Back in Nov 2021, I wrote about calling Stored procedure from Java and demonstrated how we can call a simple stored procedure from Java or a one that contains a IN parameter. I have done some more playing around with calling Stored procedure from Java so this blog is about calling a stored procedure with…
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There are many advantages to using bind variables in SQL statements, especially in conditional statements. Using bind variables can save the trouble to parse and optimize the query in every execution. There are also disadvantages such as bind variable will make optimizer lost its prediction accuracy and cause performance decrease. In PostgreSQL are represented by…
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A hierarchical query is built upon parent-child relationship, the relationship exist in the same table or view. The relationship dictates that each child can have one parent while a parent can have many children. Hierarchical query is a SQL query that handles data of hierarchical model i.e. an organisation structure where every employee has one…
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Bloating in database is created when tables or indexes are updated, an update is essentially a delete and insert operation. The diskspace used by the delete is available for reuse but it is not reclaimed hence creating the bloat. Same is the case with PostgreSQL database, frequent UPDATE and DELETE operations can leave a lot…
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A key aspect of maintaining a high performance database is continuous monitoring of system resources, as any issues anywhere on the system can potentially lead to downtime. There are options aplenty for monitoring, so reinventing the wheel doesn’t make much sense. For that purpose, I’ve selected a couple of options that are simple to deploy,…
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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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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 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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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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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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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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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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In computing, a hash table (hash map) is a data structure that implements an associative array abstract data type, a structure that can map keys to values. A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value…
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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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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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HighGo Software Canada (a subsidiary of HighGo Software Inc.) is pleased to release HighGo Postgres Server 2.1 General Availability (HG-PGSQL 2.1 GA) on its website https://www.highgo.ca/products/highgo-postgresql-server/2-1-2/. The GA release contains everything that was released with HG-PGSQL 2.0 beta few weeks earlier with the addition of some important bug fixes and updates to user documentation. With…
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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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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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TDE is an important feature missing from PostgreSQL, it is also a crucial tick in the box which people are deciding to move to PostgreSQL from other DBMS systems. The community has been trying to add this feature in PG however it has taken too long because of lack of attention from serious community members…
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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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