On Fri, Sep 26, 2008 at 5:03 PM, John Huttley <John@xxxxxxxxxxxxxxxxxx> wrote: > Hi Andrew, > There are two problems. > The first is the that if there is a table with a index and an update is > performed on a non indexed field, > the index is still re indexed. I assume you mean updated, not reindexed, as reindexed has a different meaning as regards postgresql. Also, this is no longer true as of version 8.3. If you're updating non-indexed fields a lot and you're not running 8.3 you are doing yourself a huge disservice. >this is part of the trade-offs of MVCC. was... was a part of the trade-offs. > We should reasonably expect that the total amount of IO will go up, over a > non-indexed table. > > The second thing is that the disk IO throughput goes way down. > > This is not an issue with MVCC, as such, except that it exposes the effect > of a write to an indexed field. It's really an effect of parallel updates / writes / accesses, and is always an issue for a database running on a poor storage subsystem. A db with a two drive mirror set is always going to be at a disadvantage to one running on a dozen or so drives in a RAID-10
