User transaction may commit fail when concurrent DDL is running
Open
nextgen
severity/major
type/bug
- Dominant language
- Go
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Description
## Bug Report
For transactions in TiDB-X, or optimistic transactions for classic kernel, it is possible for a user transaction to fail to commit due to write conflict with a concurrent DDL job.
DDL doesn't lock row keys now. When a DDL and a user txn both modifies temp index key, write conflicts can happen when the user txn try to commit.
While we expect that user transaction should not fail because of DDL
### 4. What is your TiDB version? (Required)
TiDB-X (test `TestExchangePartition` failure when using client-go 108d20a439f29b4f9d8c8b5e4ee2eb60fedf86d2)
or
Classic (via theoretical analysis)
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Assessment
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