MaxDB Optimizer

[Former Member]

Hello,

to check the database access by the programs i use the database analyzer to find programs with bad access.

I check the access by explain the program, so that i will see the details, how many pages the database has to read.

On the table vbak i have an index over the field vkorg, so that the optimizer uses 1250 pages for the index and at least 7389 pages to read the data.

I have an index, that contains a reference to all fields of the where condition of the program. If i'll use a hint to this index, the optimizer uses 1553 pages for the index (OK, more information in the index), but the optimizer would like to read 22913 pages, at least over 14000 pages more.

I can't understood this , because mathematical the last access must more performant than the first.

Is this a problem by the optimizer?

Regards

Andreas Vogts

[Former Member]

Hello Lars,

I 'll open a customer message in service marketplace.

Regards & nice weekend

Andreas Vogts

[lbreddemann]

Hi Andreas,

as you're a SAP customer it would be easier to analyze the issue directly on the system.

Please open a support message for this.

From the description given I would guess that in the case where you used the hint an intermediate result needs to be created. The optimizer calculates costs for this as well.

If you want to discuss this via this forum - please post

• the query

• the index definition

• the table key

• the current statistics

• the dabase opti* parameters

and of course both explain plan outputs.

regards,

Lars