default_progressive_merge_num specifies the default number of progressive compactions when a table is created.
| Attribute | Description |
|---|---|
| Type | Integer |
| Default value | 0 |
| Value range | [0, +∞) |
| Effective upon OBServer node restart | No |
OceanBase Database supports progressive compactions on table data. After performing a DDL operation that needs to rewrite the data, OceanBase Database can distribute data rewriting to multiple compaction operations. During each compaction, only some of the data is rewritten. You can use the table-level attribute progressive_merge_num to control the compaction, or use the default_progressive_merge_num parameter to set the default number of progressive compactions when you create a table.
If you do not set the progressive_merge_num attribute, OceanBase Database sets its value to the value of default_progressive_merge_num.
The values of progressive_merge_num are described as follows:
- The default value is
0, which indicates that 100 progressive compactions are performed. - If the value is set to
1, a full compaction is forcibly performed. - If the value is set to an integer X, the full data is rewritten in X rounds, and 1/X of the full data is rewritten in each round.