How Can I Configure init_td

Transaction directory (TD) is a unique structure used by Ustore tables to store page transaction information. The number of TDs determines the maximum number of concurrent transactions supported on a page. When creating a table or index, you can specify the initial TD size init_td, whose default value is 4. That is, four concurrent transactions are supported to modify the page. The maximum value of init_td is 128.

You can configure init_td based on the service concurrency requirements. Besides, you can also configure it based on the occurrence frequency of wait available td events during service running. Generally, the value of wait available td is 0. If the value of wait available td is not 0, there are events waiting for available TDs. In this case, you are advised to increase the value of init_td. If the value 0 is an occasional situation, you are not advised to adjust init_td because extra TD slots occupy more space. You are advised to gradually increase the value in ascending order, such as 8, 16, 32, 48, ..., and 128, and check whether the number of wait events decreases significantly in this process. Use the minimum value of init_td with few wait events as the default value to save space. For details about how to configure and modify init_td, see "SQL Reference > SQL Syntax > CREATE TABLE" in Developer Guide.