How long does it takes to sync plenty of `ADD COLUMN` DDL to a partitioned table with many partitions
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Description
General Question
In the v5.4 version, we observed that executing 30 ADD COLUMN DDL to a partitioned table with 450 partitions cause more than 1 minute. And this will make all the queries to TiFlash stuck until the schema sync is done.
Since v7.2, we have a new DDL framework, which is to expected to:
- Shorten the duration of TiFlash Schema Sync with TiDB
- Mitigate the problem of blocking other queries to the tables that is not relevant to the DDLs
We want to confirm how long executing 30 ADD COLUMN DDL to a partitioned table with 450 partitions takes after v7.5.
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Research direction
Start by reproducing the reported workload: 30 ADD COLUMN DDL statements on a partitioned table with 450 partitions, using the post-v7.2 DDL framework targeted by the report. Measure schema-sync duration and whether TiFlash queries remain blocked, then document the results for the v7.5 comparison requested.
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Assessment
- Tech stack
- sql
- Domain
- databases, performance
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 20/100