Обсуждение: pgsql: Prevent autovacuum transactions from running in serializable mod

Prevent autovacuum transactions from running in serializable mode.

Force the transaction isolation level to READ COMMITTED in autovacuum
worker and launcher processes.  There is no benefit to using a higher
isolation level, and doing so could result in delaying foreground
transactions (or maybe even causing unnecessary serialization failures?).
Noted by Dan Ports.

Also, make sure we disable zero_damaged_pages and statement_timeout in
the autovac launcher, not only workers.  Now that the launcher can run
transactions, these settings could affect its behavior, and it seems
like the same arguments apply to the launcher as the workers.

Branch
------
REL9_1_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/2767158978796f4ce5cf39d28f29d32b66ee142e

Modified Files
--------------
src/backend/postmaster/autovacuum.c |   32 +++++++++++++++++++++++++++++++-
1 files changed, 31 insertions(+), 1 deletions(-)