On 09/10/13 13:38, Tyler Romeo wrote: > Hello, > > So recently I've been trying to find a method where I could test database > queries on production data. I originally thought Tool Labs might help, but > I found out due to a bug in MySQL you can't perform EXPLAIN queries in the > database replicas. And naturally I don't have access to the actual > production cluster because I'm not on ops. > > My last method to try is going to be downloading the enwiki database dump > and setting up my own replica. However, this involves hard drive space that > I don't have.
EXPLAIN on a small wiki will usually give you the same query plan as EXPLAIN on a large wiki, if the indexes are the same. So you can try running your EXPLAIN against your local test wiki. But for the most part, we estimate query performance a priori, based on code review and what we know about MySQL, rather than measuring performance during testing. Note that EXPLAIN can be misleading even if it is run against a production database. Even actual performance measurement in production can be misleading, if the test is run against a small table which will gain rows over time. And measuring execution time doesn't tell you everything about the performance of the server -- for example, it doesn't show buffer pool usage. -- Tim Starling _______________________________________________ Wikitech-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikitech-l
