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First Sphinx Conference is Announced

 | September 10, 2010 |  Posted In: Events and Announcements

The First ever Sphinx Users Conference is announced to take place in Moscow, Russia on October 24th, which is the Sunday before Highload.ru conference, so if you’re attending that you may just drop by to this event too. this is going to be free technically focused event, close in spirit to Percona Performance Conference, we […]

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When the subselect runs faster

 | March 18, 2010 |  Posted In: Insight for Developers, MySQL

A few weeks ago, we had a query optimization request from one of our customer. The query was very simple like:

This column in the table is looks like this:

The table have 549252 rows and of course, there is an index on the col1. MySQL estimated the cardinality of that index as […]

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How many partitions can you have ?

 | December 5, 2009 |  Posted In: Benchmarks, Insight for DBAs, MySQL

I had an interesting case recently. The customer dealing with large MySQL data warehouse had the table which was had data merged into it with INSERT ON DUPLICATE KEY UPDATE statements. The performance was extremely slow. I turned out it is caused by hundreds of daily partitions created for this table. What is the most […]

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More on table_cache

 | November 26, 2009 |  Posted In: Benchmarks, Insight for DBAs, MySQL

In my previous post I looked into how large table_cache actually can decrease performance. The “miss” path is getting more expensive very quickly as table cache growths so if you’re going to have high miss ratio anyway you’re better off with small table cache. What I have not checked though is how does table_cache (or […]

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table_cache negative scalability

 | November 16, 2009 |  Posted In: Benchmarks

Couple of months ago there was a post by FreshBooks on getting great performance improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning caches is to get them as large as you can if you have enough resources (such as memory). With MySQL […]

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Quick comparison of MyISAM, Infobright, and MonetDB

 | September 29, 2009 |  Posted In: MySQL

Recently I was doing a little work for a client who has MyISAM tables with many columns (the same one Peter wrote about recently). The client’s performance is suffering in part because of the number of columns, which is over 200. The queries are generally pretty simple (sums of columns), but they’re ad-hoc (can access […]

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