How Web Services world affect LAMP Stack

In connection to my previous post I was thinking how Web 2.0 with its massive use of Web Services affect LAMP Stack ? Well actually there are serious difference both for client and server application development which you might want to take into account.
If you’re developing Web Service Server application you will most likely […]

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Speedup your LAMP stack with LigHTTPD

Apache Web server could frequently be bottleneck for your LAMP stack, or you might be wasting resources on your web servers. The problem with Apache server comes from “client per process” architecture which you have to stick to at least for dynamic content served by PHP or ModPerl. With “client per process” you end […]

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Group commit and XA

Returning to post Group commit and real fsync I made several experiments:
I ran sysbench update_key benchmarks without —log-bin, with —log-bin, and with —log-bin and —innodb-support-xa=0 (default value is 1). Results (in transactions / sec)

threads
without —log-bin
—log-bin
—log-bin and
—innodb_support-xa=0

1
1218.68
614.94
1010.44

4
2686.36
667.77
1162.60

16
3993.59
666.14
1161.56

64
3630.55
665.18
1151.36

So we can see group commit is not only broken when XA is enabled but also if XA […]

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MySQL Server Memory Usage

Every so often people ask me the question how should they estimate memory consumption by MySQL Server in given configuration. What is the formula they could use.
The reasons to worry about memory usage are quite understandable. If you configure MySQL Server so it uses too small amount of memory it will likey perform suboptimally. […]

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To pack or not to pack – MyISAM Key compression

MyISAM storage engine has key compression which makes its indexes much smaller, allowing better fit in caches and so improving performance dramatically. Actually packed indexes not a bit longer rows is frequent reason of MyISAM performing better than Innodb. In this article I’ll get in a bit more details about packed keys and performance […]

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Mess with innodb_thread_concurrency

In MySQL 5.0.19 the meaning of innodb_thread_concurrency variable was changed (yeah, again).
Now innodb_thread_concurrency=0 means unlimitied count of concurrent threads inside InnoDB. It’s logical, but there was long way. In MySQL versions below 5.0.8 for unlimited threads you had to set innodb_thread_concurrency over 500 (and default value for innodb_thread_concurrency was 8 ).
Starting with MySQL 5.0.8, […]

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Operation Systems do not provide good IO interface for Database Servers

Thinking more about the problems I wrote about yesterday I had a question why so ugly workaround and guesses or manual configuration is needed ? The answer seems to be Operation Interfaces just do not provide IO interface which is good enough. The big missing piece is priority. There are process and threads priorities […]

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Innodb Fuzzy checkpointing woes

As you might know Innodb storage engines uses Fuzzy Checkpointing technique as part of it recovery strategy.  It is very nice approach which means database never needs to “stall” to perform total modified pages flush but instead flushing of dirty pages happens gradually in small chunks so database load is very even.
This works great […]

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Descending indexing and loose index scan

Comments to my previous posts, especially this one by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support. None of these are actially related to Innodb tables in general – these are features MySQL should get for all storage engines at […]

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