Ben wrote:
I've got a long-running, update-heavy transaction that increasingly
slows down the longer it runs. I would expect that behavior, if there
was some temp file creation going on. But monitoring vmstat over the
life of the transaction shows virtually zero disk activity. Instead, the
system has its CPU pegged the whole time.
So.... why the slowdown? Is it a MVCC thing? A side effect of calling
stored proceedures a couple hundred thousand times in a single
transaction? Or am I just doing something wrong?
My guess is that the updates are creating a lot of old row versions, and
a command within the transaction is doing a seq scan that has to scan
through all of them. Or something like that. It's hard to tell without
more details.
Calling stored procedures repeatedly shouldn't cause a slowdown over time.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
