pgsql: pgstat: replace double lookup with IsSharedRelation()

pgstat: replace double lookup with IsSharedRelation()

As the list of shared relations is fixed, we can just dispatch based
IsSharedRelation(), instead of first trying to look up stats for a non-shared
rel and falling back to shared stats.

Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de
Discussion: https://postgr.es/m/8c1851a2-a98e-e1bc-7729-37b0b95f66ec@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/061bf98fb8f468b9a8c9fb617bb30136db1cc812

Modified Files
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src/backend/utils/activity/pgstat_relation.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)