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Reporting Queries with Sphinx

Reporting queries (I will use this term here) are the queries which summaries and groups data over the certain period of time. For example, in Social Network site we want to know how many messages have been sent for the given period of time, group by region and status (sent, received, etc), order by number of messages sent.

As an example I will take a table which is used to send SMS (text messages).

SQL: select concat('+', substring(region_code,1 ,2), 'xxx') as reg, status, count(*) as cnt
from messages
where submition_date between '2009-01-01' and '2009-04-01' group by reg, status
having cnt>100 order by cnt desc, status limit 100;

This query will do a range scan over the submition_date and perform a filesort. There are common well known approaches which can be used to optimize table (“covered index”, “summary tables”, using external data warehouse, etc). …

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FOSS: War is over (if you want it)

At the Open World Forum event in Paris this morning I presented a quick overview of the state of free and open source software in 2009 and a look at the trends shaping FOSS into the next decade. The presentation was just 10 minutes rather than the 20 I had originally understood it to be, so I wanted to use the blog to expand a little on the discussion and my thinking.



War is over (if you want it)

Aside from the ongoing adoption of open source, one of the trends that has defined FOSS in 2009 has been the numerous declarations

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Update: Find Query Per certain Seconds

In my old post there is a bug when run in MySQL 5.1.30 and old, because the status variable Queries was added in MySQL 5.1.31. So i change to choose between Queries and Questions status variables, and I think the Queries represent more accurate result.

http://forge.mysql.com/tools/tool.php?id=217

By the way:

# Queries The number of statements executed by the server. This variable includes

table_raw_reader – reading the table proto from disk and examining everything

Ever wondered exactly *what* was in a Drizzle Table proto? Well, wonder no more. A while back this little utility called table_raw_reader hit the drizzle codebase. It’s a simple command line utility that takes a .proto file as an argument, reads it off disk and then prints out a text representation using the TextFormat class of the protobuf library.

An example:

stewart@willster:~/drizzle/jay-and-stewart-remove-pack_flag$ ./drizzled/message/table_raw_reader ./tests/var/master-data/test/t1.dfe
name: "t1"
engine {
  name: "InnoDB"
}
field {
  name: "id"
  type: INTEGER
  format: DefaultFormat
  options {
    length: 11
  }
}
field {
  name: "padding"
  type: VARCHAR
  format: DefaultFormat
  options {
    length: 800
  }
  string_options { …
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pack_flag is dead!

(At least in Drizzle)

Brian merged my jay-and-stewart-remove-pack_flag branch and it’s now in trunk. Removing pack_flag was a task for the bell milestone and in true collaborative effort, it took more than one person to unravel its dark mysteries. Hats go off to Jay who bravely ripped more of it out with the aid of excellent Seattle coffee. I finished it off with removing the last remnants and fixing an outstanding bug (and at the same time making us look at the DECIMAL code and shuddering in fear of what it may mean).

With pack_flag gone, we can now do insane things like remove the last bits of TINYINT from the code, as previous to removing pack_flag, if you did that, things …

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A few changes for sysbench

I use sysbench a lot for performance tests. It is a great tool and on top of that the code is easy to read and modify. I added a few changes to my Launchpad branch. I will describe the changes by the new options:

  • --seed-rng -- sets the seed for the random number generator. I used this when running query cache tests to increase the cache hit rate. I ran sysbench twice with the same seed and as a result, most of the queries on the second run match those from the first run and re-use results from the query cache.
  • --oltp-point-select-mysql-handler -- apart from having a really long name, this makes sysbench use HANDLER READ statements rather than SELECT …
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Forum rewritten

Recently I decided to build my own forum software so I'm able to better control spam posts and make posting easier than it ever was.

All user accounts including passwords were imported into my new database. Only the name of the permanent cookie has changed so you might have to login once before posting now.

Email addresses are nowhere displayed, except for the settings page where you only see the more compact options, including a checkbox to turn email notification on replies on and off.

I'm going to add some formatting buttons to the posting form, and maybe some pulldown for smilies. Currently you can only post plain text messages, which is sufficient in many cases.

I'm also going to add support for creating Subversion revision URLs, automatically created if you type

r1234

. Same goes for issue ids when you want to refer to a bug report.

I hope you like …

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Admin notice: comments again broken

(This note should not go to PlanetMySQL, sorry if it goes).
We again have problem with comments to blog posts. It's technical problem, we did upgrade some components and it seems it affected captcha. We are working on fix.
We are sorry for the inconvenience and thank for reports about the problem.

Entry posted by Vadim | No comment

Add to: | | …

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usefulness of the query cache

Lot of talk lately about the effectiveness or lack thereof of the MySQL query cache.  I’m kind of surprised we are still having this discussion in late 2009, I really thought these issues have been long settled.

It’s well known that the query cache is terrible for environments with a constant stream of writes.  Each write invalidates the cached results for every query touching that table.  This means that your database needs to be constantly inserting and purging the query cache in an environment with mixed reads and writes (aka the most common type of “Web …

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Former MySQL CEO Mickos joins Benchmark

The open-source database company's one-time chief executive is now entrepreneur in residence at a leading Silicon Valley venture capital firm.

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