I am sending this mail in order to get things straight about table corruption which I am experiencing with 4.0(as well as previous versions).
1)System specs: PIII x1000MHz, 1GB RAM, HD 37GB SCSI, AHA29160N SCSI controller 2) Database MyISam tables, BUT 21000 tables in the database(this is for performance reasons. I need for each such table to run a number of queries and in this way I already have 'VIEWS', except they are permament). I could split that in 4 different databases if it is a problem. 3) I import the data from mysqldumps(that is, the program that reads the data does not directly import them in the database, partly because of the corruption problems, but also partly because I want backups anyway and instead produces files that are importable just like mysqldumps. These files are of the form 'INSERT INTO TABLE1 (.....);' .... conceivably for all 21000 tables. 4) Corruption is a tossup. The import always works. However, when I run the queries sometimes they all run fine, while other times I get an error 127 on the table it is working on. myisamchk NEVER manages a complete recovery of all records(typically 25% of the records). This makes it hard to tell for sure if this has anythingto do with the size of data imported, since the more files I import the larger the probability of having corruption. I have had corruption on a single import too though. 5)Before writing a bug report(the problem may be that this is erratic and even on my PC corruption is not consistent, e.g. I may import a file and get corruption, or I may import another file without corruption) and hence reproducibility may be problematic., I would appreciiate someone setting me straight on the filedescriptor issues(thanks Sinisa thus far): -It is not clear to me if the problem may be that when mysql is importing data, it may be having more files open than it(or the fs-reiser in this case) can handle. Could this be the reason for (table)corruption? -If so, accordingto the manual, there are 2 ways around: either decrease table_cache in /etc/my.cnf (currently 512) which however may also affect performance as I have a lot of tables or increase ulimit/open-files-limit -The question on this first option(table_cache) is: if now I have 2000 open files and reduce the cache to 256 does it mean I will be getting half the open files? -Regarding the more desirable option of increasing the limit, are the two ways equivalent(that is, does open- file-limit call ulimit?) Is changing either of them enough , or-as I assume does one really have to change ulimit? -I have a ulimit -a limit giving a 1024 open file limit while cat /proc/sys/fs/file-nr gives a hard limit of 8192. However, the man page says the system may not allow you to change ulimit I did a ulimit -n 8192 as root then ulimit -a limit says 8192 but when I open a window as a regular user, and do ulimit -a limit it is still 1024. Rebooting comes back with 1024 Is it at all possible to change it? -Also, if I can/have to change open-files-limit, do I need to do it in /etc/my.cnf /usr/bin/mysqld_safe /both? Last, I have a start_Mysql=yes in rc.config but in contrast to other systems used mysql, mysql does not start when the system boots. Any ideas why? Sorry for the many questions. Thanks in advance S.Alexiou --------------------------------------------------------------------- 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
