Rearm statement_timeout after each executed query.
Previously statement_timeout, in the extended protocol, affected all
messages till a Sync message. For clients that pipeline/batch query
execution that's problematic.
Instead disable timeout after each Execute message, and enable, if
necessary, the timer in start_xact_command(). As that's done only for
Execute and not Parse / Bind, pipelining the latter two could still
cause undesirable timeouts. But a survey of protocol implementations
shows that all drivers issue Sync messages when preparing, and adding
timeout rearming to both is fairly expensive for the common parse /
bind / execute sequence.
Author: Tatsuo Ishii, editorialized by Andres Freund
Reviewed-By: Takayuki Tsunakawa, Andres Freund
Discussion: https://postgr.es/m/
20170222.115044.
1665674502985097185.t-ishii@sraoss.co.jp