Reorg of key compressed indexes

[Former Member]

Hi experts,

We used to sap note 1109743 to compress indexes on SAP ERP system.

Now while doing reorg of index, it gets uncompressed.

What is procedure to reorg an key compressed index so that resulting index is compressed with same compression factor?

thanks in advaance,

Daljit

[stefan_koehler]

Hello Daljit,

> What is procedure to reorg an key compressed index so that resulting index is compressed with same compression factor?

1) If you check sapnote #1289494 (Point 5) you will see the following limitation:

The ABAP Dictionary does not support index compression. If you reconstruct an index using transaction SE14 or as part of a transport, the index loses its compression attributes.

So don't use the SAP system itself for reorg compress indexes. The compression will be lost.

2) If you reorg your indexes with the BRTools - the compression will be kept, because of the BRTools are reading all the index definitions and will use them to rebuild the index.

A little bit more information about the internals of the BR*Tools is posted in this thread:

So the procedure is quite simple.. just use the BR*Tools and the index compression will be kept by a reorg.

Regards

Stefan

[former_member204746]

how have you reorg'ed the index? If you did this from within SAP, this might be normal because I beleive that SAP's data dictionary does not check for compression.

you will need to re-compress them again.

[Former Member]

problem is that some of 40+ GB indexes were compressed to 1/10 size and moved to smaller tablespace. In order to reorg now it will need lot of disk space in uncompressed for and then it has to be compressed again.

there must be an option to use its current compression factor and use it while reorganizing?

[Former Member]

when you reorg it recompresses... you have to recompress... i also got good results on compression but response time increased on some queries...still trying to determine why...i am thinking that the first couple columns are very selective and is having adverse affect...