pgsql: Fixes for query_id feature

Fixes for query_id feature

Ignore parallel workers in pg_stat_statements
Oversight in 4f0b0966c8 which exposed queryid in parallel workers.
Counters are aggregated by the main backend process so parallel workers
would report duplicated activity, and could also report activity for the
wrong entry as they are only aware of the top level queryid.

Fix thinko in pg_stat_get_activity when retrieving the queryid.

Remove unnecessary call to pgstat_report_queryid().

Reported-by: Amit Kapila, Andres Freund, Thomas Munro

Discussion: https://postgr.es/m/20210408051735.lfbdzun5zdlax5gd@alap3.anarazel.de p634GTSOqnDW86Owrn6qDAVosC5dJjXjp7BMfc5Gz1Q(at)mail(dot)gmail(dot)com

Author: Julien Rouhaud

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0f61727b75b93915ca9a9f20c996ed7020996a38

Modified Files
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contrib/pg_stat_statements/pg_stat_statements.c | 4 +++-
src/backend/executor/execParallel.c | 1 -
src/backend/utils/adt/pgstatfuncs.c | 2 +-
3 files changed, 4 insertions(+), 3 deletions(-)