I wonder whether such a whole-row-var would arise from the nullable side of a join? I guess not. Not that I'm saying we shouldn't account for that case at all since any and every whole-row-var in the targetlist currently gets that treatment, even those that are known non-nullable. Couldn't we have prevented the latter somehow? IOW, only generate the CASE WHEN when a Var being deparsed is known nullable as the comment there says:
deparse.c:
1639 /* 1640 * In case the whole-row reference is under an outer join then it has 1641 * to go NULL whenver the rest of the row goes NULL. Deparsing a join 1642 * query would always involve multiple relations, thus qualify_col 1643 * would be true. 1644 */ 1645 if (qualify_col) 1646 { 1647 appendStringInfoString(buf, "CASE WHEN"); 1648 ADD_REL_QUALIFIER(buf, varno); 1649 appendStringInfo(buf, "* IS NOT NULL THEN "); 1650 }
But I guess just fixing the expression as your patch does may be just fine.
I thought about that, but it means that we have compute the nullable relids (which isn't a big deal I guess). That's something more than necessary for fixing the bug, which is the focus in beta stage right now.
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Best Wishes, Ashutosh Bapat EnterpriseDB Corporation The Postgres Database Company