Re: [sqlite] 500 sqlites on one server machine?
ye, at the fifth question of the SQLite FAQ, at http://www.sqlite.org/faq.html, it is explained why using a sqlite file by multiple nodes over a network with a NFS filesystem is not a good idea. I would avoid it although the FAQ does not say 'it does not work', it only says 'it might not work'. You might want to take a look at GlusterFS (www.glusterfs.org), it's a clustered filesystem that works well with fcntl() (the locking system). If you need a smaller latency, it will also work with infiniband. Best regards, Daniel Colchete ye wrote: > Hi, Igor: > Thanks for reply! > Yes, I just noticed the sqlite data file is nothing but a empty file. > Thanks! > About the remote visit, if the sqlite data file is created on a NFS, will > the remote visiting process be considered as a equal local process? > > regards > ye > > ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] Ignoring "The"
Andrew Gatt wrote: > I have a table of music artist names which i'd like to output in order. > Normally i just use: > > select * from artists order by artist_name; > > What i'd really like to do is order the artists by name but ignore any > "the" or "the," preceding it. > > Any ideas? > > Thanks > > Andrew > ___ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > Store it like "Beatles, The" them make the transformation latter, if necessary? That's one idea. Best, Daniel ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] UTF8
Cesar David Rodas Maldonado wrote: > I wanted to ask how can i know if a given text is UTF8 or ISO-8859-1? Well, there might be a way if you only want to know if the text is UTF-8 or ISO-8859-1 (it means that you already know that is one is the other). There are some invalid UTF-8 sequences. If you have something like 0xE5 0x61, that in ISO-8859-1 means 'a' = 'áa', you have an invalid UTF-8 sequence and then you know that it is not an UTF-8 charset. How do you test it? If you're using Linux you can try to convert your string from UTF-8 to UTF-16 using glibc's iconv. If it is an ISO-8859-1 text and you are lucky enough to be an invalid UTF-8 (most likely) then you have it! If you are not using Linux then you should learn how unicode chars are encoded in UTF-8 (like in http://en.wikipedia.org/wiki/UTF-8) to make your own algorithm. There is a very good chance it will work fine for you. Every ISO-8859-1 document with non-ASCII chars I try to open with UTF-8 editors gives me errors. What do you think? Besides that, I know that there are a few probabilistic methods to determine the charset a text is encoded. Mozilla Firefox uses them a lot. There are many papers on this subject on the internet. Google is your friend. Best regards, Daniel Colchete
Re: [sqlite] A littel question...
Cesar David Rodas Maldonado wrote: > Hello to everybody > > If I have a table with 100.000 unique words I am wondering if SQLite > select > if faster an cheaper (RAM, Processor, etc), or If i have to help SQLite > using a Hash function, and what could be that Hash function? > > Thanks. > Cesar, you should consider using an index: http://www.sqlite.org/lang_createindex.html Best regards, Daniel Colchete
Re: [sqlite] Using prepare, step, finalize and handling BUSY answers
Jay Sprenkle wrote:
> Here's some example code:
>
> sqlite3*db;
>
> // connect to database
> if ( sqlite3_open( "test.db", ) )
> throw "Can't open database";
>
> char* sql;
>
> // two forms of the same sql
> sql = "SELECT one.test1, two.test2"
> " FROM one"
> " INNER JOIN two ON one.id = two.id"
> ;
> sqlite3_stmt* pStmt;
>
> if ( sqlite3_prepare( db, sql, strlen(sql), , NULL ) != SQLITE_OK )
> {
> string str = "Cannot prepare sql: ";
> str += sql[t];
> str += ", Error: ";
> str += sqlite3_errmsg(db);
> throw str.c_str();
> }
>
> bool Loop = true;
> while ( Loop )
> switch ( sqlite3_step( pStmt ) )
> {
> case SQLITE_ROW:
>// retrieve the results
>char* p = (char *) sqlite3_column_text( pStmt, 0 );
>string test1 = string( p ? p : "" );
>
>p = (char *) sqlite3_column_text( pStmt, 1 );
>string test2 = string( p ? p : "" );
>
>break;
> case SQLITE_DONE:
>Loop = false;
>break;
> case SQLITE_BUSY:
> case SQLITE_LOCKED:
> default:
>string str = "Cannot execute sql: ";
>str += sql[t];
>str += ", Error: ";
>str += sqlite3_errmsg(db);
>throw str.c_str();
>break;
> }
>
> // clean up when finished
> sqlite3_finalize( pStmt );
>
> sqlite3_close( db );
Jay, thank you very much man! That answers a lot. And it showed me that
I was not checking the SQLITE_LOCKED case.
But, from what I can see, if your database is busy or locked you just
stop your program execution, or you will end this function WITHOUT
running neither sqlite3_finalize nor sqlite3_close. Either way you will
have a memory leak and this is not a good thing when you're running an
daemon (my case).
What if you put an loop = false instead of the throw at the 'default'
case? Do you have to you use sqlite3_interrupt before sqlite3_finalize?
Best regards,
Daniel Colchete
[sqlite] Using prepare, step, finalize and hadling BUSY answers
Hello everyone,
I'm new on this list and I have only a few months of experience with
SQLITE. I use SQLITE 3.3.6 for Linux with C++.
I'm having a few problems with locking. But before describing the
problem itself, I would like to check if I'm doing something wrong.
That's what I do when I try to INSERT something in my database:
PREPARE
BIND
EC = STEP
while EC = BUSY {
TRY AGAIN 10 TIMES; // SQLITE is set to sleep 1 sec if BUSY.
IF TIME > 10 { BREAK; }
}
And then I do some other selects and inserts. Now I read that there is
another function I should be using: sqlite3_finalize. From what I
understood I should be doing:
PREPARE
BIND
EC = STEP
while EC = BUSY {
TRY AGAIN 10 TIMES; // SQLITE is set to sleep 1 sec if BUSY.
IF TIME > 10 { BREAK; }
}
FINALIZE
Am I right?
Question: what if a PREPARE returns BUSY? What should I do? Why would a
PREPARE return BUSY?
I'm having problems understanding the SQLite docs. At the 'C/C++
Interface for SQLite Version 3' it says that sqlite3_exec is a wrapper
to 'prepare, finalize, reset' without a step. But a little bit down the
document it says you should use and step. But again, what if I don't
want to wait the busy state anymore? Should I use finalize or interrupt
and then finalize?
Thank you very much for your help!
Best regards,
Daniel Colchete
