Informix ISAM error 136: no more extents

Technote (troubleshooting)


Problem(Abstract)

When attempting to insert rows into a table, the following error is returned to the client:

ISAM error 136 : no more extents

Cause

IDS can only allocate a maximum of 16,775,215 disk pages per table partition or fragment. It should also be noted that this is independent of the dbspace configured page size.
Also, IDS can only track approximately 200 extents (logical grouping of disk pages) per table partition or fragment. The most likely root cause will be that one or both these values have been realized.


Diagnosing the problem

As user informix, run "oncheck -pt <database>:<table name >".


In the resulting output, examine the value for "Number of pages used" or "Number of pages allocated". If either one is equated to 16,775,215 then this is the most likely root cause of the problem.

However, should these values not be close to 16,775,215 then it's likely that the table has already allocated a high number of smaller extents (logical grouping of data or index pages).
If so , then the value for "Number of extents" will be close to or greater than 200, (there is no 'hard' limit due to various architectural reasons).

Example output to oncheck -pt :

TBLspace Report for dbase:informix.customer

Physical Address 1:36878
Creation date 801 Page Locking
TBLspace use 4 bit bit-maps
Maximum row size 134
Number of special columns 0
Number of keys 0
Number of extents 186
Current serial value 10139
Current SERIAL8 value 1
Current BIGSERIAL value 1
Current REFID value 2
First extent size 8
Next extent size 16
Number of pages allocated 16775215
Number of pages used 16775215
Number of data pages 16775215
Number of rows 1118341
Partition partnum 1049005
Partition lockid 1049005


Resolving the problem

If the value for Number of pages used or allocated is at 16775215, then try one of the following recommendations:

Non Fragmented Tables:

1. If the indexes defined for the table are attached , drop and recreate the table's indexes as "detached" (in their own separate partitions).

Note: A CREATE INDEX statement that does not specify IN TABLE as its storage clause creates indexes that store their pages in separate partitions from the data pages by default.

2. Fragment the table using a Round Robin or an Expression Based strategy. This will result in additional partitions being created in order to track the table internally.

If the value for Number of extents is close or exceeds 200, then :

Reorganize the table using a larger initial extent size to defeat a high number of smaller extents being allocated.

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Document information


More support for:

Informix Servers

Software version:

11.1, 11.5, 11.7, 11.70, 12.1

Operating system(s):

AIX, HP-UX, Linux, Mac OS X, Solaris, Windows

Reference #:

1395852

Modified date:

2014-01-10

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