentially fetched disk page.",
                        RELOPT_KIND_TABLESPACE,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, DBL_MAX
        },
        {
                {
                        "random_page_cost",
                        "Sets the planner's estimate of the cost of a nonsequentially fetched disk page.",
                        RELOPT_KIND_TABLESPACE,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, DBL_MAX
        },
        {
                {
                        "n_distinct",
                        "Sets the planner's estimate of the number of distinct values appearing in a column (excluding child relations).",
                        RELOPT_KIND_ATTRIBUTE,
                        ShareUpdateExclusiveLock
                },
                0, -1.0, DBL_MAX
        },
        {
                {
                        "n_distinct_inherited",
                        "Sets the planner's estimate of the number of distinct values appearing in a column (including child relations).",
                        RELOPT_KIND_ATTRIBUTE,
                        ShareUpdateExclusiveLock
                },
                0, -1.0, DBL_MAX
        },
        {
                {
                        "vacuum_cleanup_index_scale_factor",
                        "Deprecated B-Tree parameter.",
                        RELOPT_KIND_BTREE,
                        ShareUpdateExclusiveLock
                },
                -1, 0.0, 1e10
        },
        /* list terminator */
        {{NULL}}
};

/* values from StdRdOptIndexCleanup */
static relopt_enum_elt_def StdRdOptIndexCleanupValues[] =
{
        {"auto", STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO},
        {"on", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
        {"off", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
        {"true", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
        {"false", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
        {"yes", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
        {"no", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
        {"1", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
        {"0", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
        {(const char *) NULL}           /* list terminator */
};

/* values from GistOptBufferingMode */
static relopt_enum_elt_def gistBufferingOptValues[] =
{
        {"auto", GIST_OPTION_BUFFERING_AUTO},
        {"on", GIST_OPTION_BUFFERING_ON},
        {"off", GIST_OPTION_BUFFERING_OFF},
        {(const char *) NULL}           /* list terminator */
};

/* values from ViewOptCheckOption */
static relopt_enum_elt_def viewCheckOptValues[] =
{
        /* no value for NOT_SET */
        {"local", VIEW_OPTION_CHECK_OPTION_LOCAL},
        {"cascaded", VIEW_OPTION_CHECK_OPTION_CASCADED},
        {(const char *) NULL}           /* list terminator */
};

static relopt_enum enumRelOpts[] =
{
        {
                {
                        "vacuum_index_cleanup",
                        "Controls index vacuuming and index cleanup",
                        RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
                        ShareUpdateExclusiveLock
                },
                StdRdOptIndexCleanupValues,
                STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO,
                gettext_noop("Valid values are \"on\", \"off\", and \"auto\".")
        },
        {
                {
                        "buffering",
                        "Enables buffering build for this GiST index",
                        RELOPT_KIND_GIST,
                        AccessExclusiveLock
                },
                gistBufferingOptValues,
                GIST_OPTION_BUFFERING_AUTO,
                gettext_noop("Valid values are \"on\", \"off\", and \"auto\".")
        },
        {
                {
                        "check_option",
                        "View has WITH CHECK OPTION defined (local or cascaded).",
                        RELOPT_KIND_VIEW,
                        AccessExclusiveLock
                },
                viewCheckOptValues,
                VIEW_OPTION_CHECK_OPTION_NOT_SET,
                gettext_noop("Valid values are \"local\" and \"cascaded\".")
        },
        /* list terminator */
        {{NULL}}
};

static relopt_string stringRelOpts[] =
{
        /* list terminator */
        {{NULL}}
};

static relopt_gen **relOpts = NULL;
static bits32 last_assigned_kind = RELOPT_KIND_LAST_DEFAULT;

static int      num_custom_options = 0;
static relopt_gen **custom_options = NULL;
static bool need_initialization = true;

static void initialize_reloptions(void);
static void parse_one_reloption(relopt_value *option, char *text_str,
                                                                int text_len, bool validate);

/*
 * Get the length of a string reloption (either default or the user-defined
 * value).  This is used for allocation purposes when building a set of
 * relation options.
 */
#define GET_STRING_RELOPTION_LEN(option) \
        ((option).isset ? strlen((option).values.string_val) : \
         ((relopt_string *) (option).gen)->default_len)

/*
 * initialize_reloptions
 *              initialization routine, must be called before parsing
 *
 * Initialize the relOpts array and fill each variable's type and name length.
 */
static void
initialize_reloptions(void)
{
        int                     i;
        int                     j;

        j = 0;
        for (i = 0; boolRelOpts[i].gen.name; i++)
        {
                Assert(DoLockModesConflict(boolRelOpts[i].gen.lockmode,
                                                                   boolRelOpts[i].gen.lockmode));
                j++;
        }
        for (i = 0; intRelOpts[i].gen.name; i++)
        {
                Assert(DoLockModesConflict(intRelOpts[i].gen.lockmode,
                                                                   intRelOpts[i].gen.lockmode));
                j++;
        }
        for (i = 0; realRelOpts[i].gen.name; i++)
        {
                Assert(DoLockModesConflict(realRelOpts[i].gen.lockmode,
                                                                   realRelOpts[i].gen.lockmode));
                j++;
        }
        for (i = 0; enumRelOpts[i].gen.name; i++)
        {
                Assert(DoLockModesConflict(enumRelOpts[i].gen.lockmode,
                                                                   enumRelOpts[i].gen.lockmode));
                j++;
        }
        for (i = 0; stringRelOpts[i].gen.name; i++)
        {
                Assert(DoLockModesConflict(stringRelOpts[i].gen.lockmode,
                                                                   stringRelOpts[i].gen.lockmode));
                j++;
        }
        j += num_custom_options;

        if (relOpts)
                pfree(relOpts);
        relOpts = MemoryContextAlloc(TopMemoryContext,
                                                                 (j + 1) * sizeof(relopt_gen *));

        j = 0;
        for (i = 0; boolRelOpts[i].gen.name; i++)
        {
                relOpts[j] = &boolRelOpts[i].gen;
                relOpts[j]->type = RELOPT_TYPE_BOOL;
                relOpts[j]->namelen = strlen(relOpts[j]->name);
                j++;
        }

        for (i = 0; intRelOpts[i].gen.name; i++)
        {
                relOpts[j] = &intRelOpts[i].gen;
                relOpts[j]->type = RELOPT_TYPE_INT;
                relOpts[j]->namelen = strlen(relOpts[j]->name);
                j++;
        }

        for (i = 0; realRelOpts[i].gen.name; i++)
        {
                relOpts[j] = &realRelOpts[i].gen;
                relOpts[j]->type = RELOPT_TYPE_REAL;
                relOpts[j]->namelen = strlen(relOpts[j]->name);
                j++;
        }

        for (i = 0; enumRelOpts[i].gen.name; i++)
        {
                relOpts[j] = &enumRelOpts[i].gen;
                relOpts[j]->type = RELOPT_TYPE_ENUM;
                relOpts[j]->namelen = strlen(relOpts[j]->name);
                j++;
        }

        for (i = 0; stringRelOpts[i].gen.name; i++)
        {
                relOpts[j] = &stringRelOpts[i].gen;
                relOpts[j]->type = RELOPT_TYPE_STRING;
                relOpts[j]->namelen = strlen(relOpts[j]->name);
                j++;
        }

        for (i = 0; i < num_custom_options; i++)
        {
                relOpts[j] = custom_options[i];
                j++;
        }

        /* add a list terminator */
        relOpts[j] = NULL;

        /* flag the work is complete */
        need_initialization = false;
}

/*
 * add_reloption_kind
 *              Create a new relopt_kind value, to be used in custom reloptions by
 *              user-defined AMs.
 */
relopt_kind
add_reloption_kind(void)
{
        /* don't hand out the last bit so that the enum's behavior is portable */
        if (last_assigned_kind >= RELOPT_KIND_MAX)
                ereport(ERROR,
                                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                                 errmsg("user-defined relation parameter types limit exceeded")));
        last_assigned_kind <<= 1;
        return (relopt_kind) last_assigned_kind;
}

/*
 * add_reloption
 *              Add an already-created custom reloption to the list, and recompute the
 *              main parser table.
 */
static void
add_reloption(relopt_gen *newoption)
{
        static int      max_custom_options = 0;

        if (num_custom_options >= max_custom_options)
        {
                MemoryContext oldcxt;

                oldcxt = MemoryContextSwitchTo(TopMemoryContext);

                if (max_custom_options == 0)
                {
                        max_custom_options = 8;
                        custom_options = palloc(max_custom_options * sizeof(relopt_gen *));
                }
                else
                {
                        max_custom_options *= 2;
                        custom_options = repalloc(custom_options,
                                                                          max_custom_options * sizeof(relopt_gen *));
                }
                MemoryContextSwitchTo(oldcxt);
        }
        custom_options[num_custom_options++] = newoption;

        need_initialization = true;
}

/*
 * init_local_reloptions
 *              Initialize local reloptions that will parsed into bytea structure of
 *              'relopt_struct_size'.
 */
void
init_local_reloptions(local_relopts *relopts, Size relopt_struct_size)
{
        relopts->options = NIL;
        relopts->validators = NIL;
        relopts->relopt_struct_size = relopt_struct_size;
}

/*
 * register_reloptions_validator
 *              Register custom validation callback that will be called at the end of
 *              build_local_reloptions().
 */
void
register_reloptions_validator(local_relopts *relopts, relopts_validator validator)
{
        relopts->validators = lappend(relopts->validators, validator);
}

/*
 * add_local_reloption
 *              Add an already-created custom reloption to the local list.
 */
static void
add_local_reloption(local_relopts *relopts, relopt_gen *newoption, int offset)
{
        local_relopt *opt = palloc(sizeof(*opt));

        Assert(offset < relopts->relopt_struct_size);

        opt->option = newoption;
        opt->offset = offset;

        relopts->options = lappend(relopts->options, opt);
}

/*
 * allocate_reloption
 *              Allocate a new reloption and initialize the type-agnostic fields
 *              (for types other than string)
 */
static relopt_gen *
allocate_reloption(bits32 kinds, int type, const char *name, const char *desc,
                                   LOCKMODE lockmode)
{
        MemoryContext oldcxt;
        size_t          size;
        relopt_gen *newoption;

        if (kinds != RELOPT_KIND_LOCAL)
                oldcxt = MemoryContextSwitchTo(TopMemoryContext);
        else
                oldcxt = NULL;

        switch (type)
        {
                case RELOPT_TYPE_BOOL:
                        size = sizeof(relopt_bool);
                        break;
                case RELOPT_TYPE_INT:
                        size = sizeof(relopt_int);
                        break;
                case RELOPT_TYPE_REAL:
                        size = sizeof(relopt_real);
                        break;
                case RELOPT_TYPE_ENUM:
                        size = sizeof(relopt_enum);
                        break;
                case RELOPT_TYPE_STRING:
                        size = sizeof(relopt_string);
                        break;
                default:
                        elog(ERROR, "unsupported reloption type %d", type);
                        return NULL;            /* keep compiler quiet */
        }

        newoption = palloc(size);

        newoption->name = pstrdup(name);
        if (desc)
                newoption->desc = pstrdup(desc);
        else
                newoption->desc = NULL;
        newoption->kinds = kinds;
        newoption->namelen = strlen(name);
        newoption->type = type;
        newoption->lockmode = lockmode;

        if (oldcxt != NULL)
                MemoryContextSwitchTo(oldcxt);

        return newoption;
}

/*
 * init_bool_reloption
 *              Allocate and initialize a new boolean reloption
 */
static relopt_bool *
init_bool_reloption(bits32 kinds, const char *name, const char *desc,
                                        bool default_val, LOCKMODE lockmode)
{
        relopt_bool *newoption;

        newoption = (relopt_bool *) allocate_reloption(kinds, RELOPT_TYPE_BOOL,
                                                                                                   name, desc, lockmode);
        newoption->default_val = default_val;

        return newoption;
}

/*
 * add_bool_reloption
 *              Add a new boolean reloption
 */
void
add_bool_reloption(bits32 kinds, const char *name, const char *desc,
                                   bool default_val, LOCKMODE lockmode)
{
        relopt_bool *newoption = init_bool_reloption(kinds, name, desc,
                                                                                                 default_val, lockmode);

        add_reloption((relopt_gen *) newoption);
}

/*
 * add_local_bool_reloption
 *              Add a new boolean local reloption
 *
 * 'offset' is offset of bool-typed field.
 */
void
add_local_bool_reloption(local_relopts *relopts, const char *name,
                                                 const char *desc, bool default_val, int offset)
{
        relopt_bool *newoption = init_bool_reloption(RELOPT_KIND_LOCAL,
                                                                                                 name, desc,
                                                                                                 default_val, 0);

        add_local_reloption(relopts, (relopt_gen *) newoption, offset);
}


/*
 * init_real_reloption
 *              Allocate and initialize a new integer reloption
 */
static relopt_int *
init_int_reloption(bits32 kinds, const char *name, const char *desc,
                                   int default_val, int min_val, int max_val,
                                   LOCKMODE lockmode)
{
        relopt_int *newoption;

        newoption = (relopt_int *) allocate_reloption(kinds, RELOPT_TYPE_INT,
                                                                                                  name, desc, lockmode);
        newoption->default_val = default_val;
        newoption->min = min_val;
        newoption->max = max_val;

        return newoption;
}

/*
 * add_int_reloption
 *              Add a new integer reloption
 */
void
add_int_reloption(bits32 kinds, const char *name, const char *desc, int default_val,
                                  int min_val, int max_val, LOCKMODE lockmode)
{
        relopt_int *newoption = init_int_reloption(kinds, name, desc,
                                                                                           default_val, min_val,
                                                                                           max_val, lockmode);

        add_reloption((relopt_gen *) newoption);
}

/*
 * add_local_int_reloption
 *              Add a new local integer reloption
 *
 * 'offset' is offset of int-typed field.
 */
void
add_local_int_reloption(local_relopts *relopts, const char *name,
                                                const char *desc, int default_val, int min_val,
                                                int max_val, int offset)
{
        relopt_int *newoption = init_int_reloption(RELOPT_KIND_LOCAL,
                                                                                           name, desc, default_val,
                                                                                           min_val, max_val, 0);

        add_local_reloption(relopts, (relopt_gen *) newoption, offset);
}

/*
 * init_real_reloption
 *              Allocate and initialize a new real reloption
 */
static relopt_real *
init_real_reloption(bits32 kinds, const char *name, const char *desc,
                                        double default_val, double min_val, double max_val,
                                        LOCKMODE lockmode)
{
        relopt_real *newoption;

        newoption = (relopt_real *) allocate_reloption(kinds, RELOPT_TYPE_REAL,
                                                                                                   name, desc, lockmode);
        newoption->default_val = default_val;
        newoption->min = min_val;
        newoption->max = max_val;

        return newoption;
}

/*
 * add_real_reloption
 *              Add a new float reloption
 */
void
add_real_reloption(bits32 kinds, const char *name, const char *desc,
                                   double default_val, double min_val, double max_val,
                                   LOCKMODE lockmode)
{
        relopt_real *newoption = init_real_reloption(kinds, name, desc,
                                                                                                 default_val, min_val,
                                                                                                 max_val, lockmode);

        add_reloption((relopt_gen *) newoption);
}

/*
 * add_local_real_reloption
 *              Add a new local float reloption
 *
 * 'offset' is offset of double-typed field.
 */
void
add_local_real_reloption(local_relopts *relopts, const char *name,
                                                 const char *desc, double default_val,
                                                 double min_val, double max_val, int offset)
{
        relopt_real *newoption = init_real_reloption(RELOPT_KIND_LOCAL,
                                                                                                 name, desc,
                                                                                                 default_val, min_val,
                                                                                                 max_val, 0);

        add_local_reloption(relopts, (relopt_gen *) newoption, offset);
}

/*
 * init_enum_reloption
 *              Allocate and initialize a new enum reloption
 */
static relopt_enum *
init_enum_reloption(bits32 kinds, const char *name, const char *desc,
                                        relopt_enum_elt_def *members, int default_val,
                                        const char *detailmsg, LOCKMODE lockmode)
{
        relopt_enum *newoption;

        newoption = (relopt_enum *) allocate_reloption(kinds, RELOPT_TYPE_ENUM,
                                                                                                   name, desc, lockmode);
        newoption->members = members;
        newoption->default_val = default_val;
        newoption->detailmsg = detailmsg;

        return newoption;
}


/*
 * add_enum_reloption
 *              Add a new enum reloption
 *
 * The members array must have a terminating NULL entry.
 *
 * The detailmsg is shown when unsupported values are passed, and has this
 * form:   "Valid values are \"foo\", \"bar\", and \"bar\"."
 *
 * The members array and detailmsg are not copied -- caller must ensure that
 * they are valid throughout the life of the process.
 */
void
add_enum_reloption(bits32 kinds, const char *name, const char *desc,
                                   relopt_enum_elt_def *members, int default_val,
                                   const char *detailmsg, LOCKMODE lockmode)
{
        relopt_enum *newoption = init_enum_reloption(kinds, name, desc,
                                                                                                 members, default_val,
                                                                                                 detailmsg, lockmode);

        add_reloption((relopt_gen *) newoption);
}

/*
 * add_local_enum_reloption
 *              Add a new local enum reloption
 *
 * 'offset' is offset of int-typed field.
 */
void
add_local_enum_reloption(local_relopts *relopts, const char *name,
                                                 const char *desc, relopt_enum_elt_def *members,
                                                 int default_val, const char *detailmsg, int offset)
{
        relopt_enum *newoption = init_enum_reloption(RELOPT_KIND_LOCAL,
                                                                                                 name, desc,
                                                                                                 members, default_val,
                                                                                                 detailmsg, 0);

        add_local_reloption(relopts, (relopt_gen *) newoption, offset);
}

/*
 * init_string_reloption
 *              Allocate and initialize a new string reloption
 */
static relopt_string *
init_string_reloption(bits32 kinds, const char *name, const char *desc,
                                          const char *default_val,
                                          validate_string_relopt validator,
                                          fill_string_relopt filler,
                                          LOCKMODE lockmode)
{
        relopt_string *newoption;

        /* make sure the validator/default combination is sane */
        if (validator)
                (validator) (default_val);

        newoption = (relopt_string *) allocate_reloption(kinds, RELOPT_TYPE_STRING,
                                                                                                         name, desc, lockmode);
        newoption->validate_cb = validator;
        newoption->fill_cb = filler;
        if (default_val)
        {
                if (kinds == RELOPT_KIND_LOCAL)
                        newoption->default_val = strdup(default_val);
                else
                        newoption->default_val = MemoryContextStrdup(TopMemoryContext, default_val);
                newoption->default_len = strlen(default_val);
                newoption->default_isnull = false;
        }
        else
        {
                newoption->default_val = "";
                newoption->default_len = 0;
                newoption->default_isnull = true;
        }

        return newoption;
}

/*
 * add_string_reloption
 *              Add a new string reloption
 *
 * "validator" is an optional function pointer that can be used to test the
 * validity of the values.  It must elog(ERROR) when the argument string is
 * not acceptable for the variable.  Note that the default value must pass
 * the validation.
 */
void
add_string_reloption(bits32 kinds, const char *name, const char *desc,
                                         const char *default_val, validate_string_relopt validator,
                                         LOCKMODE lockmode)
{
        relopt_string *newoption = init_string_reloption(kinds, name, desc,
                                                                                                         default_val,
                                                                                                         validator, NULL,
                                                                                                         lockmode);

        add_reloption((relopt_gen *) newoption);
}

/*
 * add_local_string_reloption
 *              Add a new local string reloption
 *
 * 'offset' is offset of int-typed field that will store offset of string value
 * in the resulting bytea structure.
 */
void
add_local_string_reloption(local_relopts *relopts, const char *name,
                                                   const char *desc, const char *default_val,
                                                   validate_string_relopt validator,
                                                   fill_string_relopt filler, int offset)
{
        relopt_string *newoption = init_string_reloption(RELOPT_KIND_LOCAL,
                                                                                                         name, desc,
                                                                                                         default_val,
                                                                                                         validator, filler,
                                                                                                         0);

        add_local_reloption(relopts, (relopt_gen *) newoption, offset);
}

/*
 * Transform a relation options list (list of DefElem) into the text array
 * format that is kept in pg_class.reloptions, including only those options
 * that are in the passed namespace.  The output values do not include the
 * namespace.
 *
 * This is used for three cases: CREATE TABLE/INDEX, ALTER TABLE SET, and
 * ALTER TABLE RESET.  In the ALTER cases, oldOptions is the existing
 * reloptions value (possibly NULL), and we replace or remove entries
 * as needed.
 *
 * If acceptOidsOff is true, then we allow oids = false, but throw error when
 * on. This is solely needed for backwards compatibility.
 *
 * Note that this is not responsible for determining whether the options
 * are valid, but it does check that namespaces for all the options given are
 * listed in validnsps.  The NULL namespace is always valid and need not be
 * explicitly listed.  Passing a NULL pointer means that only the NULL
 * namespace is valid.
 *
 * Both oldOptions and the result are text arrays (or NULL for "default"),
 * but we declare them as Datums to avoid including array.h in reloptions.h.
 */
Datum
transformRelOptions(Datum oldOptions, List *defList, const char *namspace,
                                        char *validnsps[], bool acceptOidsOff, bool isReset)
{
        Datum           result;
        ArrayBuildState *astate;
        ListCell   *cell;

        /* no change if empty list */
        if (defList == NIL)
                return oldOptions;

        /* We build new array using accumArrayResult */
        astate = NULL;

        /* Copy any oldOptions that aren't to be replaced */
        if (PointerIsValid(DatumGetPointer(oldOptions)))
        {
                ArrayType  *array = DatumGetArrayTypeP(oldOptions);
                Datum      *oldoptions;
                int                     noldoptions;
                int                     i;

                deconstruct_array_builtin(array, TEXTOID, &oldoptions, NULL, &noldoptions);

                for (i = 0; i < noldoptions; i++)
                {
                        char       *text_str = VARDATA(oldoptions[i]);
                        int                     text_len = VARSIZE(oldoptions[i]) - VARHDRSZ;

                        /* Search for a match in defList */
                        foreach(cell, defList)
                        {
                                DefElem    *def = (DefElem *) lfirst(cell);
                                int                     kw_len;

                                /* ignore if not in the same namespace */
                                if (namspace == NULL)
                                {
                                        if (def->defnamespace != NULL)
                                                continue;
                                }
                                else if (def->defnamespace == NULL)
                                        continue;
                                else if (strcmp(def->defnamespace, namspace) != 0)
                                        continue;

                                kw_len = strlen(def->defname);
                                if (text_len > kw_len && text_str[kw_len] == '=' &&
                                        strncmp(text_str, def->defname, kw_len) == 0)
                                        break;
                        }
                        if (!cell)
                        {
                                /* No match, so keep old option */
                                astate = accumArrayResult(astate, oldoptions[i],
                                                                                  false, TEXTOID,
                                                                                  CurrentMemoryContext);
                        }
                }
        }

        /*
         * If CREATE/SET, add new options to array; if RESET, just check that the
         * user didn't say RESET (option=val).  (Must do this because the grammar
         * doesn't enforce it.)
         */
        foreach(cell, defList)
        {
                DefElem    *def = (DefElem *) lfirst(cell);

                if (isReset)
                {
                        if (def->arg != NULL)
                                ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("RESET must not include values for parameters")));
                }
                else
                {
                        text       *t;
                        const char *value;
                        Size            len;

                        /*
                         * Error out if the namespace is not valid.  A NULL namespace is
                         * always valid.
                         */
                        if (def->defnamespace != NULL)
                        {
                                bool            valid = false;
                                int                     i;

                                if (validnsps)
                                {
                                        for (i = 0; validnsps[i]; i++)
                                        {
                                                if (strcmp(def->defnamespace, validnsps[i]) == 0)
                                                {
                                                        valid = true;
                                                        break;
                                                }
                                        }
                                }

                                if (!valid)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("unrecognized parameter namespace \"%s\"",
                                                                        def->defnamespace)));
                        }

                        /* ignore if not in the same namespace */
                        if (namspace == NULL)
                        {
                                if (def->defnamespace != NULL)
                                        continue;
                        }
                        else if (def->defnamespace == NULL)
                                continue;
                        else if (strcmp(def->defnamespace, namspace) != 0)
                                continue;

                        /*
                         * Flatten the DefElem into a text string like "name=arg". If we
                         * have just "name", assume "name=true" is meant.  Note: the
                         * namespace is not output.
                         */
                        if (def->arg != NULL)
                                value = defGetString(def);
                        else
                                value = "true";

                        /*
                         * This is not a great place for this test, but there's no other
                         * convenient place to filter the option out. As WITH (oids =
                         * false) will be removed someday, this seems like an acceptable
                         * amount of ugly.
                         */
                        if (acceptOidsOff && def->defnamespace == NULL &&
                                strcmp(def->defname, "oids") == 0)
                        {
                                if (defGetBoolean(def))
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                                         errmsg("tables declared WITH OIDS are not supported")));
                                /* skip over option, reloptions machinery doesn't know it */
                                continue;
                        }

                        len = VARHDRSZ + strlen(def->defname) + 1 + strlen(value);
                        /* +1 leaves room for sprintf's trailing null */
                        t = (text *) palloc(len + 1);
                        SET_VARSIZE(t, len);
                        sprintf(VARDATA(t), "%s=%s", def->defname, value);

                        astate = accumArrayResult(astate, PointerGetDatum(t),
                                                                          false, TEXTOID,
                                                                          CurrentMemoryContext);
                }
        }

        if (astate)
                result = makeArrayResult(astate, CurrentMemoryContext);
        else
                result = (Datum) 0;

        return result;
}


/*
 * Convert the text-array format of reloptions into a List of DefElem.
 * This is the inverse of transformRelOptions().
 */
List *
untransformRelOptions(Datum options)
{
        List       *result = NIL;
        ArrayType  *array;
        Datum      *optiondatums;
        int                     noptions;
        int                     i;

        /* Nothing to do if no options */
        if (!PointerIsValid(DatumGetPointer(options)))
                return result;

        array = DatumGetArrayTypeP(options);

        deconstruct_array_builtin(array, TEXTOID, &optiondatums, NULL, &noptions);

        for (i = 0; i < noptions; i++)
        {
                char       *s;
                char       *p;
                Node       *val = NULL;

                s = TextDatumGetCString(optiondatums[i]);
                p = strchr(s, '=');
                if (p)
                {
                        *p++ = '\0';
                        val = (Node *) makeString(p);
                }
                result = lappend(result, makeDefElem(s, val, -1));
        }

        return result;
}

/*
 * Extract and parse reloptions from a pg_class tuple.
 *
 * This is a low-level routine, expected to be used by relcache code and
 * callers that do not have a table's relcache entry (e.g. autovacuum).  For
 * other uses, consider grabbing the rd_options pointer from the relcache entry
 * instead.
 *
 * tupdesc is pg_class' tuple descriptor.  amoptions is a pointer to the index
 * AM's options parser function in the case of a tuple corresponding to an
 * index, or NULL otherwise.
 */
bytea *
extractRelOptions(HeapTuple tuple, TupleDesc tupdesc,
                                  amoptions_function amoptions)
{
        bytea      *options;
        bool            isnull;
        Datum           datum;
        Form_pg_class classForm;

        datum = fastgetattr(tuple,
                                                Anum_pg_class_reloptions,
                                                tupdesc,
                                                &isnull);
        if (isnull)
                return NULL;

        classForm = (Form_pg_class) GETSTRUCT(tuple);

        /* Parse into appropriate format; don't error out here */
        switch (classForm->relkind)
        {
                case RELKIND_RELATION:
                case RELKIND_TOASTVALUE:
                case RELKIND_MATVIEW:
                        options = heap_reloptions(classForm->relkind, datum, false);
                        break;
                case RELKIND_PARTITIONED_TABLE:
                        options = partitioned_table_reloptions(datum, false);
                        break;
                case RELKIND_VIEW:
                        options = view_reloptions(datum, false);
                        break;
                case RELKIND_INDEX:
                case RELKIND_PARTITIONED_INDEX:
                        options = index_reloptions(amoptions, datum, false);
                        break;
                case RELKIND_FOREIGN_TABLE:
                        options = NULL;
                        break;
                default:
                        Assert(false);          /* can't get here */
                        options = NULL;         /* keep compiler quiet */
                        break;
        }

        return options;
}

static void
parseRelOptionsInternal(Datum options, bool validate,
                                                relopt_value *reloptions, int numoptions)
{
        ArrayType  *array = DatumGetArrayTypeP(options);
        Datum      *optiondatums;
        int                     noptions;
        int                     i;

        deconstruct_array_builtin(array, TEXTOID, &optiondatums, NULL, &noptions);

        for (i = 0; i < noptions; i++)
        {
                char       *text_str = VARDATA(optiondatums[i]);
                int                     text_len = VARSIZE(optiondatums[i]) - VARHDRSZ;
                int                     j;

                /* Search for a match in reloptions */
                for (j = 0; j < numoptions; j++)
                {
                        int                     kw_len = reloptions[j].gen->namelen;

                        if (text_len > kw_len && text_str[kw_len] == '=' &&
                                strncmp(text_str, reloptions[j].gen->name, kw_len) == 0)
                        {
                                parse_one_reloption(&reloptions[j], text_str, text_len,
                                                                        validate);
                                break;
                        }
                }

                if (j >= numoptions && validate)
                {
                        char       *s;
                        char       *p;

                        s = TextDatumGetCString(optiondatums[i]);
                        p = strchr(s, '=');
                        if (p)
                                *p = '\0';
                        ereport(ERROR,
                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                         errmsg("unrecognized parameter \"%s\"", s)));
                }
        }

        /* It's worth avoiding memory leaks in this function */
        pfree(optiondatums);

        if (((void *) array) != DatumGetPointer(options))
                pfree(array);
}

/*
 * Interpret reloptions that are given in text-array format.
 *
 * options is a reloption text array as constructed by transformRelOptions.
 * kind specifies the family of options to be processed.
 *
 * The return value is a relopt_value * array on which the options actually
 * set in the options array are marked with isset=true.  The length of this
 * array is returned in *numrelopts.  Options not set are also present in the
 * array; this is so that the caller can easily locate the default values.
 *
 * If there are no options of the given kind, numrelopts is set to 0 and NULL
 * is returned (unless options are illegally supplied despite none being
 * defined, in which case an error occurs).
 *
 * Note: values of type int, bool and real are allocated as part of the
 * returned array.  Values of type string are allocated separately and must
 * be freed by the caller.
 */
static relopt_value *
parseRelOptions(Datum options, bool validate, relopt_kind kind,
                                int *numrelopts)
{
        relopt_value *reloptions = NULL;
        int                     numoptions = 0;
        int                     i;
        int                     j;

        if (need_initialization)
                initialize_reloptions();

        /* Build a list of expected options, based on kind */

        for (i = 0; relOpts[i]; i++)
                if (relOpts[i]->kinds & kind)
                        numoptions++;

        if (numoptions > 0)
        {
                reloptions = palloc(numoptions * sizeof(relopt_value));

                for (i = 0, j = 0; relOpts[i]; i++)
                {
                        if (relOpts[i]->kinds & kind)
                        {
                                reloptions[j].gen = relOpts[i];
                                reloptions[j].isset = false;
                                j++;
                        }
                }
        }

        /* Done if no options */
        if (PointerIsValid(DatumGetPointer(options)))
                parseRelOptionsInternal(options, validate, reloptions, numoptions);

        *numrelopts = numoptions;
        return reloptions;
}

/* Parse local unregistered options. */
static relopt_value *
parseLocalRelOptions(local_relopts *relopts, Datum options, bool validate)
{
        int                     nopts = list_length(relopts->options);
        relopt_value *values = palloc(sizeof(*values) * nopts);
        ListCell   *lc;
        int                     i = 0;

        foreach(lc, relopts->options)
        {
                local_relopt *opt = lfirst(lc);

                values[i].gen = opt->option;
                values[i].isset = false;

                i++;
        }

        if (options != (Datum) 0)
                parseRelOptionsInternal(options, validate, values, nopts);

        return values;
}

/*
 * Subroutine for parseRelOptions, to parse and validate a single option's
 * value
 */
static void
parse_one_reloption(relopt_value *option, char *text_str, int text_len,
                                        bool validate)
{
        char       *value;
        int                     value_len;
        bool            parsed;
        bool            nofree = false;

        if (option->isset && validate)
                ereport(ERROR,
                                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                 errmsg("parameter \"%s\" specified more than once",
                                                option->gen->name)));

        value_len = text_len - option->gen->namelen - 1;
        value = (char *) palloc(value_len + 1);
        memcpy(value, text_str + option->gen->namelen + 1, value_len);
        value[value_len] = '\0';

        switch (option->gen->type)
        {
                case RELOPT_TYPE_BOOL:
                        {
                                parsed = parse_bool(value, &option->values.bool_val);
                                if (validate && !parsed)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("invalid value for boolean option \"%s\": %s",
                                                                        option->gen->name, value)));
                        }
                        break;
                case RELOPT_TYPE_INT:
                        {
                                relopt_int *optint = (relopt_int *) option->gen;

                                parsed = parse_int(value, &option->values.int_val, 0, NULL);
                                if (validate && !parsed)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("invalid value for integer option \"%s\": %s",
                                                                        option->gen->name, value)));
                                if (validate && (option->values.int_val < optint->min ||
                                                                 option->values.int_val > optint->max))
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("value %s out of bounds for option \"%s\"",
                                                                        value, option->gen->name),
                                                         errdetail("Valid values are between \"%d\" and \"%d\".",
                                                                           optint->min, optint->max)));
                        }
                        break;
                case RELOPT_TYPE_REAL:
                        {
                                relopt_real *optreal = (relopt_real *) option->gen;

                                parsed = parse_real(value, &option->values.real_val, 0, NULL);
                                if (validate && !parsed)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("invalid value for floating point option \"%s\": %s",
                                                                        option->gen->name, value)));
                                if (validate && (option->values.real_val < optreal->min ||
                                                                 option->values.real_val > optreal->max))
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("value %s out of bounds for option \"%s\"",
                                                                        value, option->gen->name),
                                                         errdetail("Valid values are between \"%f\" and \"%f\".",
                                                                           optreal->min, optreal->max)));
                        }
                        break;
                case RELOPT_TYPE_ENUM:
                        {
                                relopt_enum *optenum = (relopt_enum *) option->gen;
                                relopt_enum_elt_def *elt;

                                parsed = false;
                                for (elt = optenum->members; elt->string_val; elt++)
                                {
                                        if (pg_strcasecmp(value, elt->string_val) == 0)
                                        {
                                                option->values.enum_val = elt->symbol_val;
                                                parsed = true;
                                                break;
                                        }
                                }
                                if (validate && !parsed)
                                        ereport(ERROR,
                                                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                         errmsg("invalid value for enum option \"%s\": %s",
                                                                        option->gen->name, value),
                                                         optenum->detailmsg ?
                                                         errdetail_internal("%s", _(optenum->detailmsg)) : 0));

                                /*
                                 * If value is not among the allowed string values, but we are
                                 * not asked to validate, just use the default numeric value.
                                 */
                                if (!parsed)
                                        option->values.enum_val = optenum->default_val;
                        }
                        break;
                case RELOPT_TYPE_STRING:
                        {
                                relopt_string *optstring = (relopt_string *) option->gen;

                                option->values.string_val = value;
                                nofree = true;
                                if (validate && optstring->validate_cb)
                                        (optstring->validate_cb) (value);
                                parsed = true;
                        }
                        break;
                default:
                        elog(ERROR, "unsupported reloption type %d", option->gen->type);
                        parsed = true;          /* quiet compiler */
                        break;
        }

        if (parsed)
                option->isset = true;
        if (!nofree)
                pfree(value);
}

/*
 * Given the result from parseRelOptions, allocate a struct that's of the
 * specified base size plus any extra space that's needed for string variables.
 *
 * "base" should be sizeof(struct) of the reloptions struct (StdRdOptions or
 * equivalent).
 */
static void *
allocateReloptStruct(Size base, relopt_value *options, int numoptions)
{
        Size            size = base;
        int                     i;

        for (i = 0; i < numoptions; i++)
        {
                relopt_value *optval = &options[i];

                if (optval->gen->type == RELOPT_TYPE_STRING)
                {
                        relopt_string *optstr = (relopt_string *) optval->gen;

                        if (optstr->fill_cb)
                        {
                                const char *val = optval->isset ? optval->values.string_val :
                                optstr->default_isnull ? NULL : optstr->default_val;

                                size += optstr->fill_cb(val, NULL);
                        }
                        else
                                size += GET_STRING_RELOPTION_LEN(*optval) + 1;
                }
        }

        return palloc0(size);
}

/*
 * Given the result of parseRelOptions and a parsing table, fill in the
 * struct (previously allocated with allocateReloptStruct) with the parsed
 * values.
 *
 * rdopts is the pointer to the allocated struct to be filled.
 * basesize is the sizeof(struct) that was passed to allocateReloptStruct.
 * options, of length numoptions, is parseRelOptions' output.
 * elems, of length numelems, is the table describing the allowed options.
 * When validate is true, it is expected that all options appear in elems.
 */
static void
fillRelOptions(void *rdopts, Size basesize,
                           relopt_value *options, int numoptions,
                           bool validate,
                           const relopt_parse_elt *elems, int numelems)
{
        int                     i;
        int                     offset = basesize;

        for (i = 0; i < numoptions; i++)
        {
                int                     j;
                bool            found = false;

                for (j = 0; j < numelems; j++)
                {
                        if (strcmp(options[i].gen->name, elems[j].optname) == 0)
                        {
                                relopt_string *optstring;
                                char       *itempos = ((char *) rdopts) + elems[j].offset;
                                char       *string_val;

                                switch (options[i].gen->type)
                                {
                                        case RELOPT_TYPE_BOOL:
                                                *(bool *) itempos = options[i].isset ?
                                                        options[i].values.bool_val :
                                                        ((relopt_bool *) options[i].gen)->default_val;
                                                break;
                                        case RELOPT_TYPE_INT:
                                                *(int *) itempos = options[i].isset ?
                                                        options[i].values.int_val :
                                                        ((relopt_int *) options[i].gen)->default_val;
                                                break;
                                        case RELOPT_TYPE_REAL:
                                                *(double *) itempos = options[i].isset ?
                                                        options[i].values.real_val :
                                                        ((relopt_real *) options[i].gen)->default_val;
                                                break;
                                        case RELOPT_TYPE_ENUM:
                                                *(int *) itempos = options[i].isset ?
                                                        options[i].values.enum_val :
                                                        ((relopt_enum *) options[i].gen)->default_val;
                                                break;
                                        case RELOPT_TYPE_STRING:
                                                optstring = (relopt_string *) options[i].gen;
                                                if (options[i].isset)
                                                        string_val = options[i].values.string_val;
                                                else if (!optstring->default_isnull)
                                                        string_val = optstring->default_val;
                                                else
                                                        string_val = NULL;

                                                if (optstring->fill_cb)
                                                {
                                                        Size            size =
                                                        optstring->fill_cb(string_val,
                                                                                           (char *) rdopts + offset);

                                                        if (size)
                                                        {
                                                                *(int *) itempos = offset;
                                                                offset += size;
                                                        }
                                                        else
                                                                *(int *) itempos = 0;
                                                }
                                                else if (string_val == NULL)
                                                        *(int *) itempos = 0;
                                                else
                                                {
                                                        strcpy((char *) rdopts + offset, string_val);
                                                        *(int *) itempos = offset;
                                                        offset += strlen(string_val) + 1;
                                                }
                                                break;
                                        default:
                                                elog(ERROR, "unsupported reloption type %d",
                                                         options[i].gen->type);
                                                break;
                                }
                                found = true;
                                break;
                        }
                }
                if (validate && !found)
                        elog(ERROR, "reloption \"%s\" not found in parse table",
                                 options[i].gen->name);
        }
        SET_VARSIZE(rdopts, offset);
}


/*
 * Option parser for anything that uses StdRdOptions.
 */
bytea *
default_reloptions(Datum reloptions, bool validate, relopt_kind kind)
{
        static const relopt_parse_elt tab[] = {
                {"fillfactor", RELOPT_TYPE_INT, offsetof(StdRdOptions, fillfactor)},
                {"autovacuum_enabled", RELOPT_TYPE_BOOL,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, enabled)},
                {"autovacuum_vacuum_threshold", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_threshold)},
                {"autovacuum_vacuum_insert_threshold", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_ins_threshold)},
                {"autovacuum_analyze_threshold", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, analyze_threshold)},
                {"autovacuum_vacuum_cost_limit", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_cost_limit)},
                {"autovacuum_freeze_min_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, freeze_min_age)},
                {"autovacuum_freeze_max_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, freeze_max_age)},
                {"autovacuum_freeze_table_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, freeze_table_age)},
                {"autovacuum_multixact_freeze_min_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, multixact_freeze_min_age)},
                {"autovacuum_multixact_freeze_max_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, multixact_freeze_max_age)},
                {"autovacuum_multixact_freeze_table_age", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, multixact_freeze_table_age)},
                {"autovacuum_freeze_strategy_threshold", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, freeze_strategy_threshold)},
                {"log_autovacuum_min_duration", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, log_min_duration)},
                {"toast_tuple_target", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, toast_tuple_target)},
                {"autovacuum_vacuum_cost_delay", RELOPT_TYPE_REAL,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_cost_delay)},
                {"autovacuum_vacuum_scale_factor", RELOPT_TYPE_REAL,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_scale_factor)},
                {"autovacuum_vacuum_insert_scale_factor", RELOPT_TYPE_REAL,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, vacuum_ins_scale_factor)},
                {"autovacuum_analyze_scale_factor", RELOPT_TYPE_REAL,
                offsetof(StdRdOptions, autovacuum) + offsetof(AutoVacOpts, analyze_scale_factor)},
                {"user_catalog_table", RELOPT_TYPE_BOOL,
                offsetof(StdRdOptions, user_catalog_table)},
                {"parallel_workers", RELOPT_TYPE_INT,
                offsetof(StdRdOptions, parallel_workers)},
                {"vacuum_index_cleanup", RELOPT_TYPE_ENUM,
                offsetof(StdRdOptions, vacuum_index_cleanup)},
                {"vacuum_truncate", RELOPT_TYPE_BOOL,
                offsetof(StdRdOptions, vacuum_truncate)}
        };

        return (bytea *) build_reloptions(reloptions, validate, kind,
                                                                          sizeof(StdRdOptions),
                                                                          tab, lengthof(tab));
}

/*
 * build_reloptions
 *
 * Parses "reloptions" provided by the caller, returning them in a
 * structure containing the parsed options.  The parsing is done with
 * the help of a parsing table describing the allowed options, defined
 * by "relopt_elems" of length "num_relopt_elems".
 *
 * "validate" must be true if reloptions value is freshly built by
 * transformRelOptions(), as opposed to being read from the catalog, in which
 * case the values contained in it must already be valid.
 *
 * NULL is returned if the passed-in options did not match any of the options
 * in the parsing table, unless validate is true in which case an error would
 * be reported.
 */
void *
build_reloptions(Datum reloptions, bool validate,
                                 relopt_kind kind,
                                 Size relopt_struct_size,
                                 const relopt_parse_elt *relopt_elems,
                                 int num_relopt_elems)
{
        int                     numoptions;
        relopt_value *options;
        void       *rdopts;

        /* parse options specific to given relation option kind */
        options = parseRelOptions(reloptions, validate, kind, &numoptions);
        Assert(numoptions <= num_relopt_elems);

        /* if none set, we're done */
        if (numoptions == 0)
        {
                Assert(options == NULL);
                return NULL;
        }

        /* allocate and fill the structure */
        rdopts = allocateReloptStruct(relopt_struct_size, options, numoptions);
        fillRelOptions(rdopts, relopt_struct_size, options, numoptions,
                                   validate, relopt_elems, num_relopt_elems);

        pfree(options);

        return rdopts;
}

/*
 * Parse local options, allocate a bytea struct that's of the specified
 * 'base_size' plus any extra space that's needed for string variables,
 * fill its option's fields located at the given offsets and return it.
 */
void *
build_local_reloptions(local_relopts *relopts, Datum options, bool validate)
{
        int                     noptions = list_length(relopts->options);
        relopt_parse_elt *elems = palloc(sizeof(*elems) * noptions);
        relopt_value *vals;
        void       *opts;
        int                     i = 0;
        ListCell   *lc;

        foreach(lc, relopts->options)
        {
                local_relopt *opt = lfirst(lc);

                elems[i].optname = opt->option->name;
                elems[i].opttype = opt->option->type;
                elems[i].offset = opt->offset;

                i++;
        }

        vals = parseLocalRelOptions(relopts, options, validate);
        opts = allocateReloptStruct(relopts->relopt_struct_size, vals, noptions);
        fillRelOptions(opts, relopts->relopt_struct_size, vals, noptions, validate,
                                   elems, noptions);

        foreach(lc, relopts->validators)
                ((relopts_validator) lfirst(lc)) (opts, vals, noptions);

        if (elems)
                pfree(elems);

        return opts;
}

/*
 * Option parser for partitioned tables
 */
bytea *
partitioned_table_reloptions(Datum reloptions, bool validate)
{
        if (validate && reloptions)
                ereport(ERROR,
                                errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                errmsg("cannot specify storage parameters for a partitioned table"),
                                errhint("Specify storage parameters for its leaf partitions, instead."));
        return NULL;
}

/*
 * Option parser for views
 */
bytea *
view_reloptions(Datum reloptions, bool validate)
{
        static const relopt_parse_elt tab[] = {
                {"security_barrier", RELOPT_TYPE_BOOL,
                offsetof(ViewOptions, security_barrier)},
                {"security_invoker", RELOPT_TYPE_BOOL,
                offsetof(ViewOptions, security_invoker)},
                {"check_option", RELOPT_TYPE_ENUM,
                offsetof(ViewOptions, check_option)}
        };

        return (bytea *) build_reloptions(reloptions, validate,
                                                                          RELOPT_KIND_VIEW,
                                                                          sizeof(ViewOptions),
                                                                          tab, lengthof(tab));
}

/*
 * Parse options for heaps, views and toast tables.
 */
bytea *
heap_reloptions(char relkind, Datum reloptions, bool validate)
{
        StdRdOptions *rdopts;

        switch (relkind)
        {
                case RELKIND_TOASTVALUE:
                        rdopts = (StdRdOptions *)
                                default_reloptions(reloptions, validate, RELOPT_KIND_TOAST);
                        if (rdopts != NULL)
                        {
                                /* adjust default-only parameters for TOAST relations */
                                rdopts->fillfactor = 100;
                                rdopts->autovacuum.analyze_threshold = -1;
                                rdopts->autovacuum.analyze_scale_factor = -1;
                        }
                        return (bytea *) rdopts;
                case RELKIND_RELATION:
                case RELKIND_MATVIEW:
                        return default_reloptions(reloptions, validate, RELOPT_KIND_HEAP);
                default:
                        /* other relkinds are not supported */
                        return NULL;
        }
}


/*
 * Parse options for indexes.
 *
 *      amoptions       index AM's option parser function
 *      reloptions      options as text[] datum
 *      validate        error flag
 */
bytea *
index_reloptions(amoptions_function amoptions, Datum reloptions, bool validate)
{
        Assert(amoptions != NULL);

        /* Assume function is strict */
        if (!PointerIsValid(DatumGetPointer(reloptions)))
                return NULL;

        return amoptions(reloptions, validate);
}

/*
 * Option parser for attribute reloptions
 */
bytea *
attribute_reloptions(Datum reloptions, bool validate)
{
        static const relopt_parse_elt tab[] = {
                {"n_distinct", RELOPT_TYPE_REAL, offsetof(AttributeOpts, n_distinct)},
                {"n_distinct_inherited", RELOPT_TYPE_REAL, offsetof(AttributeOpts, n_distinct_inherited)}
        };

        return (bytea *) build_reloptions(reloptions, validate,
                                                                          RELOPT_KIND_ATTRIBUTE,
                                                                          sizeof(AttributeOpts),
                                                                          tab, lengthof(tab));
}

/*
 * Option parser for tablespace reloptions
 */
bytea *
tablespace_reloptions(Datum reloptions, bool validate)
{
        static const relopt_parse_elt tab[] = {
                {"random_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, random_page_cost)},
                {"seq_page_cost", RELOPT_TYPE_REAL, offsetof(TableSpaceOpts, seq_page_cost)},
                {"effective_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, effective_io_concurrency)},
                {"maintenance_io_concurrency", RELOPT_TYPE_INT, offsetof(TableSpaceOpts, maintenance_io_concurrency)}
        };

        return (bytea *) build_reloptions(reloptions, validate,
                                                                          RELOPT_KIND_TABLESPACE,
                                                                          sizeof(TableSpaceOpts),
                                                                          tab, lengthof(tab));
}

/*
 * Determine the required LOCKMODE from an option list.
 *
 * Called from AlterTableGetLockLevel(), see that function
 * for a longer explanation of how this works.
 */
LOCKMODE
AlterTableGetRelOptionsLockLevel(List *defList)
{
        LOCKMODE        lockmode = NoLock;
        ListCell   *cell;

        if (defList == NIL)
                return AccessExclusiveLock;

        if (need_initialization)
                initialize_reloptions();

        foreach(cell, defList)
        {
                DefElem    *def = (DefElem *) lfirst(cell);
                int                     i;

                for (i = 0; relOpts[i]; i++)
                {
                        if (strncmp(relOpts[i]->name,
                                                def->defname,
                                                relOpts[i]->namelen + 1) == 0)
                        {
                                if (lockmode < relOpts[i]->lockmode)
                                        lockmode = relOpts[i]->lockmode;
                        }
                }
        }

        return lockmode;
}