Re: pg_dump blocks insert update on table

[Bindra Bambharoliya <bindra.bambharoliya@xxxxxxxxx>]

Also same time I checked backup logs.

It is at same table. Dumping data for stage.etl_logs.

On Thu, 29 Feb 2024, 23:03 Bindra Bambharoliya, <bindra.bambharoliya@xxxxxxxxx> wrote:

Hi,

I executed below query and 

SELECT blocked_locks.pid     AS blocked_pid,
         blocked_activity.usename  AS blocked_user,
         blocking_locks.pid     AS blocking_pid,
         blocking_activity.usename AS blocking_user,
         blocked_activity.query    AS blocked_statement,
         blocking_activity.query   AS current_statement_in_blocking_process
   FROM  pg_catalog.pg_locks         blocked_locks
    JOIN pg_catalog.pg_stat_activity blocked_activity  ON blocked_activity.pid = blocked_locks.pid
    JOIN pg_catalog.pg_locks         blocking_locks 
        ON blocking_locks.locktype = blocked_locks.locktype
        AND blocking_locks.database IS NOT DISTINCT FROM blocked_locks.database
        AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
        AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
        AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
        AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
        AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
        AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
        AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
        AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
        AND blocking_locks.pid != blocked_locks.pid

    JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
   WHERE NOT blocked_locks.granted;

Output I got is blocked_statement--call etl_master();

current_statement_in_blocking_process-- copy stage.etl_logs(....) to stdout.

Hope this helps. Let me know if more details required..

Thanks & Regards

Bindra Bambharoliya 

On Thu, 29 Feb 2024, 22:45 Tom Lane, <tgl@xxxxxxxxxxxxx> wrote:

Bindra <11bindra11@xxxxxxxxx> writes:
> We are using PostgreSQL 11.17

You realize that 11.x is out of support, right?

> While doing pg_dumpall, it blocks insert/update on some table where copy
> statemnets is executed.

pg_dump only takes AccessShareLock on tables it dumps.  That does not
block inserts or updates.  What may be happening is that you have some
third process that is trying to take an exclusive lock on the table.
It will queue up behind pg_dump's nonexclusive lock, and then other
operations such as insert/update will block behind it.  This is just
speculation since you've provided zero detail, but that's what I'd
look for.  The pg_locks view could help you identify the culprit.

                        regards, tom lane