Hi! All, After using strace, we found the root cause. SQLite will use some temporary files to keep the select (with union all) result. See: http://www.sqlite.org/tempfiles.html
In our system, we allocated 32M for /, and there are only 19M after booting up the system. SQLite can not get enough space for the temporary files (strace shows "write error: space is not enough") After adding a compiling configuration -DSQLITE_TEMP_STORE=3 to SQLIte's Makefile, we can finish this job. http://www.sqlite.org/compile.html#temp_store Also, we can change the location of the temporary files to solve this issue. France Hsu wrote: > Hi! All, > > We recently got an error "Disk I/O error" while using the select > command on attached DBs. > These DBs have same table format > We only execute select, insert, and attach commands > > The environment is as follows: > SQLite: V3.5.6 > OS: Linux 2.6.24.2 > Platform Power PC (MPC8543) > Memory: 256M > DB Location: SATA hard drive, within a 512-maga-byte partition > > The error is happened when the size of one DB file is larger than 10M, > Ex: > -rw-r--r-- 1 root root 10600448 Aug 1 14:38 system_log-07.db > -rw-r--r-- 1 root root 27648 Aug 7 22:18 system_log-08.db > > ./sqlite3 system_log-08.db > sqlite> attach ''system_log-07.db' as db1; > sqlite> select * from main.disk_log union all select * from > db1.disk_log order by timestamp desc; > SQL error: disk I/O error > > Available partition size: 467.2M > Sometimes I executed the command "select count(*) ..." successfully, > but sometimes failed. > The total number of the result is about 150000. > Sometimes I executed the command "select * ... limit 0, 30000" > successfully, but sometimes failed. > As observing top when executing sqlite, the available memory is enough > (about 120-140M). > > Would you provide some comments or some solutions? > Thank you all very much. > -- Best Regards, France Hsu _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
