Re: wip: functions median and percentile
Hitoshi Harada <umi.tanuki@gmail.com>
From: Hitoshi Harada <umi.tanuki@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, David Fetter <david@fetter.org>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2010-10-01T15:16:03Z
Lists: pgsql-hackers
2010/10/2 Tom Lane <tgl@sss.pgh.pa.us>: > Hitoshi Harada <umi.tanuki@gmail.com> writes: >> Another suggestion? > > The implementation I would've expected to see is to do the sort and then > have two code paths for retrieving the median, depending on whether the > sort result is all in memory or not. > Hm? The problem we encountered in the middle of the patch is there is no chance to call tuplesort_end if median is called in moving frame window aggregate because final function is called multiple times during moving. The nearest pattern was array_agg() which uses on-memory state and throw its responsibility to clear memory to executor (nodeAgg / nodeWindowAgg). Am I missing something? Regards, -- Hitoshi Harada