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Comment by ngsayjoe | Hacker News Reader

I tried caching the hell out of Rails, kept adding indexes to my SQL tables, created 4 MySQL replicas, added more RAM to my linodes, tuned many default parameters in my.cnf, but the website was still slow to a crawl.

This parameter saved it all "innodb_buffer_pool_size = 768M" ... how am I supposed to know that Rails creates InnoDB by default, i thought MySQL default was always MyISAM.

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MySQL's default may be MyISAM, but it's a bad default. It is a good thing that Rails uses InnoDB by default.

I think MySQL 5.5 onwards the default would be InnoDB.

This is changing because MyISAM is not really a true database (in the ACID compliant sense of the term). I guess I would have assumed they were MyISAM too but they don't perform differently enough at low usage levels that you would notice it right? How big was this was application?

About 5 million pageviews / month. The website is quite processing intensive.

That's only two pageviews a second, on average.

We can agree that traffic rarely comes in at an average rate.

Assuming the standard bell curve it's six pageviews a second, at peak.

And that's apparently spread across four read-only slaves, too. I'm more inclined to blame the code than the database in this case.

No, it is not the code. It is InnoDB's default buffer pool set to 8MB that cause my website to be so slow ...

Dumping the schema from the database itself will reveal the table type. Knowing the physical organization of the schema is required for optimization work. If you only used the logical organization information (UML diagram for example) you were doing it wrong.

In real RDBMS systems, tables can be clustered (index organized in Oracle-speak) or not, nested or not, in different tablespaces, with many different parameters that do not change the semantic of DML/queries but change the performance significantly.

Yes i know, but it just never cross my mind that my tables have been InnoDB all these while ... among all the optimization, this is one i overlook, well i'm not a DBA afterall.

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