Looking back, by far the largest change in the period Sep 1 - Sep 11 was the
lazy xid calculation and read-only transactions. That seems like the most
likely culprit.
But given Tom's comments this commit stands out too:
Log Message:
-----------
Release the exclusive lock on the table early after truncating it in lazy
vacuum, instead of waiting till commit.
Modified Files:
--------------
pgsql/src/backend/commands:
vacuumlazy.c (r1.92 -> r1.93)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c?r1=1.92&r2=1.93)
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--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com