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Data manager ID generated for every query -> SQL plan cache is ignored

Hi!

I've noticed in my system that for every query (no matter via RSRT or via infoprovider data view in RSA1) in generated SQL-statement system appends a string with DMUID like:

     SELECT something

     FROM somewhere

     WHERE where_clause

      /*$ dmuid=0005PZGODYOBXA2JK5IWZ4IWL */

This leads to total ignoring of HANA SQL plan cache because every query gets own unique DMUID. And therefore reduces performance. I think it's some BW statistical stuff. Maybe someone knows how to disable that?

Thanks, Andrey.

replied

That's a good observation Andrey and not too uncommon for database literate folks to remark when they get a bit deeper into SAP BW.

The main point here is that the comment with the DMUID is generated newly for every different SAP BW query. That means the DMUID will change when the rest of the query changes, which in turn leads to the same number of new SQL queries than without the comment.

So, disabling this wouldn't enhance the usage of the SQL plan cache.

BTW: the plan cache is never ignored, disabled or not used. The SQL queries are put into the cache and it can be used to analyse issues, e.g. performance problems on DB level and link the SQL queries back to SAP BW terms.

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