[pgpool-general: 714] Load Balancing / Streaming Replication / Isolation Level serializable

Philip Hofstetter phofstetter at sensational.ch
Thu Jul 12 00:04:26 JST 2012


Hi,

in an application of ours, we have a very small amount of transactions
that need to run in serializable isolation level.

Unfortunately it seems that pgpool 3.1.1 (stock Ubuntu Precise
Package) insists on sending commands to start such a transaction to
the slave (using streaming replication):

pilif at tali:~|⇒  psql  -h pgpool demo
psql (9.1.1, server 9.1.4)
Type "help" for help.

demo=> begin work isolation level serializable;
ERROR:  kind mismatch among backends. Possible last query was: "begin
work isolation level serializable;" kind details are: 0[C] 1[E: cannot
use serializable mode in a hot standby]
HINT:  check data consistency among db nodes
ERROR:  kind mismatch among backends. Possible last query was: "begin
work isolation level serializable;" kind details are: 0[C] 1[E: cannot
use serializable mode in a hot standby]
HINT:  check data consistency among db nodes
The connection to the server was lost. Attempting reset: Succeeded.
demo=>

This doesn't make sense to me as according to
http://www.pgpool.net/docs/latest/doc/pgpool-en.html there's a
specific provision in the code not to do that.

Any idea what's going on here?

Philip


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