LTXEHWM

onconfig.std
value

60

units

Percent

range of values

LTXHWM through 100

takes effect

When shared memory is initialized

utilities

onutil

refer to

The following material:

• LTXHWM
• Avoiding long transactions in the chapter on what is the logical log in the IBM Informix: Administrator's Guide

LTXEHWM specifies the long-transaction, exclusive-access, high-water mark. If a single long transaction spans LTXEHWM percent of the logical log, it is given exclusive access to the logical log. For example, if you set LTXEHWM to 60 percent of the logical-log space, and a transaction spans to that percentage, at that point the thread that is rolling back the long transaction is given exclusive access to the logical log. The term exclusive is not entirely accurate. Most database server activity is suspended until the transaction has completed its rollback, but transactions that are in the process of rolling back or committing a transaction retain access to the logical log.

When the database server is initialized, if LTXEHWM is set greater than the recommended value 60, and DYNAMIC_LOGS is set to 0, a warning is issued. In this case, it is recommended that you decrease the value of LTXEHWM or set DYNAMIC_LOGS to a non-zero value.

For more information about setting high-water marks, see the logical-log chapter in the IBM Informix: Administrator's Guide.

To modify the LTXEHWM parameter dynamically, use the onutil SET command. Example:

% onutil
> SET LTXEHWM 80;