From: Tom Lane <tgl@sss.pgh.pa.us>
To: Steinar H. Gunderson <sgunderson@bigfoot.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Materializing a sequential scan
Date: Wed, 26 Oct 2005 19:53:02 -0400
Message-ID: <12708.1130370782@sss.pgh.pa.us> (raw)
In-Reply-To: <20051026232219.GA6390@uio.no>
References: <20051019174544.GA32303@samfundet.no>
<20051026213730.GA2295@uio.no>
<12333.1130367975@sss.pgh.pa.us>
<20051026232219.GA6390@uio.no>
"Steinar H. Gunderson" <sgunderson@bigfoot.com> writes:
> On Wed, Oct 26, 2005 at 07:06:15PM -0400, Tom Lane wrote:
>> AFAICS, subplan_is_hashable() is testing the same conditions in 7.4 and
>> HEAD, so this isn't clear. Want to step through it and see where it's
>> deciding not to hash?
> (gdb) print opid
> $3 = 2373
I don't think you're getting a correct reading for optup, but OID
2373 is timestamp = date:
regression=# select * from pg_operator where oid = 2373;
oprname | oprnamespace | oprowner | oprkind | oprcanhash | oprleft | oprright | oprresult | oprcom | oprnegate | oprlsortop | oprrsortop | oprltcmpop | oprgtcmpop | oprcode | oprrest | oprjoin
---------+--------------+----------+---------+------------+---------+----------+-----------+--------+-----------+------------+------------+------------+------------+-------------------+---------+-----------
= | 11 | 10 | b | f | 1114 | 1082 | 16 | 2347 | 2376 | 2062 | 1095 | 2371 | 2375 | timestamp_eq_date | eqsel | eqjoinsel
(1 row)
which is marked not hashable, quite correctly since the input datatypes
aren't even the same.
My recollection is that there was no such operator in 7.4; probably in
7.4 the IN ended up using timestamp = timestamp which is hashable.
What's not clear though is why you're getting that operator --- aren't
both sides of the IN of type "date"?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, sgunderson@bigfoot.com
Subject: Re: Materializing a sequential scan
In-Reply-To: <12708.1130370782@sss.pgh.pa.us>
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