postgresql/src/backend/catalog/pg_constraint.c

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/*-------------------------------------------------------------------------
*
* pg_constraint.c
* routines to support manipulation of the pg_constraint relation
*
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* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/catalog/pg_constraint.c,v 1.45 2009/06/11 14:48:55 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tqual.h"
/*
* CreateConstraintEntry
* Create a constraint table entry.
*
* Subsidiary records (such as triggers or indexes to implement the
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* 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,
const Oid *pfEqOp,
const Oid *ppEqOp,
const Oid *ffEqOp,
int foreignNKeys,
char foreignUpdateType,
char foreignDeleteType,
char foreignMatchType,
Oid indexRelId,
Node *conExpr,
const char *conBin,
const char *conSrc,
bool conIsLocal,
int conInhCount)
{
Relation conDesc;
Oid conOid;
HeapTuple tup;
bool nulls[Natts_pg_constraint];
Datum values[Natts_pg_constraint];
ArrayType *conkeyArray;
ArrayType *confkeyArray;
ArrayType *conpfeqopArray;
ArrayType *conppeqopArray;
ArrayType *conffeqopArray;
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 *fkdatums;
fkdatums = (Datum *) palloc(foreignNKeys * sizeof(Datum));
for (i = 0; i < foreignNKeys; i++)
fkdatums[i] = Int16GetDatum(foreignKey[i]);
confkeyArray = construct_array(fkdatums, foreignNKeys,
INT2OID, 2, true, 's');
for (i = 0; i < foreignNKeys; i++)
fkdatums[i] = ObjectIdGetDatum(pfEqOp[i]);
conpfeqopArray = construct_array(fkdatums, foreignNKeys,
OIDOID, sizeof(Oid), true, 'i');
for (i = 0; i < foreignNKeys; i++)
fkdatums[i] = ObjectIdGetDatum(ppEqOp[i]);
conppeqopArray = construct_array(fkdatums, foreignNKeys,
OIDOID, sizeof(Oid), true, 'i');
for (i = 0; i < foreignNKeys; i++)
fkdatums[i] = ObjectIdGetDatum(ffEqOp[i]);
conffeqopArray = construct_array(fkdatums, foreignNKeys,
OIDOID, sizeof(Oid), true, 'i');
}
else
{
confkeyArray = NULL;
conpfeqopArray = NULL;
conppeqopArray = NULL;
conffeqopArray = NULL;
}
/* initialize nulls and values */
for (i = 0; i < Natts_pg_constraint; i++)
{
nulls[i] = false;
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);
values[Anum_pg_constraint_conislocal - 1] = BoolGetDatum(conIsLocal);
values[Anum_pg_constraint_coninhcount - 1] = Int32GetDatum(conInhCount);
if (conkeyArray)
values[Anum_pg_constraint_conkey - 1] = PointerGetDatum(conkeyArray);
else
nulls[Anum_pg_constraint_conkey - 1] = true;
if (confkeyArray)
values[Anum_pg_constraint_confkey - 1] = PointerGetDatum(confkeyArray);
else
nulls[Anum_pg_constraint_confkey - 1] = true;
if (conpfeqopArray)
values[Anum_pg_constraint_conpfeqop - 1] = PointerGetDatum(conpfeqopArray);
else
nulls[Anum_pg_constraint_conpfeqop - 1] = true;
if (conppeqopArray)
values[Anum_pg_constraint_conppeqop - 1] = PointerGetDatum(conppeqopArray);
else
nulls[Anum_pg_constraint_conppeqop - 1] = true;
if (conffeqopArray)
values[Anum_pg_constraint_conffeqop - 1] = PointerGetDatum(conffeqopArray);
else
nulls[Anum_pg_constraint_conffeqop - 1] = true;
/*
* initialize the binary form of the check constraint.
*/
if (conBin)
values[Anum_pg_constraint_conbin - 1] = CStringGetTextDatum(conBin);
else
nulls[Anum_pg_constraint_conbin - 1] = true;
/*
* initialize the text form of the check constraint
*/
if (conSrc)
values[Anum_pg_constraint_consrc - 1] = CStringGetTextDatum(conSrc);
else
nulls[Anum_pg_constraint_consrc - 1] = true;
tup = heap_form_tuple(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))
{
/*
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* Register auto dependency from constraint to owning relation, or to
* specific column(s) if any are mentioned.
*/
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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
*/
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ObjectAddress domobject;
domobject.classId = TypeRelationId;
domobject.objectId = domainId;
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domobject.objectSubId = 0;
recordDependencyOn(&conobject, &domobject, DEPENDENCY_AUTO);
}
if (OidIsValid(foreignRelId))
{
/*
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* Register normal dependency from constraint to foreign relation, or
* to specific column(s) if any are mentioned.
*/
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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))
{
/*
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* 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 (foreignNKeys > 0)
{
/*
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* Register normal dependencies on the equality operators that support
* a foreign-key constraint. If the PK and FK types are the same then
* all three operators for a column are the same; otherwise they are
* different.
*/
ObjectAddress oprobject;
oprobject.classId = OperatorRelationId;
oprobject.objectSubId = 0;
for (i = 0; i < foreignNKeys; i++)
{
oprobject.objectId = pfEqOp[i];
recordDependencyOn(&conobject, &oprobject, DEPENDENCY_NORMAL);
if (ppEqOp[i] != pfEqOp[i])
{
oprobject.objectId = ppEqOp[i];
recordDependencyOn(&conobject, &oprobject, DEPENDENCY_NORMAL);
}
if (ffEqOp[i] != pfEqOp[i])
{
oprobject.objectId = ffEqOp[i];
recordDependencyOn(&conobject, &oprobject, DEPENDENCY_NORMAL);
}
}
}
if (conExpr != NULL)
{
/*
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* 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)))
{
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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.
*
* name1, name2, and label are used the same way as for makeObjectName(),
* except that the label can't be NULL; digits will be appended to the label
* if needed to create a name that is unique within the specified namespace.
*
* 'others' can be a list of string names already chosen within the current
* command (but not yet reflected into the catalogs); we will not choose
* a duplicate of one of these either.
*
* Note: it is theoretically possible to get a collision anyway, if someone
* else chooses the same name concurrently. This is fairly unlikely to be
* a problem in practice, especially if one is holding an exclusive lock on
* the relation identified by name1.
*
* Returns a palloc'd string.
*/
char *
ChooseConstraintName(const char *name1, const char *name2,
const char *label, Oid namespace,
List *others)
{
int pass = 0;
char *conname = NULL;
char modlabel[NAMEDATALEN];
Relation conDesc;
SysScanDesc conscan;
ScanKeyData skey[2];
bool found;
ListCell *l;
conDesc = heap_open(ConstraintRelationId, AccessShareLock);
/* try the unmodified label first */
StrNCpy(modlabel, label, sizeof(modlabel));
for (;;)
{
conname = makeObjectName(name1, name2, modlabel);
found = false;
foreach(l, others)
{
if (strcmp((char *) lfirst(l), conname) == 0)
{
found = true;
break;
}
}
if (!found)
{
ScanKeyInit(&skey[0],
Anum_pg_constraint_conname,
BTEqualStrategyNumber, F_NAMEEQ,
CStringGetDatum(conname));
ScanKeyInit(&skey[1],
Anum_pg_constraint_connamespace,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(namespace));
conscan = systable_beginscan(conDesc, ConstraintNameNspIndexId, true,
SnapshotNow, 2, skey);
found = (HeapTupleIsValid(systable_getnext(conscan)));
systable_endscan(conscan);
}
if (!found)
break;
/* found a conflict, so try a new name component */
pfree(conname);
snprintf(modlabel, sizeof(modlabel), "%s%d", label, ++pass);
}
heap_close(conDesc, AccessShareLock);
return conname;
}
/*
* Delete a single constraint record.
*/
void
RemoveConstraintById(Oid conId)
{
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Relation conDesc;
HeapTuple tup;
Form_pg_constraint con;
conDesc = heap_open(ConstraintRelationId, RowExclusiveLock);
tup = SearchSysCache(CONSTROID,
ObjectIdGetDatum(conId),
0, 0, 0);
if (!HeapTupleIsValid(tup)) /* should not happen */
elog(ERROR, "cache lookup failed for constraint %u", conId);
con = (Form_pg_constraint) GETSTRUCT(tup);
/*
* Special processing depending on what the constraint is for.
*/
if (OidIsValid(con->conrelid))
{
Relation rel;
/*
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* If the constraint is for a relation, open and exclusive-lock the
* relation it's for.
*/
rel = heap_open(con->conrelid, AccessExclusiveLock);
/*
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* We need to update the relcheck count if it is a check constraint
* being dropped. This update will force backends to rebuild relcache
* entries when we commit.
*/
if (con->contype == CONSTRAINT_CHECK)
{
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Relation pgrel;
HeapTuple relTup;
Form_pg_class classForm;
pgrel = heap_open(RelationRelationId, RowExclusiveLock);
relTup = SearchSysCacheCopy(RELOID,
ObjectIdGetDatum(con->conrelid),
0, 0, 0);
if (!HeapTupleIsValid(relTup))
elog(ERROR, "cache lookup failed for relation %u",
con->conrelid);
classForm = (Form_pg_class) GETSTRUCT(relTup);
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if (classForm->relchecks == 0) /* should not happen */
elog(ERROR, "relation \"%s\" has relchecks = 0",
RelationGetRelationName(rel));
classForm->relchecks--;
simple_heap_update(pgrel, &relTup->t_self, relTup);
CatalogUpdateIndexes(pgrel, relTup);
heap_freetuple(relTup);
heap_close(pgrel, RowExclusiveLock);
}
/* Keep lock on constraint's rel until end of xact */
heap_close(rel, NoLock);
}
else if (OidIsValid(con->contypid))
{
/*
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* XXX for now, do nothing special when dropping a domain constraint
*
* Probably there should be some form of locking on the domain type,
* but we have no such concept at the moment.
*/
}
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else
elog(ERROR, "constraint %u is not of a known type", conId);
/* Fry the constraint itself */
simple_heap_delete(conDesc, &tup->t_self);
/* Clean up */
ReleaseSysCache(tup);
heap_close(conDesc, RowExclusiveLock);
}
/*
* RenameConstraintById
* Rename a constraint.
*
* Note: this isn't intended to be a user-exposed function; it doesn't check
* permissions etc. Currently this is only invoked when renaming an index
* that is associated with a constraint, but it's made a little more general
* than that with the expectation of someday having ALTER TABLE RENAME
* CONSTRAINT.
*/
void
RenameConstraintById(Oid conId, const char *newname)
{
Relation conDesc;
HeapTuple tuple;
Form_pg_constraint con;
conDesc = heap_open(ConstraintRelationId, RowExclusiveLock);
tuple = SearchSysCacheCopy(CONSTROID,
ObjectIdGetDatum(conId),
0, 0, 0);
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for constraint %u", conId);
con = (Form_pg_constraint) GETSTRUCT(tuple);
/*
* We need to check whether the name is already in use --- note that there
* currently is not a unique index that would catch this.
*/
if (OidIsValid(con->conrelid) &&
ConstraintNameIsUsed(CONSTRAINT_RELATION,
con->conrelid,
con->connamespace,
newname))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("constraint \"%s\" for relation \"%s\" already exists",
newname, get_rel_name(con->conrelid))));
if (OidIsValid(con->contypid) &&
ConstraintNameIsUsed(CONSTRAINT_DOMAIN,
con->contypid,
con->connamespace,
newname))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("constraint \"%s\" for domain \"%s\" already exists",
newname, format_type_be(con->contypid))));
/* OK, do the rename --- tuple is a copy, so OK to scribble on it */
namestrcpy(&(con->conname), newname);
simple_heap_update(conDesc, &tuple->t_self, tuple);
/* update the system catalog indexes */
CatalogUpdateIndexes(conDesc, tuple);
heap_freetuple(tuple);
heap_close(conDesc, RowExclusiveLock);
}
/*
* AlterConstraintNamespaces
* Find any constraints belonging to the specified object,
* and move them to the specified new namespace.
*
* isType indicates whether the owning object is a type or a relation.
*/
void
AlterConstraintNamespaces(Oid ownerId, Oid oldNspId,
Oid newNspId, bool isType)
{
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Relation conRel;
ScanKeyData key[1];
SysScanDesc scan;
HeapTuple tup;
conRel = heap_open(ConstraintRelationId, RowExclusiveLock);
if (isType)
{
ScanKeyInit(&key[0],
Anum_pg_constraint_contypid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(ownerId));
scan = systable_beginscan(conRel, ConstraintTypidIndexId, true,
SnapshotNow, 1, key);
}
else
{
ScanKeyInit(&key[0],
Anum_pg_constraint_conrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(ownerId));
scan = systable_beginscan(conRel, ConstraintRelidIndexId, true,
SnapshotNow, 1, key);
}
while (HeapTupleIsValid((tup = systable_getnext(scan))))
{
Form_pg_constraint conform = (Form_pg_constraint) GETSTRUCT(tup);
if (conform->connamespace == oldNspId)
{
tup = heap_copytuple(tup);
conform = (Form_pg_constraint) GETSTRUCT(tup);
conform->connamespace = newNspId;
simple_heap_update(conRel, &tup->t_self, tup);
CatalogUpdateIndexes(conRel, tup);
/*
* Note: currently, the constraint will not have its own
* dependency on the namespace, so we don't need to do
* changeDependencyFor().
*/
}
}
systable_endscan(scan);
heap_close(conRel, RowExclusiveLock);
}