Table Extents

[dspjkr]

I came across the below statement...

"Monitor the number of extents per table with the following SQL. When a large number of extents have been allocated, schedule a time to perform preventative maintenance on the table. Theoretically, a table could have 200 extents, but realistically, problems start showing up at about 60 to 80 extents. You do not want to have anywhere near that quantity of extents, however, because performance starts dropping at about 7 to 8 extents. "

How true is this, I just took over administration of an Informix server and only have minimal experience with Informix Is this statement true, I have several table over 100 extents and a large amount above 50 extents. How bad off is this system?

 

[ladwig]

Hi,
it depends on the size of the table and how fast the table is growing. But it is always the best take care that extents reduce < 50 extens. If the limit is reached you get problem, no row can be inserted any more in that table.

 

[mjldba]

I read somewhere (don't remember where) that performance is adversely affected when there are more than 8 - 10 extents.

As previously stated, the size and volatility of the heavily fragmented table(s) will be the primary determining factors regarding to what extent (no pun intended) endusers response time is affected negatively.