The following bug has been logged on the website:
Bug reference: 8307
Logged by: Michael Enke
Email address: michael.enke@wincor-nixdorf.com
PostgreSQL version: 9.1.8
Operating system: Linux/CentOS 6.2
Description:
Hi,
after hitting the above error and found that this is a long lasting one
which nobody knows how to reproduce, I found a way to reproduce it:
In one session create tables in a schema,
in another session drop that schema.
Here comes my test script:
#!/bin/sh
DB=testdb # change if you need
NUM=2000 # adjust so that creation takes enough time to issue drop schema
CREATE=/tmp/$DB.sql
START=/tmp/testdb.start
END=/tmp/testdb.end
LANG=C
rm -f $START $END
>$CREATE
for I in $(seq $NUM); do
echo "create table t$I(at text, bt text, ct text, dt text);" >> $CREATE
echo "create table tt$I as select g1.*, t$I.* from g1, t$I where 1=2;" >>
$CREATE
echo "drop table t$I;" >> $CREATE
done
(
psql -U postgres -d template1 <<!
\set ON_ERROR_STOP
drop database $DB;
create database $DB;
\connect $DB
create schema testschema;
set search_path = testschema,"\$user",public;
create table g1(ag text, bg text, cg text, dg text);
\echo now create $NUM tables
\o $START
\o /dev/null
\i $CREATE
\o $END
!
rm -f $CREATE
sleep 2
pg_dump -U postgres $DB > testdb.dump
)&
while [ ! -f $START ]; do usleep 100000; done
sleep 1
psql -U postgres -d $DB -c "drop schema testschema cascade" 2>&1 | grep
"^NOTICE"
if [ -f $END ]; then
echo "too late"
fi
wait
rm -f $START $END
# end script
There are 3 possible errors reported (I executed 10x):
1: Deadlock detected: 1x
2: Could not open relation for Create: 4x
3: cache lookup failed: 5x
In case of 2 or 3 pg_dump reports above error.
If I modify the creation to only one line:
echo "create table tt$I as select g1.* from g1 where 1=2;" >> $CREATE
then in 100% I get the case number 2.
Hope it helps tracking down the reason.
