At present, we do not support SQL MODE which is similar to MySQL. In MySQL, SQL MODE is stored in global session and session with a 64 bit address，and every bit 0 or 1 on this address represents a mode state. Besides, MySQL supports combine mode which is composed of several modes.
We should support SQL MODE to deal with sql dialect problems. We can heuristically use the MySQL way to store SQL MODE in session and parse it into string when we need to return it back to client.
This commit suggests a solution to support SQL MODE. But it's just a sample, and the mode types in SqlModeHelper.java are not really meaningful from now on.
Mainly fix the following issues:
1. A null pointer exception is raised when a database or table is dropped. The expected behavior is that the routine load job is stopped.
2. Memory leaks. Batch routine load task submissions are no longer performed, and modifications are submitted separately for each task.
3. Unreasonable task timeout.
Routine load tasks should not be queued in the BE thread pool for execution. The task sent to the BE should be executed immediately, otherwise the task in the FE will be timeout first. Eventually leads to constant timeout for all subsequent tasks.
4. All routine load job should be scheduled once it being submitted. Not waiting the available BE slot. Otherwise, all later submitted jobs may not be scheduled forever.
ISSUE-2069: This kind of query could be stuck.
The sender failed to send the last packet to receiver.
Also, the failure does not be reportted to FE , so the query is not cancelled.
The error log sames as "body_size=xxxx from xxx:xxx is too large".
The reason of the socket is that the packet of the query is too big which is more then the max_body_size of brpc.
This commit add a config named brpc_max_body_size whcih is used to change the max_body_size of brpc.
Also, user can change the max_body_size directly on-the-fly by "http://host:brpc_port/flags".
1. Support specifying label to Insert Into stmt.
INSERT INTO tbl1 WITH LABEL label1 ...;
2. Return job' state corresponding to the existing label in result of stream load.
...
"Status": "Label Already Exists",
"ExistingJobStatus": "FINISHED"
...
3. Return the recent 2000 transactions in SHOW PROC '/transactions'
