I have only looked at 0001, but I am wondering why
query_id_const_merge is a pg_stat_statements GUC
rather than a core GUC?
The dependency of pg_stat_statements to take advantage
of this useful feature does not seem right.
For example if the user does not have pg_stat_statements enabled,
but are sampling top queryId from pg_stat_activity, they will
likely want this merge behavior to build meaningful database
load graphs.
Other extensions that consume queryIds may also want this
behavior without needing to enable pg_stat_statements.
Also, we have compute_query_id as a core parameter, this
new guc will become an option for how to compute a queryId.
In the future we may want to introduce other controls for how a
queryId is generated.
Regards,
Sami
