malisper.me

malisper.me

General

  • About Me
  • Twitter
  • Table of Contents for Postgres Posts
  • RSS

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Skip to content

malisper.me

Category: Query Execution

Speeding up Postgres Index Scans with Index-Only Scans

As mentioned previously, indexes are a datastructure that allow for both quickly locating rows that satisfy some condition and for obtaining rows sorted by some order. To execute a regular index scan, Postgres scans through the index to find … Read the rest

Posted on May 29, 2017April 20, 2019 by malisper 0

Using Explain Analyze in Postgres

In the last post, we discussed EXPLAIN and how it can be used to obtain the query plan for a query. EXPLAIN ANALYZE is a variation of EXPLAIN that provides additional information about the query. In addition to displaying all … Read the rest

Posted on May 24, 2017May 25, 2017 by malisper 3

Using Explain in Postgres

If you are ever doing any sort of query optimization in Postgres, knowledge of EXPLAIN is an absolute must. EXPLAIN let’s you see what algorithms Postgres is using under the hood in order to execute a query. Let’s look at … Read the rest

Posted on May 23, 2017April 13, 2019 by malisper 0

Postgres Merge Joins

This is the last part of a three part series examining the Postgres join algorithms.

While a hash join is usually the fastest join algorithm, it is only so when it can be performed in memory. When Postgres thinks the hash … Read the rest

Posted on May 22, 2017April 20, 2019 by malisper 1

Postgres Hash Joins

This is part two of a three part series examining the Postgres join algorithms.

Of the join algorithms Postgres has available, the hash join is usually the fastest. The main downside is hash joins only work where the join condition is an … Read the rest

Posted on May 19, 2017April 20, 2019 by malisper 0

Postgres Nested Loop Joins

This is the first part of a three part series examining the Postgres join algorithms.

For those who need a reminder, a join between two tables results in every pair of rows where some condition is true. Given a query of … Read the rest

Posted on May 18, 2017April 20, 2019 by malisper 0

Postgres Bitmap Scans

This is the final part of a three part series exploring the different ways Postgres can retrieve rows from a table.

One major restriction with regular index scans is that they can only use a single index. Sometimes a query … Read the rest

Posted on May 17, 2017April 20, 2019 by malisper

Postgres Index Scans

This is part two of a three part series examining the different ways Postgres can fetch rows from a table.

Usually a sequential scan winds up being pretty slow. A sequential scan needs to read the entire table in order … Read the rest

Posted on May 16, 2017April 13, 2019 by malisper

Postgres Sequential Scans

This is part one of a three part series on the main ways Postgres has of fetching rows from a table. 

Of the three main ways Postgres has fetching rows from a table, a sequential scan is the most basic. … Read the rest

Posted on May 15, 2017May 25, 2017 by malisper
Proudly powered by WordPress ~ Theme: Scrawl by WordPress.com.