Thank you for your answer Sergei, It's all clear now, and I'm glad to know where the problem comes from.
Now if I understand correctly, my only solution is to manage to create indexes in my tables that ALL have the same block size (1024). This would mean reducing the size of the indexes on my Varchar fields, which I think I can. What is the max characters I should use when indexing my Varchar so that block size are 1024 ? (if possible of course). I have no idea how to calculate this. And is there absolutly no way to force 1024 block size even for varchar ? Thx again for your enlightment On Mon, 21 Feb 2005 17:41:40 +0100, Sergei Golubchik <[EMAIL PROTECTED]> wrote: > Hi! > > On Feb 21, HMax wrote: > > So this means we cannot combine both FULLTEXT and classical indexes if > > we want to use a LOAD INDEX INTO CACHE, and that we won't ever be able > > to ? > > No. FULLTEXT indexes now have small block size (1024) so they should > load ok. Only long varchar indexes will be a problem (but not > 'ever', see below :) > > > How about being able to specify the indexes we want to load into the > > cache. It's supposed to work this way (but it is told in the doc it > > doesn't yet). This would solve the problem I believe, if we specify > > what index we want in cache. > > Right, it's in the TODO. > Here's the problem: LOAD INDEX reads the complete MYI file > sequentially, block after a block, and loads them in cache. > If blocks would have different sizes it would be not possible, because > block header does not store block size. > > Loading only a selected index does not work either, because block > header does not store what index it belongs to. > > The only solution would be to traverse the index tree from the root - > but it'd be slow, because it implies random reads from the index file > :( > > Instead, we plan to store index number in every block, but it means > incompatible change in MYI file format, so it's not for 4.1 (and not > even for 5.0 which is almost frozen now). > > > What I don't undestand is that when not cached using LOAD INDEX INTO > > CACHE, FULLTEXT indexes can be into cache, the ones on VARCHAR too, > > and this does not see to cause any trouble. > > See above, regular btree traversal is not a problem. Sequential MYI file > access is. > > > But using LOAD INDEX, it doesn't work. Is there really no workaround ? > > We have for about 1.5Go of fulltext indexes and if they were in cache, > > this would speed up things so much ! > > It's fixed in 4.1.8. > > Regards, > Sergei > > -- > __ ___ ___ ____ __ > / |/ /_ __/ __/ __ \/ / Sergei Golubchik <[EMAIL PROTECTED]> > / /|_/ / // /\ \/ /_/ / /__ MySQL AB, Senior Software Developer > /_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany > <___/ www.mysql.com > -- HMax -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
