Russell Smith wrote:
On Fri, 18 Feb 2005 04:38 pm, Kevin Brown wrote:
Tom Lane wrote:
No, the entire point of this discussion is to whup the DBA upside the
head with a big enough cluestick to get him to install autovacuum.
Once autovacuum is default, it won't matter anymore.
I have a concern about this that I hope is just based on some
misunderstanding on my part.
My concern is: suppose that a database is modified extremely
infrequently? So infrequently, in fact, that over a billion read
transactions occur before the next write transaction. Once that write
transaction occurs, you're hosed, right? Autovacuum won't catch this
because it takes action based on the write activity that occurs in the
tables.
So: will autovacuum be coded to explicitly look for transaction
wraparound, or to automatically vacuum every N number of transactions
(e.g., 500 million)?
autovacuum already checks for both Transaction wraparound, and table updates.
It vacuums individual tables as they need it, from a free space/recovery point
of view.
It also does checks to ensure that no database is nearing transaction
wraparound, if it
is, it initiates a database wide vacuum to resolve that issue.
Right, the check that autovacuum does for wraparound is totally separate
from the monitoring of inserts updates and deletes.
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