On Sat, Jan 10, 2009 at 08:00:29AM -0800, mailinglists@xxxxxxxxxxxxxxx wrote: > Hello, > > I have a couple of questions regarding how MVCC (in postges 8.3.3 if it > makes a difference) affects vacuum. > > #1. If I am doing an update to a row and none of the values have changed, > will that cause a "hole" that requires vacuum to reclaim? Yes. There are various ways to work wih this, depending on your capabilties. > #2. I have a column in my table (called "status", if you can believe > *that*). This contains 1 of 4 values: > > -1: row is expired, but needs to be marked deleted from index > 0: row is expired, and has been indexed > 1: row is active, and has been indexed > 2: row is new or updated, and needs to be indexed How wide is the row otherwise. Each status update will make a copy of the complete row. One thought is to think about how often you need the status anyway and decide if it's worthwhile to split the status off into a seperate table, which will be much smaller and vacuum quicker. Hope this helps, -- Martijn van Oosterhout <kleptog@xxxxxxxxx> http://svana.org/kleptog/ > Please line up in a tree and maintain the heap invariant while > boarding. Thank you for flying nlogn airlines.
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