GetTransactionSnapshot() in enum.c

Hi,

ISTM that we shouldn't use GetTransactionSnapshot() in enum.c but
GetLatestSnapshot() in <= 9.3 and NULL/GetCatalogSnapshot() > 9.3.

typecache.c's usage was converted to GetLatestSnapshot() but enum.c's
was not.

I don't seem to have full mental capacity right now, but I think the
current usage could cause problems with a range type index over a enum
column. Index predicates might also be problematic.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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