Function ProcessSubqueryToJoin_walker

src/backend/cdb/cdbsubselect.c:228–276

}

static void
ProcessSubqueryToJoin_walker(Node *jtree, ConvertSubqueryToJoinContext *context)
{
	if (IsA(jtree, JoinExpr))
	{
		JoinExpr   *je = (JoinExpr *) jtree;

		/*
		 * If subselect's join tree is not a plain relation or an inner join,
		 * we refuse to convert.
		 */
		if (je->jointype != JOIN_INNER)
		{
			context->safeToConvert = false;
			return;
		}

		ProcessSubqueryToJoin_walker(je->larg, context);
		if (!context->safeToConvert)
			return;
		ProcessSubqueryToJoin_walker(je->rarg, context);
		if (!context->safeToConvert)
			return;

		SubqueryToJoinWalker(je->quals, context);
	}
	else if (IsA(jtree, FromExpr))
	{
		FromExpr   *fe = (FromExpr *) jtree;
		ListCell   *lc;

		foreach(lc, fe->fromlist)
		{
			ProcessSubqueryToJoin_walker(lfirst(lc), context);
			if (!context->safeToConvert)
				return;
		}

		SubqueryToJoinWalker(fe->quals, context);
	}
	else if (IsA(jtree, RangeTblRef))
	{
		/* nothing to do */
	}
	else
	{
		elog(ERROR, "unexpected node of type %d in join tree", jtree->type);
	}
}

/**
 * Wipe out join quals i.e. top-level where clause and any quals in the top-level inner join.