Paweł Rychlik pawelrychlik

PostgreSQL is Enough

Background and Cron Jobs

Charts are from different sources and thus colors are inconsistent, please carefully read the chart's legends.

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Kafka 0.11.0.0 (Confluent 3.3.0) added support to manipulate offsets for a consumer group via cli kafka-consumer-groups command.

List the topics to which the group is subscribed

kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --describe

Note the values under "CURRENT-OFFSET" and "LOG-END-OFFSET". "CURRENT-OFFSET" is the offset where this consumer group is currently at in each of the partitions.

Reset the consumer offset for a topic (preview)

Parens And Performance

Years ago, some smart folks that worked on JS engines realized that not all JS that's loaded into a page/app initially is needed right away. They implemented JIT to optimize this situation.

JIT means Just-In-Time, which means essentially that the engine can defer processing (parsing, compiling) certain parts of a JS program until a later time, for example when the function in question is actually needed. This deferral means the engine is freer to spend the important cycles right now on the code that's going to run right now. This is a really good thing for JS performance.

Some time later, some JS engine devs realized that they needed to get some hints from the code as to which functions would run right away, and which ones wouldn't. In technical speak, these hints are called heuristics.

So they realized that one very common pattern for knowing that a function was going to run right away is if the first character before the function keyword was a (, because that usually m

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

Processing JSON using jq

jq is useful to slice, filter, map and transform structured json data.

Installing jq

On Mac OS

brew install jq

Project Title

One Paragraph of project description goes here

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes. See deployment for notes on how to deploy the project on a live system.

	-- https://www.geekytidbits.com/performance-tuning-postgres/
	-- http://www.craigkerstiens.com/2012/10/01/understanding-postgres-performance/
	-- http://okigiveup.net/what-postgresql-tells-you-about-its-performance/
	-- https://wiki.postgresql.org/wiki/Introduction_to_VACUUM,_ANALYZE,_EXPLAIN,_and_COUNT
	-- https://devcenter.heroku.com/articles/postgresql-indexes#b-trees-and-sorting
	-- http://www.databasesoup.com/2014/05/new-finding-unused-indexes-query.html
	-- performance tools
	-- https://www.vividcortex.com/resources/network-analyzer-for-postgresql

	-- show running queries (pre 9.2)

	"use strict";

	// Registering cleanup callback before requiring flightplan.
	process.on("SIGINT", interruptedCleanup);

	const util = require("util"),
	moment = require("moment"),
	_ = require("lodash"),
	plan = require("flightplan"),
	request = require("request-promise");

	import requests
	import time
	import json

	token = ''

	#Delete files older than this:
	ts_to = int(time.time()) - 30 * 24 * 60 * 60

	def list_files():