Drop Down MenusCSS Drop Down MenuPure CSS Dropdown Menu

PostgreSQL pg_lsn Data Type

-
  • The pg_lsn data type can be used to store LSN (Log Sequence Number) data which is a pointer to a location in the XLOG. This type is a representation of XLogRecPtr and an internal system type of PostgreSQL.
  • Internally, an LSN is a 64-bit integer, representing a byte position in the write-ahead log stream. It is printed as two hexadecimal numbers of up to 8 digits each, separated by a slash; for example, 16/B374D848. The pg_lsn type supports the standard comparison operators, like = and >. Two LSNs can be subtracted using the - operator; the result is the number of bytes separating those write-ahead log positions.

Comments

Post a Comment

Popular posts from this blog

How to find the server is whether standby (slave) or primary(master) in Postgresql replication ?

-
Method 1 You can check the mode of the server using "pg_controldata". [pgsql@test~]$ pg_controldata /usr/local/pgsql/data84/ Database cluster state: in archive recovery --> This is Standby Database Database cluster state: in production --> This is Production Database [Master] Method 2 You can use pg_is_in_recovery() which returns True if recovery is still in progress(so the server is running in standby mode or slave) postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- t (1 row) If Return    false   so the server is running in primary mode or master postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- f (1 row)
Read more

7 Steps to configure BDR replication in postgresql

-
Image
 The  BDR  (Bi-Directional Replication) project adds multi-master replication to PostgreSQL 9.4.  Postgres-BDR has a lower impact on the masters(s) than trigger-based replication solutions. There is no write-amplification, as it does not require triggers to write to queue tables in order to replicate writes.   Here We are using  postgres version 9.4.12 and bdr version 1.0.2. for configuring  multi master replication . Simply Following 7 steps you can configure the multi master replication in postgresql. To download the bdr in below link. .   https://github.com/2ndQuadrant/bdr/archive/bdr-pg/REL9_4_12-1.tar.gz $ tar -xzvf REL9_4_12-1.tar.gz $ wget https://github.com/2ndQuadrant/bdr/archive/bdr-plugin/1.0.2.tar.gz $ tar -xzvf 1.0.2.tar.gz 1. To install BDR. $ cd ~/bdr-bdr-pg-REL9_4_12-1 $ ./configure --prefix=/usr/lib/postgresql/9.4 --enable-debug --with-openssl $ make -j4 -s install-world $ cd ~/bdr-bdr-plugin-1.0.2 $ PATH=/usr/lib/postgresql/9.4/bin:"$PATH" ./c
Read more

How to Get Table Size, Database Size, Indexes Size, schema Size, Tablespace Size, column Size in PostgreSQL Database

-
In this post, I am sharing few important function for finding the size of database, table and index in PostgreSQL. Finding object size in postgresql database is very important and common. Is it very useful to know the exact size occupied by the object at the tablespace. The object size in the following scripts is in GB. The scripts have been formatted to work very easily with PUTTY SQL Editor. 1. Checking table size excluding table dependency: SELECT pg_size_pretty(pg_relation_size('mhrordhu_shk.mut_kharedi_audit')); pg_size_pretty ---------------- 238 MB (1 row) 2. Checking table size including table dependency: SELECT pg_size_pretty(pg_total_relation_size('mhrordhu_shk.mut_kharedi_audit')); pg_size_pretty ---------------- 268 MB (1 row) 3. Finding individual postgresql database size SELECT pg_size_pretty(pg_database_size('db_name')); 4. Finding individual table size for postgresql database -including dependency index: SELECT pg_size_pretty(pg_total_rel
Read more

Ora2PG - Oracle/MySQL to Postgres DB migration Version 20.0

-
Ora2Pg is a free tool used to  migrate  an  Oracle  or MySQL database to a  PostgreSQL  compatible schema. It connects your  Oracle  database, scan it automatically and extracts its structure or data, it then generates SQL scripts that you can load into your  PostgreSQL  database. ora2pg version 20.0 software : ora2pg-20.0.tar ora2pg-20.0   https://github.com/darold/ora2pg/releases/tag/v20.0 Some Blogs about DB Migration : https://2ndquadrant.in/postgresmigration/oracle-to-postgresql-migration/ https://2ndquadrant.in/database-migration-from-oracle-to-postgres/ INSTALLATION All Perl modules can always be found at CPAN ( http://search.cpan.org/ ). Just type the full name of the module (ex: DBD::Oracle) into the search input box, it will brings you the page for download. Releases of Ora2Pg stay at SF.net ( https://sourceforge.net/projects/ora2pg/ ). Under Windows you should install Strawberry Perl ( http://strawberryperl.com/ ) and the OSes corresponding Oracle clients. I
Read more

PostgreSQL Introduction

-
PostgreSQL tutorial provides basic and advanced concepts of SQL. Our PostgreSQL tutorial is designed for beginners and professionals. PostgreSQL is an opens-source object-relational database management system (ORDBMS). Our PostgreSQL tutorial includes all topics of PostgreSQL language such as create database, create table, drop database, drop table, select database, select table, insert record, update record, delete record, triggers, functions, procedures, cursors etc. There are also given PostgreSQL interview questions and quizzes to help you better understand the PostgreSQL language. Prerequisite: Before you start doing practice with various types of examples given in this reference, I'm making an assumption that you are already aware about what is database, especially RDBMS and what is a computer programming language. you must have the basic knowledge of SQL Problem: We assure that you will not find any problem in this PostgreSQL tutorial. But if there is any mistake
Read more