Re: Explanation of tbcheck -pt output

Jinu.Joseph@citicorp.com wrote: > > Hi, > The following is the output of the command tbcheck -pt for a table in my > database : > ... > ... > Maximum row size 1549 > Number of special columns 5 > Number of keys 6 > Number of extents 32 > Current serial value 1 > First extent size 460800 > Next extent size 184320 > Number of pages allocated 5312017 > Number of pages used 5246787 > Number of data pages 3134215 > Number of data bytes 554916459 > Number of rows 3134215 > ... > ... > > Need the answer for the following questions: > 1. Why is there a difference between pages allocated and pages used ? Pages allocated is the total of all pages allocated to that table including pages used and free pages. > 2. When monitoring on a daily basis only the value of data pages > increases. Pages used stays constant. Why? It sounds like index pages are reducing and data pages are increasing for some reason. > 3. How do I find out the actual space usage of the table ? Add up all the pages used values. Each one represents each fragment or detached index in that table. > 4. When is the next extent added to a tblspace and how does it compute > the space required ? It is added when there are no more free pages and you try to use a new data or index page. It does not compute the next extent size, it relies on the value you set, which in this case is 184320. > I am trying to develop a utily that will send out a warning when the > tablespace reaches a threshold limit of say 80% 80% of what? 80% of the allocated pages are used or 80% of the dbspace is used? The latter becomes more difficult for fragmented tables or detached indexes. Cheers, -- Mark. +----------------------------------------------------------+-----------+ | Mark D. Stock mailto:mdstock@mydas.freeserve.co.uk |//////// /| | http://www.informix.com http://www.informixhandbook.com |///// / //| | http://www.iiug.org +-----------------------------------+//// / ///| | |This email will self-destruct in |/// / ////| | |10 sec. If you received this email |// / /////| | |in error, sorry about the mess. |/ ////////| +----------------------+-----------------------------------+-----------+