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On Wed, 1999-09-22 16:22:54 -0400, James Manning wrote: > [ Wednesday, September 22, 1999 ] Martin Ramsch wrote: > > On Tue, 1999-09-21 21:16:55 +0200, Jimmy Posius wrote: > > > 1) each merchant gets his own (mysql) database. Thisway 500-2500 (or > > > more) databases will be created on a Linux system, > > > > > > 2) create ONE big database and tabelnames get a prefix > > > This way there's 1 database with a lot of small tables (> 1000-5000). [...] > > Speed. [...] > > Having that many tables (5000) in case 2 could be slow because the > > operating system might become slow when scanning the database > > directory with so many files (5000 x 3 = 15000). > > In this respect, solution 1 is much better. > > I don't quite get this paragraph... in both 1 and 2, there's going > to be thousands of files... in 2 they're all in the same dir, in 1 > they're scatter among dirs... If there are 3 tables per merchant only, it's 5000 directory entries each holding 9 files (in case 1) versus 45000 files (in case 2) in only one directory. The more tables per merchant there are the more interesting this difference will become. > I'd like #2 since we're infinitely more likely to keep the dcache of > the kernel well-populated, and our worst-case appears to the open() > on a infrequently-accessed table. #1 would appear to force > often-cold dcache entries to be accessed, adding delay to table > access... could be lost in the noise... check it out with > benchmark() :) I have to admit, that I haven't done test cases with so many files ... How much is the speed penalty for scanning directories with 45000 entries and more versus the caching issue? I don't know. Regards, Martin -- Martin Ramsch <m.ramsch_(at)_computer.org> <URL: http://home.pages.de/~ramsch/ > PGP KeyID=0xE8EF4F75 FiPr=52 44 5E F3 B0 B1 38 26 E4 EC 80 58 7B 31 3A D7 --- *** Abmelden von dieser Mailingliste funktioniert per E-Mail *** an mysql-de-request_(at)_lists.4t2.com mit Betreff/Subject: unsubscribe
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