indexcmds.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	 * error checks)
	 */
	if (isconstraint && !quiet)
		ereport(NOTICE,
		  (errmsg("%s %s will create implicit index \"%s\" for table \"%s\"",
				  is_alter_table ? "ALTER TABLE / ADD" : "CREATE TABLE /",
				  primary ? "PRIMARY KEY" : "UNIQUE",
				  indexRelationName, RelationGetRelationName(rel))));

	index_create(relationId, indexRelationName, indexRelationId,
				 indexInfo, accessMethodId, tablespaceId, classObjectId,
				 primary, isconstraint,
				 allowSystemTableMods, skip_build);

	/*
	 * We update the relation's pg_class tuple even if it already has
	 * relhasindex = true.	This is needed to cause a shared-cache-inval
	 * message to be sent for the pg_class tuple, which will cause other
	 * backends to flush their relcache entries and in particular their cached
	 * lists of the indexes for this relation.
	 */
	setRelhasindex(relationId, true, primary, InvalidOid);
}


/*
 * CheckPredicate
 *		Checks that the given partial-index predicate is valid.
 *
 * This used to also constrain the form of the predicate to forms that
 * indxpath.c could do something with.	However, that seems overly
 * restrictive.  One useful application of partial indexes is to apply
 * a UNIQUE constraint across a subset of a table, and in that scenario
 * any evaluatable predicate will work.  So accept any predicate here
 * (except ones requiring a plan), and let indxpath.c fend for itself.
 */
static void
CheckPredicate(Expr *predicate)
{
	/*
	 * We don't currently support generation of an actual query plan for a
	 * predicate, only simple scalar expressions; hence these restrictions.
	 */
	if (contain_subplans((Node *) predicate))
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("cannot use subquery in index predicate")));
	if (contain_agg_clause((Node *) predicate))
		ereport(ERROR,
				(errcode(ERRCODE_GROUPING_ERROR),
				 errmsg("cannot use aggregate in index predicate")));

	/*
	 * A predicate using mutable functions is probably wrong, for the same
	 * reasons that we don't allow an index expression to use one.
	 */
	if (contain_mutable_functions((Node *) predicate))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
		   errmsg("functions in index predicate must be marked IMMUTABLE")));
}

static void
ComputeIndexAttrs(IndexInfo *indexInfo,
				  Oid *classOidP,
				  List *attList,	/* list of IndexElem's */
				  Oid relId,
				  char *accessMethodName,
				  Oid accessMethodId,
				  bool isconstraint)
{
	ListCell   *rest;
	int			attn = 0;

	/*
	 * process attributeList
	 */
	foreach(rest, attList)
	{
		IndexElem  *attribute = (IndexElem *) lfirst(rest);
		Oid			atttype;

		if (attribute->name != NULL)
		{
			/* Simple index attribute */
			HeapTuple	atttuple;
			Form_pg_attribute attform;

			Assert(attribute->expr == NULL);
			atttuple = SearchSysCacheAttName(relId, attribute->name);
			if (!HeapTupleIsValid(atttuple))
			{
				/* difference in error message spellings is historical */
				if (isconstraint)
					ereport(ERROR,
							(errcode(ERRCODE_UNDEFINED_COLUMN),
						  errmsg("column \"%s\" named in key does not exist",
								 attribute->name)));
				else
					ereport(ERROR,
							(errcode(ERRCODE_UNDEFINED_COLUMN),
							 errmsg("column \"%s\" does not exist",
									attribute->name)));
			}
			attform = (Form_pg_attribute) GETSTRUCT(atttuple);
			indexInfo->ii_KeyAttrNumbers[attn] = attform->attnum;
			atttype = attform->atttypid;
			ReleaseSysCache(atttuple);
		}
		else if (attribute->expr && IsA(attribute->expr, Var))
		{
			/* Tricky tricky, he wrote (column) ... treat as simple attr */
			Var		   *var = (Var *) attribute->expr;

			indexInfo->ii_KeyAttrNumbers[attn] = var->varattno;
			atttype = get_atttype(relId, var->varattno);
		}
		else
		{
			/* Index expression */
			Assert(attribute->expr != NULL);
			indexInfo->ii_KeyAttrNumbers[attn] = 0;		/* marks expression */
			indexInfo->ii_Expressions = lappend(indexInfo->ii_Expressions,
												attribute->expr);
			atttype = exprType(attribute->expr);

			/*
			 * We don't currently support generation of an actual query plan
			 * for an index expression, only simple scalar expressions; hence
			 * these restrictions.
			 */
			if (contain_subplans(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot use subquery in index expression")));
			if (contain_agg_clause(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_GROUPING_ERROR),
				errmsg("cannot use aggregate function in index expression")));

			/*
			 * A expression using mutable functions is probably wrong, since
			 * if you aren't going to get the same result for the same data
			 * every time, it's not clear what the index entries mean at all.
			 */
			if (contain_mutable_functions(attribute->expr))
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
						 errmsg("functions in index expression must be marked IMMUTABLE")));
		}

		classOidP[attn] = GetIndexOpClass(attribute->opclass,
										  atttype,
										  accessMethodName,
										  accessMethodId);
		attn++;
	}
}

/*
 * Resolve possibly-defaulted operator class specification
 */
static Oid
GetIndexOpClass(List *opclass, Oid attrType,
				char *accessMethodName, Oid accessMethodId)
{
	char	   *schemaname;
	char	   *opcname;
	HeapTuple	tuple;
	Oid			opClassId,
				opInputType;

	/*
	 * Release 7.0 removed network_ops, timespan_ops, and datetime_ops, so we
	 * ignore those opclass names so the default *_ops is used.  This can be
	 * removed in some later release.  bjm 2000/02/07
	 *
	 * Release 7.1 removes lztext_ops, so suppress that too for a while.  tgl
	 * 2000/07/30
	 *
	 * Release 7.2 renames timestamp_ops to timestamptz_ops, so suppress that
	 * too for awhile.	I'm starting to think we need a better approach. tgl
	 * 2000/10/01
	 *
	 * Release 8.0 removes bigbox_ops (which was dead code for a long while
	 * anyway).  tgl 2003/11/11
	 */
	if (list_length(opclass) == 1)
	{
		char	   *claname = strVal(linitial(opclass));

		if (strcmp(claname, "network_ops") == 0 ||
			strcmp(claname, "timespan_ops") == 0 ||
			strcmp(claname, "datetime_ops") == 0 ||
			strcmp(claname, "lztext_ops") == 0 ||
			strcmp(claname, "timestamp_ops") == 0 ||
			strcmp(claname, "bigbox_ops") == 0)
			opclass = NIL;
	}

	if (opclass == NIL)
	{
		/* no operator class specified, so find the default */
		opClassId = GetDefaultOpClass(attrType, accessMethodId);
		if (!OidIsValid(opClassId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("data type %s has no default operator class for access method \"%s\"",
							format_type_be(attrType), accessMethodName),
					 errhint("You must specify an operator class for the index or define a default operator class for the data type.")));
		return opClassId;
	}

	/*
	 * Specific opclass name given, so look up the opclass.
	 */

	/* deconstruct the name list */
	DeconstructQualifiedName(opclass, &schemaname, &opcname);

	if (schemaname)
	{
		/* Look in specific schema only */
		Oid			namespaceId;

		namespaceId = LookupExplicitNamespace(schemaname);
		tuple = SearchSysCache(CLAAMNAMENSP,
							   ObjectIdGetDatum(accessMethodId),
							   PointerGetDatum(opcname),
							   ObjectIdGetDatum(namespaceId),
							   0);
	}
	else
	{
		/* Unqualified opclass name, so search the search path */
		opClassId = OpclassnameGetOpcid(accessMethodId, opcname);
		if (!OidIsValid(opClassId))
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
							opcname, accessMethodName)));
		tuple = SearchSysCache(CLAOID,
							   ObjectIdGetDatum(opClassId),
							   0, 0, 0);
	}

	if (!HeapTupleIsValid(tuple))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("operator class \"%s\" does not exist for access method \"%s\"",
						NameListToString(opclass), accessMethodName)));

	/*
	 * Verify that the index operator class accepts this datatype.	Note we
	 * will accept binary compatibility.
	 */
	opClassId = HeapTupleGetOid(tuple);
	opInputType = ((Form_pg_opclass) GETSTRUCT(tuple))->opcintype;

	if (!IsBinaryCoercible(attrType, opInputType))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("operator class \"%s\" does not accept data type %s",
					  NameListToString(opclass), format_type_be(attrType))));

	ReleaseSysCache(tuple);

	return opClassId;
}

/*
 * GetDefaultOpClass
 *
 * Given the OIDs of a datatype and an access method, find the default
 * operator class, if any.	Returns InvalidOid if there is none.
 */
Oid
GetDefaultOpClass(Oid type_id, Oid am_id)
{
	int			nexact = 0;
	int			ncompatible = 0;
	Oid			exactOid = InvalidOid;
	Oid			compatibleOid = InvalidOid;
	Relation	rel;
	ScanKeyData skey[1];
	SysScanDesc scan;
	HeapTuple	tup;

	/* If it's a domain, look at the base type instead */
	type_id = getBaseType(type_id);

	/*
	 * We scan through all the opclasses available for the access method,
	 * looking for one that is marked default and matches the target type
	 * (either exactly or binary-compatibly, but prefer an exact match).
	 *
	 * We could find more than one binary-compatible match, in which case we
	 * require the user to specify which one he wants.	If we find more than
	 * one exact match, then someone put bogus entries in pg_opclass.
	 */
	rel = heap_open(OperatorClassRelationId, AccessShareLock);

	ScanKeyInit(&skey[0],
				Anum_pg_opclass_opcamid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(am_id));

	scan = systable_beginscan(rel, OpclassAmNameNspIndexId, true,
							  SnapshotNow, 1, skey);

	while (HeapTupleIsValid(tup = systable_getnext(scan)))
	{
		Form_pg_opclass opclass = (Form_pg_opclass) GETSTRUCT(tup);

		if (opclass->opcdefault)
		{
			if (opclass->opcintype == type_id)
			{
				nexact++;
				exactOid = HeapTupleGetOid(tup);
			}
			else if (IsBinaryCoercible(type_id, opclass->opcintype))
			{
				ncompatible++;
				compatibleOid = HeapTupleGetOid(tup);
			}
		}
	}

	systable_endscan(scan);

	heap_close(rel, AccessShareLock);

	if (nexact == 1)
		return exactOid;
	if (nexact != 0)
		ereport(ERROR,
				(errcode(ERRCODE_DUPLICATE_OBJECT),
		errmsg("there are multiple default operator classes for data type %s",
			   format_type_be(type_id))));
	if (ncompatible == 1)
		return compatibleOid;

	return InvalidOid;
}

/*
 *	makeObjectName()
 *
 *	Create a name for an implicitly created index, sequence, constraint, etc.
 *
 *	The parameters are typically: the original table name, the original field
 *	name, and a "type" string (such as "seq" or "pkey").	The field name
 *	and/or type can be NULL if not relevant.
 *
 *	The result is a palloc'd string.
 *
 *	The basic result we want is "name1_name2_label", omitting "_name2" or
 *	"_label" when those parameters are NULL.  However, we must generate
 *	a name with less than NAMEDATALEN characters!  So, we truncate one or
 *	both names if necessary to make a short-enough string.	The label part
 *	is never truncated (so it had better be reasonably short).
 *
 *	The caller is responsible for checking uniqueness of the generated
 *	name and retrying as needed; retrying will be done by altering the
 *	"label" string (which is why we never truncate that part).
 */
char *
makeObjectName(const char *name1, const char *name2, const char *label)
{
	char	   *name;