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

ticdc: refine faq doc (#20547) #20617

Merged
merged 3 commits into from
Mar 21, 2025
+9 −1
Merged

ticdc: refine faq doc (#20547) #20617

Changes from 1 commit
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
4d7fa3c
Add temp.md
qiancai Mar 17, 2025
9dc7ed7
Delete temp.md
qiancai Mar 17, 2025
ccb9891
add translation
qiancai Mar 17, 2025
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
Prev Previous commit
Loading
Loading status checks…
add translation
@qiancai @ti-chi-bot
qiancai authored and ti-chi-bot committed Mar 21, 2025
commit ccb98916c4dc28ded64ba60b0ba088a14cc1c035
10 changes: 9 additions & 1 deletion ticdc/ticdc-faq.md
View file
Original file line number Diff line number Diff line change
@@ -292,7 +292,15 @@

## How much PD storage does TiCDC use?

TiCDC uses etcd in PD to store and regularly update the metadata. Because the time interval between the MVCC of etcd and PD's default compaction is one hour, the amount of PD storage that TiCDC uses is proportional to the amount of metadata versions generated within this hour. However, in v4.0.5, v4.0.6, and v4.0.7, TiCDC has a problem of frequent writing, so if there are 1000 tables created or scheduled in an hour, it then takes up all the etcd storage and returns the `etcdserver: mvcc: database space exceeded` error. You need to clean up the etcd storage after getting this error. See [etcd maintenance space-quota](https://etcd.io/docs/v3.4.0/op-guide/maintenance/#space-quota) for details. It is recommended to upgrade your cluster to v4.0.9 or later versions.
When using TiCDC, you might encounter the `etcdserver: mvcc: database space exceeded` error, which is primarily related to the mechanism that TiCDC uses etcd in PD to store metadata.

etcd uses Multi-Version Concurrency Control (MVCC) to store data, and the default compaction interval in PD is 1 hour. This means that etcd retains multiple versions of all data for 1 hour before compaction.

Before v6.0.0, TiCDC uses etcd in PD to store and update metadata for all tables in a changefeed. Therefore, the PD storage space used by TiCDC is proportional to the number of tables being replicated by the changefeed. When TiCDC is replicating a large number of tables, the etcd storage space could fill up quickly, increasing the probability of the `etcdserver: mvcc: database space exceeded` error.

Check warning on line 299 in ticdc/ticdc-faq.md

GitHub Actions / vale 

[vale] reported by reviewdog 🐶
[PingCAP.Ambiguous] Consider using a clearer word than 'a large number of' because it may cause confusion.

Raw Output:
{"message": "[PingCAP.Ambiguous] Consider using a clearer word than 'a large number of' because it may cause confusion.", "location": {"path": "ticdc/ticdc-faq.md", "range": {"start": {"line": 299, "column": 247}}}, "severity": "INFO"}

If you encounter this error, refer to [etcd maintenance space-quota](https://etcd.io/docs/v3.4.0/op-guide/maintenance/#space-quota) to clean up the etcd storage space.

Starting from v6.0.0, TiCDC optimizes its metadata storage mechanism, effectively avoiding the etcd storage space issues caused by the preceding reasons. If your TiCDC version is earlier than v6.0.0, it is recommended to upgrade to v6.0.0 or later versions.

## Does TiCDC support replicating large transactions? Is there any risk?