Transaction Question - Permanent locking problem

[alex Lewis]

Two questions about transactions in MySQL.
I am in particular using BDB (BerkeleyDB) tables. and sending statements via PHP. I do not have shell access.
Using PHP - 4.3.10
using MYSQL - 3.23.56

1)
If several users were accessing the MySQL database at the same time (User 1, User 2, User 3)
If User 1 starts a transaction :
> BEGIN;

But before User 1 COMMITS their transaction to the DB, User 2 issues a COMMIT statement
> COMMIT;

Will the locking started when User 1 started the transaction prevent User 2 from doing this Or Will the COMMIT statement actually inadvertently COMMIT User 1's statements before he/she is ready to COMMIT.



2)
If I start a transaction
> BEGIN;

And before i send the COMMIT statement - the application sending the statements goes faulty and stops sending the statements. The database gets stuck inside the transaction.

As the application is faulty there is no chance of sending a rollback statement. Is there a way of telling the MySQL database via the statements sent in PHP to rollback the transaction if not COMMIT or ROLLBACK is sent and the database becomes locked.

At the moment - all my tables seem to lock up after a begin statement. And if COMMIT or ROLLBACK is never sent then all users are locked out for at least 10 mins (thats only as far as i have timed it - it could be a permanent lock out)