Add Java table functions support

CMakeLists.txt

@@ -592,8 +592,12 @@ add_library(duckdb_java SHARED
   src/jni/bindings_data_chunk.cpp
   src/jni/bindings_logical_type.cpp
   src/jni/bindings_scalar_function.cpp
+  src/jni/bindings_table_function.cpp
+  src/jni/bindings_table_function_bind.cpp
+  src/jni/bindings_table_function_init.cpp
   src/jni/bindings_validity.cpp
   src/jni/bindings_vector.cpp
+  src/jni/bindings_value.cpp
   src/jni/config.cpp
   src/jni/duckdb_java.cpp
   src/jni/functions.cpp

CMakeLists.txt.in

@@ -110,8 +110,12 @@ add_library(duckdb_java SHARED
   src/jni/bindings_data_chunk.cpp
   src/jni/bindings_logical_type.cpp
   src/jni/bindings_scalar_function.cpp
+  src/jni/bindings_table_function.cpp
+  src/jni/bindings_table_function_bind.cpp
+  src/jni/bindings_table_function_init.cpp
   src/jni/bindings_validity.cpp
   src/jni/bindings_vector.cpp
+  src/jni/bindings_value.cpp
   src/jni/config.cpp
   src/jni/duckdb_java.cpp
   src/jni/functions.cpp

UDF.MD

@@ -87,8 +87,9 @@ Common class mappings include:
 
 Notes:
 
-- `UHUGEINT` is supported through explicit `DuckDBColumnType.UHUGEINT`/`DuckDBLogicalType` declarations.
-- Java class auto-mapping for `BigInteger` remains `HUGEINT`.
+- `UHUGEINT` is supported through explicit `DuckDBColumnType.UHUGEINT`/`DuckDBLogicalType` declarations
+- Java class auto-mapping for `BigInteger` remains `HUGEINT`
+- composite types like `STRUCT` or `LIST` are currently not supported, this intended to be added in future versions
 
 Use `DuckDBLogicalType.decimal(width, scale)` for explicit DECIMAL precision/scale.
 
@@ -153,9 +154,6 @@ This registry provides bookkeeping for functions registered through the JDBC API
 
 - `name()`
 - `functionKind()`
-- `isScalar()`
-- parameter and return type metadata
-- callback and flags used at registration time
 
 To inspect Java-side registrations:
 
@@ -207,3 +205,68 @@ try (Connection conn = DriverManager.getConnection("jdbc:duckdb:"); Statement st
 ```sql
 SELECT java_event_label(TIMESTAMP '2026-04-04 12:00:00', 'launch', 4.5);
 ```
+
+## Table functions (`DuckDBTableFunction`)
+
+Similar to scalar functions, a table function can be registered using `DuckDBFunctions.tableFunction()`.
+
+Table function callback must implement `DuckDBTableFunction` interface:
+
+ - `bind` - called during `PREPARE` stage, must register output columns; has access to input parameters using `.getParameter()` and `.getNamedParameter()`; can return a "bind data" object
+  that can be used during function execution
+ - `init` - called once before the function execution, has access to bind data, returns an object used to track the state during function execution
+ - `localInit` (optional) - called once for every thread before the function execution, returns an object used to track thread-local state during function execution
+ - `apply` - has access to bind data, global init data and local init date, writes results into output vectors, returns a number of written row, is called by the engine repeatedly until it return zero rows
+
+All callback arguments (including parameter objects) are only valid during the callback execution.
+
+In general, Java table functions interface exposes the [C API table function interface](https://github.com/duckdb/duckdb-java/blob/2f4ed44df2fd1f89594cc7af28f9f8daba5fa582/src/duckdb/src/include/duckdb.h#L4145-L4478)
+as close as possible.
+
+Example:
+
+```java
+try (Connection conn = DriverManager.getConnection("jdbc:duckdb:"); Statement stmt = conn.createStatement()) {
+    DuckDBFunctions.tableFunction()
+        .withName("java_table_basic")
+        .withParameter(int.class)
+        .withNamedParameter("param1", String.class)
+        .withFunction(new DuckDBTableFunction<Integer, AtomicBoolean, Object>() {
+            @Override
+            public Integer bind(DuckDBTableFunctionBindInfo info) throws Exception {
+                info.addResultColumn("col1", Integer.TYPE).addResultColumn("col2", String.class);
+                DuckDBValue param = info.getParameter(0);
+                assertThrows(param::getBoolean, FunctionException.class);
+                DuckDBValue namedParam = info.getNamedParameter("param1");
+                assertEquals(namedParam.getString(), "foobar");
+                return param.getInt();
+            }
+
+            @Override
+            public AtomicBoolean init(DuckDBTableFunctionInitInfo info) throws Exception {
+                return new AtomicBoolean(false);
+            }
+
+            @Override
+            public long apply(DuckDBTableFunctionCallInfo info, DuckDBDataChunkWriter output) throws Exception {
+                Integer bindData = info.getBindData();
+                AtomicBoolean done = info.getInitData();
+                if (done.get()) {
+                    return 0;
+                }
+                output.vector(0).setInt(0, bindData);
+                output.vector(1).setString(0, "foo");
+                output.vector(0).setNull(1);
+                output.vector(1).setString(1, "bar");
+                done.set(true);
+                return 2;
+            }
+        })
+        .register(conn);
+...
+}
+```
+```sql
+FROM java_table_basic(42, param1='foobar')
+```
+

duckdb_java.def

@@ -114,6 +114,67 @@ Java_org_duckdb_DuckDBBindings_duckdb_1appender_1column_1type
 Java_org_duckdb_DuckDBBindings_duckdb_1append_1data_1chunk
 Java_org_duckdb_DuckDBBindings_duckdb_1append_1default_1to_1chunk
 
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1add_1result_1column
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter_1count
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1named_1parameter
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1bind_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1cardinality
+Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1error
+
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1bind_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1init_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1count
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1index
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1max_1threads
+Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1error
+
+Java_org_duckdb_DuckDBBindings_duckdb_1create_1table_1function
+Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1table_1function
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1name
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1parameter
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1named_1parameter
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1extra_1info
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1bind
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1init
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1local_1init
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1function
+Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1supports_1projection_1pushdown
+Java_org_duckdb_DuckDBBindings_duckdb_1register_1table_1function
+Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1bind_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1init_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1local_1init_1data
+Java_org_duckdb_DuckDBBindings_duckdb_1function_1set_1error
+
+Java_org_duckdb_DuckDBBindings_duckdb_1is_1null_1value
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1value_1type
+Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1value
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1bool
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1int8
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint8
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1int16
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint16
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1int32
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint32
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1int64
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint64
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1hugeint
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1uhugeint
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1bignum
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1decimal
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1float
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1double
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1date
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1time
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1ns
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1tz
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1tz
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1s
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ms
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ns
+Java_org_duckdb_DuckDBBindings_duckdb_1get_1varchar
+
 duckdb_adbc_init
 duckdb_add_aggregate_function_to_set
 duckdb_add_replacement_scan

duckdb_java.exp

@@ -111,6 +111,67 @@ _Java_org_duckdb_DuckDBBindings_duckdb_1appender_1column_1type
 _Java_org_duckdb_DuckDBBindings_duckdb_1append_1data_1chunk
 _Java_org_duckdb_DuckDBBindings_duckdb_1append_1default_1to_1chunk
 
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1add_1result_1column
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter_1count
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1named_1parameter
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1bind_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1cardinality
+_Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1error
+
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1bind_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1init_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1count
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1index
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1max_1threads
+_Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1error
+
+_Java_org_duckdb_DuckDBBindings_duckdb_1create_1table_1function
+_Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1table_1function
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1name
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1parameter
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1named_1parameter
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1extra_1info
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1bind
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1init
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1local_1init
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1function
+_Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1supports_1projection_1pushdown
+_Java_org_duckdb_DuckDBBindings_duckdb_1register_1table_1function
+_Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1bind_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1init_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1local_1init_1data
+_Java_org_duckdb_DuckDBBindings_duckdb_1function_1set_1error
+
+_Java_org_duckdb_DuckDBBindings_duckdb_1is_1null_1value
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1value_1type
+_Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1value
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1bool
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1int8
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint8
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1int16
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint16
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1int32
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint32
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1int64
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint64
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1hugeint
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1uhugeint
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1bignum
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1decimal
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1float
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1double
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1date
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1time
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1ns
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1tz
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1tz
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1s
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ms
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ns
+_Java_org_duckdb_DuckDBBindings_duckdb_1get_1varchar
+
 _duckdb_adbc_init
 _duckdb_add_aggregate_function_to_set
 _duckdb_add_replacement_scan

duckdb_java.map

@@ -113,6 +113,67 @@ DUCKDB_JAVA {
     Java_org_duckdb_DuckDBBindings_duckdb_1append_1data_1chunk;
     Java_org_duckdb_DuckDBBindings_duckdb_1append_1default_1to_1chunk;
 
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1add_1result_1column;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter_1count;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1parameter;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1get_1named_1parameter;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1bind_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1cardinality;
+    Java_org_duckdb_DuckDBBindings_duckdb_1bind_1set_1error;
+
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1bind_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1init_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1count;
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1get_1column_1index;
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1max_1threads;
+    Java_org_duckdb_DuckDBBindings_duckdb_1init_1set_1error;
+
+    Java_org_duckdb_DuckDBBindings_duckdb_1create_1table_1function;
+    Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1table_1function;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1name;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1parameter;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1add_1named_1parameter;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1extra_1info;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1bind;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1init;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1local_1init;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1set_1function;
+    Java_org_duckdb_DuckDBBindings_duckdb_1table_1function_1supports_1projection_1pushdown;
+    Java_org_duckdb_DuckDBBindings_duckdb_1register_1table_1function;
+    Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1bind_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1init_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1function_1get_1local_1init_1data;
+    Java_org_duckdb_DuckDBBindings_duckdb_1function_1set_1error;
+
+    Java_org_duckdb_DuckDBBindings_duckdb_1is_1null_1value;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1value_1type;
+    Java_org_duckdb_DuckDBBindings_duckdb_1destroy_1value;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1bool;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1int8;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint8;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1int16;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint16;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1int32;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint32;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1int64;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1uint64;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1hugeint;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1uhugeint;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1bignum;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1decimal;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1float;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1double;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1date;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1time;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1ns;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1time_1tz;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1tz;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1s;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ms;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1timestamp_1ns;
+    Java_org_duckdb_DuckDBBindings_duckdb_1get_1varchar;
+
     duckdb_adbc_init;
     duckdb_add_aggregate_function_to_set;
     duckdb_add_replacement_scan;