Planner estimates have already been discussed on this blog in my previous posting and also in some posting before that. A couple of years ago I stumbled over an interesting issue which is commonly known as “cross correlation”. Let us consider the following example: test=# CREATE TABLE t_test (a int, b int); CREATE TABLE test=# […]

In 99% of all cases the PostgreSQL planner is doing a perfect job to optimize your queries and to make sure, that you can enjoy high performance and low response times. The infrastructure ensuring this is both sophisticated as well as robust. However, there are some corner cases, which can turn out to be quite […]