Hi Gabriel, No, you can't currently modify compressed tables.
For in memory tables, are you aware of the HEAP type for non-critical data? You're probably talking regular permanent tables, though. For those, the OS will use all free memory (that programs aren't using) to cache file data after it's accessed, so you shouldn't have to worry about doing anything special. Provided you don't have your key_buffer (or other global vars) set too large, most of that 4.3GB database should be able to be cached by the OS. Of course, the disk is still used for writes, but should hardly ever need to be hit for reads. BTW, I don't really know what memory mapped means... Surely this doesn't mean data is kept in memory *by MySQL*?? A big compressed table would take all your memory! Hmm. Matt ----- Original Message ----- From: "Gabriel Ricard" Sent: Thursday, October 09, 2003 7:09 PM Subject: storing tables in ram / compressed myisam tables > So, we just got this handy dandy new G5 with 4GB of RAM and I'm trying > to get it to store as much of our 4.3GB database in RAM as possible. > I've tuned most of the usual parameters (query cache, tmp table size, > sort buffer, key buffer, record buffer, table cache, myisam sort > buffer, etc.) but then I was reading the section of the manual about > how mysql uses memory (http://www.mysql.com/doc/en/Memory_use.html) and > it said this: > > "Only the compressed ISAM / MyISAM tables are memory mapped. This is > because the 32-bit memory space of 4 GB is not large enough for most > big tables. When systems with a 64-bit address space become more common > we may add general support for memory mapping." > > I tried to find some more information about compressed ISAM / MyISAM > tables. I found the options for CREATE TABLE to create a compressed > table, but then I was reading about myisampack and I think I got > confused. Can you still modify a compressed table? Or is it read only? > Will it be mmap'd so the access is faster? Or is this configurable? If > I could, I'd select a few of the tables to have stored in RAM to make > the access as fast as possible. Can I do this? > > Also, considering that 64 bit systems like the PowerMac G5 and Athlon64 > FX boxes are readily available now, will there soon be an option to > choose whether or not a table (of any type) can be maintained in RAM > via mmap like the manual said? > > TIA > > - Gabriel -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
