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lightning: update the feature desc of pausing scheduling on table lev…
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…el (#12153)
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ran-huang authored Mar 7, 2023
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4 changes: 2 additions & 2 deletions releases/release-6.2.0.md
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Expand Up @@ -22,7 +22,7 @@ In v6.2.0-DMR, the key new features and improvements are as follows:
* A new concurrent DDL framework: Less DDL statements blocked and higher execution efficiency.
* TiKV supports [automatically tuning the CPU usage](/tikv-configuration-file.md#background-quota-limiter), thus ensuring stable and efficient database operations.
* [Point-in-time recovery (PITR)](/br/backup-and-restore-overview.md) is introduced to restore a snapshot of a TiDB cluster to a new cluster from any given time point in the past.
* TiDB Lightning supports [importing data to production clusters in the physical import mode](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#import-data-into-a-cluster-in-production).
* TiDB Lightning supports [pausing the scheduling on the table level](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#pause-scheduling-on-the-table-level) in the physical import mode, instead of on the cluster level.
* BR supports [restoring user and privilege data](/br/br-snapshot-guide.md#restore-tables-in-the-mysql-schema), making backup and restore smoother.
* TiCDC unlocks more data replication scenarios by supporting [filtering specific types of DDL events](/ticdc/ticdc-filter.md).
* The [`SAVEPOINT` mechanism](/sql-statements/sql-statement-savepoint.md) is supported, with which you can flexibly control the rollback points within a transaction.
Expand Down Expand Up @@ -221,7 +221,7 @@ In v6.2.0-DMR, the key new features and improvements are as follows:

This feature does not need manual configuration. If your TiDB cluster is v6.1.0 or later versions and TiDB Lightning is v6.2.0 or later versions, the new physical import mode takes effect automatically.

[User document](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#import-data-into-a-cluster-in-production) [#35148](https://github.com/pingcap/tidb/issues/35148) @[gozssky](https://github.com/gozssky)
[User document](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#pause-scheduling-on-the-table-level) [#35148](https://github.com/pingcap/tidb/issues/35148) @[gozssky](https://github.com/gozssky)

* Refactor the [user documentation of TiDB Lightning](/tidb-lightning/tidb-lightning-overview.md) to make its structure more reasonable and clear. The terms for "backend" is also modified to lower the understanding barrier for new users:

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6 changes: 2 additions & 4 deletions tidb-lightning/tidb-lightning-physical-import-mode-usage.md
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Expand Up @@ -130,11 +130,9 @@ mysql> select table_name,index_name,key_data,row_data from conflict_error_v1 lim

You can manually identify the records that need to be retained and insert these records into the table.

## Import data into a cluster in production
## Pause scheduling on the table level

Starting from TiDB Lightning v6.2.0, you can import data into a cluster in production using the physical import mode. TiDB Lightning implements a new mechanism to limit the impact of the import on the online application.

With the new mechanism, TiDB Lightning does not pause the global scheduling, but only pauses scheduling for the region that stores the target table data. This significantly reduces the impact of the import on the online application.
Starting from v6.2.0, TiDB Lightning implements a mechanism to limit the impact of data import on online applications. With the new mechanism, TiDB Lightning does not pause the global scheduling, but only pauses scheduling for the region that stores the target table data. This significantly reduces the impact of the import on online applications.

<Note>
TiDB Lightning does not support importing data into a table that already contains data.
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2 changes: 1 addition & 1 deletion tidb-lightning/tidb-lightning-physical-import-mode.md
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Expand Up @@ -62,7 +62,7 @@ It is recommended that you allocate CPU more than 32 cores and memory greater th

### Limitations

- Do not use the physical import mode to directly import data to TiDB clusters in production. It has severe performance implications. If you need to do so, refer to [Import data into a cluster in production](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#import-data-into-a-cluster-in-production).
- Do not use the physical import mode to directly import data to TiDB clusters in production. It has severe performance implications. If you need to do so, refer to [Pause scheduling on the table level](/tidb-lightning/tidb-lightning-physical-import-mode-usage.md#pause-scheduling-on-the-table-level).
- Do not use multiple TiDB Lightning instances to import data to the same TiDB cluster by default. Use [Parallel Import](/tidb-lightning/tidb-lightning-distributed-import.md) instead.
- When you use multiple TiDB Lightning to import data to the same target, do not mix the backends. That is, do not use the physical import mode and the logical import mode at the same time.
- During the process of importing data, do not perform write operations in the target table. Otherwise the import will fail or the data will be inconsistent. At the same time, it is not recommended to perform read operations, because the data you read might be inconsistent. You can perform read and write operations after the import operation is completed.
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