MX, > to my understanding, vacuum just marks the dead rows of a table so that from > that point on that space would be re-used for new inserts and new updates on > that specific table. however, if there is an open transaction, vacuum can > only do what is described above up to the point that the open transaction > was started. so if for example there is a query running for 1 day, no matter > how many times i will have vacuumed the table (manual or auto), the dead > rows wont be possible to be marked as re-usable space. > -is the above correct? More or less. The transactionID isn't a timestamp, so the "stop point" is based on snapshots rather than a point-in-time. But that's a fine distinction. > -is there something more about vacuum in that case i am describing? would > for example mark the rows as 'semi-dead' so that when a scan would be made > these rows wouldn't be checked and so the queries would be faster? is there > anything else for this specific case? Well, vacuum does some other work, yes. > -would there be any effect from the vacuum on the indexes of the table?like > i said above for the table, would the entries of the index not be scanned > for a query, due to some reason? Vacuum also does some pruning dead index pointers. Otherwise, I'm not sure what you're asking. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
