Re: [sqlite] Locking issue on NFS filesystem
On 14 Jun 2010, at 3:16am, Prakash Reddy Bande wrote: > I have stumbled upon the issue as described in http://sqlite.org/faq.html#q5 > (But use caution: this locking mechanism might not work correctly if the > database file is kept on an NFS filesystem.) > > The question is, do we have a workaround. Our application has to store data > in user home directory (RHEL/SLES/CentOS) and the home directory might be on > a NFS device (as is my home directory). > stat -f -c %X /users/prakash returns nfs. Which version of NFS ? Locking was introduced in version 4. However, locking even under NFS sucks. That warning in the SQLite FAQ isn't there because the writers of SQLite are bad programmers, it's there because locking under many NFS installations is not implemented properly. You may have an alternative of accessing your NFS drive as a shared drive. If you do this, then locking is implemented by the networking protocol, not by the driver of the space being shared. So if you have a way of sharing your NFS drive via SMB or AFS, or some other common space-sharing system, you might be able to get around the NFS problems completely. Simon. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] Locking issue on NFS filesystem
Hi, I have stumbled upon the issue as described in http://sqlite.org/faq.html#q5 (But use caution: this locking mechanism might not work correctly if the database file is kept on an NFS filesystem.) The question is, do we have a workaround. Our application has to store data in user home directory (RHEL/SLES/CentOS) and the home directory might be on a NFS device (as is my home directory). stat -f -c %X /users/prakash returns nfs. I am vaguely imagining if we could (at compile or run time) have SQLite use dot file locking. Let me describe the problem I am facing. The database file does not exist and the call to sqlite3_open, does not return (or atleast does not return as long as I waited ~10 mins). I killed the process using kill / kill -9, but process went into zombie state. Also I observed that the database file got created (may not be usable) and another file nfs00. was created and locked by my app. I compiled the latest sqlite 3.6.23.1 and ran the following command sqlite /users/prakash/test.db I got the sqlite command prompt, however, the command .tables resulted in hang. So, again, I am trying to figure out a solution/workaround. Concurrency is not the most major concern and hence if we can use a different locking mechanism, that will be nice. Regards, Prakash ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] [bug] documentation error SELECT statement GROUP BY clause
On Sun, Jun 13, 2010 at 10:04:51PM +0200, Kees Nuyt scratched on the wall: > There appears to be an error in the description of the > SELECT statement on http://www.sqlite.org/lang_select.html . The syntax diagrams have several instances of things that the diagrams allow, but are not legal SQL statements. I think this would be included in that category. The diagrams are more of a guide than definitive documentation on the parse syntax or the allowed language (which is a bit different than what the parser allows). Consider that "SELECT * FROM t1 NATURAL CROSS JOIN t2 ON (ex)" is allowed by the diagrams, yet that makes no sense. There are several other examples. -j -- Jay A. Kreibich < J A Y @ K R E I B I.C H > "Intelligence is like underwear: it is important that you have it, but showing it to the wrong people has the tendency to make them feel uncomfortable." -- Angela Johnson ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] [bug] documentation error SELECT statement GROUP BY clause
Hi, There appears to be an error in the description of the SELECT statement on http://www.sqlite.org/lang_select.html . The GROUP BY clause in the select-core part http://www.sqlite.org/images/syntax/select-core.gif refers to ordering-term. Ordering-term http://www.sqlite.org/images/syntax/ordering-term.gif suggests it is possible to specify ASC or DESC, which of course is true for ORDER BY, but not for GROUP BY. Thanks to 'iSteve' on Internet Relay Chat (network freenode.net, channel #sqlite) for bringing this to our attention. -- ( Kees Nuyt ) c[_] ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] SqlLite not working properly after large data integration tests
I have a lengthy question about sqllite, involving a problem with the repeatability of a test harness that uses a sqllite in-memory database. I have posted it on stackoverflow: http://stackoverflow.com/questions/3030198/sqllite-fluent-nhibernate-integration-test-harness-initialization-not-repeatable Any info or debugging advice would be greatly appreciated! Thanks! Mark ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
