4bd5d4f163
This pull request includes some implementations of the statistics(https://github.com/apache/incubator-doris/issues/6370), it will not affect any existing code and users will not be able to create statistics job. After receiving the statistics statement and dividing the collection task, here we will start implementing the scheduling statistics task and updating the job information. Mainly include the following: - Create a thread pool to schedule a certain number of tasks, and the number of concurrency is related to the configuration `cbo_concurrency_statistics_task_num`. - After the task is completed, update the information of of the statistics Job.