From: Timothy S. <ti...@op...> - 2005-05-17 21:49:26
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Karsten Hilbert wrote: >On Tue, May 17, 2005 at 09:01:14AM +1000, Timothy Smith wrote: > > >>is it possible to mke a progress bar for queries? say i have a query >>that will take 20 seconds, i'd like to give some feed back to users on >>how long this will take. >> >> >It is sure possible but it is not very useful because > >- you will need the number of rows in the result >- which could be gotten by "select count(*) from ... where ..." >- which, however, takes pretty much the same time as the query itself >- which is in part due to PostgreSQL's MVCC nature >- which cannot be sped up by using an index >- because current tuple visibility is not stored in the index >- and doing so would create overhead for insert/update > >Karsten > > it's a very useful feature, however as you pointed out it'd be almost impossible to implement |