On Monday, August 4, 2014 11:59:36 PM UTC-4, Michael Bayer wrote: > > > ah because ROW_NUMBER() needs…the row number! that is, we need to count > the rows between PK values. Well if you have truly increment-by-one > primary keys and that’s what you’re windowing on, you can make that the > “rownum”…otherwise, you’re looking for windows of N rows within the whole > set of rows. Counting is necessary, I’m not sure how to force it to use an > index-only scan to figure this out. I haven’t looked into this that > deeply. >
Yeah, I played with it for a while and dug deep into some psql listserves and dba forums trying to trick it. i might jump on the postgres list for some insight next. > add a WHERE clause to the query that is selecting the windows, that is > instead of: > i ended up cobbling one together to do that. though to eek out a bit of better performance, i used a series of temp tables. i was just wondering if anyone had pulled together a drop-in recipe yet that inspected the base-query for any filters, and pushed that into the 'select' that generates the iterables. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
