2017-05-03 19:33 GMT+02:00 Alvaro Herrera <alvhe...@2ndquadrant.com>:
> David Fetter wrote: > > > When we add a "temporary" GUC, we're taking on a gigantic burden. > > Either we support it forever somehow, or we put it on a deprecation > > schedule immediately and expect to be answering questions about it for > > years after it's been removed. > > > > -1 for the GUC. > > Absolutely. > > So ISTM we have three choices: > > 1) we switch unmarked CTEs as inlineable by default in pg11. What seems > likely to happen for a user that upgrades to pg11 is that 5 out of 10 > CTE-using queries are going to become faster than with pg10, and they > are going to be happy; 4 out of five are going to see no difference, but > they didn't have to do anything about it; and the remaining query is > going to become slower, either indistinguishably so (in which case they > don't care and they remain happy because of the other improvements) or > notably so, in which case they can easily figure where to add the > MATERIALIZED option and regain the original performance. > > > 2) unmarked CTEs continue to be an optimization barrier, but we add > "WITH INLINED" so that they're inlineable. Some users may wonder about > it and waste a lot of time trying to figure out which CTEs to add it to. > They see a benefit in half the queries, which makes them happy, but they > are angry that they had to waste all that time on the other queries. > > > 3) We don't do anything, because we all agree that GUCs are not > suitable. No progress. No anger, but nobody is happy either. > yes, these variants are all. @2 is only little bit better than bad @3 - is not nice to have default behave different than any other and than what 90% developers expects. Regards Pavel > > -- > Álvaro Herrera https://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
