Consultor Eletrônico

TXE Latch Reasons to get TXE Latch

This kbase is written to help to address TXE latch contention. It
provides some of the reasons that a TXE latch is used under. It is by
no means the all-encompassing list, but a good start. At the end is a
an example of a worst case scenario.

The TXE latch is called during transaction end processing.
It can also be called in conjunction with MTX as well.
This happens at the beginning of MTX (or microtransaction)
processing. The TXE is gotten every time a "logical operation"
happens.

A logical operation constitutes:

1) schema change adding table or index.
2) splitting an index.
3) deleting an index entry.
4) deleting a key in a key field.
5) creating a record that spans 2 blocks.
6) updating a record that spans 2 blocks.
7) Anything else that constitutes updating of 2 blocks.

Worst Case Scenario:
Creating a record that is larger than the database block size will
force the TXE latch. If the BI file needs to extend then we will hold

the latch while the BI file extends. To do this we may have to go to
the OS to get the disk space. If we have to extend the database as
well then we will hold the same TXE while the DB extends, again going
to the OS to get the disk to extend.
In this scenario we have had to go to the OS to get the disk space
twice before we have even started writing the record to the database.

Progress Software Technical Support Note # 17532