On 25.09.2011 05:09, Marti Raudsepp wrote:
This is the third version of my CacheExpr patch.
This seems to have bitrotted, thanks to the recent refactoring in eval_const_expressions().
For explanation about design decisions, please read these earlier messages: http://archives.postgresql.org/pgsql-hackers/2011-09/msg00579.php http://archives.postgresql.org/pgsql-hackers/2011-09/msg00812.php http://archives.postgresql.org/pgsql-hackers/2011-09/msg00833.php
I wonder if it would be better to add the CacheExpr nodes to the tree as a separate pass, instead of shoehorning it into eval_const_expressions? I think would be more readable that way, even though a separate pass would be more expensive. And there are callers of eval_const_expressions() that have no use for the caching, like process_implied_equality().
This comment in RelationGetExpressions() also worries me:
/* * Run the expressions through eval_const_expressions. This is not just an * optimization, but is necessary, because the planner will be comparing * them to similarly-processed qual clauses, and may fail to detect valid * matches without this. We don't bother with canonicalize_qual, however. */ result = (List *) eval_const_expressions(NULL, (Node *) result);
Do the injected CacheExprs screw up that equality? Or the constraint exclusion logic in predtest.c?
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers