On Tue, Dec 1, 2020 at 8:05 PM Julien Rouhaud <rjuju123@gmail.com> wrote:
Hi,
Someone raised an interested point recently on pg_stat_kcache extension for handling nested statements, which also applies to pg_stat_statements.
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The only idea I have for that is to add a new field to entry key, for instance is_toplevel.
This particular problem often bothered me when dealing with pg_stat_statements contents operating under "track = all" (especially when performing the aggregated analysis, like you showed).
I think the idea of having a flag to distinguish the top-level entries is great.
The immediate cons is obviously that it could amplify quite a lot the number of entries tracked, so people may need to increase pg_stat_statements.max to avoid slowdown if that makes them reach frequent entry eviction.
If all top-level records in pg_stat_statements have "true" in the new column (is_toplevel), how would this lead to the need to increase pg_stat_statements.max? The number of records would remain the same, as before extending pg_stat_statements.
