pqReadData() -- backend closed the channel unexpectedly. - Mailing list pgsql-general

I have recently installed postgresql 6.4.2 on a Linux 2.2.0 box, and I keep
getting this error message when I queue a a few queries in a Perl script:

pqReadData() -- backend closed the channel unexpectedly.

My script has a loop that performs three queries for every hour of a single
day: the first two queries select records from a master table ("day", see
below) and insert them into two temporary tables ("tmporig" and "tmpfrom"),
and the third query selects records out of those two temp tables, and
inserts them into a fourth table ("week"). for every step of my loop, I
create and drop the two temp tables. So that means 24 (hours = steps in my
loop) x 3 queries = 72 queries, * 24 x 1 drop.
What happens is, the loop never gets past step 11 or 12, and then I get the
error above.

Should I insert code in my script to wait for some event from postgresql, or
what?

Here are the details on my tables, queries, etc.

Table    = day
+----------------------------------+----------------------------------+-----
--+
|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-----
--+
| origine                          | inet                             |
var |
| destinazione                     | inet                             |
var |
| packets                          | int4                             |
4 |
| bytes                            | int4                             |
4 |
| when                             | datetime                         |
8 |
+----------------------------------+----------------------------------+-----
--+

Table    = week
+----------------------------------+----------------------------------+-----
--+
|              Field               |              Type                |
Length|
+----------------------------------+----------------------------------+-----
--+
| address                          | inet                             |
var |
| origbytes                        | int4                             |
4 |
| destbytes                        | int4                             |
4 |
| when                             | datetime                         |
8 |
+----------------------------------+----------------------------------+-----
--+

- Loop starts here

- 1st query (the datetime values get changed in the loop, from
00:00:00/00:59:59 to 23:00:00/23:59:59):
select origine as address, sum(bytes) as origbytes into tmporig from day
where origine << '194.74.133.0/24' and when between '09/02/1999 9:00:01' and
'09/02/1999 9:59:59' group by address;
(table tmporig gets created)

- 2nd query:
 select destinazione as address, sum(bytes) as destbytes into tmpdest from
day where destinazione << '194.74.133.0/24' and when between '09/02/1999
9:00:01' and '09/02/1999 9:59:59' group by address;
(table tmpfrom gets created)

- 3rd query:
insert into week select o.address,o.origbytes, d.destbytes, '09/02/1999
9:00:01' as when from tmporig o, tmpdest d where o.address=d.address;

- Temp tables get dropped here and the loop continues

- output from postmaster does not say anything, here are the last lines from
one of the crashes (notice that postgresql hangs halfway through the loop
(12:00:00):

StartTransactionCommand
query:  select destinazione as address, sum(bytes) as destbytes into tmpdest
fr
om day where destinazione << '194.74.133.0/24' and when between '09/02/1999
12:
00:01' and '09/02/1999 12:59:59' group by address
ProcessQuery
CommitTransactionCommand
LockReleaseAll: lockmethod=1, pid=17290
LockReleaseAll: reinitializing lockQueue
LockReleaseAll: done
StartTransactionCommand
query:  insert into week select o.address,o.origbytes, d.destbytes,
'09/02/1999
 12:00:01' as when from tmporig o, tmpdest d where o.address=d.address
ProcessQuery


- output from the script (perl + dbi) from the same crash:

dbd_st_execute
dbd_st_execute: statement = > select destinazione as address, sum(bytes) as
des
tbytes into tmpdest from day where destinazione << '194.74.133.0/24' and
when b
etween '09/02/1999 12:00:01' and '09/02/1999 12:59:59' group by address<
    <- execute= -1 at ipacct2.pl line 27.
    -> execute for DBD::Pg::st (DBI::st=HASH(0x8171e48)~0x8171e90
'09/02/1999 1
2:00:01')
dbd_bind_ph
         bind :p1 <== '09/02/1999 12:00:01' (type 0)
dbd_st_rebind
bind :p1 <== '09/02/1999 12:00:01' (size 19/20/19, ptype 4, otype 1043)
dbd_st_execute
dbd_st_execute: statement = > insert into week select o.address,o.origbytes,
d.
destbytes, '09/02/1999 12:00:01' as when from tmporig o, tmpdest d where
o.addr
ess=d.address<
    ERROR EVENT 7 'pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally before or
while p
rocessing the request.


Thanks for any help,

Ludovico