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Optimizing table_cache - Open files?
Posted by: Shashidhar Y
Date: August 04, 2011 05:08AM

Hello there,

We are trying to tune our mysql and optimize all parameters & queries inside.

Keeping our configurations in mind, I am reading "High Performance MYSQL book", Awesome is not the word appreciate this book, many thanks to the authors.

My Problem is, while trying to understand various variables I found below lines something interesting for table_cache, open_files and opened_files

"
Open_tables and Opened_tables:
Check this value against your table_cache value. If you see many Opened_tables
per second, your table_cache value might not be large enough. Explicit temporary
tables can also cause a growing number of opened tables even when the
table cache isn’t fully used, though, so it might be nothing to worry about.
"

I have below variable values on my server -

Open_tables | 282
Opened_tables | 12600
table_cache | 300
open_files_limit | 65535
max_connections | 100

Total No.of Tables in server - 200

I'm really puzzled now, I know something is going strange with these parameters and need some improvements.

I may have to increase table_cache value, but what could be the metrics to calculate this for exact value?
If I increase without knowing that may affect something else?

Can any one of you here advice me, what value would be appropriate for table_cache(or in fact some other variable, if that matters) and whY?

I really appreciate your help in this regard.

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