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The Hitchhiker’s Guide to the EXPLAIN PLAN Part 39: Unfriending the optimizer statistics

We can’t help attaching meaning to optimizer statistics. After all, they represent our data, don’t they? So we refresh them as frequently as possible and use the largest sample sizes that we can use. Recently, for the first time in my life, I encountered a group of DBAs who understood that statistics do not have any intrinsic meaning; that they are nothing more than a collection of numbers that influence the generation of query plans. In the case of these DBAs, they found that the strategy that worked best for their applications was to treat the optimizer statistics just as they would treat program code. Statistics were checked into the source code repository just as program code was checked into the source code repository.(read more)