I am writing some new SQL queries and want to check the query plans that the Oracle query optimiser would come up with in production.
My development database doesn’t have anything like the data volumes of the production database.
How can I export database statistics from a production database and re-import them into a development database? I don’t have access to the production database, so I can’t simply generate explain plans on production without going through a third party hosting organisation. This is painful. So I want a local database which is in some way representative of production on which I can try out different things.
Also, this is for a legacy application. I’d like to “improve” the schema, by adding appropriate indexes. constraints, etc.
I need to do this in my development database first, before rolling out to test and production.
If I add an index and re-generate statistics in development, then the statistics will be generated around the development data volumes, which makes it difficult to assess the impact my changes on production.
Does anyone have any tips on how to deal with this? Or is it just a case of fixing unexpected behaviour once we’ve discovered it on production? I do have a staging database with production volumes, but again I have to go through a third party to run queries against this, which is painful. So I’m looking for ways to cut out the middle man as much as possible.
All this is using Oracle 9i.
Thanks.
See the documentation for the DBMS_STATS.EXPORT_SCHEMA_STATS and DBMS_STATS.IMPORT_SCHEMA_STATS packages. You’ll have to have someone with the necessary privileges do the export in the production database for you if you don’t have access. If your development hardware is significantly different than your production hardware, you should also export/import the system statistics with the EXPORT/IMPORT_SYSTEM_STATS procedures.
Remember to turn off any jobs in the development database that recalculate statistics after you do this.