pgsql: Do not access indclass through Form_pg_index

Do not access indclass through Form_pg_index

Normally, accessing variable-length members of catalog structures past
the first one doesn't work at all. Here, it happened to work because
indnatts was checked to be 1, and so the defined FormData_pg_index
layout, using int2vector[1] and oidvector[1] for variable-length
arrays, happened to match the actual memory layout. But it's a very
fragile assumption, and it's not in a performance-critical path, so
code it properly using heap_getattr() instead.

bug analysis by Tom Lane

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/8a3f745f160d8334ad978676828d3926ac949f43

Modified Files
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src/backend/utils/cache/relcache.c | 17 ++++++++++++++++-
1 files changed, 16 insertions(+), 1 deletions(-)