Checking for slow queries

After inspecting pg_stat_activity, it makes sense to take a look at slow time-consuming queries. Basically, there are two ways to approach the problem:

  • Look for individual slow queries in the log
  • Look for types of queries that take too much time

Finding single, slow queries is the classic approach to performance tuning. By setting the log_min_duration_statement variable to a desired threshold, PostgreSQL will start to write a log line for each query exceeding this threshold. By default, the slow-query log is off:

test=# SHOW log_min_duration_statement; log_min_duration_statement----------------------------                         -1(1 row)

However, setting this variable to a reasonably good value makes perfect sense. Depending on your ...

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