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From Bojan Smojver <bo...@rexursive.com>
Subject SQLite3 transactions
Date Fri, 28 Apr 2006 00:22:43 GMT
Been playing with transactions for SQLite3 DBD and noticed this code  
in the dbd_sqlite_end_transaction():

----------------------------------
     if (trans) {
         ret = dbd_sqlite3_query(trans->handle, &nrows, "END TRANSACTION;");
         if (trans->errnum) {
             trans->errnum = 0;
             ret = dbd_sqlite3_query(trans->handle, &nrows, "ROLLBACK;");
         } else {
             ret = dbd_sqlite3_query(trans->handle, &nrows, "COMMIT;");
         }
         trans->handle->trans = NULL;
     }

     return ret;
----------------------------------

I'm reading this as: if there is a transaction and "END TRANSACTION"  
is successful (i.e. trans->errnum is zero), then do "COMMIT". If  
something like that is tried in SQlite3 command line tool, the output  
looks like this:

----------------------------------
[bsmojver@itpi00 t]$ sqlite3 test.db
SQLite version 3.3.3
Enter ".help" for instructions
sqlite> create table test (a text);
sqlite> begin;
sqlite> insert into test values ('test');
sqlite> end;
sqlite> commit;
SQL error: cannot commit - no transaction is active
----------------------------------

So, it would seem that you cannot "COMMIT" when you issued "END  
TRANSACTION" already (i.e. it's already been done) in SQLite3. As a  
result of this, dbd_sqlite_end_transaction() appears to be returning a  
non-zero value, signaling to the caller that the transaction didn't  
end successfully, when in fact it did.

Note that the data did end up in the database on "END":
----------------------------------
sqlite> select * from test;
test
----------------------------------

I also think that the "ROLLBACK" bit is probably unnecessary as well.  
If the transaction failed, it will be rolled back anyway when "END  
TRANSACTION" is issued. This is not a big problem, but it can probably  
be removed.

Is there something I missed here or does that look like a real bug in  
SQLite DBD driver?

-- 
Bojan

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