LYD031106 commented on code in PR #2888:
URL:
https://github.com/apache/incubator-hugegraph/pull/2888#discussion_r2466062592
##########
hugegraph-server/hugegraph-mysql/src/main/java/org/apache/hugegraph/backend/store/mysql/MysqlStore.java:
##########
@@ -223,6 +223,7 @@ public void truncate() {
this.checkOpened();
this.truncateTables();
+ this.init();
Review Comment:
**Root Cause**
The issue stems from the fact that backend stores such as MySQL, HBase, and
RocksDB persist metadata (e.g., `driverVersion`) to the backend storage. When
the `truncate()` operation is executed to clear all table data, this metadata
is also deleted. As a result, subsequent operations fail due to missing
metadata or state conflicts.
**Analysis by Backend**
- **RocksDB**:
Although affected by the same problem, its `truncate()` method explicitly
calls `this.init()` after clearing data to reinitialize the metadata, thereby
avoiding errors.
```
@Override
public synchronized void truncate() {
Lock writeLock = this.storeLock.writeLock();
writeLock.lock();
try {
this.checkOpened();
this.clear(false);
this.init();
// Clear write-batch
this.dbs.values().forEach(BackendSessionPool::forceResetSessions);
LOG.debug("Store truncated: {}", this.store);
} finally {
writeLock.unlock();
}
}
```
- **HBase**:
Confirmed to have the same issue as MySQL.
Action Required: A follow-up PR is needed to fix the HBase backend
accordingly.
- **Memory / HStore**:
These backends are not affected because they do not persist critical
version information or similar metadata to the backend storage.
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