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Processing SQL queries in Oracle and PostgreSQL

Initial parsing phase of SQL query processing is pretty much similar for the both Oracle and PostgreSQL databases.

However, when paersing completed, there is a big difference,.Oracle stores compiled queries in a Global Library Cache, which is available for all sessions for a running Oracle Instance. PostgreSQL, stores pre-processed queries in a process local memory.

Enable wait events in PostgreSQL

Reading and understanding top wait events is and is a key apsect of a database performance tunning, as it helps in troubleshooting of various  performance issues (like long running and hanging sessions in database).

Now wait events and related dynamic views are becoming available in PostgreSQL as a plugable extension, 

In this article, we are going to  

  1.  install and enable *pg_stat_wait* extension from source 
  2.  query-up new performance views for a top waiting events and top waiting sessions, 
  3.  enable session tracing for these event in Posgresql database