Re: RFC: Logging plan of the running query

torikoshia <torikoshia@oss.nttdata.com>

From: torikoshia <torikoshia@oss.nttdata.com>

To: pgsql-hackers@lists.postgresql.org

Cc: Étienne BERSAC <etienne.bersac@dalibo.com>, Andres Freund <andres@anarazel.de>, jtc331@gmail.com, ashutosh.bapat.oss@gmail.com, rafaelthca@gmail.com, jian.universality@gmail.com

Date: 2024-02-14T06:29:35Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

ecpg: Catch zero-length Unicode identifiers correctly
- a18b6d2dc288 15.0 cited
Improve warning message in pg_signal_backend()
- 7fa945b857cc 15.0 cited
Add assert to ensure that page locks don't participate in deadlock cycle.
- 72e78d831ab5 13.0 cited

Attachments

v36-0001-Add-function-to-log-the-plan-of-the-query.patch (text/x-diff) patch v36-0001

On 2024-02-13 11:30, torikoshia wrote:

> I'll update the patch including other points such as removing ensuring
> no page lock code.

Updated the patch.

> Using injection point support we should be able to add tests for
> testing pg_log_query_plan behaviour when there are page locks held or
> when auto_explain (with instrumentation) and pg_log_query_plan() work
> on the same query plan. Use injection point to make the backend
> running query wait at a suitable point to delay its execution and fire
> pg_log_query_plan() from other backend. May be the same test could
> examine the server log file to see if the plan is indeed output to the
> server log file.

Attached patch uses injection point as below:

- There may be more points to inject, but added an injection point at 
ExecutorRun(), which seems to be the first interruption point where 
plans can be reliably displayed.
- At injection point, it'd be possible to wait for some duration and 
fire pg_log_plan_query() as you suggested. However, I'm not sure how 
long duration is appropriate considering the variety of testing 
environments. Instead, attached patch calls 
HandleLogQueryPlanInterrupt() directly and set InterruptPending.
- Tests both pg_log_plan_query() and auto_explain logs for their output, 
and the logged plans are the same.


-- 
Regards,

--
Atsushi Torikoshi
NTT DATA Group Corporation