Bug #936: pq_flush: send() failed on big query

From: pgsql-bugs(at)postgresql(dot)org
To: pgsql-bugs(at)postgresql(dot)org
Subject: Bug #936: pq_flush: send() failed on big query
Date: 2003-04-07 11:18:07
Message-ID: 20030407111807.53569475F39@postgresql.org
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Jaroslaw Maruszewski (j(dot)maruszewski(at)zkz(dot)com(dot)pl) reports a bug with a severity of 3
The lower the number the more severe it is.

Short Description
pq_flush: send() failed on big query

Long Description
PostgreSQL 7.3.2 on i686-pc-linux-gnu, compiled by GCC 2.95.4

A stupid (accidentaly isuued) query with plan:

Nested Loop (cost=0.00..44837482.16 rows=1162184800 width=238)
-> Nested Loop (cost=0.00..10354.16 rows=207533 width=155)
-> Index Scan using dkj_probka_pk on dkj_probka (cost=0.00..594.50 rows=5609 width=137)
-> Seq Scan on dkj_kopalnia (cost=0.00..1.37 rows=37 width=18)
-> Seq Scan on dkj_dostawa (cost=0.00..160.00 rows=5600 width=83)

log (with statement_timeout = 900000):

2003-04-07 12:33:41 [8924] LOG: connection received: host=[local]
2003-04-07 12:33:41 [8924] LOG: connection authorized: user=jm database=tst
2003-04-07 12:33:41 [8924] LOG: query: begin; select getdatabaseencoding(); commit
2003-04-07 12:33:41 [8924] LOG: duration: 0.021872 sec
2003-04-07 12:33:41 [8924] LOG: query: SELECT
2003-04-07 12:38:32 [8924] LOG: pq_flush: send() failed: connection reset by peer
2003-04-07 12:38:32 [8924] LOG: pq_flush: send() failed: broken pipe
2003-04-07 12:48:41 [8924] ERROR: Query was cancelled.
2003-04-07 12:48:41 [8924] LOG: pq_recvbuf: unexpected EOF on client connection

Whats, imho, wrong: Big query cause shortage of resources and
postmaster isue misleading error message. Also, postmaster task should
be killed immediatelly, not by timeout.
Regards

Sample Code
SELECT
dkj_probka."nrproby", dkj_probka."wt", dkj_probka."ad", dkj_probka."vd", dkj_probka."vdaf",
dkj_probka."std", dkj_probka."a", dkj_probka."b", dkj_probka."ri", dkj_probka."cl",
dkj_probka."p", dkj_probka."alkalia",
dkj_dostawa."nrlistuprzew", dkj_dostawa."datadostawy", dkj_dostawa."tonaz",
dkj_dostawa."wt", dkj_dostawa."ad", dkj_dostawa."vdaf", dkj_dostawa."ri", dkj_dostawa."std",
dkj_kopalnia."knazwa"
FROM
"public"."dkj_probka" dkj_probka,
"public"."dkj_dostawa" dkj_dostawa,
"public"."dkj_kopalnia" dkj_kopalnia
ORDER BY
dkj_probka."nrproby" ASC;

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