powa_wait_sampling_snapshot(0) query is running by active state for a long time

[powa-team]

powa_wait_sampling_snapshot(0) query is running by active state for a long time

[rjuju]

Hi,

It looks like a long-standing bug in pg_wait_sampling that has been fixed in 1.1.3. See for instance a previous report at powa-team/powa#142.

Could you try to update pg_wait_sampling?

[fatihmtekin]

Thank you for your information. I updated the pg_wait_sampling rpm package with rpm Uvh, then I update the extension in the database with "ALTER EXTENTION pg_wait_sampling UPDATE;", but I got a notice :
"NOTICE: version "1.1" of extension "pg_wait_sampling" is already installed"
Should I restart the database for the update process? I cannot restart the database now, because it is a production system.

[rjuju]

Yes, a restart is always required to apply modification in the C code of an extension in shared_preload_libraries. An ALTER EXTENSION ... UPDATE will only change the SQL definition, but won't reload the shared library.

Let me know once you get a maintenance window to restart the database. For the record the bug you hit isn't critical, as it won't lead to a crash or extra resource consumption. It will only make pg_wait_sampling unavailable until the database is restarted. That's not ideal but usually not critical.

[fatihmtekin]

Ok, thank you again for clear and detailed information. I will let you know after restarting the database.

[fatihmtekin]

Hi again,
I updated the pg_wait_sampling extension and restarted the database. The problem is solved. Thank you for your help.