Force a checkpoint in CREATE DATABASE before starting to copy the files,

[PostgreSQL.git] / src / bin / pg_dump / pg_dump_sort.c

/*-------------------------------------------------------------------------
 *
 * pg_dump_sort.c
 *        Sort the items of a dump into a safe order for dumping
 *
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *        $PostgreSQL$
 *
 *-------------------------------------------------------------------------
 */
#include "pg_backup_archiver.h"


static const char *modulename = gettext_noop("sorter");

/*
 * Sort priority for object types when dumping a pre-7.3 database.
 * Objects are sorted by priority levels, and within an equal priority level
 * by OID.      (This is a relatively crude hack to provide semi-reasonable
 * behavior for old databases without full dependency info.)
 */
static const int oldObjectTypePriority[] =
{
        1,                                                      /* DO_NAMESPACE */
        2,                                                      /* DO_TYPE */
        2,                                                      /* DO_SHELL_TYPE */
        2,                                                      /* DO_FUNC */
        3,                                                      /* DO_AGG */
        3,                                                      /* DO_OPERATOR */
        4,                                                      /* DO_OPCLASS */
        4,                                                      /* DO_OPFAMILY */
        5,                                                      /* DO_CONVERSION */
        6,                                                      /* DO_TABLE */
        8,                                                      /* DO_ATTRDEF */
        13,                                                     /* DO_INDEX */
        14,                                                     /* DO_RULE */
        15,                                                     /* DO_TRIGGER */
        12,                                                     /* DO_CONSTRAINT */
        16,                                                     /* DO_FK_CONSTRAINT */
        2,                                                      /* DO_PROCLANG */
        2,                                                      /* DO_CAST */
        9,                                                      /* DO_TABLE_DATA */
        7,                                                      /* DO_TABLE_TYPE */
        3,                                                      /* DO_TSPARSER */
        4,                                                      /* DO_TSDICT */
        3,                                                      /* DO_TSTEMPLATE */
        5,                                                      /* DO_TSCONFIG */
        10,                                                     /* DO_BLOBS */
        11                                                      /* DO_BLOB_COMMENTS */
};

/*
 * Sort priority for object types when dumping newer databases.
 * Objects are sorted by type, and within a type by name.
 */
static const int newObjectTypePriority[] =
{
        1,                                                      /* DO_NAMESPACE */
        3,                                                      /* DO_TYPE */
        3,                                                      /* DO_SHELL_TYPE */
        4,                                                      /* DO_FUNC */
        5,                                                      /* DO_AGG */
        6,                                                      /* DO_OPERATOR */
        7,                                                      /* DO_OPCLASS */
        7,                                                      /* DO_OPFAMILY */
        9,                                                      /* DO_CONVERSION */
        10,                                                     /* DO_TABLE */
        12,                                                     /* DO_ATTRDEF */
        17,                                                     /* DO_INDEX */
        18,                                                     /* DO_RULE */
        19,                                                     /* DO_TRIGGER */
        16,                                                     /* DO_CONSTRAINT */
        20,                                                     /* DO_FK_CONSTRAINT */
        2,                                                      /* DO_PROCLANG */
        8,                                                      /* DO_CAST */
        13,                                                     /* DO_TABLE_DATA */
        11,                                                     /* DO_TABLE_TYPE */
        5,                                                      /* DO_TSPARSER */
        6,                                                      /* DO_TSDICT */
        5,                                                      /* DO_TSTEMPLATE */
        7,                                                      /* DO_TSCONFIG */
        14,                                                     /* DO_BLOBS */
        15                                                      /* DO_BLOB_COMMENTS */
};


static int      DOTypeNameCompare(const void *p1, const void *p2);
static int      DOTypeOidCompare(const void *p1, const void *p2);
static bool TopoSort(DumpableObject **objs,
                 int numObjs,
                 DumpableObject **ordering,
                 int *nOrdering);
static void addHeapElement(int val, int *heap, int heapLength);
static int      removeHeapElement(int *heap, int heapLength);
static void findDependencyLoops(DumpableObject **objs, int nObjs, int totObjs);
static bool findLoop(DumpableObject *obj,
                 DumpId startPoint,
                 DumpableObject **workspace,
                 int depth,
                 int *newDepth);
static void repairDependencyLoop(DumpableObject **loop,
                                         int nLoop);
static void describeDumpableObject(DumpableObject *obj,
                                           char *buf, int bufsize);


/*
 * Sort the given objects into a type/name-based ordering
 *
 * Normally this is just the starting point for the dependency-based
 * ordering.
 */
void
sortDumpableObjectsByTypeName(DumpableObject **objs, int numObjs)
{
        if (numObjs > 1)
                qsort((void *) objs, numObjs, sizeof(DumpableObject *),
                          DOTypeNameCompare);
}

static int
DOTypeNameCompare(const void *p1, const void *p2)
{
        DumpableObject *obj1 = *(DumpableObject **) p1;
        DumpableObject *obj2 = *(DumpableObject **) p2;
        int                     cmpval;

        /* Sort by type */
        cmpval = newObjectTypePriority[obj1->objType] -
                newObjectTypePriority[obj2->objType];

        if (cmpval != 0)
                return cmpval;

        /*
         * Sort by namespace.  Note that all objects of the same type should
         * either have or not have a namespace link, so we needn't be fancy about
         * cases where one link is null and the other not.
         */
        if (obj1->namespace && obj2->namespace)
        {
                cmpval = strcmp(obj1->namespace->dobj.name,
                                                obj2->namespace->dobj.name);
                if (cmpval != 0)
                        return cmpval;
        }

        /* Sort by name */
        cmpval = strcmp(obj1->name, obj2->name);
        if (cmpval != 0)
                return cmpval;

        /* Probably shouldn't get here, but if we do, sort by OID */
        return oidcmp(obj1->catId.oid, obj2->catId.oid);
}


/*
 * Sort the given objects into a type/OID-based ordering
 *
 * This is used with pre-7.3 source databases as a crude substitute for the
 * lack of dependency information.
 */
void
sortDumpableObjectsByTypeOid(DumpableObject **objs, int numObjs)
{
        if (numObjs > 1)
                qsort((void *) objs, numObjs, sizeof(DumpableObject *),
                          DOTypeOidCompare);
}

static int
DOTypeOidCompare(const void *p1, const void *p2)
{
        DumpableObject *obj1 = *(DumpableObject **) p1;
        DumpableObject *obj2 = *(DumpableObject **) p2;
        int                     cmpval;

        cmpval = oldObjectTypePriority[obj1->objType] -
                oldObjectTypePriority[obj2->objType];

        if (cmpval != 0)
                return cmpval;

        return oidcmp(obj1->catId.oid, obj2->catId.oid);
}


/*
 * Sort the given objects into a safe dump order using dependency
 * information (to the extent we have it available).
 */
void
sortDumpableObjects(DumpableObject **objs, int numObjs)
{
        DumpableObject **ordering;
        int                     nOrdering;

        if (numObjs <= 0)
                return;

        ordering = (DumpableObject **) malloc(numObjs * sizeof(DumpableObject *));
        if (ordering == NULL)
                exit_horribly(NULL, modulename, "out of memory\n");

        while (!TopoSort(objs, numObjs, ordering, &nOrdering))
                findDependencyLoops(ordering, nOrdering, numObjs);

        memcpy(objs, ordering, numObjs * sizeof(DumpableObject *));

        free(ordering);
}

/*
 * TopoSort -- topological sort of a dump list
 *
 * Generate a re-ordering of the dump list that satisfies all the dependency
 * constraints shown in the dump list.  (Each such constraint is a fact of a
 * partial ordering.)  Minimize rearrangement of the list not needed to
 * achieve the partial ordering.
 *
 * The input is the list of numObjs objects in objs[].  This list is not
 * modified.
 *
 * Returns TRUE if able to build an ordering that satisfies all the
 * constraints, FALSE if not (there are contradictory constraints).
 *
 * On success (TRUE result), ordering[] is filled with a sorted array of
 * DumpableObject pointers, of length equal to the input list length.
 *
 * On failure (FALSE result), ordering[] is filled with an unsorted array of
 * DumpableObject pointers of length *nOrdering, listing the objects that
 * prevented the sort from being completed.  In general, these objects either
 * participate directly in a dependency cycle, or are depended on by objects
 * that are in a cycle.  (The latter objects are not actually problematic,
 * but it takes further analysis to identify which are which.)
 *
 * The caller is responsible for allocating sufficient space at *ordering.
 */
static bool
TopoSort(DumpableObject **objs,
                 int numObjs,
                 DumpableObject **ordering,             /* output argument */
                 int *nOrdering)                /* output argument */
{
        DumpId          maxDumpId = getMaxDumpId();
        int                *pendingHeap;
        int                *beforeConstraints;
        int                *idMap;
        DumpableObject *obj;
        int                     heapLength;
        int                     i,
                                j,
                                k;

        /*
         * This is basically the same algorithm shown for topological sorting in
         * Knuth's Volume 1.  However, we would like to minimize unnecessary
         * rearrangement of the input ordering; that is, when we have a choice of
         * which item to output next, we always want to take the one highest in
         * the original list.  Therefore, instead of maintaining an unordered
         * linked list of items-ready-to-output as Knuth does, we maintain a heap
         * of their item numbers, which we can use as a priority queue.  This
         * turns the algorithm from O(N) to O(N log N) because each insertion or
         * removal of a heap item takes O(log N) time.  However, that's still
         * plenty fast enough for this application.
         */

        *nOrdering = numObjs;           /* for success return */

        /* Eliminate the null case */
        if (numObjs <= 0)
                return true;

        /* Create workspace for the above-described heap */
        pendingHeap = (int *) malloc(numObjs * sizeof(int));
        if (pendingHeap == NULL)
                exit_horribly(NULL, modulename, "out of memory\n");

        /*
         * Scan the constraints, and for each item in the input, generate a count
         * of the number of constraints that say it must be before something else.
         * The count for the item with dumpId j is stored in beforeConstraints[j].
         * We also make a map showing the input-order index of the item with
         * dumpId j.
         */
        beforeConstraints = (int *) malloc((maxDumpId + 1) * sizeof(int));
        if (beforeConstraints == NULL)
                exit_horribly(NULL, modulename, "out of memory\n");
        memset(beforeConstraints, 0, (maxDumpId + 1) * sizeof(int));
        idMap = (int *) malloc((maxDumpId + 1) * sizeof(int));
        if (idMap == NULL)
                exit_horribly(NULL, modulename, "out of memory\n");
        for (i = 0; i < numObjs; i++)
        {
                obj = objs[i];
                j = obj->dumpId;
                if (j <= 0 || j > maxDumpId)
                        exit_horribly(NULL, modulename, "invalid dumpId %d\n", j);
                idMap[j] = i;
                for (j = 0; j < obj->nDeps; j++)
                {
                        k = obj->dependencies[j];
                        if (k <= 0 || k > maxDumpId)
                                exit_horribly(NULL, modulename, "invalid dependency %d\n", k);
                        beforeConstraints[k]++;
                }
        }

        /*
         * Now initialize the heap of items-ready-to-output by filling it with the
         * indexes of items that already have beforeConstraints[id] == 0.
         *
         * The essential property of a heap is heap[(j-1)/2] >= heap[j] for each j
         * in the range 1..heapLength-1 (note we are using 0-based subscripts
         * here, while the discussion in Knuth assumes 1-based subscripts). So, if
         * we simply enter the indexes into pendingHeap[] in decreasing order, we
         * a-fortiori have the heap invariant satisfied at completion of this
         * loop, and don't need to do any sift-up comparisons.
         */
        heapLength = 0;
        for (i = numObjs; --i >= 0;)
        {
                if (beforeConstraints[objs[i]->dumpId] == 0)
                        pendingHeap[heapLength++] = i;
        }

        /*--------------------
         * Now emit objects, working backwards in the output list.      At each step,
         * we use the priority heap to select the last item that has no remaining
         * before-constraints.  We remove that item from the heap, output it to
         * ordering[], and decrease the beforeConstraints count of each of the
         * items it was constrained against.  Whenever an item's beforeConstraints
         * count is thereby decreased to zero, we insert it into the priority heap
         * to show that it is a candidate to output.  We are done when the heap
         * becomes empty; if we have output every element then we succeeded,
         * otherwise we failed.
         * i = number of ordering[] entries left to output
         * j = objs[] index of item we are outputting
         * k = temp for scanning constraint list for item j
         *--------------------
         */
        i = numObjs;
        while (heapLength > 0)
        {
                /* Select object to output by removing largest heap member */
                j = removeHeapElement(pendingHeap, heapLength--);
                obj = objs[j];
                /* Output candidate to ordering[] */
                ordering[--i] = obj;
                /* Update beforeConstraints counts of its predecessors */
                for (k = 0; k < obj->nDeps; k++)
                {
                        int                     id = obj->dependencies[k];

                        if ((--beforeConstraints[id]) == 0)
                                addHeapElement(idMap[id], pendingHeap, heapLength++);
                }
        }

        /*
         * If we failed, report the objects that couldn't be output; these are the
         * ones with beforeConstraints[] still nonzero.
         */
        if (i != 0)
        {
                k = 0;
                for (j = 1; j <= maxDumpId; j++)
                {
                        if (beforeConstraints[j] != 0)
                                ordering[k++] = objs[idMap[j]];
                }
                *nOrdering = k;
        }

        /* Done */
        free(pendingHeap);
        free(beforeConstraints);
        free(idMap);

        return (i == 0);
}

/*
 * Add an item to a heap (priority queue)
 *
 * heapLength is the current heap size; caller is responsible for increasing
 * its value after the call.  There must be sufficient storage at *heap.
 */
static void
addHeapElement(int val, int *heap, int heapLength)
{
        int                     j;

        /*
         * Sift-up the new entry, per Knuth 5.2.3 exercise 16. Note that Knuth is
         * using 1-based array indexes, not 0-based.
         */
        j = heapLength;
        while (j > 0)
        {
                int                     i = (j - 1) >> 1;

                if (val <= heap[i])
                        break;
                heap[j] = heap[i];
                j = i;
        }
        heap[j] = val;
}

/*
 * Remove the largest item present in a heap (priority queue)
 *
 * heapLength is the current heap size; caller is responsible for decreasing
 * its value after the call.
 *
 * We remove and return heap[0], which is always the largest element of
 * the heap, and then "sift up" to maintain the heap invariant.
 */
static int
removeHeapElement(int *heap, int heapLength)
{
        int                     result = heap[0];
        int                     val;
        int                     i;

        if (--heapLength <= 0)
                return result;
        val = heap[heapLength];         /* value that must be reinserted */
        i = 0;                                          /* i is where the "hole" is */
        for (;;)
        {
                int                     j = 2 * i + 1;

                if (j >= heapLength)
                        break;
                if (j + 1 < heapLength &&
                        heap[j] < heap[j + 1])
                        j++;
                if (val >= heap[j])
                        break;
                heap[i] = heap[j];
                i = j;
        }
        heap[i] = val;
        return result;
}

/*
 * findDependencyLoops - identify loops in TopoSort's failure output,
 *              and pass each such loop to repairDependencyLoop() for action
 *
 * In general there may be many loops in the set of objects returned by
 * TopoSort; for speed we should try to repair as many loops as we can
 * before trying TopoSort again.  We can safely repair loops that are
 * disjoint (have no members in common); if we find overlapping loops
 * then we repair only the first one found, because the action taken to
 * repair the first might have repaired the other as well.      (If not,
 * we'll fix it on the next go-round.)
 *
 * objs[] lists the objects TopoSort couldn't sort
 * nObjs is the number of such objects
 * totObjs is the total number of objects in the universe
 */
static void
findDependencyLoops(DumpableObject **objs, int nObjs, int totObjs)
{
        /*
         * We use a workspace array, the initial part of which stores objects
         * already processed, and the rest of which is used as temporary space to
         * try to build a loop in.      This is convenient because we do not care
         * about loops involving already-processed objects (see notes above); we
         * can easily reject such loops in findLoop() because of this
         * representation.      After we identify and process a loop, we can add it to
         * the initial part of the workspace just by moving the boundary pointer.
         *
         * When we determine that an object is not part of any interesting loop,
         * we also add it to the initial part of the workspace.  This is not
         * necessary for correctness, but saves later invocations of findLoop()
         * from uselessly chasing references to such an object.
         *
         * We make the workspace large enough to hold all objects in the original
         * universe.  This is probably overkill, but it's provably enough space...
         */
        DumpableObject **workspace;
        int                     initiallen;
        bool            fixedloop;
        int                     i;

        workspace = (DumpableObject **) malloc(totObjs * sizeof(DumpableObject *));
        if (workspace == NULL)
                exit_horribly(NULL, modulename, "out of memory\n");
        initiallen = 0;
        fixedloop = false;

        for (i = 0; i < nObjs; i++)
        {
                DumpableObject *obj = objs[i];
                int                     newlen;

                workspace[initiallen] = NULL;   /* see test below */

                if (findLoop(obj, obj->dumpId, workspace, initiallen, &newlen))
                {
                        /* Found a loop of length newlen - initiallen */
                        repairDependencyLoop(&workspace[initiallen], newlen - initiallen);
                        /* Add loop members to workspace */
                        initiallen = newlen;
                        fixedloop = true;
                }
                else
                {
                        /*
                         * Didn't find a loop, but add this object to workspace anyway,
                         * unless it's already present.  We piggyback on the test that
                         * findLoop() already did: it won't have tentatively added obj to
                         * workspace if it's already present.
                         */
                        if (workspace[initiallen] == obj)
                                initiallen++;
                }
        }

        /* We'd better have fixed at least one loop */
        if (!fixedloop)
                exit_horribly(NULL, modulename, "could not identify dependency loop\n");

        free(workspace);
}

/*
 * Recursively search for a circular dependency loop that doesn't include
 * any existing workspace members.
 *
 *      obj: object we are examining now
 *      startPoint: dumpId of starting object for the hoped-for circular loop
 *      workspace[]: work array for previously processed and current objects
 *      depth: number of valid entries in workspace[] at call
 *      newDepth: if successful, set to new number of workspace[] entries
 *
 * On success, *newDepth is set and workspace[] entries depth..*newDepth-1
 * are filled with pointers to the members of the loop.
 *
 * Note: it is possible that the given starting object is a member of more
 * than one cycle; if so, we will find an arbitrary one of the cycles.
 */
static bool
findLoop(DumpableObject *obj,
                 DumpId startPoint,
                 DumpableObject **workspace,
                 int depth,
                 int *newDepth)
{
        int                     i;

        /*
         * Reject if obj is already present in workspace.  This test serves three
         * purposes: it prevents us from finding loops that overlap
         * previously-processed loops, it prevents us from going into infinite
         * recursion if we are given a startPoint object that links to a cycle
         * it's not a member of, and it guarantees that we can't overflow the
         * allocated size of workspace[].
         */
        for (i = 0; i < depth; i++)
        {
                if (workspace[i] == obj)
                        return false;
        }

        /*
         * Okay, tentatively add obj to workspace
         */
        workspace[depth++] = obj;

        /*
         * See if we've found a loop back to the desired startPoint; if so, done
         */
        for (i = 0; i < obj->nDeps; i++)
        {
                if (obj->dependencies[i] == startPoint)
                {
                        *newDepth = depth;
                        return true;
                }
        }

        /*
         * Recurse down each outgoing branch
         */
        for (i = 0; i < obj->nDeps; i++)
        {
                DumpableObject *nextobj = findObjectByDumpId(obj->dependencies[i]);

                if (!nextobj)
                        continue;                       /* ignore dependencies on undumped objects */
                if (findLoop(nextobj,
                                         startPoint,
                                         workspace,
                                         depth,
                                         newDepth))
                        return true;
        }

        return false;
}

/*
 * A user-defined datatype will have a dependency loop with each of its
 * I/O functions (since those have the datatype as input or output).
 * Break the loop and make the I/O function depend on the associated
 * shell type, instead.
 */
static void
repairTypeFuncLoop(DumpableObject *typeobj, DumpableObject *funcobj)
{
        TypeInfo   *typeInfo = (TypeInfo *) typeobj;

        /* remove function's dependency on type */
        removeObjectDependency(funcobj, typeobj->dumpId);

        /* add function's dependency on shell type, instead */
        if (typeInfo->shellType)
        {
                addObjectDependency(funcobj, typeInfo->shellType->dobj.dumpId);
                /* Mark shell type as to be dumped if any I/O function is */
                if (funcobj->dump)
                        typeInfo->shellType->dobj.dump = true;
        }
}

/*
 * Because we force a view to depend on its ON SELECT rule, while there
 * will be an implicit dependency in the other direction, we need to break
 * the loop.  If there are no other objects in the loop then we can remove
 * the implicit dependency and leave the ON SELECT rule non-separate.
 */
static void
repairViewRuleLoop(DumpableObject *viewobj,
                                   DumpableObject *ruleobj)
{
        /* remove rule's dependency on view */
        removeObjectDependency(ruleobj, viewobj->dumpId);
}

/*
 * However, if there are other objects in the loop, we must break the loop
 * by making the ON SELECT rule a separately-dumped object.
 *
 * Because findLoop() finds shorter cycles before longer ones, it's likely
 * that we will have previously fired repairViewRuleLoop() and removed the
 * rule's dependency on the view.  Put it back to ensure the rule won't be
 * emitted before the view...
 */
static void
repairViewRuleMultiLoop(DumpableObject *viewobj,
                                                DumpableObject *ruleobj)
{
        /* remove view's dependency on rule */
        removeObjectDependency(viewobj, ruleobj->dumpId);
        /* pretend view is a plain table and dump it that way */
        ((TableInfo *) viewobj)->relkind = 'r';         /* RELKIND_RELATION */
        /* mark rule as needing its own dump */
        ((RuleInfo *) ruleobj)->separate = true;
        /* put back rule's dependency on view */
        addObjectDependency(ruleobj, viewobj->dumpId);
}

/*
 * Because we make tables depend on their CHECK constraints, while there
 * will be an automatic dependency in the other direction, we need to break
 * the loop.  If there are no other objects in the loop then we can remove
 * the automatic dependency and leave the CHECK constraint non-separate.
 */
static void
repairTableConstraintLoop(DumpableObject *tableobj,
                                                  DumpableObject *constraintobj)
{
        /* remove constraint's dependency on table */
        removeObjectDependency(constraintobj, tableobj->dumpId);
}

/*
 * However, if there are other objects in the loop, we must break the loop
 * by making the CHECK constraint a separately-dumped object.
 *
 * Because findLoop() finds shorter cycles before longer ones, it's likely
 * that we will have previously fired repairTableConstraintLoop() and
 * removed the constraint's dependency on the table.  Put it back to ensure
 * the constraint won't be emitted before the table...
 */
static void
repairTableConstraintMultiLoop(DumpableObject *tableobj,
                                                           DumpableObject *constraintobj)
{
        /* remove table's dependency on constraint */
        removeObjectDependency(tableobj, constraintobj->dumpId);
        /* mark constraint as needing its own dump */
        ((ConstraintInfo *) constraintobj)->separate = true;
        /* put back constraint's dependency on table */
        addObjectDependency(constraintobj, tableobj->dumpId);
}

/*
 * Attribute defaults behave exactly the same as CHECK constraints...
 */
static void
repairTableAttrDefLoop(DumpableObject *tableobj,
                                           DumpableObject *attrdefobj)
{
        /* remove attrdef's dependency on table */
        removeObjectDependency(attrdefobj, tableobj->dumpId);
}

static void
repairTableAttrDefMultiLoop(DumpableObject *tableobj,
                                                        DumpableObject *attrdefobj)
{
        /* remove table's dependency on attrdef */
        removeObjectDependency(tableobj, attrdefobj->dumpId);
        /* mark attrdef as needing its own dump */
        ((AttrDefInfo *) attrdefobj)->separate = true;
        /* put back attrdef's dependency on table */
        addObjectDependency(attrdefobj, tableobj->dumpId);
}

/*
 * CHECK constraints on domains work just like those on tables ...
 */
static void
repairDomainConstraintLoop(DumpableObject *domainobj,
                                                   DumpableObject *constraintobj)
{
        /* remove constraint's dependency on domain */
        removeObjectDependency(constraintobj, domainobj->dumpId);
}

static void
repairDomainConstraintMultiLoop(DumpableObject *domainobj,
                                                                DumpableObject *constraintobj)
{
        /* remove domain's dependency on constraint */
        removeObjectDependency(domainobj, constraintobj->dumpId);
        /* mark constraint as needing its own dump */
        ((ConstraintInfo *) constraintobj)->separate = true;
        /* put back constraint's dependency on domain */
        addObjectDependency(constraintobj, domainobj->dumpId);
}

/*
 * Fix a dependency loop, or die trying ...
 *
 * This routine is mainly concerned with reducing the multiple ways that
 * a loop might appear to common cases, which it passes off to the
 * "fixer" routines above.
 */
static void
repairDependencyLoop(DumpableObject **loop,
                                         int nLoop)
{
        int                     i,
                                j;

        /* Datatype and one of its I/O functions */
        if (nLoop == 2 &&
                loop[0]->objType == DO_TYPE &&
                loop[1]->objType == DO_FUNC)
        {
                repairTypeFuncLoop(loop[0], loop[1]);
                return;
        }
        if (nLoop == 2 &&
                loop[1]->objType == DO_TYPE &&
                loop[0]->objType == DO_FUNC)
        {
                repairTypeFuncLoop(loop[1], loop[0]);
                return;
        }

        /* View and its ON SELECT rule */
        if (nLoop == 2 &&
                loop[0]->objType == DO_TABLE &&
                loop[1]->objType == DO_RULE &&
                ((RuleInfo *) loop[1])->ev_type == '1' &&
                ((RuleInfo *) loop[1])->is_instead &&
                ((RuleInfo *) loop[1])->ruletable == (TableInfo *) loop[0])
        {
                repairViewRuleLoop(loop[0], loop[1]);
                return;
        }
        if (nLoop == 2 &&
                loop[1]->objType == DO_TABLE &&
                loop[0]->objType == DO_RULE &&
                ((RuleInfo *) loop[0])->ev_type == '1' &&
                ((RuleInfo *) loop[0])->is_instead &&
                ((RuleInfo *) loop[0])->ruletable == (TableInfo *) loop[1])
        {
                repairViewRuleLoop(loop[1], loop[0]);
                return;
        }

        /* Indirect loop involving view and ON SELECT rule */
        if (nLoop > 2)
        {
                for (i = 0; i < nLoop; i++)
                {
                        if (loop[i]->objType == DO_TABLE)
                        {
                                for (j = 0; j < nLoop; j++)
                                {
                                        if (loop[j]->objType == DO_RULE &&
                                                ((RuleInfo *) loop[j])->ev_type == '1' &&
                                                ((RuleInfo *) loop[j])->is_instead &&
                                                ((RuleInfo *) loop[j])->ruletable == (TableInfo *) loop[i])
                                        {
                                                repairViewRuleMultiLoop(loop[i], loop[j]);
                                                return;
                                        }
                                }
                        }
                }
        }

        /* Table and CHECK constraint */
        if (nLoop == 2 &&
                loop[0]->objType == DO_TABLE &&
                loop[1]->objType == DO_CONSTRAINT &&
                ((ConstraintInfo *) loop[1])->contype == 'c' &&
                ((ConstraintInfo *) loop[1])->contable == (TableInfo *) loop[0])
        {
                repairTableConstraintLoop(loop[0], loop[1]);
                return;
        }
        if (nLoop == 2 &&
                loop[1]->objType == DO_TABLE &&
                loop[0]->objType == DO_CONSTRAINT &&
                ((ConstraintInfo *) loop[0])->contype == 'c' &&
                ((ConstraintInfo *) loop[0])->contable == (TableInfo *) loop[1])
        {
                repairTableConstraintLoop(loop[1], loop[0]);
                return;
        }

        /* Indirect loop involving table and CHECK constraint */
        if (nLoop > 2)
        {
                for (i = 0; i < nLoop; i++)
                {
                        if (loop[i]->objType == DO_TABLE)
                        {
                                for (j = 0; j < nLoop; j++)
                                {
                                        if (loop[j]->objType == DO_CONSTRAINT &&
                                                ((ConstraintInfo *) loop[j])->contype == 'c' &&
                                                ((ConstraintInfo *) loop[j])->contable == (TableInfo *) loop[i])
                                        {
                                                repairTableConstraintMultiLoop(loop[i], loop[j]);
                                                return;
                                        }
                                }
                        }
                }
        }

        /* Table and attribute default */
        if (nLoop == 2 &&
                loop[0]->objType == DO_TABLE &&
                loop[1]->objType == DO_ATTRDEF &&
                ((AttrDefInfo *) loop[1])->adtable == (TableInfo *) loop[0])
        {
                repairTableAttrDefLoop(loop[0], loop[1]);
                return;
        }
        if (nLoop == 2 &&
                loop[1]->objType == DO_TABLE &&
                loop[0]->objType == DO_ATTRDEF &&
                ((AttrDefInfo *) loop[0])->adtable == (TableInfo *) loop[1])
        {
                repairTableAttrDefLoop(loop[1], loop[0]);
                return;
        }

        /* Indirect loop involving table and attribute default */
        if (nLoop > 2)
        {
                for (i = 0; i < nLoop; i++)
                {
                        if (loop[i]->objType == DO_TABLE)
                        {
                                for (j = 0; j < nLoop; j++)
                                {
                                        if (loop[j]->objType == DO_ATTRDEF &&
                                                ((AttrDefInfo *) loop[j])->adtable == (TableInfo *) loop[i])
                                        {
                                                repairTableAttrDefMultiLoop(loop[i], loop[j]);
                                                return;
                                        }
                                }
                        }
                }
        }

        /* Domain and CHECK constraint */
        if (nLoop == 2 &&
                loop[0]->objType == DO_TYPE &&
                loop[1]->objType == DO_CONSTRAINT &&
                ((ConstraintInfo *) loop[1])->contype == 'c' &&
                ((ConstraintInfo *) loop[1])->condomain == (TypeInfo *) loop[0])
        {
                repairDomainConstraintLoop(loop[0], loop[1]);
                return;
        }
        if (nLoop == 2 &&
                loop[1]->objType == DO_TYPE &&
                loop[0]->objType == DO_CONSTRAINT &&
                ((ConstraintInfo *) loop[0])->contype == 'c' &&
                ((ConstraintInfo *) loop[0])->condomain == (TypeInfo *) loop[1])
        {
                repairDomainConstraintLoop(loop[1], loop[0]);
                return;
        }

        /* Indirect loop involving domain and CHECK constraint */
        if (nLoop > 2)
        {
                for (i = 0; i < nLoop; i++)
                {
                        if (loop[i]->objType == DO_TYPE)
                        {
                                for (j = 0; j < nLoop; j++)
                                {
                                        if (loop[j]->objType == DO_CONSTRAINT &&
                                                ((ConstraintInfo *) loop[j])->contype == 'c' &&
                                                ((ConstraintInfo *) loop[j])->condomain == (TypeInfo *) loop[i])
                                        {
                                                repairDomainConstraintMultiLoop(loop[i], loop[j]);
                                                return;
                                        }
                                }
                        }
                }
        }

        /*
         * If all the objects are TABLE_DATA items, what we must have is a
         * circular set of foreign key constraints (or a single self-referential
         * table).  Print an appropriate complaint and break the loop arbitrarily.
         */
        for (i = 0; i < nLoop; i++)
        {
                if (loop[i]->objType != DO_TABLE_DATA)
                        break;
        }
        if (i >= nLoop)
        {
                write_msg(NULL, "NOTICE: there are circular foreign-key constraints among these table(s):\n");
                for (i = 0; i < nLoop; i++)
                        write_msg(NULL, "  %s\n", loop[i]->name);
                write_msg(NULL, "You may not be able to restore the dump without using --disable-triggers or temporarily dropping the constraints.\n");
                write_msg(NULL, "Consider using a full dump instead of a --data-only dump to avoid this problem.\n");
                if (nLoop > 1)
                        removeObjectDependency(loop[0], loop[1]->dumpId);
                else                                            /* must be a self-dependency */
                        removeObjectDependency(loop[0], loop[0]->dumpId);
                return;
        }

        /*
         * If we can't find a principled way to break the loop, complain and break
         * it in an arbitrary fashion.
         */
        write_msg(modulename, "WARNING: could not resolve dependency loop among these items:\n");
        for (i = 0; i < nLoop; i++)
        {
                char            buf[1024];

                describeDumpableObject(loop[i], buf, sizeof(buf));
                write_msg(modulename, "  %s\n", buf);
        }

        if (nLoop > 1)
                removeObjectDependency(loop[0], loop[1]->dumpId);
        else                                            /* must be a self-dependency */
                removeObjectDependency(loop[0], loop[0]->dumpId);
}

/*
 * Describe a dumpable object usefully for errors
 *
 * This should probably go somewhere else...
 */
static void
describeDumpableObject(DumpableObject *obj, char *buf, int bufsize)
{
        switch (obj->objType)
        {
                case DO_NAMESPACE:
                        snprintf(buf, bufsize,
                                         "SCHEMA %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TYPE:
                        snprintf(buf, bufsize,
                                         "TYPE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_SHELL_TYPE:
                        snprintf(buf, bufsize,
                                         "SHELL TYPE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_FUNC:
                        snprintf(buf, bufsize,
                                         "FUNCTION %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_AGG:
                        snprintf(buf, bufsize,
                                         "AGGREGATE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_OPERATOR:
                        snprintf(buf, bufsize,
                                         "OPERATOR %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_OPCLASS:
                        snprintf(buf, bufsize,
                                         "OPERATOR CLASS %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_OPFAMILY:
                        snprintf(buf, bufsize,
                                         "OPERATOR FAMILY %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_CONVERSION:
                        snprintf(buf, bufsize,
                                         "CONVERSION %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TABLE:
                        snprintf(buf, bufsize,
                                         "TABLE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_ATTRDEF:
                        snprintf(buf, bufsize,
                                         "ATTRDEF %s.%s  (ID %d OID %u)",
                                         ((AttrDefInfo *) obj)->adtable->dobj.name,
                                         ((AttrDefInfo *) obj)->adtable->attnames[((AttrDefInfo *) obj)->adnum - 1],
                                         obj->dumpId, obj->catId.oid);
                        return;
                case DO_INDEX:
                        snprintf(buf, bufsize,
                                         "INDEX %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_RULE:
                        snprintf(buf, bufsize,
                                         "RULE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TRIGGER:
                        snprintf(buf, bufsize,
                                         "TRIGGER %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_CONSTRAINT:
                        snprintf(buf, bufsize,
                                         "CONSTRAINT %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_FK_CONSTRAINT:
                        snprintf(buf, bufsize,
                                         "FK CONSTRAINT %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_PROCLANG:
                        snprintf(buf, bufsize,
                                         "PROCEDURAL LANGUAGE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_CAST:
                        snprintf(buf, bufsize,
                                         "CAST %u to %u  (ID %d OID %u)",
                                         ((CastInfo *) obj)->castsource,
                                         ((CastInfo *) obj)->casttarget,
                                         obj->dumpId, obj->catId.oid);
                        return;
                case DO_TABLE_DATA:
                        snprintf(buf, bufsize,
                                         "TABLE DATA %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TABLE_TYPE:
                        snprintf(buf, bufsize,
                                         "TABLE TYPE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TSPARSER:
                        snprintf(buf, bufsize,
                                         "TEXT SEARCH PARSER %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TSDICT:
                        snprintf(buf, bufsize,
                                         "TEXT SEARCH DICTIONARY %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TSTEMPLATE:
                        snprintf(buf, bufsize,
                                         "TEXT SEARCH TEMPLATE %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_TSCONFIG:
                        snprintf(buf, bufsize,
                                         "TEXT SEARCH CONFIGURATION %s  (ID %d OID %u)",
                                         obj->name, obj->dumpId, obj->catId.oid);
                        return;
                case DO_BLOBS:
                        snprintf(buf, bufsize,
                                         "BLOBS  (ID %d)",
                                         obj->dumpId);
                        return;
                case DO_BLOB_COMMENTS:
                        snprintf(buf, bufsize,
                                         "BLOB COMMENTS  (ID %d)",
                                         obj->dumpId);
                        return;
        }
        /* shouldn't get here */
        snprintf(buf, bufsize,
                         "object type %d  (ID %d OID %u)",
                         (int) obj->objType,
                         obj->dumpId, obj->catId.oid);
}