POSTGRESQL CHEAT SHEET

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PostgreSQL - Architecture

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When you start PostgreSQL`s instance (via pg_ctl start) the main process of the databases is started. In the past versions it was known as the postmaster process and now days it is called postgres. When this processes is started it allocates memory for two main things : shared memory and other background processes. The shared memory is a memory that the database uses mainly for cashing. Its main goal is to reduce the I/O operations and as a result of that improve the performance of the database. The other processes that the postgres process starts are responsible for the ongoing work of the database.  PostgreSQL`s architecture is based on a client/server communication. In the server side there is a server process that manages the files, database operations, connection and so on.. On the client side there is a tool/program which can be a graphical tool (gui)  like pgAdmin or a command line tool(cli) like psql  that is repnsible for connection the database and all...
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POSTGRESQL DATABASE MAINTENANCE

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  Routine backup of daily database maintenance work , regular “clean up” database, periodic log file management check_postgres can be used to detect database health and report abnormal conditions 1. Daily cleaning PostgreSQL database requires periodic cleaning and maintenance. For many installations, it is sufficient to have the automatic cleanup daemon perform cleanup 1.1. Basic knowledge of cleaning The PostgreSQL VACUUM command must periodically process each table for several reasons: 1.  Restore or reuse the disk space occupied by updated or deleted rows. 2.  Update the data statistics used by the PostgreSQL query planner. 3.  Update the visibility map, it can speed up the scan using only the index. 4.  Protect old data from being lost due to transaction ID rewinding or multi-transaction ID rewinding. There are two variants of VACUUM: standard VACUUM and VACUUM FULL. VACUUM FULL can reclaim more disk space but runs slower. VACUUM FULL requires an exclusive l...
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PostgreSQL - Backup & Point In Time Recovery

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  In this post you will learn about how to restore a PostgreSQL database in Point in time. Open source databases are taking over other conventional Database softwares at very high speed. For me personally, I really like the way PostgreSQL is designed and it’s simple architecture. I have tried to write it down every possible steps which will help you to restore your Postgres database. Below Steps will be same, but few commands may vary with any other backup tool. PITR PostgreSQL Allow you to restore database to a specific moment in time PITR. It make use of live database files and WAL files. This method can only backup and restore the whole cluster, for individual database use pg_dump. It can be done when the DB is online. Step 1. If archive logs not enable then enable it, otherwise go to Step3. Create Directory for archive logs mkdir /postgres/postgres12.2/wal_archives Make changes in postgresql.conf Postgresql.conf is present under your data directory, in my case it is in /postgre...
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