[HACKERS] eval_const_expresisions and ScalarArrayOpExpr

[Heikki Linnakangas]

Eval_const_expressions() doesn't know about ScalarArrayOpExpr. We simplify the arguments, but if all the arguments are booleans, we don't take the obvious step of replacing the whole expression with a boolean Const. For example:

postgres=# explain select * from foo where 1 IN (1,2,3);
                         QUERY PLAN
-------------------------------------------------------------
 Result  (cost=0.00..35.50 rows=2550 width=4)
   One-Time Filter: (1 = ANY ('{1,2,3}'::integer[]))
   ->  Seq Scan on foo  (cost=0.00..35.50 rows=2550 width=4)
(3 rows)







- Heikki

I would've expected that to be fully evaluated at plan-time, and optimized away. That seems like an oversight. I guess that scenario doesn't happen very often in practice, but there's no reason not to do it when it does. Patch attached. On a side-note, I find it a bit awkward that ScalarArrayOpExpr uses a 2-element List to hold the scalar and array arguments. Wouldn't it be much more straightforward to have explicit "Expr *scalararg" and "Expr *arrayarg" fields?

0001-Const-eval-ScalarArrayOpExprs.patch
Description: invalid/octet-stream

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