pgsql: Remove unnecessary opening of other relation in

Log Message:
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Remove unnecessary opening of other relation in RI_FKey_keyequal_upd_pk
and RI_FKey_keyequal_upd_fk, as well as no-longer-needed calls of
ri_BuildQueryKeyFull. Aside from saving a few cycles, this avoids needless
deadlock risks when an update is not changing the columns that participate
in an RI constraint. Per a gripe from Alexey Nalbat.

Back-patch to 8.3. Earlier releases did have a need to open the other
relation due to the way in which they retrieved information about the RI
constraint, so this problem unfortunately can't easily be improved pre-8.3.

Tom Lane and Stephan Szabo

Tags:
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REL8_3_STABLE

Modified Files:
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pgsql/src/backend/utils/adt:
ri_triggers.c (r1.103 -> r1.103.2.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/ri_triggers.c?r1=1.103&r2=1.103.2.1)