Do I Need to Modify Business SQL After Enabling KV Separation?
Not required. KV separation is completely transparent to the SQL layer, and all DML syntax remains unchanged.
Can I See the Effect Immediately After Enabling It?
It takes effect immediately for newly written data. For existing data, migration to Blob files occurs only after the next Compaction. For large tables, it is recommended to enable this feature during off-peak hours and then monitor for 24 to 48 hours.
min_blob_size What Is the Recommended Setting?
The recommended range is 1 KB to 4 KB. If the threshold is set too low (for example, a few dozen bytes), a large number of small Values will also take the separation path, which increases read latency. Conversely, if it is set too high, the separation loses its purpose. It is recommended to first run a trial with 1024 and then adjust based on monitoring.
Is It a Problem If Disk Usage Increases After KV Separation is enabled?
Usually not. The reason is that overwritten/deleted old Blob data is not reclaimed until garbage collection (GC) runs. Confirm that tdstore_user_cf_enable_blob_garbage_collection = ON. If the usage continues to increase over an extended period, contact your DBA to adjust the GC parameters.
Will Point Queries (Primary Key Lookups) Become Slower?
Reading a large Value theoretically incurs an additional Blob file I/O operation each time. If your business is sensitive to point query latency, it is recommended to enable Blob Cache (tdstore_enable_blob_cache = ON, a restart is required) to keep hot Blobs resident in memory.
Can I Enable It for a Specific Large Table Only?
The current version does not support table-level switches. Workaround: Set min_blob_size higher than the maximum Value size of other tables (for example, 8 KB) to ensure small tables remain completely unaffected.
Does Enabling It Affect Backup and Recovery?
No impact. As part of the storage engine's data files, Blob files are fully incorporated into the backup/restore/Region migration processes.