Function CopyAndAddInvertedQual

src/backend/rewrite/rewriteHandler.c:2346–2385

* Modify the given query by adding 'AND rule_qual IS NOT TRUE' to its * qualification. This is used to generate suitable "else clauses" for * conditional INSTEAD rules. (Unfortunately we must use "x IS NOT TRUE", * not just "NOT x" which the planner is much smarter about, else we will * do the wrong thing when the qual evaluates to NULL.) * * The rule_qual may contain references to OLD or

 * of the related entries in the query's own targetlist.
 */
static Query *
CopyAndAddInvertedQual(Query *parsetree,
					   Node *rule_qual,
					   int rt_index,
					   CmdType event)
{
	/* Don't scribble on the passed qual (it's in the relcache!) */
	Node	   *new_qual = copyObject(rule_qual);
	acquireLocksOnSubLinks_context context;

	context.for_execute = true;

	/*
	 * In case there are subqueries in the qual, acquire necessary locks and
	 * fix any deleted JOIN RTE entries.  (This is somewhat redundant with
	 * rewriteRuleAction, but not entirely ... consider restructuring so that
	 * we only need to process the qual this way once.)
	 */
	(void) acquireLocksOnSubLinks(new_qual, &context);

	/* Fix references to OLD */
	ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0);
	/* Fix references to NEW */
	if (event == CMD_INSERT || event == CMD_UPDATE)
		new_qual = ReplaceVarsFromTargetList(new_qual,
											 PRS2_NEW_VARNO,
											 0,
											 rt_fetch(rt_index,
													  parsetree->rtable),
											 parsetree->targetList,
											 (event == CMD_UPDATE) ?
											 REPLACEVARS_CHANGE_VARNO :
											 REPLACEVARS_SUBSTITUTE_NULL,
											 rt_index,
											 &parsetree->hasSubLinks);
	/* And attach the fixed qual */
	AddInvertedQual(parsetree, new_qual);

	return parsetree;
}


/*