DBA

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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

DBA general questions crib-sheet

Technical questions is a big part of a job interview for a DBA. This post contains some of the general questions.  Each answer is giving high level overview, and on a purpose is not going into low level syntax or technical to avoid binding to a vendor-specific features.   

  • monitoring and performance tuning for Production systems
  • running load tests, stress-testing database
  • changing big schemas models on the fly (minimizing downtime)   
  • RDBMS or NoSQL? use cases, pros and cons  
  • HA solutions for Production systems 
  • backups strategies, cloning, patching and other database maintenance perfromed with no serrvices interruption     

Here you will find answers for such generic topics,    

Are you a DBA? Found post useful, wanted to add something important but yet uncovered. Found mistake or a  misconception?  I'd love to hear more and disdcuss !  

Incremental Hotbackup use case

Running continuous online backups for Production Database is an extremely important part of a DBA operations,

Being prepared for a Point-In-Time Recovery Situation is even more important,  

first part may sound easy in the beginning, when DBA manging a small, part-time loaded system,

scheduling a regular nighly full hot backup will be a way to go in this case.

Now what if we are running a Real Production Databases (2+TB of data + 500 concurrent sessions 24x7) ?

Let's talk about incremental backups under the cut ..