How to run queries on live data

From Wikitech

If you need to query the live data (rather than a dump or tools mirror), follow the following steps:

  1. Go to https://dbtree.wikimedia.org and look for a slave database server that isn't very busy (low lag, few active threads) and has the data you need (See https://noc.wikimedia.org/conf/highlight.php?file=db-eqiad.php)
  2. ssh to terbium
  3. Connect to the slave database server with the syntax 'sql <DBNAME> -h <HOSTNAME>', for example sql enwiki -h db1001
  4. Run your query

You should avoid running queries on the master databases whenever possible. Otherwise you will bog down performance of the live websites. If you absolutely must run a query on a master database, follow these instructions:

  1. ssh to terbium
  2. Connect to the master database server with the syntax 'sql <DBNAME>', for example sql enwiki
  3. Run your query

To check the current status of a database, you can click on its server name in the dbtree chart or log into the server from terbium and run 'show engine innodb status\G'.

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