RE: what happens when a table has over 200 extents
ON 5 Oct 1995 17:14:39 davek@somerset.informix.com wrote:
[SNIP]
}As of release 6.0, the TBLSPACE structure has changed, so where there was
}an array of extent structures there is now a pointer to an extent structure.
}Space is simply allocated to accomodate all the extents for the tblspace.
}So now ALL the extents can be considered "fast access". The TT structure is
}different, too, allowing > one page per tblspace, so you should not run out
}of extents due to the page limitation, but the number of extents is tracked
}by a 2 byte integer, so you are limited to 32K extents, though I wouldn't
}recommend having this many ;-).
}
But in the "Informix-Online Dynamic Server - Performance Guide Version 7.1"
(Part # 000-7708), page 3-27, under "Upper Limit on Extents", it says
different.
... The upper limit on extents depends on the page size and the table
calculation...
... pagesize = the size of a page (reported by onstat -c under the
BUFFSIZE heading)
colspace = 4 X the number of columns in the table
ixspace = 12 X the number of indexes on the table
ixparts = 4 X the number of columns named in each index
extspace = pagesize - (colspace + ixspace + ixparts +84)
The table can have no more than extspace/8 extents.
(Don't trust my typing, double check the manual)
The error number for exceeding the extent limit is -136. There is info
listed by finderr for this error, but the calculation looks eaiser.
I highly recommend the Performance Guide to all Informix 7 users.
} Anyone who says otherwise is itching for a fight.
I'm not looking for a fight, just answers.
--
Steve Berg spb@masada.nb.com