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- Handle Results 11228
- Overview Beyond the standard JDBC ResultSet , the DuckDB driver can hand results to Apache Arrow , stream large results instead of materializing them, and expose raw columnar data chunks. This page covers each of these result-handling optio
...to Java and avoids the per-row overhead required by the JDBC ResultSet interface. Chunk contents are read through the same DuckDBDataChunkReader API that is used by user-defined functions . Call query() on a DuckDBPreparedStatement to obtain a DuckDBChunkedResult , t...ckdb.DuckDBConnection; import org.duckdb.DuckDBPreparedStatement; import org.duckdb.DuckDBChunkedResult; import org.duckdb.DuckDBDataChunkReader; import org.duckdb.DuckDBReadableVector; try (DuckDBConnection conn = DriverManager .getConnection("jdbc:duckdb:") .unwrap...{ // advance to the next chunk, returns true on success while (res.nextChunk()) { // get the current chunk from the result DuckDBDataChunkReader chunk = res.chunk(); // iterate over the chunk columns, all indices are 0-based for (long col = 0; col < chunk.columnCount... - https://man.mtool.work/duckdb/2.0/clients/java/result_handling.html
- Write User Defined Functions 7485
- Overview The JDBC driver can register user-defined functions (UDFs) written in Java, including scalar functions and table functions. This page covers building and registering both, from the simple functional-interface overloads to the vecto
...atch of rows at once, register a DuckDBScalarFunction with withVectorizedFunction() . The callback receives the input as a DuckDBDataChunkReader (up to 2,048 rows) and writes results into a DuckDBWritableVector . Read each input column with input.vector(columnIndex)...String(row, value); }); }) .register(conn); } SELECT java_event_label(TIMESTAMP '2026-04-04 12:00:00', 'launch', 4.5); The DuckDBDataChunkReader , its DuckDBReadableVector columns, and the DuckDBWritableVector are valid only during callback execution and must not be...a_table_basic(42, param1 = 'foobar'); Rows are written through a DuckDBDataChunkWriter , the write-side counterpart to the DuckDBDataChunkReader used for reading results. Each output vector is addressed by column index, and values are set by row index with methods su... - https://man.mtool.work/duckdb/2.0/clients/java/functions.html
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DuckDB 2.0 Documentation / man.mtool.work