AliSQL: [Feature] Issue#5 RELAX GTID LIMITATION FOR SOME STATEMENTS

Description:

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When gtid_mode is on, MySQL has a limitation on cts(create table ... select)

and the statements mixed with transaction/non-transaction storage engines.

It doesn't allow these statements to be executed. Such a limitation brings

many inconveniences to users.

In order to remove that limitation, we implemented such a feature which can

make those statments run under rbr(row based replication) mode and gtid mode.

We introduced one global system variable 'rds_allow_unsafe_stmt_with_gtid' to

enable such a feature. When the feature is enabled, cts will be divided into

two individual transactions. The first is CREATE TABLE. The second is inserting

data into the table. For the second transaction, it will write into binlog

directly, which means not to wait for any transaction commit once the first

transaction is succesfull. The same logicfor the statements mixing

nontransactional storage engine with transactional ones.

Note if you want to use this feature, you must set gtid_next automatically.