Re: IDS 7.30: a table with 150 extents
Madison, >had to be scanned. In 7.x+ the extent table is dynamically sized so that >all of the extent information is kept in memory. So do you mean to say that having more extents in no more a serious issue? What is the max no. of extents for a table in 7.x? Thanks Vinod Bhansali >From: Madison Pruet <mpruet@informix.com> >Reply-To: madison.pruet@informix.com >To: informix-list@iiug.org >Subject: Re: IDS 7.30: a table with 150 extents >Date: Fri, 16 Jun 2000 00:43:22 -0500 > >Alex Barilo wrote: > > > Hi folks, > > > > I have this table: 4 million rows (at one point it had 17 mill), 700Mb > > and 151 (!) extents! It's not fragmented. I wasn't the one who designed > > it that way so please don't nail me for that. > > > > My question is: how come we don't see any performance problems? Is there > > optimal extents number for IDS 7.30 (like 8 for online 5)? Or is it just > > powerful box? > >The main reason for the 8 rule in online 5 was that the extent table was >fixed at 8 entries. For any table larger than 8 extents the partition page >had to be scanned. In 7.x+ the extent table is dynamically sized so that >all of the extent information is kept in memory. > > > > > > > > > Hardware: HP NetServer LH4, 4x PII Xeon 400Mhz, 2Gb RAM, 6 logical HDD's > > (12 physical, RAID 10) for dbspaces > > > > OS: SCO OS 5.0.5 > > > > Any ideas will be greately appreciated. > > > > Thanx! > > > > Alex. > > -- > > Before the accident, I could not even spell UNIX > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > >-- >Madison Pruet > >=========================================== >Enterprise Replication Product Developement >Dallas, Texas >Informix Software >=========================================== > > ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
Don't get me wrong. It is still an issue because you can get into a situation where a new extent can not be allocate, simply because the extent information will not fit within the partition page. However, the performance impact is not nearly as great as it was in 5.x. The number of extents that can be allocated depend on the number of indexes that the table has and the page size. For 2K page systems, I'd become a bit concerned if the number of extents reached 150, however, I would not be too concerned with 40. On 5.x systems, anything above 8 extents would be grounds for a table reorg/recluster. Vinod Bhansali wrote: > Madison, > > >had to be scanned. In 7.x+ the extent table is dynamically sized so that > >all of the extent information is kept in memory. > > So do you mean to say that having more extents in no more a serious issue? > What is the max no. of extents for a table in 7.x? > > Thanks > Vinod Bhansali > > >From: Madison Pruet <mpruet@informix.com> > >Reply-To: madison.pruet@informix.com > >To: informix-list@iiug.org > >Subject: Re: IDS 7.30: a table with 150 extents > >Date: Fri, 16 Jun 2000 00:43:22 -0500 > > > >Alex Barilo wrote: > > > > > Hi folks, > > > > > > I have this table: 4 million rows (at one point it had 17 mill), 700Mb > > > and 151 (!) extents! It's not fragmented. I wasn't the one who designed > > > it that way so please don't nail me for that. > > > > > > My question is: how come we don't see any performance problems? Is there > > > optimal extents number for IDS 7.30 (like 8 for online 5)? Or is it just > > > powerful box? > > > >The main reason for the 8 rule in online 5 was that the extent table was > >fixed at 8 entries. For any table larger than 8 extents the partition page > >had to be scanned. In 7.x+ the extent table is dynamically sized so that > >all of the extent information is kept in memory. > > > > > > > > > > > > > > > Hardware: HP NetServer LH4, 4x PII Xeon 400Mhz, 2Gb RAM, 6 logical HDD's > > > (12 physical, RAID 10) for dbspaces > > > > > > OS: SCO OS 5.0.5 > > > > > > Any ideas will be greately appreciated. > > > > > > Thanx! > > > > > > Alex. > > > -- > > > Before the accident, I could not even spell UNIX > > > > > > Sent via Deja.com http://www.deja.com/ > > > Before you buy. > > > >-- > >Madison Pruet > > > >=========================================== > >Enterprise Replication Product Developement > >Dallas, Texas > >Informix Software > >=========================================== > > > > > > ________________________________________________________________________ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com