mirror of https://github.com/citusdata/citus.git
Speed up GetForeignKeyOids
GetForeignKeyOids was showing up in CPU profiles when distributing schemas on systems with 100k+ constraints. The reason was that this function was doing a sequence scan of pg_constraint to get the foreign keys that referenced the requested table. This fixes that by finding the constraints referencing the table through pg_depend instead of pg_constraint. We're doing this indirection, because pg_constraint doesn't have an index that we can use, but pg_depend does.fix-all
Jelte Fennema-Nio
parent
8f4cca5e85
commit
821ca06f17
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@ -20,6 +20,7 @@
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#include "access/xact.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_constraint.h"
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#include "catalog/pg_depend.h"
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#include "catalog/pg_type.h"
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#include "utils/builtins.h"
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#include "utils/fmgroids.h"
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@ -36,6 +37,7 @@
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#include "distributed/commands.h"
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#include "distributed/commands/sequence.h"
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#include "distributed/coordinator_protocol.h"
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#include "distributed/hash_helpers.h"
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#include "distributed/listutils.h"
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#include "distributed/multi_join_order.h"
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#include "distributed/namespace_utils.h"
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@ -1199,64 +1201,16 @@ TableHasExternalForeignKeys(Oid relationId)
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/*
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* GetForeignKeyOids takes in a relationId, and returns a list of OIDs for
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* foreign constraints that the relation with relationId is involved according
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* to "flags" argument. See ExtractForeignKeyConstraintsMode enum definition
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* for usage of the flags.
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* ForeignConstraintMatchesFlags is a function with logic that's very specific
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* to GetForeignKeyOids. There's no reason to use it in any other context.
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*/
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List *
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GetForeignKeyOids(Oid relationId, int flags)
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static bool
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ForeignConstraintMatchesFlags(Form_pg_constraint constraintForm,
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int flags)
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{
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AttrNumber pgConstraintTargetAttrNumber = InvalidAttrNumber;
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bool extractReferencing = (flags & INCLUDE_REFERENCING_CONSTRAINTS);
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bool extractReferenced = (flags & INCLUDE_REFERENCED_CONSTRAINTS);
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/*
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* Only one of them should be passed at a time since the way we scan
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* pg_constraint differs for those columns. Anum_pg_constraint_conrelid
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* supports index scan while Anum_pg_constraint_confrelid does not.
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*/
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Assert(!(extractReferencing && extractReferenced));
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Assert(extractReferencing || extractReferenced);
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bool useIndex = false;
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Oid indexOid = InvalidOid;
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if (extractReferencing)
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{
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pgConstraintTargetAttrNumber = Anum_pg_constraint_conrelid;
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useIndex = true;
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indexOid = ConstraintRelidTypidNameIndexId;
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}
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else if (extractReferenced)
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{
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pgConstraintTargetAttrNumber = Anum_pg_constraint_confrelid;
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}
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bool excludeSelfReference = (flags & EXCLUDE_SELF_REFERENCES);
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List *foreignKeyOids = NIL;
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ScanKeyData scanKey[1];
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int scanKeyCount = 1;
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Relation pgConstraint = table_open(ConstraintRelationId, AccessShareLock);
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ScanKeyInit(&scanKey[0], pgConstraintTargetAttrNumber,
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BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(relationId));
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SysScanDesc scanDescriptor = systable_beginscan(pgConstraint, indexOid, useIndex,
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NULL, scanKeyCount, scanKey);
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HeapTuple heapTuple = systable_getnext(scanDescriptor);
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while (HeapTupleIsValid(heapTuple))
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{
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Form_pg_constraint constraintForm = (Form_pg_constraint) GETSTRUCT(heapTuple);
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if (constraintForm->contype != CONSTRAINT_FOREIGN)
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{
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heapTuple = systable_getnext(scanDescriptor);
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continue;
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return false;
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}
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bool inheritedConstraint = OidIsValid(constraintForm->conparentid);
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@ -1267,38 +1221,141 @@ GetForeignKeyOids(Oid relationId, int flags)
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* the table as we already process the constraints from parent tables
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* implicitly when a command is issued
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*/
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heapTuple = systable_getnext(scanDescriptor);
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continue;
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return false;
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}
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Oid constraintId = constraintForm->oid;
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bool excludeSelfReference = (flags & EXCLUDE_SELF_REFERENCES);
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bool isSelfReference = (constraintForm->conrelid == constraintForm->confrelid);
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if (excludeSelfReference && isSelfReference)
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{
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heapTuple = systable_getnext(scanDescriptor);
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continue;
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return false;
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}
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Oid otherTableId = InvalidOid;
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if (extractReferencing)
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if (flags & INCLUDE_REFERENCING_CONSTRAINTS)
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{
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otherTableId = constraintForm->confrelid;
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}
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else if (extractReferenced)
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else
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{
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otherTableId = constraintForm->conrelid;
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}
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if (!IsTableTypeIncluded(otherTableId, flags))
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return IsTableTypeIncluded(otherTableId, flags);
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}
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/*
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* GetForeignKeyOidsForReferencedTable returns a list of foreign key OIDs that
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* reference the relationId and match the given flags.
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*
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* This is separated from GetForeignKeyOids because we need to scan pg_depend
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* instead of pg_constraint directly. The reason for this is that there is no
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* index on the confrelid of pg_constraint, so searching by that column
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* requires a seqscan.
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*/
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static List *
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GetForeignKeyOidsForReferencedTable(Oid relationId, int flags)
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{
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HTAB *foreignKeyOidsSet = CreateSimpleHashSetWithName(
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Oid, "ReferencingForeignKeyOidsSet");
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List *foreignKeyOidsList = NIL;
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ScanKeyData key[2];
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HeapTuple dependTup;
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Relation depRel = table_open(DependRelationId, AccessShareLock);
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ScanKeyInit(&key[0],
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Anum_pg_depend_refclassid,
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BTEqualStrategyNumber, F_OIDEQ,
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ObjectIdGetDatum(RelationRelationId));
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ScanKeyInit(&key[1],
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Anum_pg_depend_refobjid,
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BTEqualStrategyNumber, F_OIDEQ,
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ObjectIdGetDatum(relationId));
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SysScanDesc scan = systable_beginscan(depRel, DependReferenceIndexId, true,
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NULL, lengthof(key), key);
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while (HeapTupleIsValid(dependTup = systable_getnext(scan)))
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{
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Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(dependTup);
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if (deprec->classid != ConstraintRelationId ||
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deprec->deptype != DEPENDENCY_NORMAL ||
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hash_search(foreignKeyOidsSet, &deprec->objid, HASH_FIND, NULL))
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{
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heapTuple = systable_getnext(scanDescriptor);
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continue;
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}
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foreignKeyOids = lappend_oid(foreignKeyOids, constraintId);
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heapTuple = systable_getnext(scanDescriptor);
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HeapTuple constraintTup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(
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deprec->objid));
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if (!HeapTupleIsValid(constraintTup)) /* can happen during DROP TABLE */
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{
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continue;
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}
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Form_pg_constraint constraint = (Form_pg_constraint) GETSTRUCT(constraintTup);
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if (constraint->confrelid == relationId &&
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ForeignConstraintMatchesFlags(constraint, flags))
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{
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foreignKeyOidsList = lappend_oid(foreignKeyOidsList, constraint->oid);
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hash_search(foreignKeyOidsSet, &constraint->oid, HASH_ENTER, NULL);
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}
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ReleaseSysCache(constraintTup);
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}
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systable_endscan(scan);
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table_close(depRel, AccessShareLock);
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return foreignKeyOidsList;
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}
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/*
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* GetForeignKeyOids takes in a relationId, and returns a list of OIDs for
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* foreign constraints that the relation with relationId is involved according
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* to "flags" argument. See ExtractForeignKeyConstraintsMode enum definition
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* for usage of the flags.
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*/
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List *
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GetForeignKeyOids(Oid relationId, int flags)
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{
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bool extractReferencing PG_USED_FOR_ASSERTS_ONLY = (flags &
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INCLUDE_REFERENCING_CONSTRAINTS);
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bool extractReferenced = (flags & INCLUDE_REFERENCED_CONSTRAINTS);
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/*
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* Only one of them should be passed at a time since the way we scan
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* pg_constraint differs for those columns. Anum_pg_constraint_conrelid
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* supports index scan while Anum_pg_constraint_confrelid does not.
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*/
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Assert(!(extractReferencing && extractReferenced));
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Assert(extractReferencing || extractReferenced);
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if (extractReferenced)
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{
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return GetForeignKeyOidsForReferencedTable(relationId, flags);
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}
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List *foreignKeyOids = NIL;
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ScanKeyData scanKey[1];
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int scanKeyCount = 1;
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Relation pgConstraint = table_open(ConstraintRelationId, AccessShareLock);
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ScanKeyInit(&scanKey[0], Anum_pg_constraint_conrelid,
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BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(relationId));
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SysScanDesc scanDescriptor = systable_beginscan(pgConstraint,
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ConstraintRelidTypidNameIndexId, true,
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NULL, scanKeyCount, scanKey);
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HeapTuple heapTuple;
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while (HeapTupleIsValid(heapTuple = systable_getnext(scanDescriptor)))
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{
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Form_pg_constraint constraintForm = (Form_pg_constraint) GETSTRUCT(heapTuple);
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if (ForeignConstraintMatchesFlags(constraintForm, flags))
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{
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foreignKeyOids = lappend_oid(foreignKeyOids, constraintForm->oid);
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}
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}
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systable_endscan(scanDescriptor);
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