mingnuj commented on issue #44467:
URL: https://github.com/apache/arrow/issues/44467#issuecomment-2440540273
I've been building each Flight SQL-related branch following the Arrow 15.0.0
release and identified an issue occurring after commit [GH-33475: Add parameter
binding for Prepared Statements in JDBC driver (#38404)].
After debugging last week, I observed the following:
When querying from DBeaver, the `prepareAndExecute` function is called
within `ArrowFlightMetaImpl.java` in `flight-sql-jdbc-core`. Before this
commit, the signature in `ArrowFlightMetaImpl` was a fixed value, declared as
final. However, with the parameter binding addition, the code now utilizes the
handle's signature, making it mutable.
* Previous code (ArrowFlightMetaImpl.java, line 160):
```java
final Signature signature = newSignature(query); // Immutable
final long updateCount = statementType.equals(StatementType.UPDATE) ?
preparedStatement.executeUpdate() : -1;
synchronized (callback.getMonitor()) {
callback.clear();
callback.assign(signature, null, updateCount);
}
callback.execute();
final MetaResultSet metaResultSet =
MetaResultSet.create(handle.connectionId, handle.id, false, signature, null);
```
* Updated code (ArrowFlightMetaImpl.java, line 196):
```java
PreparedStatement preparedStatement = prepareForHandle(query, handle);
final StatementType statementType = preparedStatement.getType();
final long updateCount = statementType.equals(StatementType.UPDATE) ?
preparedStatement.executeUpdate() : -1;
synchronized (callback.getMonitor()) {
callback.clear();
callback.assign(handle.signature, null, updateCount);
}
callback.execute();
final MetaResultSet metaResultSet =
MetaResultSet.create(handle.connectionId, handle.id, false, handle.signature,
null); // Mutable
```
The addition is needed for parameter binding, yet it introduces an issue
where columns are appended repeatedly. During execution, the
`executeFlightInfoQuery` function in `ArrowFlightStatement.java` (in
flight-sql-jdbc-core) is invoked, which appends columns.
```java
@Override
public FlightInfo executeFlightInfoQuery() throws SQLException {
final PreparedStatement preparedStatement =
getConnection().getMeta().getPreparedStatement(handle);
final Meta.Signature signature = getSignature();
if (signature == null) {
return null;
}
final Schema resultSetSchema = preparedStatement.getDataSetSchema();
signature.columns.addAll(ConvertUtils.convertArrowFieldsToColumnMetaDataList(resultSetSchema.getFields()));
setSignature(signature);
return preparedStatement.executeQuery();
}
```
With every query, the signature column set is duplicated and propagated. In
cases where the result has endpoints (e.g., a typical `doPut` operation in
`FlightSqlClient`), the column list seems consistent as the signature is
replaced with the result signature. However, in my case, where there are no
endpoints, the columns appear duplicated.
To address this, I temporarily fixed the issue by simply calling clear on
the column list before adding new columns.
```java
@Override
public FlightInfo executeFlightInfoQuery() throws SQLException {
final PreparedStatement preparedStatement =
getConnection().getMeta().getPreparedStatement(handle);
final Meta.Signature signature = getSignature();
if (signature == null) {
return null;
}
final Schema resultSetSchema = preparedStatement.getDataSetSchema();
signature.columns.clear();
signature.columns.addAll(ConvertUtils.convertArrowFieldsToColumnMetaDataList(resultSetSchema.getFields()));
setSignature(signature);
return preparedStatement.executeQuery();
}
```
However, I believe a more fundamental solution could be beneficial here.
Could anyone provide insights or assistance?
Thank you.
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