Failing to insert binary stream into a BLOB in hsqldb? - hsqldb

Question

I have the following hsqldb schema (as reported by SQLWorkbench):
DROP TABLE TEST CASCADE;
CREATE TABLE TEST
(
NAME VARCHAR(256),
METADATA VARCHAR(2048),
DATA BLOB
);
GRANT TRIGGER, INSERT, REFERENCES, DELETE, SELECT, UPDATE ON TEST TO DBA;
Next, I am trying to insert a file into the DATA field using the following prepared statement:
MERGE INTO test USING (VALUES ?, ?, ?) I (name, metadata, data) ON (test.name=I.name) WHEN MATCHED THEN UPDATE SET test.data = I.data, test.metadata = I.metadata WHEN NOT MATCHED THEN INSERT (name, metadata, data) VALUES (I.name, I.metadata, I.data)
Here is the code:
String name = ...;
String metadata = ...;
InputStream data = ...;
JDBCDataSource ds = new JDBCDataSource();
ds.setDatabase("jdbc:hsqldb:file:c:/tmp/file.db");
ds.setUser("sa");
ds.setPassword("");
PreparedStatement set = ds.getConnection().prepareStatement(m_setSql);
set.setString(1, name);
set.setString(2, metadata);
set.setBinaryStream(3, data);
set.executeUpdate();
The setBinaryStream fails, because the parameter type is deemed to be VARCHAR, rather than BLOB. Indeed, the function org.hsqldb.jdbc.JDBCPreparedStatement.setBinStream has the following statement:
if (parameterTypes[parameterIndex - 1].typeCode == Types.SQL_BLOB) {
setBlobParameter(parameterIndex, x, length);
return;
}
For the parameterIndex 3 it should enter the if-statement and invoke the setBlobParameter. But, for some reason, typeCode returns 12, which corresponds to VARCHAR, the if-statement is skipped and in the end an org.hsqldb.HsqlException is raised with the message of incompatible data type in conversion.
What am I doing wrong?

Answer 1

The types of the parameter values in the MERGE statement are unknown and default to VARCHAR. You need to cast the BLOB parameter to BLOB.
MERGE INTO test USING (VALUES ?, ?, CAST(? AS BLOB)) I (name, metadata, data)
ON (test.name=I.name)
WHEN MATCHED THEN UPDATE SET test.data = I.data, test.metadata = I.metadata
WHEN NOT MATCHED THEN INSERT (name, metadata, data) VALUES (I.name, I.metadata, I.data)