Re: the explain of tbcheck -pt

In article <36080690.702A@bellsouth.net>, "Carlson@WHSmith" <carlson1@bellsouth.net> wrote: > jjdai@hotmail.com wrote: > > . . . snip snip snip . . . > > > Hi John , > > > > I am JianJun , thanks for you answer , to my understanding of your reply , > > you said only one extend for this table , so only the first extent is > > allocated, but there are 34 pages of data in the table , and the size of the > > first extent is 23 pages , so , I think there should have 3 (1 first and 2 > > next ) extents for this table , but why there is only one extent the tbcheck > > told to me . > > > > When Informix loads data, it will load the data into contiguous groups > on the disk. Since there are no gaps in the data (in your instance), it > calls it one extent. > > > Thanks > > > > Further , I still have a question to ask , one morning I found one of my > > DBspace is full , how can I find the space occupied status of each database on > > this dbspace , and how can I find the space occupied status of each table on > > each database ? > > > > onstat -d will give you basic chunk info, including free space. For the > tables, > oncheck -pt <database>:<table name> will give you used pages versus> allocated pages. > > If you're using 7.x or higher, you can get all of this information > through queries against the sysmaster database. > > John Carlson > Informix DBA > WH Smith, Inc. > snip , snip , snip ....... Hi John , Thanks for reply , I got a clear understanding from your reply , I think you are a practical DBA of informix , is your daily work to maintain your informix or to develop applications . By the way , I still want your help , Is there any limitation of the number of extents for a table ? I heard that if the number of extents for a table exceed 8 , the performance will down quickly . how about your viewpoints ? If I do a dbexport and drop the database and then do a dbimport , will the number of extents for each table become to only one , or is there any other methods to defrage the extents to improve the performance ? Thanks Jianjun jjdai@pek-co.cn.dhl.com -----== Posted via Deja News, The Leader in Internet Discussion ==----- http://www.dejanews.com/rg_mkgrp.xp Create Your Own Free Member Forum