Today is the first day at the conference (aside from the tutorials, which were yesterday). Here’s what I went to: New Subquery Optimizations in 6.0 By Sergey Petrunia. This was a similar session to one I went to last year. MySQL has a few cases where subqueries are badly optimized, and this session went into the details of how this is being addressed in MySQL 6.0. There are several new optimization techniques for all types of subqueries, such as inside-out subqueries, materialization, and converting to joins.

If you’re at the MySQL Conference and Expo, you can get a free sample chapter of the upcoming High Performance MySQL Second Edition. Just go to the exhibition area. As you go through the doors, take an immediate left and look for the sample chapter on O’Reilly’s table. It’s a rough draft and contains typos and my incredibly crude drawings instead of those that will go into the final book, but it should serve to give you an idea of the book’s depth and scope.

• Suicide
  • having no backups
  • depending on slaves for backup
  • keeping backups on same SAN
  • having a single DBA - Frank didn't like this one at all
  • not keeping binlogs
• Restoring from backup
  • how much time?
  • uncompressed backup ready to mount?
  • separate network for recovery?
• In Fotolog, 1TB of data was severely hit.
  • first problem: backup was highly compressed (tar.gz)
  • uncompressing took hours
  • so keep uncompressed backups (at least last N days)
  • it should be mountable, rather than transferable
• Frank going over recovery modes at …

I'm now at MySQL Conference and have just finished my New Subquery Optimizations in MySQL 6.0 talk. If you're eager to get the slides, here is the link to the pdf file and a mirror.

The talk has the same name as this MySQL University session but the slides have been thoroughly re-worked, and also there is new content:

• More detailed explanation of subquery handling in 4.1/5.x
• More reliable/justified benchmark numbers
• Observations about subquery demographics
• An attempt at comparative analysis of how MySQL's …

Here is the notes from “InnoDB status, architecture and new features” by Heikki Tuuri and Ken Jocobs.

• Introduction
  • Announced Plugin 1.0 for MySQL 5.1
  • fast, reliable, proven
  • fast
    • row-level locking, MVCC -> high concurrency & throughput
    • high performance CPU, memory and I/O architecture
    • efficient indexing (covering)
  • reliable
    • automatic crash recovery
    • integrated referencial integrity and transactions
    • online backup
    • well written, well tested and large user community
  …

I had a chance to visit the Kickfire booth after the keynotes and before the first presentation. They gave me a kicking t-shirt, followed by a presentation on the newly announced Kickfire appliance (now in beta, shipping in Fall 2008). Here are some notes I jotted down:

• von Neumann bottleneck
• SQL chip (SQC), packs the power of 10s of conventional CPUs
• Query parallelization on the chip
• On-chip memory - 64GB. No registers - no von Neumann bottleneck
• Beats the performance of a given 3 server, 32 CPU, 130TB box (1TB of actual data - space is used for distributing IO)
• SQC uses column-store, compression, intelligent indexing
• SQL Chip, PCI connection, plugs into a Linux server
  • SQL execution
  • Memory management
  • Loader acceleration
• KDB (Kickfire storage engine), plugs into MySQL …

Baron Schwartz gave a most interesting talk about EXPLAIN. You will definitely want to read his slides (filled with detail), when they make their way online. These notes are very sparse, just bits that I didn’t see in the slides, that Baron mentioned verbally. Plenty of good questions, and plenty of interaction.

EXPLAIN only works for SELECT queries.

How does MySQL execute queries? Optimisation happens even as the query is being executed. As the query is being optimised, some execution happens as well. Execution Plan is a data structure, not bytecode.

When EXPLAIN’s output is generated, MySQL actually executes the query. It just set’s DESCRIBE on it, rather than executing it. Everything is a JOIN to MySQL (union, SELECT 1 [simplest base case join], etc…).

key_len - to know if your table is indexed well.

rows: estimated number of rows to read, but not the number of rows in the result set. In 5.1 …

Here is the presentation material I used for my "Testing PHP/MySQL Applications with PHPUnit/DbUnit" presentation at the MySQL Conference in Santa Clara, CA today.

| View | Upload your own

A PDF version of the presentation is available here, notes by Joe Stump (Digg.com) are …

• Baron Schwartz presents
• only works for SELECTs
• nobody dares admit if they've never seen EXPLAIN
• MySQL actually executes the query
• at each JOIN, instead of executing the query, it fills the EXPLAIN result set
• everything is a JOIN (even SELECT 1)
• Columns in EXPLAIN
  • id: which SELECT the row belongs to
  • select_type
    • simple
    • subquery
    • derived
    • union
    • union result
  • table: the table accessed or its alias
  • type:
    • join
    • range
    • …
  • possible_keys: which indexes looked useful to the …

Speaker: Mike Zinner

Developed a design tool called DBDesigner4 as his own schema design tool, had 1.5 million downloads. Tool was built on Delphi, became outdated. Project brought him to the attention of MySQL AB, resulted in a job offer.

After signing on he began work on basic MySQL GUI tools such as MySQL Administrator, MySQL Query Browser, Migration Toolkit, and MySQL Windows installer and configuration wizard.

Project existed from DBDesigner, then in 2005 a preview version of Workbench was released. Workbench was re-architected in 2007-2008 and was released in April 2008.

Workbench is a fully featured schema design tool for MySQL developers. Two editions: one open source and one commercial. Commercial version has additional functionality.

Intended for developers, architects, DBAs.

Provides schema design features, schema documentation features, database sync, schema validation, internal …