Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

faq: update description and delete repeated question #467

Merged
merged 1 commit into from
May 15, 2018
Merged

faq: update description and delete repeated question #467

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 4 additions & 8 deletions FAQ.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -302,9 +302,9 @@ Take `Release Version: v1.0.3-1-ga80e796` as an example of version number descri

#### What's the difference between various TiDB master versions? How to avoid using the wrong TiDB-Ansible version?

The TiDB community is highly active. After the GA release, the engineers have been keeping optimizing and fixing bugs. Therefore, the TiDB version is updated quite fast. If you want to keep informed of the latest version, see [TiDB Weekly update](https://pingcap.com/weekly/).
The TiDB community is highly active. After the 1.0 GA release, the engineers have been keeping optimizing and fixing bugs. Therefore, the TiDB version is updated quite fast. If you want to keep informed of the latest version, see [TiDB Weekly update](https://pingcap.com/weekly/).

It is recommended to deploy the TiDB cluster using the latest version of TiDB-Ansible, which will also be updated along with the TiDB version. Besides, TiDB has a unified management of the version number after GA release. You can view the version number using the following two methods:
It is recommended to deploy the TiDB cluster using the latest version of TiDB-Ansible, which will also be updated along with the TiDB version. Besides, TiDB has a unified management of the version number after the 1.0 GA release. You can view the version number using the following two methods:

- `select tidb_version()`
- `tidb-server -V`
Expand Down Expand Up @@ -674,10 +674,6 @@ There are [similar limits](https://cloud.google.com/spanner/docs/limits) on Goog

3. As for `delete` and `update`, you can use `limit` plus circulation to operate.

#### Does TiDB release space immediately after deleting data?

`DELETE`, `TRUNCATE` and `DROP` do not release space immediately. For `TRUNCATE` and `DROP` operations, TiDB deletes the data and releases the space after reaching the GC (garbage collection) time (10 minutes by default). For the `DELETE` operation, TiDB deletes the data and does not release the space based on the GC mechanism, but reuses the space when subsequent data is committed to RocksDB and compacted.

#### Can I execute DDL operations on the target table when loading data?

No. None of the DDL operations can be executed on the target table when you load data, otherwise the data fails to be loaded.
Expand All @@ -686,9 +682,9 @@ No. None of the DDL operations can be executed on the target table when you load

Yes. But the `load data` does not support the `replace into` syntax.

#### How long does it take to reclaim disk space after deleting data?
#### Does TiDB release space immediately after deleting data?

None of the `Delete`, `Truncate` and `Drop` operations releases data immediately. For the `Truncate` and `Drop` operations, after the TiDB GC (Garbage Collection) time (10 minutes by default), the data is deleted and the space is released. For the `Delete` operation, the data is deleted but the space is not released according to TiDB GC. When data is written into RocksDB and executes `Compact`, the space is reused.
None of the `DELETE`, `TRUNCATE` and `DROP` operations release data immediately. For the `TRUNCATE` and `DROP` operations, after the TiDB GC (Garbage Collection) time (10 minutes by default), the data is deleted and the space is released. For the `DELETE` operation, the data is deleted but the space is not released according to TiDB GC. When subsequent data is written into RocksDB and executes `COMPACT`, the space is reused.

#### Why does the query speed getting slow after deleting data?

Expand Down