Categoria: Internet

Tropeçando 80

Autor do post Por rafael
Data de publicação fevereiro 19, 2018
Nenhum comentário em Tropeçando 80

Experienced PostgreSQL users and developers rattle off the terms “MVCC” and “VACUUM” as if everyone should know what they are and how they work, but in fact many people don’t. This blog post is my attempt to explain what MVCC is and why PostgreSQL uses it, what VACUUM is and how it works, and why we need VACUUM to implement MVCC. In addition, I’ll include a few useful links for further reading for those who may want to know more.

Setting up psql, the PostgreSQL CLI

PostgreSQL ships with an interactive console with the command line tool named psql. It can be used both for scripting and interactive usage and is moreover quite a powerful tool. Interactive features includes autocompletion, readline support (history searches, modern keyboard movements, etc), input and output redirection, formatted output, and more.

A Replication Cheat-Sheet

New flexbox guides on MDN

In preparation for CSS Grid shipping in browsers in March 2017, I worked on a number of guides and reference materials for the CSS Grid specification, which were published on MDN. With that material updated, we thought it would be nice to complete the documentation with similar guides for Flexbox, and so I updated the existing material to reflect the core use cases of Flexbox.

introduction to pgBackRest

pgBackRest (http://pgbackrest.org/) aims to be a simple, reliable backup and restore system that can seamlessly scale up to the largest databases and workloads.

Instead of relying on traditional backup tools like tar and rsync, pgBackRest implements all backup features internally and uses a custom protocol for communicating with remote systems. Removing reliance on tar and rsync allows for better solutions to database-specific backup challenges. The custom remote protocol allows for more flexibility and limits the types of connections that are required to perform a backup which increases security.

Tags backup, css, PostGreSQL

Tropeçando

Tropeçando 79

Autor do post Por rafael
Data de publicação dezembro 27, 2017
Nenhum comentário em Tropeçando 79

Plan for the unexpected: install diagnostic tools on your PostgreSQL servers

There’s a lot of information out there on how to configure PostgreSQL, on the importance of backups and testing them, etc.

But what about the server you run PostgreSQL on? We tend to pay a lot less attention to tools that you won’t need unless something breaks. But it’s worth taking some time to do so now, because that’s time you won’t have when your server is down and you’re in a rush.

SQL Feature Comparison

This comparison focuses on SQL features that can be used in SQL statements or self-contained SQL scripts that don't require additional software (e.g. a compiler) to be usable. Features for database administration or deployment are also not the focus of this comparison.

Building the DOM faster: speculative parsing, async, defer and preload

In 2017, the toolbox for making sure your web page loads fast includes everything from minification and asset optimization to caching, CDNs, code splitting and tree shaking. However, you can get big performance boosts with just a few keywords and mindful code structuring, even if you’re not yet familiar with the concepts above and you’re not sure how to get started.

How we tweaked Postgres upsert performance to be 2-3* faster than MongoDB

As we all know, relational databases are fine if you’re dealing with small amounts of data but for web-scale high performance high inserts speed and masses of queries per second, NoSQL is what you need. At least, that’s the conventional wisdom/hype surrounding NoSQL databases such as MongoDB. However as we’ve recently discovered this is very wrong indeed.

Painful Varnish mistakes

This post was initially titled "Top 6 Varnish mistakes", to echo Espen's blog. Even though his material is three years old, the content is still relevant. Plus, there's a healthy colleague competition going on here, and I can't just mimic Espen if I hope to beat him, so I had to do something different.

NULL in SQL: Indicating the Absence of Data

Tags aplicação, Banco de dados, infraestrutura, performance, PostGreSQL, varnish

Tropeçando

Tropeçando 78

Autor do post Por rafael
Data de publicação novembro 1, 2017
Nenhum comentário em Tropeçando 78

Replicação: o que mudou

Detalhes das mudanças na replicação do PostgreSQL desde a versão 9.0 até a 9.6.

What the hell are Generics and would I want them in PHP?

So everyone is talking about this hip “new” kid on the block for PHP: Generics. The RFC is on the table and a lot of people are getting all excited about it, but you don’t fully see the excitement? Let’s explore what it’s all about!

The Easy Way to Setup PostgreSQL 10 Logical Replication

PostgreSQL workings in one picture

With the below illustration I attempted to capture key processes that encompass Postgres workflow. Here is a quick overview.

Speeding up Application Development with Bootstrap

Bootstrap is one of the best and most used HTML/CSS/JS front-end frameworks. Almost any web developer who has made a website or two has heard of this popular framework. It offers so many ready-made components and resources, Bootstrap can significantly speed up your application development.

Tags Banco de dados, bootstrap, css, front-end, php, PostGreSQL

Tropeçando

Tropeçando 77

Autor do post Por rafael
Data de publicação abril 10, 2017
Nenhum comentário em Tropeçando 77

How to Measure Execution Time in Node.js

Design Pattern Workshop

Recently on the pgsql-performance mailing list, a question popped up regarding Postgres RAM usage. In this instance Pietro wondered why Postgres wasn’t using more RAM, and why his process was taking so long. There were a few insightful replies, and they’re each interesting for reasons that aren’t immediately obvious. Let’s see what is really going on here, and perhaps answer a question while we’re at it.

Ativando o Optimus NVIDIA GPU no Dell XPS 15 com Linux, mesmo na bateria

New Features Coming in PostgreSQL 10

Postgres 10 highlight - SCRAM authentication

Tags Banco de dados, linux, Node.JS, PostGreSQL

Tropeçando

Tropeçando 76

Autor do post Por rafael
Data de publicação março 17, 2017
Nenhum comentário em Tropeçando 76

Crie um proxy SOCKS em um servidor Linux com SSH para ignorar filtros de conteúdo

O método mais rápido para melhorar o desempenho de qualquer Servidor de Aplicações Web PHP usando MySQL ou PostgreSQL

Getting first and last values per group

Every so often someone needs solution to getting first (or couple of first) values for given column. Or last. For some cases (when there is not many groups) you can use recursive queries. But it's not always the best choice. Let's try to implement first() and last() aggregates, so these could be easily used by anybody.

Roadmap to becoming a web developer in 2017

Tags MySQL, performance, php, PostGreSQL, ssh

Tropeçando

Tropeçando 75

Autor do post Por rafael
Data de publicação fevereiro 6, 2017
Nenhum comentário em Tropeçando 75

Promise Anti-patterns

Promises are very simple once you get your head around them, but there are a few gotchas that can leave you with your head scratching. Here are a few that got me.

PG Phriday: Why Postgres

Generic HTTP Error Handling in AngularJS

Lately during development at one of our clients, Ravello Systems, we decided we wanted better HTTP error handling.

Basically, our perfect solution would have generic handlers for errors, and most calls in the code will not have to do any special work for handling errors. This means that things like authentication problems, server unavailability issues, etc. will be handled in one place — like adding a generic “something went wrong” modal.

The Fastest Method to Evaluate Tune the Performance of Any PHP Web Application Server using MySQL or PostgreSQL

In the Web development world, we often have the problem of choosing the right server to use in the production environment of a Web application.

Maybe we need to buy a new server to handle the expected load, or maybe the customer wants to deploy in an existing server.

In any case, if after deploying and running the application it will show poor performance, then we need to ask the team what we can do to make the application faster or use a better server.

Therefore we need to determine if the application is performing well. Read this article to learn how to quickly determine the performance of an application on the current server.

Postgres 9.6 Features

PostgreSQL is now on version 16. Check the release notes

The Definitive Guide to DateTime Manipulation

As a software developer, you can’t run away from date manipulation. Almost every app a developer builds will have some component where date/time needs to be obtained from the user, stored in a database, and displayed back to the user.

collect-exec.sh – My personal OS report

The script collects a lot of information about the running system and save the output of each commands in a text file, and saves copies of important files in a directory named files. At the end of the script everything is compressed with tar in the global directory.

Faster PostgreSQL Counting

Everybody counts, but not always quickly. This article is a close look into how PostgreSQL optimizes counting. If you know the tricks there are ways to count rows orders of magnitude faster than you do already.

Tags AngularJS, api, Banco de dados, desenvolvimento, infraestrutura, JavaScript, Node.JS, performance, php, PostGreSQL, shell

Tropeçando

Tropeçando 73

Autor do post Por rafael
Data de publicação outubro 30, 2016
Nenhum comentário em Tropeçando 73

Tables and indexes vs. HDD and SSD

Although in the future most database servers (particularly those handling OLTP-like workloads) will use a flash-based storage, we’re not there yet – flash storage is still considerably more expensive than traditional hard drives, and so many systems use a mix of SSD and HDD drives.

pgBackRest 1.0 Released

The first stable of release of pgBackRest introduces a new, more capable repository format, simpler configuration, and comprehensive support for backup and restore of symlinked directories and files.

Visualização de Postgres Plan Query

Uma ferramenta que pode fazer planos (EXPLAIN) simples de entender e visualmente agradável.

PG Phriday: Trusty Table Tiers

Well, there is another way to do partitioning that’s almost never mentioned. The idea is to actually utilize the base table as a storage target, and in lieu of triggers, schedule data movement during low-volume time periods. The primary benefit to this is that there’s no more trigger overhead.

Safe and unsafe operations for high volume PostgreSQL

If I run a bad command, it can lock out updates to a table for a long time. For example, if I create a new index on table, I cannot create new record in this table while that index is building. Anyone who tries to make a record in this table will block, and possibly time out, causing a partial outage. In general, I am ok with database operations taking a long time. However, any operation that locks a table for updates for more than a few seconds means downtime for me.

I decided to make a list of an operations, which can be done safe (without downtime) and usafe.

Tags Banco de dados, PostGreSQL, storage

Tropeçando

Tropeçando 72

Autor do post Por rafael
Data de publicação fevereiro 11, 2016
Nenhum comentário em Tropeçando 72

A simple JSON difference function

A function that would take two JSONB objects in PostgreSQL, and return how the left-hand side differs from the right-hand side.

Deadlocks in PostgreSQL

Compreenda os tipos de lock existentes no PostgreSQL, como ocorre um deadlock e pesquisar o causador do lock.

PG Phriday: COPY and Alternative Import Methods

Alternativa para cópia de conteúdo de arquivos para o banco de dados.

Always Do This #4: Put stats_temp_directory on a memory file system

The PostgreSQL statistics collector generates a lot of very important statistics about the state of the database. If it’s not working, autovacuum doesn’t work, among other problems. But it does generate a lot of write activity, and by default, that goes back onto the database volume.

Instead, always set statstempdirectory to point to a RAM disk (which has to be owned by the postgres user, with 0600 permissions). The statistics are written back to the database on shutdown, so in normal operations, you won’t lose anything on a reboot. (You’ll lose the most recent statistics on a crash, but you will anyway; the statistics are reset on recovery operations, including restart from a crash.)

This can substantially cut down the amount of write I/O the main database storage volume has to receive, and it’s free!

Putting stats_temp_directory on a ramdisk

When statistics are not generated, we can have, among other problems, the halt of the autovacuum execution. As a consequence of the problems caused by the interruption of statistics collection, large spikes in writing activity end up occurring, which overloads server utilization. Changing the stat_temp_directory setting can prevent this.

Tags performance, PostGreSQL, tuning

Tropeçando

Tropeçando 71

Autor do post Por rafael
Data de publicação janeiro 20, 2016
Nenhum comentário em Tropeçando 71

PG Phriday: Displaced Durability

Há tabelas que possuem dados com os quais você não se importa de perdê-los. São situações de dados transientes, como áreas de dados passageiros, tabelas temporárias persistentes, tabelas com dados crus de importação. Por quê não aproveitar o fato do PostgreSQL oferecer a opção de ser UNLOGGED? Ainda mais porque pode-se evitar usar recursos do servidor desnecessariamente.

Check your pg_dump compression levels

Ao realizar backups do banco PostgreSQL, há muitas situações em que encontramos uma sobrecarga inesperada e o nível de compressão escolhido para fazer o backup pode ter ação direta sobre isso. Como a compressão nem sempre é tão importante, não esquecer este detalhe pode poupar incômodos desnecessários em operações de backup que não as rotineiras.

How to install an Opensource VPN Server on Linux

Instalação de VPN própria para assegurar o controle do tráfego em conexões.

Filtrando e validando dados no PHP com filter_var()

Entrada de dados é uma característica de quase a totalidade dos sistema ou sites. É indispensável, para segurança dos dados, filtrar esta entrada a fim de evitar invasões, roubo de dados ou inconsistência. No PHP, aprenda a fazer isso usando filter_var().

FFmpeg no Ubuntu: veja como instalar esse pacote no 14.04/14.10 via repositório

Trabalhando com logs no PostgreSQL

Dicas de configurações de log em servidores PostgreSQL. As informações contidas em logs são essenciais em muitos problemas e importantes para a saúde da aplicação e do sistema de banco de dados.