From: Bruce Momjian <bruce@momjian.us> Date: Mon, 27 Sep 1999 17:05:08 +0000 (+0000) Subject: Update TODO list. X-Git-Tag: REL7_0~1447 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=99fb237da26c75977b7d0a7262094137382ee013;p=postgresql Update TODO list. --- diff --git a/doc/TODO b/doc/TODO index 9dbd3254d7..7a19c83b5a 100644 --- a/doc/TODO +++ b/doc/TODO @@ -1,6 +1,6 @@ TODO list for PostgreSQL ======================== -Last updated: Mon Sep 27 11:20:02 EDT 1999 +Last updated: Mon Sep 27 13:02:57 EDT 1999 Current maintainer: Bruce Momjian (maillist@candle.pha.pa.us) @@ -250,6 +250,7 @@ MISC * Make oid use oidin/oidout not int4in/int4out in pg_type.h * Improve Subplan list handling * Allow Subplans to use efficient joins(hash, merge) with upper variable + [subquery] * use fmgr_info()/fmgr_faddr() instead of fmgr() calls in high-traffic places, like GROUP BY, UNIQUE, index processing, etc. * improve dynamic memory allocation by introducing tuple-context memory diff --git a/doc/TODO.detail/subquery b/doc/TODO.detail/subquery new file mode 100644 index 0000000000..cbf3a9b88c --- /dev/null +++ b/doc/TODO.detail/subquery @@ -0,0 +1,76 @@ +From vadim@krs.ru Fri Aug 6 00:02:02 1999 +Received: from sunpine.krs.ru (SunPine.krs.ru [195.161.16.37]) + by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id AAA22890 + for <maillist@candle.pha.pa.us>; Fri, 6 Aug 1999 00:02:00 -0400 (EDT) +Received: from krs.ru (dune.krs.ru [195.161.16.38]) + by sunpine.krs.ru (8.8.8/8.8.8) with ESMTP id MAA23302; + Fri, 6 Aug 1999 12:01:59 +0800 (KRSS) +Sender: root@sunpine.krs.ru +Message-ID: <37AA5E35.66C03F2E@krs.ru> +Date: Fri, 06 Aug 1999 12:01:57 +0800 +From: Vadim Mikheev <vadim@krs.ru> +Organization: OJSC Rostelecom (Krasnoyarsk) +X-Mailer: Mozilla 4.5 [en] (X11; I; FreeBSD 3.0-RELEASE i386) +X-Accept-Language: ru, en +MIME-Version: 1.0 +To: Bruce Momjian <maillist@candle.pha.pa.us> +CC: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgreSQL.org +Subject: Re: [HACKERS] Idea for speeding up uncorrelated subqueries +References: <199908060331.XAA22277@candle.pha.pa.us> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Status: RO + +Bruce Momjian wrote: +> +> Isn't it something that takes only a few hours to implement. We can't +> keep telling people to us EXISTS, especially because most SQL people +> think correlated queries are slower that non-correlated ones. Can we +> just on-the-fly rewrite the query to use exists? + +This seems easy to implement. We could look does subquery have +aggregates or not before calling union_planner() in +subselect.c:_make_subplan() and rewrite it (change +slink->subLinkType from IN to EXISTS and add quals). + +Without caching implemented IN-->EXISTS rewriting always +has sence. + +After implementation of caching we probably should call union_planner() +for both original/modified subqueries and compare costs/sizes +of EXISTS/IN_with_caching plans and maybe even make +decision what plan to use after parent query is planned +and we know for how many parent rows subplan will be executed. + +Vadim + +From tgl@sss.pgh.pa.us Fri Aug 6 00:15:23 1999 +Received: from sss.sss.pgh.pa.us (sss.pgh.pa.us [209.114.166.2]) + by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id AAA23058 + for <maillist@candle.pha.pa.us>; Fri, 6 Aug 1999 00:15:22 -0400 (EDT) +Received: from sss.sss.pgh.pa.us (localhost [127.0.0.1]) + by sss.sss.pgh.pa.us (8.9.1/8.9.1) with ESMTP id AAA06786; + Fri, 6 Aug 1999 00:14:50 -0400 (EDT) +To: Bruce Momjian <maillist@candle.pha.pa.us> +cc: Vadim Mikheev <vadim@krs.ru>, pgsql-hackers@postgreSQL.org +Subject: Re: [HACKERS] Idea for speeding up uncorrelated subqueries +In-reply-to: Your message of Thu, 5 Aug 1999 23:31:01 -0400 (EDT) + <199908060331.XAA22277@candle.pha.pa.us> +Date: Fri, 06 Aug 1999 00:14:50 -0400 +Message-ID: <6783.933912890@sss.pgh.pa.us> +From: Tom Lane <tgl@sss.pgh.pa.us> +Status: RO + +Bruce Momjian <maillist@candle.pha.pa.us> writes: +> Isn't it something that takes only a few hours to implement. We can't +> keep telling people to us EXISTS, especially because most SQL people +> think correlated queries are slower that non-correlated ones. Can we +> just on-the-fly rewrite the query to use exists? + +I was just about to suggest exactly that. The "IN (subselect)" +notation seems to be a lot more intuitive --- at least, people +keep coming up with it --- so why not rewrite it to the EXISTS +form, if we can handle that more efficiently? + + regards, tom lane +