MySQL Cluster transaction isolation level - READ_COMMITTED
- by Doori Bar
I'm learning by mostly reading the documentation. Unfortunately, http://dev.mysql.com/doc/refman/5.1/en/set-transaction.html#isolevel_read-committed
doesn't say anything, while it says everything. Confused? Me too.
ndb engine supports only "READ_COMMITTED" transaction isolation level.
A. It starts by saying "sets and reads its own fresh snapshot", which I translate to: The transaction is having a separated 'zone' which whatever it stores there - is what it reads back.
B. While out-side of the transaction, the old-values are unlocked.
C. It continues with: "for locking reads" sentence - No idea what it means.
Question: they claim only READ_COMMITTED transaction isolation level is supported, but while handling a BLOB or a TEXT, they say the isolation is now "locked for reading" too. So is it a contradiction? can a transaction LOCK for reading just as well while handling something other than BLOB/TEXT? (such as integers)
