pg_constraint.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * pg_constraint.c
 *	  routines to support manipulation of the pg_constraint relation
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/catalog/pg_constraint.c,v 1.27.2.1 2005/11/22 18:23:06 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "access/genam.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_depend.h"
#include "catalog/pg_trigger.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "miscadmin.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"


/*
 * CreateConstraintEntry
 *	Create a constraint table entry.
 *
 * Subsidiary records (such as triggers or indexes to implement the
 * constraint) are *not* created here.	But we do make dependency links
 * from the constraint to the things it depends on.
 */
Oid
CreateConstraintEntry(const char *constraintName,
					  Oid constraintNamespace,
					  char constraintType,
					  bool isDeferrable,
					  bool isDeferred,
					  Oid relId,
					  const int16 *constraintKey,
					  int constraintNKeys,
					  Oid domainId,
					  Oid foreignRelId,
					  const int16 *foreignKey,
					  int foreignNKeys,
					  char foreignUpdateType,
					  char foreignDeleteType,
					  char foreignMatchType,
					  Oid indexRelId,
					  Node *conExpr,
					  const char *conBin,
					  const char *conSrc)
{
	Relation	conDesc;
	Oid			conOid;
	HeapTuple	tup;
	char		nulls[Natts_pg_constraint];
	Datum		values[Natts_pg_constraint];
	ArrayType  *conkeyArray;
	ArrayType  *confkeyArray;
	NameData	cname;
	int			i;
	ObjectAddress conobject;

	conDesc = heap_open(ConstraintRelationId, RowExclusiveLock);

	Assert(constraintName);
	namestrcpy(&cname, constraintName);

	/*
	 * Convert C arrays into Postgres arrays.
	 */
	if (constraintNKeys > 0)
	{
		Datum	   *conkey;

		conkey = (Datum *) palloc(constraintNKeys * sizeof(Datum));
		for (i = 0; i < constraintNKeys; i++)
			conkey[i] = Int16GetDatum(constraintKey[i]);
		conkeyArray = construct_array(conkey, constraintNKeys,
									  INT2OID, 2, true, 's');
	}
	else
		conkeyArray = NULL;

	if (foreignNKeys > 0)
	{
		Datum	   *confkey;

		confkey = (Datum *) palloc(foreignNKeys * sizeof(Datum));
		for (i = 0; i < foreignNKeys; i++)
			confkey[i] = Int16GetDatum(foreignKey[i]);
		confkeyArray = construct_array(confkey, foreignNKeys,
									   INT2OID, 2, true, 's');
	}
	else
		confkeyArray = NULL;

	/* initialize nulls and values */
	for (i = 0; i < Natts_pg_constraint; i++)
	{
		nulls[i] = ' ';
		values[i] = (Datum) NULL;
	}

	values[Anum_pg_constraint_conname - 1] = NameGetDatum(&cname);
	values[Anum_pg_constraint_connamespace - 1] = ObjectIdGetDatum(constraintNamespace);
	values[Anum_pg_constraint_contype - 1] = CharGetDatum(constraintType);
	values[Anum_pg_constraint_condeferrable - 1] = BoolGetDatum(isDeferrable);
	values[Anum_pg_constraint_condeferred - 1] = BoolGetDatum(isDeferred);
	values[Anum_pg_constraint_conrelid - 1] = ObjectIdGetDatum(relId);
	values[Anum_pg_constraint_contypid - 1] = ObjectIdGetDatum(domainId);
	values[Anum_pg_constraint_confrelid - 1] = ObjectIdGetDatum(foreignRelId);
	values[Anum_pg_constraint_confupdtype - 1] = CharGetDatum(foreignUpdateType);
	values[Anum_pg_constraint_confdeltype - 1] = CharGetDatum(foreignDeleteType);
	values[Anum_pg_constraint_confmatchtype - 1] = CharGetDatum(foreignMatchType);

	if (conkeyArray)
		values[Anum_pg_constraint_conkey - 1] = PointerGetDatum(conkeyArray);
	else
		nulls[Anum_pg_constraint_conkey - 1] = 'n';

	if (confkeyArray)
		values[Anum_pg_constraint_confkey - 1] = PointerGetDatum(confkeyArray);
	else
		nulls[Anum_pg_constraint_confkey - 1] = 'n';

	/*
	 * initialize the binary form of the check constraint.
	 */
	if (conBin)
		values[Anum_pg_constraint_conbin - 1] = DirectFunctionCall1(textin,
													CStringGetDatum(conBin));
	else
		nulls[Anum_pg_constraint_conbin - 1] = 'n';

	/*
	 * initialize the text form of the check constraint
	 */
	if (conSrc)
		values[Anum_pg_constraint_consrc - 1] = DirectFunctionCall1(textin,
													CStringGetDatum(conSrc));
	else
		nulls[Anum_pg_constraint_consrc - 1] = 'n';

	tup = heap_formtuple(RelationGetDescr(conDesc), values, nulls);

	conOid = simple_heap_insert(conDesc, tup);

	/* update catalog indexes */
	CatalogUpdateIndexes(conDesc, tup);

	conobject.classId = ConstraintRelationId;
	conobject.objectId = conOid;
	conobject.objectSubId = 0;

	heap_close(conDesc, RowExclusiveLock);

	if (OidIsValid(relId))
	{
		/*
		 * Register auto dependency from constraint to owning relation, or to
		 * specific column(s) if any are mentioned.
		 */
		ObjectAddress relobject;

		relobject.classId = RelationRelationId;
		relobject.objectId = relId;
		if (constraintNKeys > 0)
		{
			for (i = 0; i < constraintNKeys; i++)
			{
				relobject.objectSubId = constraintKey[i];

				recordDependencyOn(&conobject, &relobject, DEPENDENCY_AUTO);
			}
		}
		else
		{
			relobject.objectSubId = 0;

			recordDependencyOn(&conobject, &relobject, DEPENDENCY_AUTO);
		}
	}

	if (OidIsValid(domainId))
	{
		/*
		 * Register auto dependency from constraint to owning domain
		 */
		ObjectAddress domobject;

		domobject.classId = TypeRelationId;
		domobject.objectId = domainId;
		domobject.objectSubId = 0;

		recordDependencyOn(&conobject, &domobject, DEPENDENCY_AUTO);
	}

	if (OidIsValid(foreignRelId))
	{
		/*
		 * Register normal dependency from constraint to foreign relation, or
		 * to specific column(s) if any are mentioned.
		 */
		ObjectAddress relobject;

		relobject.classId = RelationRelationId;
		relobject.objectId = foreignRelId;
		if (foreignNKeys > 0)
		{
			for (i = 0; i < foreignNKeys; i++)
			{
				relobject.objectSubId = foreignKey[i];

				recordDependencyOn(&conobject, &relobject, DEPENDENCY_NORMAL);
			}
		}
		else
		{
			relobject.objectSubId = 0;

			recordDependencyOn(&conobject, &relobject, DEPENDENCY_NORMAL);
		}
	}

	if (OidIsValid(indexRelId))
	{
		/*
		 * Register normal dependency on the unique index that supports a
		 * foreign-key constraint.
		 */
		ObjectAddress relobject;

		relobject.classId = RelationRelationId;
		relobject.objectId = indexRelId;
		relobject.objectSubId = 0;

		recordDependencyOn(&conobject, &relobject, DEPENDENCY_NORMAL);
	}

	if (conExpr != NULL)
	{
		/*
		 * Register dependencies from constraint to objects mentioned in CHECK
		 * expression.
		 */
		recordDependencyOnSingleRelExpr(&conobject, conExpr, relId,
										DEPENDENCY_NORMAL,
										DEPENDENCY_NORMAL);
	}

	return conOid;
}


/*
 * Test whether given name is currently used as a constraint name
 * for the given object (relation or domain).
 *
 * This is used to decide whether to accept a user-specified constraint name.
 * It is deliberately not the same test as ChooseConstraintName uses to decide
 * whether an auto-generated name is OK: here, we will allow it unless there
 * is an identical constraint name in use *on the same object*.
 *
 * NB: Caller should hold exclusive lock on the given object, else
 * this test can be fooled by concurrent additions.
 */
bool
ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,
					 Oid objNamespace, const char *conname)
{
	bool		found;
	Relation	conDesc;
	SysScanDesc conscan;
	ScanKeyData skey[2];
	HeapTuple	tup;

	conDesc = heap_open(ConstraintRelationId, AccessShareLock);

	found = false;

	ScanKeyInit(&skey[0],
				Anum_pg_constraint_conname,
				BTEqualStrategyNumber, F_NAMEEQ,
				CStringGetDatum(conname));

	ScanKeyInit(&skey[1],
				Anum_pg_constraint_connamespace,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(objNamespace));

	conscan = systable_beginscan(conDesc, ConstraintNameNspIndexId, true,
								 SnapshotNow, 2, skey);

	while (HeapTupleIsValid(tup = systable_getnext(conscan)))
	{
		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tup);

		if (conCat == CONSTRAINT_RELATION && con->conrelid == objId)
		{
			found = true;
			break;
		}
		else if (conCat == CONSTRAINT_DOMAIN && con->contypid == objId)
		{
			found = true;
			break;
		}
	}

	systable_endscan(conscan);
	heap_close(conDesc, AccessShareLock);

	return found;
}

/*
 * Select a nonconflicting name for a new constraint.
 *
 * The objective here is to choose a name that is unique within the
 * specified namespace.  Postgres does not require this, but the SQL
 * spec does, and some apps depend on it.  Therefore we avoid choosing
 * default names that so conflict.