Document Type | Troubleshooting
Category | Administration
Applicable Product Version | 7FS02, 7FS02PS
Document Number | TADTS021
Issue
When creating an index in parallel, the Segment Size may increase proportionally to the DOP (Degree of Parallelism), or a Tablespace Full error may occur.
NoteThis environment is Tibero7 FS02.
Additionally, in the following two cases or when both conditions are combined, the Segment Size may increase or a Tablespace Full error may occur.
- When the _TX_IDX_SGMT_ALLOC_SIZE value is set larger than the default for large data migration
- When the Block Size is set larger than the default (8192) during database creation
Cause
- When _TX_IDX_SGMT_ALLOC_SIZE=2048 and parallel=16
- If one extent size is 32KB * 2048 = 64MB based on 32KB blocks (Zetta)
โ Based on DOP 16, a total of 1GB (1024MB) of space is allocated.
Therefore, when creating an index on TOBE regardless of the index size, a segment of at least 1GB is created.
Thus, if there are many indexes, a TOBE Tablespace Full error may occur.
Solutions
Adjust the _TX_IDX_SGMT_ALLOC_SIZE parameter.
- _TX_IDX_SGMT_ALLOC_SIZE is a parameter that determines how many blocks make up one extent when adding extents to an index segment.
- Reducing the default value from 2048 to 128 allocates relatively smaller extents, reducing unnecessary space waste.
Example sizes when setting _TX_IDX_SGMT_ALLOC_SIZE = 128
| PARALLEL | Size (MB) |
|---|---|
| PARALLEL OFF | 4 |
| PARALLEL 8 | 32 |
| PARALLEL 16 | 64 |