Thread

1. Backend crash on query with UNION subselect

   PostgreSQL Bugs List <pgsql-bugs@postgresql.org> — 2001-01-12T09:26:45Z

   Vladimir Zamiussky (ltd@ippe.obninsk.ru) reports a bug with a severity of 1
   The lower the number the more severe it is.
   
   Short Description
   Backend crash on query with UNION subselect
   
   Long Description
   There are two nearly identical tables, differ from each other by the length of corresponding fields of type CHARACTER (one has CHARACTER(20) field, other has CHARACTER(30) field). 
   when i do "select * from table1 union select * from table2" backend crashes with message:
   FATAL 1: Memory exhausted in AllocSetAlloc()
   pqReadData() -- backend closed channel unexpectadly.
   	This probably means the backend terminated abnormally before or while 		processing the request.
   
   When char fileds have the same size, crash does not occur.
   
   This bug takes place on 7.0.2 and 7.0.3 versions
   
   Sample Code
   create table pipe_alarms(
   	dtime timestamp default now(),
   	pipe_name char(30),
   	alarm_name char(30) );
   
   create table gauge_alarms(
   	dtime timestamp default now(),
   	gauge_name char(20),
   	alarm_name char(30) );
   
   insert into pipe_alarms(pipe_name,alarm_name) values('Pipe 1','LEAK');
   insert into pipe_alarms(pipe_name,alarm_name) values('Pipe 2','No leaks');
   insert into gauge_alarms(gauge_name,alarm_name) values('sensor_1','OverLimit');
   insert into gauge_alarms(gauge_name,alarm_name) values('sensor_2','OverLimit');
   insert into gauge_alarms(gauge_name,alarm_name) values('sensor_3','OverLimit');
   
   select * from gauge_alarms union all select * from pipe_alarms
   
   
   No file was uploaded with this report
   
   
   

2. Re: Backend crash on query with UNION subselect

   Tom Lane <tgl@sss.pgh.pa.us> — 2001-01-12T15:12:01Z

   pgsql-bugs@postgresql.org writes:
   > There are two nearly identical tables, differ from each other by the
   > length of corresponding fields of type CHARACTER (one has
   > CHARACTER(20) field, other has CHARACTER(30) field).
   > when i do "select * from table1 union select * from table2" backend
   > crashes with message:
   > FATAL 1: Memory exhausted in AllocSetAlloc()
   > When char fileds have the same size, crash does not occur.
   > This bug takes place on 7.0.2 and 7.0.3 versions
   
   This is fixed for 7.1.  Older versions have quite a few problems with
   cross-datatype UNIONs :-(
   
   			regards, tom lane