src/backend/statistics/relation_stats.c

   1 /*-------------------------------------------------------------------------
   2  * relation_stats.c
   3  *
   4  *        PostgreSQL relation statistics manipulation
   5  *
   6  * Code supporting the direct import of relation statistics, similar to
   7  * what is done by the ANALYZE command.
   8  *
   9  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
  10  * Portions Copyright (c) 1994, Regents of the University of California
  11  *
  12  * IDENTIFICATION
  13  *       src/backend/statistics/relation_stats.c
  14  *
  15  *-------------------------------------------------------------------------
  16  */
  17
  18 #include "postgres.h"
  19
  20 #include "access/heapam.h"
  21 #include "catalog/indexing.h"
  22 #include "statistics/stat_utils.h"
  23 #include "utils/fmgrprotos.h"
  24 #include "utils/syscache.h"
  25
  26 #define DEFAULT_RELPAGES Int32GetDatum(0)
  27 #define DEFAULT_RELTUPLES Float4GetDatum(-1.0)
  28 #define DEFAULT_RELALLVISIBLE Int32GetDatum(0)
  29
  30 /*
  31  * Positional argument numbers, names, and types for
  32  * relation_statistics_update().
  33  */
  34
  35 enum relation_stats_argnum
  36 {
  37         RELATION_ARG = 0,
  38         RELPAGES_ARG,
  39         RELTUPLES_ARG,
  40         RELALLVISIBLE_ARG,
  41         NUM_RELATION_STATS_ARGS
  42 };
  43
  44 static struct StatsArgInfo relarginfo[] =
  45 {
  46         [RELATION_ARG] = {"relation", REGCLASSOID},
  47         [RELPAGES_ARG] = {"relpages", INT4OID},
  48         [RELTUPLES_ARG] = {"reltuples", FLOAT4OID},
  49         [RELALLVISIBLE_ARG] = {"relallvisible", INT4OID},
  50         [NUM_RELATION_STATS_ARGS] = {0}
  51 };
  52
  53 static bool relation_statistics_update(FunctionCallInfo fcinfo, int elevel);
  54
  55 /*
  56  * Internal function for modifying statistics for a relation.
  57  */
  58 static bool
  59 relation_statistics_update(FunctionCallInfo fcinfo, int elevel)
  60 {
  61         Oid                     reloid;
  62         Relation        crel;
  63         HeapTuple       ctup;
  64         Form_pg_class pgcform;
  65         int                     replaces[3] = {0};
  66         Datum           values[3] = {0};
  67         bool            nulls[3] = {0};
  68         int                     ncols = 0;
  69         TupleDesc       tupdesc;
  70         HeapTuple       newtup;
  71
  72
  73         stats_check_required_arg(fcinfo, relarginfo, RELATION_ARG);
  74         reloid = PG_GETARG_OID(RELATION_ARG);
  75
  76         stats_lock_check_privileges(reloid);
  77
  78         /*
  79          * Take RowExclusiveLock on pg_class, consistent with
  80          * vac_update_relstats().
  81          */
  82         crel = table_open(RelationRelationId, RowExclusiveLock);
  83
  84         tupdesc = RelationGetDescr(crel);
  85         ctup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(reloid));
  86         if (!HeapTupleIsValid(ctup))
  87         {
  88                 ereport(elevel,
  89                                 (errcode(ERRCODE_OBJECT_IN_USE),
  90                                  errmsg("pg_class entry for relid %u not found", reloid)));
  91                 table_close(crel, RowExclusiveLock);
  92                 return false;
  93         }
  94
  95         pgcform = (Form_pg_class) GETSTRUCT(ctup);
  96
  97         /* relpages */
  98         if (!PG_ARGISNULL(RELPAGES_ARG))
  99         {
 100                 int32           relpages = PG_GETARG_INT32(RELPAGES_ARG);
 101
 102                 if (relpages < 0)
 103                 {
 104                         ereport(elevel,
 105                                         (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 106                                          errmsg("relpages cannot be < 0")));
 107                         table_close(crel, RowExclusiveLock);
 108                         return false;
 109                 }
 110
 111                 if (relpages != pgcform->relpages)
 112                 {
 113                         replaces[ncols] = Anum_pg_class_relpages;
 114                         values[ncols] = Int32GetDatum(relpages);
 115                         ncols++;
 116                 }
 117         }
 118
 119         if (!PG_ARGISNULL(RELTUPLES_ARG))
 120         {
 121                 float           reltuples = PG_GETARG_FLOAT4(RELTUPLES_ARG);
 122
 123                 if (reltuples < -1.0)
 124                 {
 125                         ereport(elevel,
 126                                         (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 127                                          errmsg("reltuples cannot be < -1.0")));
 128                         table_close(crel, RowExclusiveLock);
 129                         return false;
 130                 }
 131
 132                 if (reltuples != pgcform->reltuples)
 133                 {
 134                         replaces[ncols] = Anum_pg_class_reltuples;
 135                         values[ncols] = Float4GetDatum(reltuples);
 136                         ncols++;
 137                 }
 138         }
 139
 140         if (!PG_ARGISNULL(RELALLVISIBLE_ARG))
 141         {
 142                 int32           relallvisible = PG_GETARG_INT32(RELALLVISIBLE_ARG);
 143
 144                 if (relallvisible < 0)
 145                 {
 146                         ereport(elevel,
 147                                         (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 148                                          errmsg("relallvisible cannot be < 0")));
 149                         table_close(crel, RowExclusiveLock);
 150                         return false;
 151                 }
 152
 153                 if (relallvisible != pgcform->relallvisible)
 154                 {
 155                         replaces[ncols] = Anum_pg_class_relallvisible;
 156                         values[ncols] = Int32GetDatum(relallvisible);
 157                         ncols++;
 158                 }
 159         }
 160
 161         /* only update pg_class if there is a meaningful change */
 162         if (ncols == 0)
 163         {
 164                 table_close(crel, RowExclusiveLock);
 165                 return false;
 166         }
 167
 168         newtup = heap_modify_tuple_by_cols(ctup, tupdesc, ncols, replaces, values,
 169                                                                            nulls);
 170
 171         CatalogTupleUpdate(crel, &newtup->t_self, newtup);
 172         heap_freetuple(newtup);
 173
 174         /* release the lock, consistent with vac_update_relstats() */
 175         table_close(crel, RowExclusiveLock);
 176
 177         return true;
 178 }
 179
 180 /*
 181  * Set statistics for a given pg_class entry.
 182  */
 183 Datum
 184 pg_set_relation_stats(PG_FUNCTION_ARGS)
 185 {
 186         PG_RETURN_BOOL(relation_statistics_update(fcinfo, ERROR));
 187 }
 188
 189 /*
 190  * Clear statistics for a given pg_class entry; that is, set back to initial
 191  * stats for a newly-created table.
 192  */
 193 Datum
 194 pg_clear_relation_stats(PG_FUNCTION_ARGS)
 195 {
 196         LOCAL_FCINFO(newfcinfo, 4);
 197
 198         InitFunctionCallInfoData(*newfcinfo, NULL, 4, InvalidOid, NULL, NULL);
 199
 200         newfcinfo->args[0].value = PG_GETARG_OID(0);
 201         newfcinfo->args[0].isnull = PG_ARGISNULL(0);
 202         newfcinfo->args[1].value = DEFAULT_RELPAGES;
 203         newfcinfo->args[1].isnull = false;
 204         newfcinfo->args[2].value = DEFAULT_RELTUPLES;
 205         newfcinfo->args[2].isnull = false;
 206         newfcinfo->args[3].value = DEFAULT_RELALLVISIBLE;
 207         newfcinfo->args[3].isnull = false;
 208
 209         PG_RETURN_BOOL(relation_statistics_update(newfcinfo, ERROR));
 210 }