analyze.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 2,222 行 · 第 1/5 页

				}
			}

			/* OK, add it to the index definition */
			iparam = makeNode(IndexElem);
			iparam->name = pstrdup(key);
			iparam->expr = NULL;
			iparam->opclass = NIL;
			index->indexParams = lappend(index->indexParams, iparam);
		}

		indexlist = lappend(indexlist, index);
	}

	/*
	 * Scan the index list and remove any redundant index specifications. This
	 * can happen if, for instance, the user writes UNIQUE PRIMARY KEY. A
	 * strict reading of SQL92 would suggest raising an error instead, but
	 * that strikes me as too anal-retentive. - tgl 2001-02-14
	 *
	 * XXX in ALTER TABLE case, it'd be nice to look for duplicate
	 * pre-existing indexes, too.
	 */
	cxt->alist = NIL;
	if (cxt->pkey != NULL)
	{
		/* Make sure we keep the PKEY index in preference to others... */
		cxt->alist = list_make1(cxt->pkey);
	}

	foreach(l, indexlist)
	{
		bool		keep = true;
		ListCell   *k;

		index = lfirst(l);

		/* if it's pkey, it's already in cxt->alist */
		if (index == cxt->pkey)
			continue;

		foreach(k, cxt->alist)
		{
			IndexStmt  *priorindex = lfirst(k);

			if (equal(index->indexParams, priorindex->indexParams))
			{
				/*
				 * If the prior index is as yet unnamed, and this one is
				 * named, then transfer the name to the prior index. This
				 * ensures that if we have named and unnamed constraints,
				 * we'll use (at least one of) the names for the index.
				 */
				if (priorindex->idxname == NULL)
					priorindex->idxname = index->idxname;
				keep = false;
				break;
			}
		}

		if (keep)
			cxt->alist = lappend(cxt->alist, index);
	}
}

static void
transformFKConstraints(ParseState *pstate, CreateStmtContext *cxt,
					   bool skipValidation, bool isAddConstraint)
{
	ListCell   *fkclist;

	if (cxt->fkconstraints == NIL)
		return;

	/*
	 * If CREATE TABLE or adding a column with NULL default, we can safely
	 * skip validation of the constraint.
	 */
	if (skipValidation)
	{
		foreach(fkclist, cxt->fkconstraints)
		{
			FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);

			fkconstraint->skip_validation = true;
		}
	}

	/*
	 * For CREATE TABLE or ALTER TABLE ADD COLUMN, gin up an ALTER TABLE ADD
	 * CONSTRAINT command to execute after the basic command is complete. (If
	 * called from ADD CONSTRAINT, that routine will add the FK constraints to
	 * its own subcommand list.)
	 *
	 * Note: the ADD CONSTRAINT command must also execute after any index
	 * creation commands.  Thus, this should run after
	 * transformIndexConstraints, so that the CREATE INDEX commands are
	 * already in cxt->alist.
	 */
	if (!isAddConstraint)
	{
		AlterTableStmt *alterstmt = makeNode(AlterTableStmt);

		alterstmt->relation = cxt->relation;
		alterstmt->cmds = NIL;
		alterstmt->relkind = OBJECT_TABLE;

		foreach(fkclist, cxt->fkconstraints)
		{
			FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);
			AlterTableCmd *altercmd = makeNode(AlterTableCmd);

			altercmd->subtype = AT_ProcessedConstraint;
			altercmd->name = NULL;
			altercmd->def = (Node *) fkconstraint;
			alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
		}

		cxt->alist = lappend(cxt->alist, alterstmt);
	}
}

/*
 * transformIndexStmt -
 *	  transforms the qualification of the index statement
 */
static Query *
transformIndexStmt(ParseState *pstate, IndexStmt *stmt)
{
	Query	   *qry;
	RangeTblEntry *rte = NULL;
	ListCell   *l;

	qry = makeNode(Query);
	qry->commandType = CMD_UTILITY;

	/* take care of the where clause */
	if (stmt->whereClause)
	{
		/*
		 * Put the parent table into the rtable so that the WHERE clause can
		 * refer to its fields without qualification.  Note that this only
		 * works if the parent table already exists --- so we can't easily
		 * support predicates on indexes created implicitly by CREATE TABLE.
		 * Fortunately, that's not necessary.
		 */
		rte = addRangeTableEntry(pstate, stmt->relation, NULL, false, true);

		/* no to join list, yes to namespaces */
		addRTEtoQuery(pstate, rte, false, true, true);

		stmt->whereClause = transformWhereClause(pstate, stmt->whereClause,
												 "WHERE");
	}

	/* take care of any index expressions */
	foreach(l, stmt->indexParams)
	{
		IndexElem  *ielem = (IndexElem *) lfirst(l);

		if (ielem->expr)
		{
			/* Set up rtable as for predicate, see notes above */
			if (rte == NULL)
			{
				rte = addRangeTableEntry(pstate, stmt->relation, NULL,
										 false, true);
				/* no to join list, yes to namespaces */
				addRTEtoQuery(pstate, rte, false, true, true);
			}
			ielem->expr = transformExpr(pstate, ielem->expr);

			/*
			 * We check only that the result type is legitimate; this is for
			 * consistency with what transformWhereClause() checks for the
			 * predicate.  DefineIndex() will make more checks.
			 */
			if (expression_returns_set(ielem->expr))
				ereport(ERROR,
						(errcode(ERRCODE_DATATYPE_MISMATCH),
						 errmsg("index expression may not return a set")));
		}
	}

	qry->hasSubLinks = pstate->p_hasSubLinks;
	stmt->rangetable = pstate->p_rtable;

	qry->utilityStmt = (Node *) stmt;

	return qry;
}

/*
 * transformRuleStmt -
 *	  transform a Create Rule Statement. The actions is a list of parse
 *	  trees which is transformed into a list of query trees.
 */
static Query *
transformRuleStmt(ParseState *pstate, RuleStmt *stmt,
				  List **extras_before, List **extras_after)
{
	Query	   *qry;
	Relation	rel;
	RangeTblEntry *oldrte;
	RangeTblEntry *newrte;

	qry = makeNode(Query);
	qry->commandType = CMD_UTILITY;
	qry->utilityStmt = (Node *) stmt;

	/*
	 * To avoid deadlock, make sure the first thing we do is grab
	 * AccessExclusiveLock on the target relation.	This will be needed by
	 * DefineQueryRewrite(), and we don't want to grab a lesser lock
	 * beforehand.
	 */
	rel = heap_openrv(stmt->relation, AccessExclusiveLock);

	/*
	 * NOTE: 'OLD' must always have a varno equal to 1 and 'NEW' equal to 2.
	 * Set up their RTEs in the main pstate for use in parsing the rule
	 * qualification.
	 */
	Assert(pstate->p_rtable == NIL);
	oldrte = addRangeTableEntryForRelation(pstate, rel,
										   makeAlias("*OLD*", NIL),
										   false, false);
	newrte = addRangeTableEntryForRelation(pstate, rel,
										   makeAlias("*NEW*", NIL),
										   false, false);
	/* Must override addRangeTableEntry's default access-check flags */
	oldrte->requiredPerms = 0;
	newrte->requiredPerms = 0;

	/*
	 * They must be in the namespace too for lookup purposes, but only add the
	 * one(s) that are relevant for the current kind of rule.  In an UPDATE
	 * rule, quals must refer to OLD.field or NEW.field to be unambiguous, but
	 * there's no need to be so picky for INSERT & DELETE.  We do not add them
	 * to the joinlist.
	 */
	switch (stmt->event)
	{
		case CMD_SELECT:
			addRTEtoQuery(pstate, oldrte, false, true, true);
			break;
		case CMD_UPDATE:
			addRTEtoQuery(pstate, oldrte, false, true, true);
			addRTEtoQuery(pstate, newrte, false, true, true);
			break;
		case CMD_INSERT:
			addRTEtoQuery(pstate, newrte, false, true, true);
			break;
		case CMD_DELETE:
			addRTEtoQuery(pstate, oldrte, false, true, true);
			break;
		default:
			elog(ERROR, "unrecognized event type: %d",
				 (int) stmt->event);
			break;
	}

	/* take care of the where clause */
	stmt->whereClause = transformWhereClause(pstate, stmt->whereClause,
											 "WHERE");

	if (list_length(pstate->p_rtable) != 2)		/* naughty, naughty... */
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
				 errmsg("rule WHERE condition may not contain references to other relations")));

	/* aggregates not allowed (but subselects are okay) */
	if (pstate->p_hasAggs)
		ereport(ERROR,
				(errcode(ERRCODE_GROUPING_ERROR),
		errmsg("rule WHERE condition may not contain aggregate functions")));

	/* save info about sublinks in where clause */
	qry->hasSubLinks = pstate->p_hasSubLinks;

	/*
	 * 'instead nothing' rules with a qualification need a query rangetable so
	 * the rewrite handler can add the negated rule qualification to the
	 * original query. We create a query with the new command type CMD_NOTHING
	 * here that is treated specially by the rewrite system.
	 */
	if (stmt->actions == NIL)
	{
		Query	   *nothing_qry = makeNode(Query);

		nothing_qry->commandType = CMD_NOTHING;
		nothing_qry->rtable = pstate->p_rtable;
		nothing_qry->jointree = makeFromExpr(NIL, NULL);		/* no join wanted */

		stmt->actions = list_make1(nothing_qry);
	}
	else
	{
		ListCell   *l;
		List	   *newactions = NIL;

		/*
		 * transform each statement, like parse_sub_analyze()
		 */
		foreach(l, stmt->actions)
		{
			Node	   *action = (Node *) lfirst(l);
			ParseState *sub_pstate = make_parsestate(pstate->parentParseState);
			Query	   *sub_qry,
					   *top_subqry;
			bool		has_old,
						has_new;

			/*
			 * Set up OLD/NEW in the rtable for this statement.  The entries
			 * are added only to relnamespace, not varnamespace, because we
			 * don't want them to be referred to by unqualified field names
			 * nor "*" in the rule actions.  We decide later whether to put
			 * them in the joinlist.
			 */
			oldrte = addRangeTableEntryForRelation(sub_pstate, rel,
												   makeAlias("*OLD*", NIL),
												   false, false);
			newrte = addRangeTableEntryForRelation(sub_pstate, rel,
												   makeAlias("*NEW*", NIL),
												   false, false);
			oldrte->requiredPerms = 0;
			newrte->requiredPerms = 0;
			addRTEtoQuery(sub_pstate, oldrte, false, true, false);
			addRTEtoQuery(sub_pstate, newrte, false, true, false);

			/* Transform the rule action statement */
			top_subqry = transformStmt(sub_pstate, action,
									   extras_before, extras_after);

			/*
			 * We cannot support utility-statement actions (eg NOTIFY) with
			 * nonempty rule WHERE conditions, because there's no way to make
			 * the utility action execute conditionally.
			 */
			if (top_subqry->commandType == CMD_UTILITY &&
				stmt->whereClause != NULL)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
						 errmsg("rules with WHERE conditions may only have SELECT, INSERT, UPDATE, or DELETE actions")));

			/*
			 * If the action is INSERT...SELECT, OLD/NEW have been pushed down
			 * into the SELECT, and that's what we need to look at. (Ugly
			 * kluge ... try to fix this when we redesign querytrees.)
			 */
			sub_qry = getInsertSelectQuery(top_subqry, NULL);

			/*
			 * If the sub_qry is a setop, we cannot attach any qualifications
			 * to it, because the planner won't notice them.  This could
			 * perhaps be relaxed someday, but for now, we may as well reject
			 * such a rule immediately.
			 */
			if (sub_qry->setOperations != NULL && stmt->whereClause != NULL)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));

			/*
			 * Validate action's use of OLD/NEW, qual too
			 */
			has_old =
				rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
				rangeTableEntry_used(stmt->whereClause, PRS2_OLD_VARNO, 0);
			has_new =
				rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
				rangeTableEntry_used(stmt->whereClause, PRS2_NEW_VARNO, 0);

			switch (stmt->event)
			{
				case CMD_SELECT:
					if (has_old)
						ereport(ERROR,
								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
								 errmsg("ON SELECT rule may not use OLD")));
					if (has_new)
						ereport(ERROR,
								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
								 errmsg("ON SELECT rule may not use NEW")));
					break;
				case CMD_UPDATE:
					/* both are OK */
					break;
				case CMD_INSERT:
					if (has_old)
						ereport(ERROR,
								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
								 errmsg("ON INSERT rule may not use OLD")));
					break;
				case CMD_DELETE:
					if (has_new)
						ereport(ERROR,
								(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
								 errmsg("ON DELETE rule may not use NEW")));
					break;
				default:
					elog(ERROR, "unrecognized event type: %d",
						 (int) stmt->event);
					break;
			}

			/*
			 * For efficiency's sake, add OLD to the rule action's jointree
			 * only if it was actually referenced in the statement or qual.
			 *
			 * For INSERT, NEW is not really a relation (only a reference to
			 * the to-be-inserted tuple) and should never be added to the
			 * jointree.
			 *
			 * For UPDATE, we treat NEW as being another kind of reference to
			 * OLD, because it represents references to *transformed* tuples
			 * of the existing relation.  It would be wrong to enter NEW
			 * separately in the jointree, since that would cause a double
			 * join of the updated relation.  It's also wrong to fail to make
			 * a jointree entry if only NEW and not OLD is mentioned.
			 */
			if (has_old || (has_new && stmt->event == CMD_UPDATE))
			{
				/*
				 * If sub_qry is a setop, manipulating its jointree will do no
				 * good at all, because the jointree is dummy. (This should be
				 * a can't-happen case because of prior tests.)
				 */
				if (sub_qry->setOperations != NULL)
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
				/* hack so we can use addRTEtoQuery() */
				sub_pstate->p_rtable = sub_qry->rtable;
				sub_pstate->p_joinlist = sub_qry->jointree->fromlist;
				addRTEtoQuery(sub_pstate, oldrte, true, false, false);
				sub_qry->jointree->fromlist = sub_pstate->p_joinlist;
			}

			newactions = lappend(newactions, top_subqry);

			release_pstate_resources(sub_pstate);
			pfree(sub_pstate);
		}