pgsql: Make the conditions in IsIndexUsableForReplicaIdentityFull() mor

Make the conditions in IsIndexUsableForReplicaIdentityFull() more explicit

IsIndexUsableForReplicaIdentityFull() described a number of conditions
that a suitable index has to fulfill. But not all of these were
actually checked in the code. Instead, it appeared to rely on
get_equal_strategy_number() to filter out any indexes that are not
btree or hash. As we look to generalize index AM capabilities, this
would possibly break if we added additional support in
get_equal_strategy_number(). Instead, write out code to check for the
required capabilities explicitly. This shouldn't change any behaviors
at the moment.

Reviewed-by: Paul Jungwirth <pj(at)illuminatedcomputing(dot)com>
Reviewed-by: vignesh C <vignesh21(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg(at)mail(dot)gmail(dot)com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/13544e790ef8c4fe9043ba59276e5182ce9a623a

Modified Files
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src/backend/replication/logical/relation.c | 52 ++++++++++++++----------------
1 file changed, 25 insertions(+), 27 deletions(-)