Consultor Eletrônico

Status: Verified

SYMPTOM(s):

Increasing temptable blocksize decreases performance due to DBI growth.

After upgrading to OpenEdge 10.1B the DBI size increases.

FACT(s) (Environment):

Increasing tmpbsize from 1kb to 8kb increases DBI size substantially.
All Supported Operating Systems
All Supported Operating Systems
Progress/OpenEdge Product Family

CHANGE:

Upgraded to 10.1B

CAUSE:

Increasing the temptable blocksize will increase the amount initially allocated for temptables. The more temptables that are defined, the more memory/DBI space is consumed.

Using an 8kb temptable blocksize will allocate approximately 8 times the amount compared to using a 1kb blocksize.

Note that it is only the initial allocation that increases to this degree. When the temptables actually get used then they are more comparable.

For example:

1kb blk 8kb blk
Defining only 442368 3538944
Populating 15884288 17629184


Due to the increase in temptable space allocation, if the DBI file is being used a lot more then it can negatively impact performance especially when large numbers of users are involved.

In 10.1B the default temptable blocksize has been increased from 1kb to 4kb.

FIX:

There are a couple of solutions to the problem:

1. Decrease the temptable blocksize by using the -tmpbsize parameter:

-tmpbsize 1

2. Increase the amount of memory each client allocates for temptable buffers by using the -Bt parameter. The DBI file is used once the temptable buffers have all been filled. Note that this memory is allocated for EACH CLIENT. Increasing this parameter on a system that doesn't have adequate memory can cause negative performance.

The -Bt parameter specifies the number of buffers to allocate, each buffer is the size of a temptable block.

In Progress versions up to 10.0B the default is -Bt 10.
In Progress version 10.1A onward the default is -Bt 255.