pgsql: Make deadlock_timeout PGC_SUSET rather than PGC_SIGHUP.

Make deadlock_timeout PGC_SUSET rather than PGC_SIGHUP.

This allows deadlock_timeout to be reduced for transactions that are
particularly likely to be involved in a deadlock, thus detecting it
more quickly. It is also potentially useful as a poor-man's deadlock
priority mechanism: a transaction with a high deadlock_timeout is less
likely to be chosen as the victim than one with a low
deadlock_timeout. Since that could be used to game the system, we
make this PGC_SUSET rather than PGC_USERSET.

At some point, it might be worth thinking about a more explicit
priority mechanism, since using this is far from fool-proof. But
let's see whether there's enough use case to justify the additional
work before we go down that route.

Noah Misch, reviewed by Shigeru Hanada

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7095003cbef630fe29c2299cc819fd37c691d0b0

Modified Files
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doc/src/sgml/config.sgml | 3 ++-
src/backend/utils/misc/guc.c | 4 ++--
2 files changed, 4 insertions(+), 3 deletions(-)