Re: How to fix 0xC0000005 exception in Postgres 9.0

Hi!

>forgot to say publish the Linux logs it may have more details what is going
>on

Linux server has older application client which replicates all data one from
andmetp table using select * from andmetp
I tried several times. Linux log contains

2020-02-21 16:18:50 EET mydbadmin mydb STATEMENT: SELECT * FROM andmetp
2020-02-21 16:18:50 EET mydbadmin mydb FATAL: connection to client lost
2020-02-21 16:18:50 EET mydbadmin mydb STATEMENT: SELECT * FROM andmetp
2020-02-21 17:19:08 EET mydbadmin mydb LOG: could not send data to client:
Connection reset by peer
2020-02-21 17:19:08 EET mydbadmin mydb STATEMENT: SELECT * FROM andmetp
2020-02-21 17:19:08 EET mydbadmin mydb FATAL: connection to client lost
2020-02-21 17:19:08 EET mydbadmin mydb STATEMENT: SELECT * FROM andmetp

It looks like only connection was terminated. “dmesg -T” does not show
postgres crash. Maybe postgres main process is not killed in Linux.

> is this happening from any client or just a specific client running ODBC?

This happene if Windows 2008 server if logged in same same server from RDP
client and in my development windows 10 workstation which logs to linux
server over VPN

>are the clients running AV if so are the AV versions the same?

In windows 2008 server antivirus was turned off like I wrote. In my devel
workstation I use Microsoft antivirus coming with windows 10.

>Given this is killing a Linux server, sounds like ODBC is sending back
>garabage data to the server crashing it.

I can try publish odbc log if this helps.

Application replicateds some tables at startup to local disk.
For tables with 5000 or more rows odbc connection hangs if there is big TCP
packet loss.
So we changed replication command

select * from mytable

to commands

select drop_table(‘temptulemus’);
create temp table temptulemus as select * from mytable;

select * from mytable offset 0 limit 900;
select * from mytable offset 900 limit 900;
select * from mytable offset 1800 limit 900;
...

etc.

In this case data was also retrieved on poor connections.
Maybe there is some better solution for this.

>There are several settings in OBDC, to change how text columns are
>processed, play around with those settings see if that helps it
>https://odbc.postgresql.org/docs/config.html

Application needs certain settings. Maybe it is better try to upgrade to
Postgres 12.2 first.

>As you have it narrowed down to a table, try querying only a few records
>at a time to see if you can identify the specific Record(s) that may be the
>issue.
>SELECT * FROM temptulemus where temptulemus.unique_id >1 offset 0 limit
>100
>and try querying the columns that do not contain the suspect data that
>could be causing this

andmetp table contains 584 record in linux server. I tried script to read
data from this table every time one more row

for i=1 to 600
? i
StartTextMerge()
TEXT TEXTMERGE NOSHOW
select * from andmetp limit <<tran(i)>>
ENDTEXT
IF !TExec()
RETURN .f.
ENDIF
endfor

this worked without error.

Andrus.