Archive for the ‘DBA’ Category

Getting started with CockRoachDB

I’ve been quite interested in CockRoachDB as it claims to be “almost impossible to take down”. Here’s a quick example for setting up a CockRoachDB cluster. This was done on a mac but should work with no, or minimal, modifications on *nix. First, download and set the path PATH ?View Code BASHwget https://binaries.cockroachdb.com/cockroach-latest.darwin-10.9-amd64.tgz tar xvzf […]

Working with the PlanCache in MongoDB

I’ve been working a little with the PlanCache in MongoDB to troubleshoot some performance problems we’ve been experiencing. The contents of the Plan Cache are json documents (obviously) and this isn’t great to work with in the shell. Here’s a couple of javascript functions I’ve come up with to make things a little easier. These […]

InfluxDB: Bash script to launch and configure two nodes

I’ve just created a quick bash script because I”m working a little with InfluxDB at the moment. InfluxDB is a time series database written in GO. The script will setup two influxdb nodes, setup some users and download and load some sample data. It’s developed on a Mac but should work in Linux (not tested […]

Bash: Count the number of databases in a gzip compressed mysqldump

A simple bash one-liner! ?View Code BASHgunzip -c /path/to/backup/mysqldump.sql.gz | grep -E "^CREATE DATABASE" | wc -l Breaking this down.. This prints the contents of a gzip compressed mysqldump to the terminal ?View Code BASHgunzip -c /path/to/backup/mysqldump.sql.gz Grep for lines that start with CREATE DATABASES… ?View Code BASHgrep -E "^CREATE DATABASE" Count the number of […]

MariaDB: subquery causes table scan

I got asked today to look at some slow queries on a MariaDB 10 instance. Here are the anonymized results of the investigation I did into this and how I solved the issue… There were a bunch of queries, expected to run very fast, that were taking 10-15 seconds to execute. The queries were all […]