File descriptors

[Chris Slominski]

I have ranges partitioned MyISAM tables. I am planning the setting of my server variables like table_cache and open_files_limit. When I access a table the first time it appears to open all partition files (2 per partition). My question is will all file descriptors for the table be held open for the table to remain in the table cache? With my scenario, older partitions will not be accessed often, so older partition files could be closed. Is being in the table cache all or nothing as far a file descriptors go? I guess I am advocating a 'partition cache' instead of a 'table cache'.

In my case the file descriptor count is going to be large; with 30,000 tables x 25 partitons each x 2 files/partition = 1,500,000 file descriptors. Only the most recent partition of each table will benefit from caching, so I could really do away with 1,440,000 file descriptors without any significant performance impact.