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For example: Statistics will be gathered on Q2 and the synopsis will be created so that the global-level statistics for SALES will be updated.Once the exchange has taken place, Q2 will need fresh statistics and a synopsis and it might also need extended statistics and histograms (if SALES has them).There is nevertheless a scenario where you might want to gather statistics on LOAD prior to the exchange.For example, if it’s likely that Q2 will be queried before statistics have been gathered on SALES then you might want to be sure that statistics are available on Q2 as soon as the exchange completes.Oracle Database 12c gives you an alternative option, so I’ll cover that below.If you want to know more about extended statistics and column usage then check out this post.This post covers how you can manage optimizer statistics efficiently when you use partition exchange load (PEL).This technique is used when large volumes of data must be loaded and maximum performance is paramount.
The list_script in Git Hub displays extended statistics and histograms for a particular table if you want to take a look at what you have.
I expect you'll have guessed from the title of this post that I’m going to assume that from now on!
I'm also going to assume that the statistics on SALES are up-to-date prior to the partition exchange load.
The effect of the exchange is to incorporate all of the data in LOAD into SALES by swapping the “identity” of LOAD with Q2.
The exchange is a logical operation: a change is made in the Oracle data dictionary and no data is moved.
This happens even if you don't choose to seed column usage.