Good day, I'm sure others on the list will add better insight, but is your task parallel enough that your nodes can work with a copy of the database and submit changes the one the others copy from when 'done' their calculation?
Are you using https://www.sqlite.org/c3ref/busy_timeout.html ? regards, Adam This may be beside the point in terms of optimization, but your query looks rather character based on int like information. On Thu, Jul 2, 2015 at 10:09 AM, Kathleen Alexander <katcalex at mit.edu> wrote: > Hi, > > I apologize if this is an incorrect forum for this question, but I am > pretty new to SQLite and have been unable to resolve this issue through > other searches. Feel free to direct me to a more appropriate forum. > > Essentially, I have written an application in C++ that interfaces (reads > and writes) with a SQLite database, and I am getting lots of 'database is > locked' errors. Right now, I am trying to establish whether those errors > are due to my improper use of SQLite itself, or if the real problem is that > SQLite is not a good fit for my application. > > My application runs on Linux (ubuntu 13.10), and is driven by a bash script > that spawns many (~60 on a 64 core workstation) instances of a serial, C++ > program, each of which opens its own connection to the database and > performs reads and writes. > > *An example SELECT query from my program looks like:* > //open db connection > sqlite3 *db; > char *zErrMsg = 0; > SQLITE3 sql(dbase.c_str()); > > statement = "SELECT * from configs_table WHERE id='31'"; > sql.exe(statement.c_str()); > if( sql.vcol_head.size() > 0 ){ > //do things with sql.vdata[] > }//end query returned results > > *An example of a write statement looks like:* > statement = "UPDATE configs_table SET searched='2' WHERE id='31'"; > sql.exe(statement.c_str()); > > About 97% of the time, the select statement works fine, but in the other 3% > of cases, I see a 'database is locked' error in the log file of my program. > About 50% of the time, the write statement returns 'database is locked'. > > Additionally, if this application is running and I try to query the > database from the terminal, I almost always get a 'database is locked' > error. > > Thus, I am wondering if I am doing something wrong in my implementation of > the C++ --> SQLite interaction, or if the real problem is that this > application is not well suited to use with SQLite (I went through the > checklist before implementing it and thought my application passed the > suitability requirements). > > Lastly: > A. if it seems like this is an implementation issue, rather than a > capability issue, if I were to scale up my method to spawn say 500-1000 > processes at a time (on a supercomputing cluster), would there be any > concern about SQLite scaling to that level? > B. If SQLite is not a good fit for my program, do you have any suggestions > of an alternative database engine that is free or might be free or > inexpensive for academic use? > > Thanks in advance, > Kathleen > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users -- -------------- VerifEye Technologies Inc. 151 Whitehall Dr. Unit 2 Markham, ON L3R 9T1
