[jira] [Created] (IGNITE-4188) Savepoints support inside of Ignite Transactions

[Anton Vinogradov (Jira)]

Denis Magda created IGNITE-4188:
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             Summary: Savepoints support inside of Ignite Transactions
                 Key: IGNITE-4188
                 URL: https://issues.apache.org/jira/browse/IGNITE-4188
             Project: Ignite
          Issue Type: Task
            Reporter: Denis Magda
             Fix For: 2.1


A savepoint is a special mark inside a transaction that allows all commands that are executed after it was established to be rolled back, restoring the transaction state to what it was at the time of the savepoint.

Here is a reference to the similar functionality implemented by some of RDBMs vendors.
https://www.postgresql.org/docs/8.1/static/sql-savepoint.html
https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_10001.htm
http://dev.mysql.com/doc/refman/5.7/en/savepoint.html

Consider the following example.

{code}
BEGIN;
INSERT INTO table1 VALUES (1);
SAVEPOINT my_savepoint;
INSERT INTO table1 VALUES (2);
ROLLBACK TO SAVEPOINT my_savepoint;
INSERT INTO table1 VALUES (3);
COMMIT;
{code}

The execution result must guarantee that only values 1 and 3 are inserted into table1.

In Ignite, it should be supported this way (preserving the same behavior as above).

{code}
Ignite ignite = ....;
IgniteCache<Integer, Integer> c = ....;

try (Transaction tx = ignite.transactions().txStart()) {    
    c.put(1, 1);
   
    tx.savepoint("mysavepoint");
   
    c.put(2, 2);
   
    tx.rollbackToSavepoint("mysavepoint");
   
    c.put(3, 3);
   
    tx.commit();
}
{code}

As a summary the following has to be supported on Ignite side:
- The {{savepoint}} method which will set a named transaction savepoint with a name of an identifier.
- Multiple savepoints defined within a transaction. The names of the savepoints have to differ from each other. If the current transaction has a savepoint with the same name, the old savepoint is deleted and a new one is set.
- The {{rollbackToSavepoint}} method that will roll back all the changes done after a specific checkpoint establishment.
- The {{releaseCheckpoint}} method that will destroy a savepoint, keeping the effects of commands executed after it was established.
- Full support of the behavior listed above at the level of ODBC and JDBC drivers and DML (will be handled under separate tickets).
- The behavior has to be support for all transactional modes.



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