SQLite Exception: SQLite Busy

问题:

Can anyone provide any input on this error. I am trying to insert into table using Objective C.

While I am doing this, I am getting an error SQLite Busy. Why this is happening?

回答1:

If I get it right, "busy" means that you cannot obtain a lock. Seems that some another process (or thread, etc) has a lock on a database.

File Locking And Concurrency In SQLite Version 3

回答2:

If you get as a result when invoking an sqlite3 function the error code SQLITE_BUSY, this means as observed by drdaeman that the db has been locked by the same process or by one thread within your process.

The proper way to deal with this situation is to try the operation in a loop, and if the return code is still SQLITE_BUSY, to wait for some time (you decide the timeout value) and then retry the operation in the next loop iteration.

For instance, the following code snippet is taken from the Objective C wrapper FMDB (http://code.google.com/p/flycode/source/browse/trunk/fmdb) shows how to prepare a statement for a query taking into account that some operations may return SQLITE_BUSY:

int numberOfRetries = 0;
BOOL retry          = NO;

if (!pStmt) {
    do {
        retry   = NO;
        rc      = sqlite3_prepare(db, [sql UTF8String], -1, &pStmt, 0);

        if (SQLITE_BUSY == rc) {
            retry = YES;
            usleep(20);

            if (busyRetryTimeout && (numberOfRetries++ > busyRetryTimeout)) {
                NSLog(@"%s:%d Database busy (%@)", __FUNCTION__, __LINE__, [self databasePath]);
                NSLog(@"Database busy");
                sqlite3_finalize(pStmt);
                [self setInUse:NO];
                return nil;
            }
        }
        else if (SQLITE_OK != rc) {


            if (logsErrors) {
                NSLog(@"DB Error: %d \"%@\"", [self lastErrorCode], [self lastErrorMessage]);
                NSLog(@"DB Query: %@", sql);
                if (crashOnErrors) {

                    NSAssert2(false, @"DB Error: %d \"%@\"", [self lastErrorCode], [self lastErrorMessage]);
                }
            }

            sqlite3_finalize(pStmt);

            [self setInUse:NO];
            return nil;
        }
    }
    while (retry);
}

By the way, if you need to access sqlite, FMDB is very handy and much simpler to use with respect to direct access through the native C APIs.

回答3:

I had a similar problem with SQLITE_BUSY on sequential INSERT INTO commands. The first row inserted ok, but when the app tried to insert a second row, I got the SQLITE_BUSY status. After Google'ing around, I learned you must call sqlite3_finalize() on statements after executing them: http://www.sqlite.org/c3ref/finalize.html. Finalizing my statements fixed my problem.

回答4:

In my case, I had forgotten to close database after using it. Following fixed mine:

sqlite3_finalize(statement);
sqlite3_close(contactDB);

FMDB can also alleviate these headaches from you easily.

回答5:

It was as simple as running command prompt as Administrator for me. Alternatively on UNIX you might be able to use sudo when starting up the database.