This bug uncovered serious issues with how the data was being stored by PSGM.
So it require a complete redesign.
pg_stat_monitor now stores the data locally within the backend process's local
memory. The data is only stored when the query completes. This reduces the
number of lock acquisitions that were previously needed during various stages
of the execution. Also, this avoids data loss in case the current bucket
changes during execution. Also, the unavailability of jumble state during later
stages of executions was causing pg_stat_monitor to save non-normalized query.
This was a major problem as well.
pg_stat_monitor specific memory context is implemented. It is used for saving
data locally. The context memory callback helps us clear the locally saved data
so that we do not store it multiple times in the shared hash.
As part of this major rewrite, pgss reference in function and variable names
is changed to pgsm. Memory footprint for the entries is reduced, data types
are corrected where needed, and we've removed unused variables, functions and
macros.
This patch was mutually created by:
Co-authored-by: Hamid Akhtar <hamid.akhtar@percona.com>
Co-authored-by: Muhammad Usama <muhammad.usama@percona.com>
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
The view now carries all the columns as pg_stat_statements. This required fixing
data types of some of the columns, renaming a few, as well inclusion of new
columns to make the view fully compatible with pg_stat_statements.
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
Updating the upgrade sql file from 1.0 to 2.0 version linked with this issue
changes.
* PG-543: pg_stat_monitor: PostgreSQL's pg_stat_statements compatible view.
Updating datum calls to use UInt64 rather than Int64.
The query status monitoring code was used to track the current query state, for example,
parsing, executing and finishing. After careful review, we have figured out that
it does not make sense while a lot of time same query is running. Therefore it
is also consuming resources. This commit will remove that feature. The upgrade
SQL from 1.0 - 2.0 is also updated.
pg_stat_monitor.pgsm_normalized_query needs to be 0 by default because
people will get Query examples. This is one of the main user-faced
advantages of pgsm over pgss (pg_stat_statements).
As the query normalization and query cleaning is always done in the
right place (pgss_store), no more parsed queries have a trailling comma
';' at the end.
Also, on error regression test, after fixing some problems with utility
related queries, we now have two entries for the RAISE WARNING case, the
first entry is the utility query itself, the second entry is the error
message logged by emit_log_hook.
Some queries have the order adjusted due to the fix introduced by the
previous commits.
Hamid Akhtar
Ibrar Ahmed
Diego Fronza
Ibrar Ahmed