Category: postgresql

Enterprise PostgreSQL Solutions

How to create a system information function in PostgreSQL

1. Overview PostgreSQL supports many System Information Functions, such as Session Information Functions, Access Privilege Inquiry Functions, Schema Visibility Inquiry Functions, System Catalog Information Functions, Transaction ID and Snapshot Information Functions, etc. However, you may want build some special functions and integrate them into the PostgreSQL. This blog is going to walk through the steps…
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How PostgreSQL Handles Sub Transaction Visibility In Streaming Replication

1. Introduction As an experienced PostgreSQL user, you may have a lot of experience in setting up streaming replication in your database clusters to make multiple backups of your data. But have you wondered how the standby is able to correctly determine if a tuple sent from the primary should be visible to the user…
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PostgreSQL Logical Replication Advantage and Step by Step Setup

PostgreSQL is one of the most advanced open source databases globally with a lot of great features. One of them is Streaming Replication which was introduced in PostgreSQL 9.0—known as Physical Replication. It works by sending the WAL segments generated by the primary PostgreSQL to another standby server also running PostgreSQL. However, if we only…
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Exploring SQL command changes in PG-14

I have spent sometime exploring all the SQL command changes in PostgreSQL 14, this blog will provide a brief summary about the SQL changes along with some examples. There are exciting new features that in progress for PG-14, this blog will only focus on the SQL changes that are committed and will be released with…
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Troubleshooting Performance Issues Due to Disk and RAM

Troubleshooting Performance Issues Due to Disk and RAM

Quite a few managers or clients expect DBAs to type away a few commands to fix a sluggish PostgreSQL instance. If only things were that simple. Unfortunately, debugging a sluggish instance that was previously running optimally requires analysis at many levels. In this blog, I will attempt to help that debugging process on Linux by…
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How PostgreSQL Inserts A New Record With The help of Table Access Method API and Buffer Manager

1. Introduction This blog talks about a high level description of the mechanism behind PostgreSQL to execute an INSERT query. This process involves many steps of processing before the data is put in the right place. These process normally involves several catalog cache lookup to determine if the destination table exists or several checking on…
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How to setup Postgres 13 WAL streaming replication on Ubuntu 18.04

1. Overview PostgreSQL supports different type of replications, i.e. logical and physical, and there are many tutorials discussed about the replications. This blog is a simply walk-through of the WAL Streaming replication using the latest Postgresql-13 on Ubuntu 18.04. 2. Install Postgresql-13 from source code In this blog, we will install Postgresql from the source…
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How PostgreSQL Executes Sequential Scans with the Help of Table Access Methods APIs

1. Introduction There are many approaches for PostgreSQL to retrieve the data back to the user. Depending on the user’s input query, the planner module is responsible for selecting the most optimum approach to retrieve the requested data. Sequential scan is one of these approaches that is mostly selected when the user requests a large…
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The mapping of oid and relfilenode in PG

A table in PostgreSQL has a relfilenode value, which specifies the file name of the table on disk (except foreign table and partition table). In general, this value can be found in the relfilenode field of the pg_class table, but there are some specific tables whose query result in the relfilenode field is 0. This…
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Checkpoints In PostgreSQL

PostgreSQL database writes all changes happening in the database to a log file before it writes them to the actual data files. These log files are called WAL (Write-Ahead Log). Until these changes are flushed to the disk, they are kept in memory and is returned from the memory when it’s asked for. Writing to…
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How to dump out a backtrace during runtime

1. Overview PostgreSQL is a great open source database developed and maintained by many great software engineers around the world. In each release, there are many features added to this open source database. For example, one feature is very helpful for developer is backtrace_functions introduced in PostgreSQL 13 , which allows a developer to dump…
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Installing PostgreSQL on CentOS6 Post EOL

If you’ve seen the following error, you know that your CentOS6 has reached end of life (EOL). Loaded plugins: fastestmirror, ovl Setting up Install Process YumRepo Error: All mirror URLs are not using ftp, http[s] or file. Eg. Invalid release/repo/arch combination/ removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.txt Error: Cannot retrieve repository metadata (repomd.xml) for…
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Bulk loading into PostgreSQL: Options and comparison

You have a file, possibly a huge CSV, and you want to import its content into your database. There are lots of options to do this but how would you decide which one to use. More often than not the question is how much time would the bulk load would take. I found my self doing the same…
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What’s the special for logical level of PostgreSQL WAL

When using logical replication with PostgreSQL, the wal level needs to be set to ‘logical’, so the logical level wal contains more data to support logical replication than the replicate wal level. I think it’s unclear to many users or DBAs about the difference between logical and replicate level. This blog is about the difference…
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2020 PG Asia Conference Ended Successfully at an Unprecedented Scale!

Introduction On November 17-20, 2020, PostgresConf.CN & PGconf.Asia2020 (referred to as 2020 PG Asia Conference) was held online for the very first time! This conference was jointly organized by the PG China Open Source Software Promotion Alliance, PostgresConf International Conference Organization, and PGConf.Asia Asian Community. This conference was broadcast exclusively via the Modb Technology Community…
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PostgreSQL High Availability: Setup and Uptime Considerations

My previous blog on “PostgreSQL High Availability: Considerations and Candidates” mostly talked about defining an HA considerations for PostgreSQL, RPO and RTO and briefly touched on some of the open source solutions available. Granted that I didn’t list them all and people shared some additional ones that I may end up reviewing as well. In…
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Calling a Stored Procedure in PostgrSQL from JAVA and its Current Limitations

This is my third blog about Stored Procedure support in PostgreSQL, the previous two blogs are reachable from the HighGo CA blogs site https://www.highgo.ca/author/ahsan-h/. The first blog was introduction and usage of Stored Procedures and its difference with Stored Functions, the second blog focussed on creating and using Procedures with Definer and Invoker rights. The…
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Technical Overview of pg_stat_monitor extension: A more detailed pg_stat_statements

Database monitoring is a very essential for most of the database system, it can prevent system crises, improve performance, database failure and auditing the traffic for identify any unwanted access. PostgreSQL has an extension called pg_stat_statements, which can capture a lot of query execution details. Recently, percona release a new extension called pg_stat_monitor which can…
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How to Analyze a PostgreSQL Crash Dump File

1. Introduction In this blog post, I will talk about how to enable the generation of crash dump file (also known as core dump) and some common GDB commands to help a developer troubleshoot a crash-related issues within PostgreSQL and also other applications. Proper analysis of the issue normally will take time and certain degree…
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Free Space Mapping file in details

1. Overview Previously, we discussed the MAIN fork file and corresponding extension at Heap file and page in details. This blog will explain a little bit more about the Free Space Mapping file and corresponding extension. 2. What is a Free Space Mapping file A Free Space Mapping, FSM, file is a file that keeps…
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