I ported/reimplemented show table_statistics for the Facebook patch on Launchpad. This first appeared in the Google patch. In this patch the Database and Rows_requested columns have been added and the Rows_changed_x_indexes column removed. This adds two commands: show table_statistics to report on per-table activity and flush table_statistics to reset the counters. Data is only collected for non-temporary MyISAM and InnoDB tables.

This is always enabled. I think it has minimal impact on performance and tests are in progress to verify that. But it is probably a bad idea to run flush table_statistics in a loop without sleeping.

One entry is listed for each table for which there was activity and includes the following …

From Stack Overflow:

Are the following queries efficient in MySQL:

SELECT  *
FROM    table
WHERE   field & number = number
-- to find values with superset of number's bits

SELECT  *
FROM    table
WHERE   field | number = number
-- to find values with subset of number's bits

, if an index for the field has been created?

If not, is there a way to make it run faster?

An index can be used for the following things:

1. To limit the number of records scanned
2. To lower the number of row lookups

When doing a full table scan, every record should be fetched and examined. If the table contains say, 1,000,000 records, and each record is 100 bytes long, then 100 …

Oracle isn't going to give up on its acquisition of MySQL because MySQL is a strategic wedge for it against Microsoft.

Firstly, I have to thank my co-workers Singer Wang and Gerry Narvaja for doing a lot of the work that resulted in this comparison.

After running both InnoDB Hot Backup and Xtrabackup, we have found that there is a measurable but not large difference between the resources that Xtrabackup and InnoDB Hot Backup consume.

Xtrabackup:

• Free
  
• takes 1.1% longer (2 min during a 3 hour backup)
  
• uses 1.4% more space (1G more in a 70G backup — this was for uncompressed backups)
  
• uses 1.115% more cpu overall
  
• split as 0.12% user, 0.66% nice, 0.025% system, …

Open source master data management got a boost on Monday when Talend announced that they acquired Xtentis MDM from Amalto. This product was geared towards creation of repository-style MDM applications, for example a product master data repository or a customer key cross-reference hub.

Xtentis was a Java and XML-based product with an Eclipse UI, so it's a reasonably good technical fit with Talend's tools. While the product information links have been removed from their web site, you can still access the Xtentis product data sheet if you're interested in the functionality and …

Some of you may have run the mysql-test-run tool which is the MySQL test suite. But did you know there are actually multiple suites? If you just run the tool, you don’t get everything!

Check out the mysql-test/suites subdirectory. That’s all the stuff you don’t get when just running the tool normally. If you take a peek at the Makefiles, you will find a target test-bt (build team) which shows the extra calls and parameters for the additional suites.

OurDelta has had some interesting cases where a build that’s otherwise ok would fail when users tried the test suite on their installation. We reckon such a test should definitely pass, and thus we had some more homework to do. So now OurDelta builds with as many tests as exist enabled, on all platforms and architectures. Slow yes, but that’s not an argument to not test something, right? Failing tests are often indicative of other issues, so at the very least …

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). …

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 …

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

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 { …