HEAP tables can have more than one index, but indexes only match "=" and "!=" -- so you can't use ">", "<", etc... Also, comparisons only match the entire index, not the left-most prefix like MyISAM tables. There are a few other quirks, also:
http://www.mysql.com/doc/en/HEAP.html --jeff > On Sunday 18 August 2002 04:17 pm, Rick Robinson wrote: >> Hi all, >> I'm testing using a HEAP table to maintain transient state in a high >> volume TP environment. So far, it looks promising, and I want to ask >> anyone about similar experiences and solicit some input. >> >> Some background: >> * I have one table; the row length is ~200 bytes and the table will >> typically never have more than 10,000 rows (more like 7,000 on >> average). * The table is accessed via one of two keys. I have an >> index on each. The EXPLAIN output indicates these are used. > > To the best of my knowledge HEAP tables can only have one index, it has > to be primary. In other words, they're basically an in-memory hashtable > accessible via SQL. > > Your application is pretty typical for session-state management. I doubt > you'll have any problems, but I'd look into those keys. > > --------------------------------------------------------------------- > 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 --------------------------------------------------------------------- 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
