On 4 Jun 2002, at 15:43, Jared Richardson wrote: > | > AVG_ROW_LENGTH=4096 MAX_ROWS=4294967295; > | > | Why do you use AVG_ROW_LENGTH=4096? It seems to me the max record | > length is 528...? | > > According to the MySql docs, the max table size is AVG_ROW_LENGTH * > MAX_ROWS > > We were trying to ensure the maximum amount of growth... this table > can grow very very large....
That's fine, but if you make the max size bigger than what you really need, you bloat your index and slow things down for no benefit. As I understand it, with the default max table size of 4 GB (for dynamic- record MyISAM tables), the index will have 4-byte pointers to the records. The next step would be 5-byte pointers, which would allow a max table size of 1024 GB (or 1 TB). But you're asking for an even higher max table size, forcing MySL to use 6-byte pointers in the index, which allows a max table size of 256 TB. I don't think there's any difference between setting AVG_ROW_LENGTH to 4096 and setting it to 528, since either will put you in the same size range when combined with MAX_ROWS=4294967295. Think about how many rows you're actually going to have and what the real average row length is. 528 may be your maximum row length, but I think it's unlikely that your VARCHARs average anywhere near 255. Most likely the numbers are low enough that the 1 TB table size is sufficient, so your indexes will only need 5-byte pointers and thus be smaller. [Filter fodder: SQL] -- Keith C. Ivey <[EMAIL PROTECTED]> Tobacco Documents Online http://tobaccodocuments.org --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
