pg_dump_sort.c

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/*-------------------------------------------------------------------------
 *
 * pg_dump_sort.c
 *    Sort the items of a dump into a safe order for dumping
 *
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/bin/pg_dump/pg_dump_sort.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"
 
#include "catalog/pg_class_d.h"
#include "common/int.h"
#include "lib/binaryheap.h"
#include "pg_backup_utils.h"
#include "pg_dump.h"
 
/*
 * Sort priority for database object types.
 * Objects are sorted by type, and within a type by name.
 *
 * Triggers, event triggers, and materialized views are intentionally sorted
 * late.  Triggers must be restored after all data modifications, so that
 * they don't interfere with loading data.  Event triggers are restored
 * next-to-last so that they don't interfere with object creations of any
 * kind.  Matview refreshes are last because they should execute in the
 * database's normal state (e.g., they must come after all ACLs are restored;
 * also, if they choose to look at system catalogs, they should see the final
 * restore state).  If you think to change this, see also the RestorePass
 * mechanism in pg_backup_archiver.c.
 *
 * On the other hand, casts are intentionally sorted earlier than you might
 * expect; logically they should come after functions, since they usually
 * depend on those.  This works around the backend's habit of recording
 * views that use casts as dependent on the cast's underlying function.
 * We initially sort casts first, and then any functions used by casts
 * will be hoisted above the casts, and in turn views that those functions
 * depend on will be hoisted above the functions.  But views not used that
 * way won't be hoisted.
 *
 * NOTE: object-type priorities must match the section assignments made in
 * pg_dump.c; that is, PRE_DATA objects must sort before DO_PRE_DATA_BOUNDARY,
 * POST_DATA objects must sort after DO_POST_DATA_BOUNDARY, and DATA objects
 * must sort between them.
 */
 
/* This enum lists the priority levels in order */
enum dbObjectTypePriorities
{
    PRIO_NAMESPACE = 1,
    PRIO_PROCLANG,
    PRIO_COLLATION,
    PRIO_TRANSFORM,
    PRIO_EXTENSION,
    PRIO_TYPE,                  /* used for DO_TYPE and DO_SHELL_TYPE */
    PRIO_CAST,
    PRIO_FUNC,
    PRIO_AGG,
    PRIO_ACCESS_METHOD,
    PRIO_OPERATOR,
    PRIO_OPFAMILY,              /* used for DO_OPFAMILY and DO_OPCLASS */
    PRIO_CONVERSION,
    PRIO_TSPARSER,
    PRIO_TSTEMPLATE,
    PRIO_TSDICT,
    PRIO_TSCONFIG,
    PRIO_FDW,
    PRIO_FOREIGN_SERVER,
    PRIO_TABLE,
    PRIO_TABLE_ATTACH,
    PRIO_DUMMY_TYPE,
    PRIO_ATTRDEF,
    PRIO_PRE_DATA_BOUNDARY,     /* boundary! */
    PRIO_TABLE_DATA,
    PRIO_SEQUENCE_SET,
    PRIO_LARGE_OBJECT,
    PRIO_LARGE_OBJECT_DATA,
    PRIO_STATISTICS_DATA_DATA,
    PRIO_POST_DATA_BOUNDARY,    /* boundary! */
    PRIO_CONSTRAINT,
    PRIO_INDEX,
    PRIO_INDEX_ATTACH,
    PRIO_STATSEXT,
    PRIO_RULE,
    PRIO_TRIGGER,
    PRIO_FK_CONSTRAINT,
    PRIO_POLICY,
    PRIO_PUBLICATION,
    PRIO_PUBLICATION_REL,
    PRIO_PUBLICATION_TABLE_IN_SCHEMA,
    PRIO_SUBSCRIPTION,
    PRIO_SUBSCRIPTION_REL,
    PRIO_DEFAULT_ACL,           /* done in ACL pass */
    PRIO_EVENT_TRIGGER,         /* must be next to last! */
    PRIO_REFRESH_MATVIEW        /* must be last! */
};
 
/* This table is indexed by enum DumpableObjectType */
static const int dbObjectTypePriority[] =
{
    [DO_NAMESPACE] = PRIO_NAMESPACE,
    [DO_EXTENSION] = PRIO_EXTENSION,
    [DO_TYPE] = PRIO_TYPE,
    [DO_SHELL_TYPE] = PRIO_TYPE,
    [DO_FUNC] = PRIO_FUNC,
    [DO_AGG] = PRIO_AGG,
    [DO_OPERATOR] = PRIO_OPERATOR,
    [DO_ACCESS_METHOD] = PRIO_ACCESS_METHOD,
    [DO_OPCLASS] = PRIO_OPFAMILY,
    [DO_OPFAMILY] = PRIO_OPFAMILY,
    [DO_COLLATION] = PRIO_COLLATION,
    [DO_CONVERSION] = PRIO_CONVERSION,
    [DO_TABLE] = PRIO_TABLE,
    [DO_TABLE_ATTACH] = PRIO_TABLE_ATTACH,
    [DO_ATTRDEF] = PRIO_ATTRDEF,
    [DO_INDEX] = PRIO_INDEX,
    [DO_INDEX_ATTACH] = PRIO_INDEX_ATTACH,
    [DO_STATSEXT] = PRIO_STATSEXT,
    [DO_RULE] = PRIO_RULE,
    [DO_TRIGGER] = PRIO_TRIGGER,
    [DO_CONSTRAINT] = PRIO_CONSTRAINT,
    [DO_FK_CONSTRAINT] = PRIO_FK_CONSTRAINT,
    [DO_PROCLANG] = PRIO_PROCLANG,
    [DO_CAST] = PRIO_CAST,
    [DO_TABLE_DATA] = PRIO_TABLE_DATA,
    [DO_SEQUENCE_SET] = PRIO_SEQUENCE_SET,
    [DO_DUMMY_TYPE] = PRIO_DUMMY_TYPE,
    [DO_TSPARSER] = PRIO_TSPARSER,
    [DO_TSDICT] = PRIO_TSDICT,
    [DO_TSTEMPLATE] = PRIO_TSTEMPLATE,
    [DO_TSCONFIG] = PRIO_TSCONFIG,
    [DO_FDW] = PRIO_FDW,
    [DO_FOREIGN_SERVER] = PRIO_FOREIGN_SERVER,
    [DO_DEFAULT_ACL] = PRIO_DEFAULT_ACL,
    [DO_TRANSFORM] = PRIO_TRANSFORM,
    [DO_LARGE_OBJECT] = PRIO_LARGE_OBJECT,
    [DO_LARGE_OBJECT_DATA] = PRIO_LARGE_OBJECT_DATA,
    [DO_PRE_DATA_BOUNDARY] = PRIO_PRE_DATA_BOUNDARY,
    [DO_POST_DATA_BOUNDARY] = PRIO_POST_DATA_BOUNDARY,
    [DO_EVENT_TRIGGER] = PRIO_EVENT_TRIGGER,
    [DO_REFRESH_MATVIEW] = PRIO_REFRESH_MATVIEW,
    [DO_POLICY] = PRIO_POLICY,
    [DO_PUBLICATION] = PRIO_PUBLICATION,
    [DO_PUBLICATION_REL] = PRIO_PUBLICATION_REL,
    [DO_PUBLICATION_TABLE_IN_SCHEMA] = PRIO_PUBLICATION_TABLE_IN_SCHEMA,
    [DO_REL_STATS] = PRIO_STATISTICS_DATA_DATA,
    [DO_SUBSCRIPTION] = PRIO_SUBSCRIPTION,
    [DO_SUBSCRIPTION_REL] = PRIO_SUBSCRIPTION_REL,
};
 
StaticAssertDecl(lengthof(dbObjectTypePriority) == NUM_DUMPABLE_OBJECT_TYPES,
                 "array length mismatch");
 
static DumpId preDataBoundId;
static DumpId postDataBoundId;
 
 
static int  DOTypeNameCompare(const void *p1, const void *p2);
static int  pgTypeNameCompare(Oid typid1, Oid typid2);
static int  accessMethodNameCompare(Oid am1, Oid am2);
static bool TopoSort(DumpableObject **objs,
                     int numObjs,
                     DumpableObject **ordering,
                     int *nOrdering);
static void findDependencyLoops(DumpableObject **objs, int nObjs, int totObjs);
static int  findLoop(DumpableObject *obj,
                     DumpId startPoint,
                     bool *processed,
                     DumpId *searchFailed,
                     DumpableObject **workspace,
                     int depth);
static void repairDependencyLoop(DumpableObject **loop,
                                 int nLoop);
static void describeDumpableObject(DumpableObject *obj,
                                   char *buf, int bufsize);
static int  int_cmp(void *a, void *b, void *arg);
 
 
/*
 * 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(objs, numObjs, sizeof(DumpableObject *),
              DOTypeNameCompare);
}
 
static int
DOTypeNameCompare(const void *p1, const void *p2)
{
    DumpableObject *obj1 = *(DumpableObject *const *) p1;
    DumpableObject *obj2 = *(DumpableObject *const *) p2;
    int         cmpval;
 
    /* Sort by type's priority */
    cmpval = dbObjectTypePriority[obj1->objType] -
        dbObjectTypePriority[obj2->objType];
 
    if (cmpval != 0)
        return cmpval;
 
    /*
     * Sort by namespace.  Typically, all objects of the same priority would
     * either have or not have a namespace link, but there are exceptions.
     * Sort NULL namespace after non-NULL in such cases.
     */
    if (obj1->namespace)
    {
        if (obj2->namespace)
        {
            cmpval = strcmp(obj1->namespace->dobj.name,
                            obj2->namespace->dobj.name);
            if (cmpval != 0)
                return cmpval;
        }
        else
            return -1;
    }
    else if (obj2->namespace)
        return 1;
 
    /*
     * Sort by name.  With a few exceptions, names here are single catalog
     * columns.  To get a fuller picture, grep pg_dump.c for "dobj.name = ".
     * Names here don't match "Name:" in plain format output, which is a
     * _tocEntry.tag.  For example, DumpableObject.name of a constraint is
     * pg_constraint.conname, but _tocEntry.tag of a constraint is relname and
     * conname joined with a space.
     */
    cmpval = strcmp(obj1->name, obj2->name);
    if (cmpval != 0)
        return cmpval;
 
    /*
     * Sort by type.  This helps types that share a type priority without
     * sharing a unique name constraint, e.g. opclass and opfamily.
     */
    cmpval = obj1->objType - obj2->objType;
    if (cmpval != 0)
        return cmpval;
 
    /*
     * To have a stable sort order, break ties for some object types.  Most
     * catalogs have a natural key, e.g. pg_proc_proname_args_nsp_index. Where
     * the above "namespace" and "name" comparisons don't cover all natural
     * key columns, compare the rest here.
     *
     * The natural key usually refers to other catalogs by surrogate keys.
     * Hence, this translates each of those references to the natural key of
     * the referenced catalog.  That may descend through multiple levels of
     * catalog references.  For example, to sort by pg_proc.proargtypes,
     * descend to each pg_type and then further to its pg_namespace, for an
     * overall sort by (nspname, typname).
     */
    if (obj1->objType == DO_FUNC || obj1->objType == DO_AGG)
    {
        FuncInfo   *fobj1 = *(FuncInfo *const *) p1;
        FuncInfo   *fobj2 = *(FuncInfo *const *) p2;
        int         i;
 
        /* Sort by number of arguments, then argument type names */
        cmpval = fobj1->nargs - fobj2->nargs;
        if (cmpval != 0)
            return cmpval;
        for (i = 0; i < fobj1->nargs; i++)
        {
            cmpval = pgTypeNameCompare(fobj1->argtypes[i],
                                       fobj2->argtypes[i]);
            if (cmpval != 0)
                return cmpval;
        }
    }
    else if (obj1->objType == DO_OPERATOR)
    {
        OprInfo    *oobj1 = *(OprInfo *const *) p1;
        OprInfo    *oobj2 = *(OprInfo *const *) p2;
 
        /* oprkind is 'l', 'r', or 'b'; this sorts prefix, postfix, infix */
        cmpval = (oobj2->oprkind - oobj1->oprkind);
        if (cmpval != 0)
            return cmpval;
        /* Within an oprkind, sort by argument type names */
        cmpval = pgTypeNameCompare(oobj1->oprleft, oobj2->oprleft);
        if (cmpval != 0)
            return cmpval;
        cmpval = pgTypeNameCompare(oobj1->oprright, oobj2->oprright);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_OPCLASS)
    {
        OpclassInfo *opcobj1 = *(OpclassInfo *const *) p1;
        OpclassInfo *opcobj2 = *(OpclassInfo *const *) p2;
 
        /* Sort by access method name, per pg_opclass_am_name_nsp_index */
        cmpval = accessMethodNameCompare(opcobj1->opcmethod,
                                         opcobj2->opcmethod);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_OPFAMILY)
    {
        OpfamilyInfo *opfobj1 = *(OpfamilyInfo *const *) p1;
        OpfamilyInfo *opfobj2 = *(OpfamilyInfo *const *) p2;
 
        /* Sort by access method name, per pg_opfamily_am_name_nsp_index */
        cmpval = accessMethodNameCompare(opfobj1->opfmethod,
                                         opfobj2->opfmethod);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_COLLATION)
    {
        CollInfo   *cobj1 = *(CollInfo *const *) p1;
        CollInfo   *cobj2 = *(CollInfo *const *) p2;
 
        /*
         * Sort by encoding, per pg_collation_name_enc_nsp_index. Technically,
         * this is not necessary, because wherever this changes dump order,
         * restoring the dump fails anyway.  CREATE COLLATION can't create a
         * tie for this to break, because it imposes restrictions to make
         * (nspname, collname) uniquely identify a collation within a given
         * DatabaseEncoding.  While pg_import_system_collations() can create a
         * tie, pg_dump+restore fails after
         * pg_import_system_collations('my_schema') does so. However, there's
         * little to gain by ignoring one natural key column on the basis of
         * those limitations elsewhere, so respect the full natural key like
         * we do for other object types.
         */
        cmpval = cobj1->collencoding - cobj2->collencoding;
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_ATTRDEF)
    {
        AttrDefInfo *adobj1 = *(AttrDefInfo *const *) p1;
        AttrDefInfo *adobj2 = *(AttrDefInfo *const *) p2;
 
        /* Sort by attribute number */
        cmpval = (adobj1->adnum - adobj2->adnum);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_POLICY)
    {
        PolicyInfo *pobj1 = *(PolicyInfo *const *) p1;
        PolicyInfo *pobj2 = *(PolicyInfo *const *) p2;
 
        /* Sort by table name (table namespace was considered already) */
        cmpval = strcmp(pobj1->poltable->dobj.name,
                        pobj2->poltable->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_RULE)
    {
        RuleInfo   *robj1 = *(RuleInfo *const *) p1;
        RuleInfo   *robj2 = *(RuleInfo *const *) p2;
 
        /* Sort by table name (table namespace was considered already) */
        cmpval = strcmp(robj1->ruletable->dobj.name,
                        robj2->ruletable->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_TRIGGER)
    {
        TriggerInfo *tobj1 = *(TriggerInfo *const *) p1;
        TriggerInfo *tobj2 = *(TriggerInfo *const *) p2;
 
        /* Sort by table name (table namespace was considered already) */
        cmpval = strcmp(tobj1->tgtable->dobj.name,
                        tobj2->tgtable->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_CONSTRAINT ||
             obj1->objType == DO_FK_CONSTRAINT)
    {
        ConstraintInfo *robj1 = *(ConstraintInfo *const *) p1;
        ConstraintInfo *robj2 = *(ConstraintInfo *const *) p2;
 
        /*
         * Sort domain constraints before table constraints, for consistency
         * with our decision to sort CREATE DOMAIN before CREATE TABLE.
         */
        if (robj1->condomain)
        {
            if (robj2->condomain)
            {
                /* Sort by domain name (domain namespace was considered) */
                cmpval = strcmp(robj1->condomain->dobj.name,
                                robj2->condomain->dobj.name);
                if (cmpval != 0)
                    return cmpval;
            }
            else
                return PRIO_TYPE - PRIO_TABLE;
        }
        else if (robj2->condomain)
            return PRIO_TABLE - PRIO_TYPE;
        else
        {
            /* Sort by table name (table namespace was considered already) */
            cmpval = strcmp(robj1->contable->dobj.name,
                            robj2->contable->dobj.name);
            if (cmpval != 0)
                return cmpval;
        }
    }
    else if (obj1->objType == DO_DEFAULT_ACL)
    {
        DefaultACLInfo *daclobj1 = *(DefaultACLInfo *const *) p1;
        DefaultACLInfo *daclobj2 = *(DefaultACLInfo *const *) p2;
 
        /*
         * Sort by defaclrole, per pg_default_acl_role_nsp_obj_index.  The
         * (namespace, name) match (defaclnamespace, defaclobjtype).
         */
        cmpval = strcmp(daclobj1->defaclrole, daclobj2->defaclrole);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_PUBLICATION_REL)
    {
        PublicationRelInfo *probj1 = *(PublicationRelInfo *const *) p1;
        PublicationRelInfo *probj2 = *(PublicationRelInfo *const *) p2;
 
        /* Sort by publication name, since (namespace, name) match the rel */
        cmpval = strcmp(probj1->publication->dobj.name,
                        probj2->publication->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_PUBLICATION_TABLE_IN_SCHEMA)
    {
        PublicationSchemaInfo *psobj1 = *(PublicationSchemaInfo *const *) p1;
        PublicationSchemaInfo *psobj2 = *(PublicationSchemaInfo *const *) p2;
 
        /* Sort by publication name, since ->name is just nspname */
        cmpval = strcmp(psobj1->publication->dobj.name,
                        psobj2->publication->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    else if (obj1->objType == DO_SUBSCRIPTION_REL)
    {
        SubRelInfo *srobj1 = *(SubRelInfo *const *) p1;
        SubRelInfo *srobj2 = *(SubRelInfo *const *) p2;
 
        /* Sort by subscription name, since (namespace, name) match the rel */
        cmpval = strcmp(srobj1->subinfo->dobj.name,
                        srobj2->subinfo->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
 
    /*
     * Shouldn't get here except after catalog corruption, but if we do, sort
     * by OID.  This may make logically-identical databases differ in the
     * order of objects in dump output.  Users will get spurious schema diffs.
     * Expect flaky failures of 002_pg_upgrade.pl test 'dump outputs from
     * original and restored regression databases match' if the regression
     * database contains objects allowing that test to reach here.  That's a
     * consequence of the test using "pg_restore -j", which doesn't fully
     * constrain OID assignment order.
     */
    Assert(false);
    return oidcmp(obj1->catId.oid, obj2->catId.oid);
}
 
/* Compare two OID-identified pg_type values by nspname, then by typname. */
static int
pgTypeNameCompare(Oid typid1, Oid typid2)
{
    TypeInfo   *typobj1;
    TypeInfo   *typobj2;
    int         cmpval;
 
    if (typid1 == typid2)
        return 0;
 
    typobj1 = findTypeByOid(typid1);
    typobj2 = findTypeByOid(typid2);
 
    if (!typobj1 || !typobj2)
    {
        /*
         * getTypes() didn't find some OID.  Assume catalog corruption, e.g.
         * an oprright value without the corresponding OID in a pg_type row.
         * Report as "equal", so the caller uses the next available basis for
         * comparison, e.g. the next function argument.
         *
         * Unary operators have InvalidOid in oprleft (if oprkind='r') or in
         * oprright (if oprkind='l').  Caller already sorted by oprkind,
         * calling us only for like-kind operators.  Hence, "typid1 == typid2"
         * took care of InvalidOid.  (v14 removed postfix operator support.
         * Hence, when dumping from v14+, only oprleft can be InvalidOid.)
         */
        Assert(false);
        return 0;
    }
 
    if (!typobj1->dobj.namespace || !typobj2->dobj.namespace)
        Assert(false);          /* catalog corruption */
    else
    {
        cmpval = strcmp(typobj1->dobj.namespace->dobj.name,
                        typobj2->dobj.namespace->dobj.name);
        if (cmpval != 0)
            return cmpval;
    }
    return strcmp(typobj1->dobj.name, typobj2->dobj.name);
}
 
/* Compare two OID-identified pg_am values by amname. */
static int
accessMethodNameCompare(Oid am1, Oid am2)
{
    AccessMethodInfo *amobj1;
    AccessMethodInfo *amobj2;
 
    if (am1 == am2)
        return 0;
 
    amobj1 = findAccessMethodByOid(am1);
    amobj2 = findAccessMethodByOid(am2);
 
    if (!amobj1 || !amobj2)
    {
        /* catalog corruption: handle like pgTypeNameCompare() does */
        Assert(false);
        return 0;
    }
 
    return strcmp(amobj1->dobj.name, amobj2->dobj.name);
}
 
 
/*
 * Sort the given objects into a safe dump order using dependency
 * information (to the extent we have it available).
 *
 * The DumpIds of the PRE_DATA_BOUNDARY and POST_DATA_BOUNDARY objects are
 * passed in separately, in case we need them during dependency loop repair.
 */
void
sortDumpableObjects(DumpableObject **objs, int numObjs,
                    DumpId preBoundaryId, DumpId postBoundaryId)
{
    DumpableObject **ordering;
    int         nOrdering;
 
    if (numObjs <= 0)           /* can't happen anymore ... */
        return;
 
    /*
     * Saving the boundary IDs in static variables is a bit grotty, but seems
     * better than adding them to parameter lists of subsidiary functions.
     */
    preDataBoundId = preBoundaryId;
    postDataBoundId = postBoundaryId;
 
    ordering = (DumpableObject **) pg_malloc(numObjs * sizeof(DumpableObject *));
    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();
    binaryheap *pendingHeap;
    int        *beforeConstraints;
    int        *idMap;
    DumpableObject *obj;
    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 = binaryheap_allocate(numObjs, int_cmp, NULL);
 
    /*
     * 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 *) pg_malloc0((maxDumpId + 1) * sizeof(int));
    idMap = (int *) pg_malloc((maxDumpId + 1) * sizeof(int));
    for (i = 0; i < numObjs; i++)
    {
        obj = objs[i];
        j = obj->dumpId;
        if (j <= 0 || j > maxDumpId)
            pg_fatal("invalid dumpId %d", j);
        idMap[j] = i;
        for (j = 0; j < obj->nDeps; j++)
        {
            k = obj->dependencies[j];
            if (k <= 0 || k > maxDumpId)
                pg_fatal("invalid dependency %d", 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.
     *
     * We enter the indexes into pendingHeap in decreasing order so that the
     * heap invariant is satisfied at the completion of this loop.  This
     * reduces the amount of work that binaryheap_build() must do.
     */
    for (i = numObjs; --i >= 0;)
    {
        if (beforeConstraints[objs[i]->dumpId] == 0)
            binaryheap_add_unordered(pendingHeap, (void *) (intptr_t) i);
    }
    binaryheap_build(pendingHeap);
 
    /*--------------------
     * 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 (!binaryheap_empty(pendingHeap))
    {
        /* Select object to output by removing largest heap member */
        j = (int) (intptr_t) binaryheap_remove_first(pendingHeap);
        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)
                binaryheap_add(pendingHeap, (void *) (intptr_t) idMap[id]);
        }
    }
 
    /*
     * 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 */
    binaryheap_free(pendingHeap);
    free(beforeConstraints);
    free(idMap);
 
    return (i == 0);
}
 
/*
 * 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 three data structures here:
     *
     * processed[] is a bool array indexed by dump ID, marking the objects
     * already processed during this invocation of findDependencyLoops().
     *
     * searchFailed[] is another array indexed by dump ID.  searchFailed[j] is
     * set to dump ID k if we have proven that there is no dependency path
     * leading from object j back to start point k.  This allows us to skip
     * useless searching when there are multiple dependency paths from k to j,
     * which is a common situation.  We could use a simple bool array for
     * this, but then we'd need to re-zero it for each start point, resulting
     * in O(N^2) zeroing work.  Using the start point's dump ID as the "true"
     * value lets us skip clearing the array before we consider the next start
     * point.
     *
     * workspace[] is an array of DumpableObject pointers, in which we try to
     * build lists of objects constituting loops.  We make workspace[] large
     * enough to hold all the objects in TopoSort's output, which is huge
     * overkill in most cases but could theoretically be necessary if there is
     * a single dependency chain linking all the objects.
     */
    bool       *processed;
    DumpId     *searchFailed;
    DumpableObject **workspace;
    bool        fixedloop;
    int         i;
 
    processed = (bool *) pg_malloc0((getMaxDumpId() + 1) * sizeof(bool));
    searchFailed = (DumpId *) pg_malloc0((getMaxDumpId() + 1) * sizeof(DumpId));
    workspace = (DumpableObject **) pg_malloc(totObjs * sizeof(DumpableObject *));
    fixedloop = false;
 
    for (i = 0; i < nObjs; i++)
    {
        DumpableObject *obj = objs[i];
        int         looplen;
        int         j;
 
        looplen = findLoop(obj,
                           obj->dumpId,
                           processed,
                           searchFailed,
                           workspace,
                           0);
 
        if (looplen > 0)
        {
            /* Found a loop, repair it */
            repairDependencyLoop(workspace, looplen);
            fixedloop = true;
            /* Mark loop members as processed */
            for (j = 0; j < looplen; j++)
                processed[workspace[j]->dumpId] = true;
        }
        else
        {
            /*
             * There's no loop starting at this object, but mark it processed
             * anyway.  This is not necessary for correctness, but saves later
             * invocations of findLoop() from uselessly chasing references to
             * such an object.
             */
            processed[obj->dumpId] = true;
        }
    }
 
    /* We'd better have fixed at least one loop */
    if (!fixedloop)
        pg_fatal("could not identify dependency loop");
 
    free(workspace);
    free(searchFailed);
    free(processed);
}
 
/*
 * Recursively search for a circular dependency loop that doesn't include
 * any already-processed objects.
 *
 *  obj: object we are examining now
 *  startPoint: dumpId of starting object for the hoped-for circular loop
 *  processed[]: flag array marking already-processed objects
 *  searchFailed[]: flag array marking already-unsuccessfully-visited objects
 *  workspace[]: work array in which we are building list of loop members
 *  depth: number of valid entries in workspace[] at call
 *
 * On success, the length of the loop is returned, and workspace[] is filled
 * with pointers to the members of the loop.  On failure, we return 0.
 *
 * 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 int
findLoop(DumpableObject *obj,
         DumpId startPoint,
         bool *processed,
         DumpId *searchFailed,
         DumpableObject **workspace,
         int depth)
{
    int         i;
 
    /*
     * Reject if obj is already processed.  This test prevents us from finding
     * loops that overlap previously-processed loops.
     */
    if (processed[obj->dumpId])
        return 0;
 
    /*
     * If we've already proven there is no path from this object back to the
     * startPoint, forget it.
     */
    if (searchFailed[obj->dumpId] == startPoint)
        return 0;
 
    /*
     * Reject if obj is already present in workspace.  This test 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 0;
    }
 
    /*
     * 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)
            return depth;
    }
 
    /*
     * Recurse down each outgoing branch
     */
    for (i = 0; i < obj->nDeps; i++)
    {
        DumpableObject *nextobj = findObjectByDumpId(obj->dependencies[i]);
        int         newDepth;
 
        if (!nextobj)
            continue;           /* ignore dependencies on undumped objects */
        newDepth = findLoop(nextobj,
                            startPoint,
                            processed,
                            searchFailed,
                            workspace,
                            depth);
        if (newDepth > 0)
            return newDepth;
    }
 
    /*
     * Remember there is no path from here back to startPoint
     */
    searchFailed[obj->dumpId] = startPoint;
 
    return 0;
}
 
/*
 * 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).
 * Similarly, a range type will have a loop with its canonicalize function,
 * if any.  Break the loop by making the 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 (always including the definition, as we need the
         * shell type defined to identify the function fully) as to be dumped
         * if any such function is
         */
        if (funcobj->dump)
            typeInfo->shellType->dobj.dump = funcobj->dump |
                DUMP_COMPONENT_DEFINITION;
    }
}
 
/*
 * 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.
 * This applies to matviews, as well.
 */
static void
repairViewRuleLoop(DumpableObject *viewobj,
                   DumpableObject *ruleobj)
{
    /* remove rule's dependency on view */
    removeObjectDependency(ruleobj, viewobj->dumpId);
    /* flags on the two objects are already set correctly for this case */
}
 
/*
 * 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.
 *
 * Note: this approach does *not* work for matviews, at the moment.
 */
static void
repairViewRuleMultiLoop(DumpableObject *viewobj,
                        DumpableObject *ruleobj)
{
    TableInfo  *viewinfo = (TableInfo *) viewobj;
    RuleInfo   *ruleinfo = (RuleInfo *) ruleobj;
 
    /* remove view's dependency on rule */
    removeObjectDependency(viewobj, ruleobj->dumpId);
    /* mark view to be printed with a dummy definition */
    viewinfo->dummy_view = true;
    /* mark rule as needing its own dump */
    ruleinfo->separate = true;
    /* put back rule's dependency on view */
    addObjectDependency(ruleobj, viewobj->dumpId);
    /* now that rule is separate, it must be post-data */
    addObjectDependency(ruleobj, postDataBoundId);
}
 
/*
 * If a matview is involved in a multi-object loop, we can't currently fix
 * that by splitting off the rule.  As a stopgap, we try to fix it by
 * dropping the constraint that the matview be dumped in the pre-data section.
 * This is sufficient to handle cases where a matview depends on some unique
 * index, as can happen if it has a GROUP BY for example.
 *
 * Note that the "next object" is not necessarily the matview itself;
 * it could be the matview's rowtype, for example.  We may come through here
 * several times while removing all the pre-data linkages.  In particular,
 * if there are other matviews that depend on the one with the circularity
 * problem, we'll come through here for each such matview and mark them all
 * as postponed.  (This works because all MVs have pre-data dependencies
 * to begin with, so each of them will get visited.)
 */
static void
repairMatViewBoundaryMultiLoop(DumpableObject *boundaryobj,
                               DumpableObject *nextobj)
{
    /* remove boundary's dependency on object after it in loop */
    removeObjectDependency(boundaryobj, nextobj->dumpId);
 
    /*
     * If that object is a matview or matview stats, mark it as postponed into
     * post-data.
     */
    if (nextobj->objType == DO_TABLE)
    {
        TableInfo  *nextinfo = (TableInfo *) nextobj;
 
        if (nextinfo->relkind == RELKIND_MATVIEW)
            nextinfo->postponed_def = true;
    }
    else if (nextobj->objType == DO_REL_STATS)
    {
        RelStatsInfo *nextinfo = (RelStatsInfo *) nextobj;
 
        if (nextinfo->relkind == RELKIND_MATVIEW)
            nextinfo->section = SECTION_POST_DATA;
    }
}
 
/*
 * If a function is involved in a multi-object loop, we can't currently fix
 * that by splitting it into two DumpableObjects.  As a stopgap, we try to fix
 * it by dropping the constraint that the function be dumped in the pre-data
 * section.  This is sufficient to handle cases where a function depends on
 * some unique index, as can happen if it has a GROUP BY for example.
 */
static void
repairFunctionBoundaryMultiLoop(DumpableObject *boundaryobj,
                                DumpableObject *nextobj)
{
    /* remove boundary's dependency on object after it in loop */
    removeObjectDependency(boundaryobj, nextobj->dumpId);
    /* if that object is a function, mark it as postponed into post-data */
    if (nextobj->objType == DO_FUNC)
    {
        FuncInfo   *nextinfo = (FuncInfo *) nextobj;
 
        nextinfo->postponed_def = true;
    }
}
 
/*
 * 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);
    /* now that constraint is separate, it must be post-data */
    addObjectDependency(constraintobj, postDataBoundId);
}
 
/*
 * 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, NOT NULL 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);
    /* now that constraint is separate, it must be post-data */
    addObjectDependency(constraintobj, postDataBoundId);
}
 
static void
repairIndexLoop(DumpableObject *partedindex,
                DumpableObject *partindex)
{
    removeObjectDependency(partedindex, partindex->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 or canonicalize 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 (including matview) and its ON SELECT rule */
    if (nLoop == 2 &&
        loop[0]->objType == DO_TABLE &&
        loop[1]->objType == DO_RULE &&
        (((TableInfo *) loop[0])->relkind == RELKIND_VIEW ||
         ((TableInfo *) loop[0])->relkind == RELKIND_MATVIEW) &&
        ((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 &&
        (((TableInfo *) loop[1])->relkind == RELKIND_VIEW ||
         ((TableInfo *) loop[1])->relkind == RELKIND_MATVIEW) &&
        ((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 (but not matview) and ON SELECT rule */
    if (nLoop > 2)
    {
        for (i = 0; i < nLoop; i++)
        {
            if (loop[i]->objType == DO_TABLE &&
                ((TableInfo *) loop[i])->relkind == RELKIND_VIEW)
            {
                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;
                    }
                }
            }
        }
    }
 
    /* Indirect loop involving matview and data boundary */
    if (nLoop > 2)
    {
        for (i = 0; i < nLoop; i++)
        {
            if (loop[i]->objType == DO_TABLE &&
                ((TableInfo *) loop[i])->relkind == RELKIND_MATVIEW)
            {
                for (j = 0; j < nLoop; j++)
                {
                    if (loop[j]->objType == DO_PRE_DATA_BOUNDARY)
                    {
                        DumpableObject *nextobj;
 
                        nextobj = (j < nLoop - 1) ? loop[j + 1] : loop[0];
                        repairMatViewBoundaryMultiLoop(loop[j], nextobj);
                        return;
                    }
                }
            }
            else if (loop[i]->objType == DO_REL_STATS &&
                     ((RelStatsInfo *) loop[i])->relkind == RELKIND_MATVIEW)
            {
                for (j = 0; j < nLoop; j++)
                {
                    if (loop[j]->objType == DO_POST_DATA_BOUNDARY)
                    {
                        DumpableObject *nextobj;
 
                        nextobj = (j < nLoop - 1) ? loop[j + 1] : loop[0];
                        repairMatViewBoundaryMultiLoop(loop[j], nextobj);
                        return;
                    }
                }
            }
        }
    }
 
    /* Indirect loop involving function and data boundary */
    if (nLoop > 2)
    {
        for (i = 0; i < nLoop; i++)
        {
            if (loop[i]->objType == DO_FUNC)
            {
                for (j = 0; j < nLoop; j++)
                {
                    if (loop[j]->objType == DO_PRE_DATA_BOUNDARY)
                    {
                        DumpableObject *nextobj;
 
                        nextobj = (j < nLoop - 1) ? loop[j + 1] : loop[0];
                        repairFunctionBoundaryMultiLoop(loop[j], nextobj);
                        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;
    }
 
    /* index on partitioned table and corresponding index on partition */
    if (nLoop == 2 &&
        loop[0]->objType == DO_INDEX &&
        loop[1]->objType == DO_INDEX)
    {
        if (((IndxInfo *) loop[0])->parentidx == loop[1]->catId.oid)
        {
            repairIndexLoop(loop[0], loop[1]);
            return;
        }
        else if (((IndxInfo *) loop[1])->parentidx == loop[0]->catId.oid)
        {
            repairIndexLoop(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 or NOT NULL constraint */
    if (nLoop == 2 &&
        loop[0]->objType == DO_TYPE &&
        loop[1]->objType == DO_CONSTRAINT &&
        (((ConstraintInfo *) loop[1])->contype == 'c' ||
         ((ConstraintInfo *) loop[1])->contype == 'n') &&
        ((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])->contype == 'n') &&
        ((ConstraintInfo *) loop[0])->condomain == (TypeInfo *) loop[1])
    {
        repairDomainConstraintLoop(loop[1], loop[0]);
        return;
    }
 
    /* Indirect loop involving domain and CHECK or NOT NULL 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])->contype == 'n') &&
                        ((ConstraintInfo *) loop[j])->condomain == (TypeInfo *) loop[i])
                    {
                        repairDomainConstraintMultiLoop(loop[i], loop[j]);
                        return;
                    }
                }
            }
        }
    }
 
    /*
     * Loop of table with itself --- just ignore it.
     *
     * (Actually, what this arises from is a dependency of a table column on
     * another column, which happened with generated columns before v15; or a
     * dependency of a table column on the whole table, which happens with
     * partitioning.  But we didn't pay attention to sub-object IDs while
     * collecting the dependency data, so we can't see that here.)
     */
    if (nLoop == 1)
    {
        if (loop[0]->objType == DO_TABLE)
        {
            removeObjectDependency(loop[0], loop[0]->dumpId);
            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)
    {
        pg_log_warning(ngettext("there are circular foreign-key constraints on this table:",
                                "there are circular foreign-key constraints among these tables:",
                                nLoop));
        for (i = 0; i < nLoop; i++)
            pg_log_warning_detail("%s", loop[i]->name);
        pg_log_warning_hint("You might not be able to restore the dump without using --disable-triggers or temporarily dropping the constraints.");
        pg_log_warning_hint("Consider using a full dump instead of a --data-only dump to avoid this problem.");
        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.
     */
    pg_log_warning("could not resolve dependency loop among these items:");
    for (i = 0; i < nLoop; i++)
    {
        char        buf[1024];
 
        describeDumpableObject(loop[i], buf, sizeof(buf));
        pg_log_warning_detail("%s", 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_EXTENSION:
            snprintf(buf, bufsize,
                     "EXTENSION %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_ACCESS_METHOD:
            snprintf(buf, bufsize,
                     "ACCESS METHOD %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_COLLATION:
            snprintf(buf, bufsize,
                     "COLLATION %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_TABLE_ATTACH:
            snprintf(buf, bufsize,
                     "TABLE ATTACH %s  (ID %d)",
                     obj->name, obj->dumpId);
            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_INDEX_ATTACH:
            snprintf(buf, bufsize,
                     "INDEX ATTACH %s  (ID %d)",
                     obj->name, obj->dumpId);
            return;
        case DO_STATSEXT:
            snprintf(buf, bufsize,
                     "STATISTICS %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
        case DO_REFRESH_MATVIEW:
            snprintf(buf, bufsize,
                     "REFRESH MATERIALIZED VIEW %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_EVENT_TRIGGER:
            snprintf(buf, bufsize,
                     "EVENT 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_TRANSFORM:
            snprintf(buf, bufsize,
                     "TRANSFORM %u lang %u  (ID %d OID %u)",
                     ((TransformInfo *) obj)->trftype,
                     ((TransformInfo *) obj)->trflang,
                     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_SEQUENCE_SET:
            snprintf(buf, bufsize,
                     "SEQUENCE SET %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
        case DO_DUMMY_TYPE:
            snprintf(buf, bufsize,
                     "DUMMY 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_FDW:
            snprintf(buf, bufsize,
                     "FOREIGN DATA WRAPPER %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
        case DO_FOREIGN_SERVER:
            snprintf(buf, bufsize,
                     "FOREIGN SERVER %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
        case DO_DEFAULT_ACL:
            snprintf(buf, bufsize,
                     "DEFAULT ACL %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
        case DO_LARGE_OBJECT:
            snprintf(buf, bufsize,
                     "LARGE OBJECT  (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_LARGE_OBJECT_DATA:
            snprintf(buf, bufsize,
                     "LARGE OBJECT DATA  (ID %d)",
                     obj->dumpId);
            return;
        case DO_POLICY:
            snprintf(buf, bufsize,
                     "POLICY (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_PUBLICATION:
            snprintf(buf, bufsize,
                     "PUBLICATION (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_PUBLICATION_REL:
            snprintf(buf, bufsize,
                     "PUBLICATION TABLE (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_PUBLICATION_TABLE_IN_SCHEMA:
            snprintf(buf, bufsize,
                     "PUBLICATION TABLES IN SCHEMA (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_SUBSCRIPTION:
            snprintf(buf, bufsize,
                     "SUBSCRIPTION (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_SUBSCRIPTION_REL:
            snprintf(buf, bufsize,
                     "SUBSCRIPTION TABLE (ID %d OID %u)",
                     obj->dumpId, obj->catId.oid);
            return;
        case DO_PRE_DATA_BOUNDARY:
            snprintf(buf, bufsize,
                     "PRE-DATA BOUNDARY  (ID %d)",
                     obj->dumpId);
            return;
        case DO_POST_DATA_BOUNDARY:
            snprintf(buf, bufsize,
                     "POST-DATA BOUNDARY  (ID %d)",
                     obj->dumpId);
            return;
        case DO_REL_STATS:
            snprintf(buf, bufsize,
                     "RELATION STATISTICS FOR %s  (ID %d OID %u)",
                     obj->name, obj->dumpId, obj->catId.oid);
            return;
    }
    /* shouldn't get here */
    snprintf(buf, bufsize,
             "object type %d  (ID %d OID %u)",
             (int) obj->objType,
             obj->dumpId, obj->catId.oid);
}
 
/* binaryheap comparator that compares "a" and "b" as integers */
static int
int_cmp(void *a, void *b, void *arg)
{
    int         ai = (int) (intptr_t) a;
    int         bi = (int) (intptr_t) b;
 
    return pg_cmp_s32(ai, bi);
}