Re: Identify transactions causing highest wal generation

On Fri, Mar 8, 2024, at 12:40 PM, Tomas Vondra wrote:
> On 3/8/24 15:50, Gayatri Singh wrote:
> > Hello Team,
> >
> > Can you help me with steps to identify transactions which caused wal
> > generation to surge ?
> >
>
> You should probably take a look at pg_waldump, which prints information
> about WAL contents, including which XID generated each record.

You can also use pg_stat_statements to obtain this information.

postgres=# select * from pg_stat_statements order by wal_bytes desc;
-[ RECORD 1 ]----------+---------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------
userid | 10
dbid | 16385
toplevel | t
queryid | -8403979585082616547
query | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
plans | 0
total_plan_time | 0
min_plan_time | 0
max_plan_time | 0
mean_plan_time | 0
stddev_plan_time | 0
calls | 238260
total_exec_time | 4642.599296000018
min_exec_time | 0.011094999999999999
max_exec_time | 0.872748
mean_exec_time | 0.01948543312347807
stddev_exec_time | 0.006370786385582063
rows | 238260
.
.
.
wal_records | 496659
wal_fpi | 19417
wal_bytes | 208501147
.
.
.

--
Euler Taveira
EDB https://www.enterprisedb.com/