zhuomingliang

🗺🐘 1000+ PostgreSQL EXTENSIONs

This is a list of URLs to PostgreSQL EXTENSION repos, listed in alphabetical order of parent repo, with active forks listed under each parent.

⭐️ >= 10 stars
⭐️⭐️ >= 100 stars
⭐️⭐️⭐️ >= 1000 stars
Numbers of stars might not be up-to-date.

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ZFS 2-3x slower than EXT4

• With the default settings that ship with Postgres, ZFS underperforms EXT4 by a factor of 2-3x.
  • Most notable setting is shared_buffers=128MB
• When benchmarks are running on ZFS, severe write amplification is reported by iotop and txg_sync is performing a lot of IO. Example:
• The DB used for benchmarking is ~30GB. The system has a total of 64GB RAM with the ARC being given a maximum of ~32GB. Irrespective of the small value of shared_buffers, almost the entire DB should be cached in the ARC and the ZFS benchmark should not suffer so greatly.

Table of contents

• Benchmark results for Postgres on ZFS vs EXT4

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Tuning ZFS + Postgres to outperform EXT4 + Postgres

Please refer to ZFS 2-3x slower than EXT4 to see how ZFS defaults + Postgres defaults severely underperform EXT4 defaults + Postgres defaults (and also to know more about the system on which these benchmarks were performed). This page documents how to tune ZFS + Postgres to give better performance for the tpcb-like benchmark.

BIG FAT WARNING

Please do not copy these settings blindly because I am myself not clear on why/how these settings had the impact they did. For example, I cannot explain why full_page_writes=off independently did not give that much boost, nor did an optimized PG configuration. However, putting both of them together gave a 2-4x boost compared to baseline numbers.

Benchmark results

zhuomingliang

--- PSQL queries which also duplicated from https://github.com/anvk/AwesomePSQLList/blob/master/README.md
--- some of them taken from https://www.slideshare.net/alexeylesovsky/deep-dive-into-postgresql-statistics-54594192

-- I'm not an expert in PSQL. Just a developer who is trying to accumulate useful stat queries which could potentially explain problems in your Postgres DB.

------------
-- Basics --
------------

-- Get indexes of tables

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** Find commmonly accessed tables and their use of indexes:

SELECT relname,seq_tup_read,idx_tup_fetch,cast(idx_tup_fetch AS numeric) / (idx_tup_fetch + seq_tup_read) AS idx_tup_pct FROM pg_stat_user_tables WHERE (idx_tup_fetch + seq_tup_read)>0 ORDER BY idx_tup_pct;

Returns output like:

       relname        | seq_tup_read | idx_tup_fetch |      idx_tup_pct       
----------------------+--------------+---------------+------------------------
 schema_migrations    |          817 |             0 | 0.00000000000000000000
 user_device_photos   |          349 |             0 | 0.00000000000000000000

zhuomingliang

/*
 * OpenSimplex Noise in Java.
 * by Kurt Spencer
 * 
 * v1.1 (October 5, 2014)
 * - Added 2D and 4D implementations.
 * - Proper gradient sets for all dimensions, from a
 *   dimensionally-generalizable scheme with an actual
 *   rhyme and reason behind it.
 * - Removed default permutation array in favor of

zhuomingliang

/*
 * fork.c
 * Experimental fork() on Windows.  Requires NT 6 subsystem or
 * newer.
 *
 * Copyright (c) 2012 William Pitcock <nenolod@dereferenced.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.

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commands:
  00_update_composer:
    command: export HOME=/root && export COMPOSER_HOME=/root && /usr/bin/composer.phar self-update

option_settings:
  - namespace: aws:elasticbeanstalk:application:environment
    option_name: COMPOSER_HOME
    value: /root
  - namespace: aws:elasticbeanstalk:application:environment
    option_name: HOME

zhuomingliang

/**
 * Based on the mysql cluster
 * @link http://jonisalonen.com/2012/k-means-clustering-in-mysql/
 */
-- SELECT
-- * FROM
--   unnest(kmeans(array(SELECT
--   (
--     lat,

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-- Create the raw events table
CREATE TABLE page_views (
    site_id int,
    path text,
    client_ip inet,
    view_time timestamptz default now(),
    view_id bigserial
);

-- Allow fast lookups of ranges of sequence IDs