During the discussion about memory contexts dumping[1], there was a comment that exposing not only memory contexts but also query plans and untruncated query string would be useful.
I also feel that it would be nice when thinking about situations such as troubleshooting a long-running query on production environments where we cannot use debuggers.
At that point of the above comment, I was considering exposing such information on the shared memory. However, since memory contexts are now exposed on the log by pg_log_backend_memory_contexts(PID), I'm thinking about defining a function that logs the plan of a running query and untruncated query string on the specified PID in the same way as below.
postgres=# SELECT * FROM pg_log_current_plan(2155192); pg_log_current_plan --------------------- t (1 row)
$ tail -f data/log/postgresql-2021-05-12.log
2021-05-12 17:37:19.481 JST [2155192] LOG: logging the plan of running query on PID 2155192 Query Text: SELECT a.filler FROM pgbench_accounts a JOIN pgbench_accounts b ON a.aid = b.aid; Merge Join (cost=0.85..83357.85 rows=1000000 width=85) Merge Cond: (a.aid = b.aid) -> Index Scan using pgbench_accounts_pkey on pgbench_accounts a (cost=0.42..42377.43 rows=1000000 width=89) -> Index Only Scan using pgbench_accounts_pkey on pgbench_accounts b (cost=0.42..25980.42 rows=1000000 width=4)
