> Date: Wed, 21 Mar 2012 11:00:59 -0400 > From: and...@dunslane.net > To: alvhe...@commandprompt.com > CC: t...@sss.pgh.pa.us; robertmh...@gmail.com; huangq...@hotmail.com; > neil.con...@gmail.com; dan...@heroku.com; j...@agliodbs.com; > pgsql-hackers@postgresql.org > Subject: Re: [HACKERS] Gsoc2012 Idea --- Social Network database schema > > > > On 03/21/2012 10:47 AM, Alvaro Herrera wrote: > > Excerpts from Tom Lane's message of mié mar 21 11:35:54 -0300 2012: > > > >> Now that would all be fine if this were a widely-desired feature, but > >> AFAIR the user demand for it has been about nil. So I'm leaning to > >> the position that we don't want it. > > I disagree with there being zero interest ... the "order by random()" > > stuff does come up occasionally. > > > > Presumably the reason that's not good enough is that is scans the whole > table (as well as being non-portable)? Maybe we could find some less > invasive way of avoiding that. > > cheers > > andrew
Thanks for your discussion and ideas. As I checked, MS SQL Server and DB2 implemented tablesample for now. At least, it is useful for QUICK sample retrieval for large dataset. I suppose this clause itself will be much faster for using random().About implementation, will the code change be really very large? But the general structure should still be about the same, right? Best Regards and ThanksHuang Qi VictorComputer Science of National University of Singapore
