diff --git a/java/src/main/java/ai/rapids/cudf/ArrowIPCWriterOptions.java b/java/src/main/java/ai/rapids/cudf/ArrowIPCWriterOptions.java
index 04abdb71910..ee5ae094b29 100644
--- a/java/src/main/java/ai/rapids/cudf/ArrowIPCWriterOptions.java
+++ b/java/src/main/java/ai/rapids/cudf/ArrowIPCWriterOptions.java
@@ -70,24 +70,24 @@ public Builder withCallback(DoneOnGpu callback) {
/**
* Add the name(s) for nullable column(s).
*
- * Column names should be flattened for the columns of nested type. For examples,
+ * Please note the column names of the nested struct columns should be flattened in sequence.
+ * For examples,
*
- * a struct column:
- * ("struct_col": {"field_1", "field_2"}),
+ * A table with an int column and a struct column:
+ * ["int_col", "struct_col":{"field_1", "field_2"}]
* output:
- * ["struct_col", "field_1", "field_2"]
+ * ["int_col", "struct_col", "field_1", "field_2"]
*
- * a list column:
- * ("list_col": [])
+ * A table with an int column and a list of non-nested type column:
+ * ["int_col", "list_col":[]]
* output:
- * ("list_col", "list_child")
+ * ["int_col", "list_col"]
*
- * a list of struct column:
- * ("list_struct_col": [{"field_1", "field_2"}])
+ * A table with an int column and a list of struct column:
+ * ["int_col", "list_struct_col":[{"field_1", "field_2"}]]
* output:
- * ["list_struct_col", "list_struct_child", "field_1", "field_2"]
+ * ["int_col", "list_struct_col", "field_1", "field_2"]
*
- * Even the child of list column has no name by default, it should be assigned a name.
*
* @param columnNames The column names corresponding to the written table(s).
*/
@@ -99,25 +99,24 @@ public Builder withColumnNames(String... columnNames) {
/**
* Add the name(s) for non-nullable column(s).
*
- * Column names should be flattened in sequence for the columns of nested type to make
- * sure each column (including children columns) has a name. For examples,
+ * Please note the column names of the nested struct columns should be flattened in sequence.
+ * For examples,
*
- * a struct column:
- * ("struct_col": {"field_1", "field_2"})
+ * A table with an int column and a struct column:
+ * ["int_col", "struct_col":{"field_1", "field_2"}]
* output:
- * ["struct_col", "field_1", "field_2"]
+ * ["int_col", "struct_col", "field_1", "field_2"]
*
- * a list column:
- * ("list_col": [])
+ * A table with an int column and a list of non-nested type column:
+ * ["int_col", "list_col":[]]
* output:
- * ("list_col", "list_child")
+ * ["int_col", "list_col"]
*
- * a list of struct column:
- * ("list_struct_col": [{"field_1", "field_2"}])
+ * A table with an int column and a list of struct column:
+ * ["int_col", "list_struct_col":[{"field_1", "field_2"}]]
* output:
- * ["list_struct_col", "list_struct_child", "field_1", "field_2"]
+ * ["int_col", "list_struct_col", "field_1", "field_2"]
*
- * Even the child of list column has no name by default, it should be assigned a name as well.
*
* @param columnNames The column names corresponding to the written table(s).
*/
diff --git a/java/src/main/native/src/TableJni.cpp b/java/src/main/native/src/TableJni.cpp
index 744bcfe47c6..85fbe3cf4bc 100644
--- a/java/src/main/native/src/TableJni.cpp
+++ b/java/src/main/native/src/TableJni.cpp
@@ -249,7 +249,7 @@ class native_arrow_ipc_writer_handle final {
initialized = false;
}
- std::vector get_column_metadata(const table_view& tview) {
+ std::vector get_column_metadata(const cudf::table_view& tview) {
if (!column_names.empty() && columns_meta.empty()) {
// Rebuild the structure of column meta according to table schema.
// All the tables written by this writer should share the same schema,
@@ -257,8 +257,10 @@ class native_arrow_ipc_writer_handle final {
columns_meta.reserve(tview.num_columns());
size_t idx = 0;
for (auto itr = tview.begin(); itr < tview.end(); ++itr) {
+ // It should consume the column names only when a column is
+ // - type of struct, or
+ // - not a child.
columns_meta.push_back(build_one_column_meta(*itr, idx));
- idx ++;
}
if (idx < column_names.size()) {
throw cudf::jni::jni_exception(
@@ -269,16 +271,23 @@ class native_arrow_ipc_writer_handle final {
}
private:
- cudf::column_metadata build_one_column_meta(const column_view& cview, size_t& idx) {
- auto col_meta = cudf::column_metadata{get_column_name(idx)};
+ cudf::column_metadata build_one_column_meta(const cudf::column_view& cview, size_t& idx,
+ const bool consume_name = true) {
+ auto col_meta = cudf::column_metadata{};
+ if (consume_name) {
+ col_meta.name = get_column_name(idx++);
+ }
+ // Process children
if (cview.type().id() == cudf::type_id::LIST) {
- // list type requires a stub metadata for offset column, index is 0.
- col_meta.children_meta = {{}, build_one_column_meta(cview.child(1), ++idx)};
+ // list type:
+ // - requires a stub metadata for offset column(index: 0).
+ // - does not require a name for the child column(index 1).
+ col_meta.children_meta = {{}, build_one_column_meta(cview.child(1), idx, false)};
} else if (cview.type().id() == cudf::type_id::STRUCT) {
- // struct type
+ // struct type always consumes the column names.
col_meta.children_meta.reserve(cview.num_children());
for (auto itr = cview.child_begin(); itr < cview.child_end(); ++itr) {
- col_meta.children_meta.push_back(build_one_column_meta(*itr, ++idx));
+ col_meta.children_meta.push_back(build_one_column_meta(*itr, idx));
}
} else if (cview.type().id() == cudf::type_id::DICTIONARY32) {
// not supported yet in JNI, nested type?
@@ -289,7 +298,7 @@ class native_arrow_ipc_writer_handle final {
std::string& get_column_name(const size_t idx) {
if (idx < 0 || idx >= column_names.size()) {
- throw cudf::jni::jni_exception("Missing names for columns or nested columns");
+ throw cudf::jni::jni_exception("Missing names for columns or nested struct columns");
}
return column_names[idx];
}
diff --git a/java/src/test/java/ai/rapids/cudf/TableTest.java b/java/src/test/java/ai/rapids/cudf/TableTest.java
index 23b87b4e124..625260b255f 100644
--- a/java/src/test/java/ai/rapids/cudf/TableTest.java
+++ b/java/src/test/java/ai/rapids/cudf/TableTest.java
@@ -4300,8 +4300,8 @@ void testArrowIPCWriteToBufferChunked() {
ArrowIPCWriterOptions options = ArrowIPCWriterOptions.builder()
.withColumnNames("first", "second", "third", "fourth", "fifth", "sixth", "seventh")
.withColumnNames("eighth", "eighth_id", "eighth_name")
- .withColumnNames("ninth", "ninth_child")
- .withColumnNames("tenth", "tenth_child", "child_id", "child_name")
+ .withColumnNames("ninth")
+ .withColumnNames("tenth", "child_id", "child_name")
.build();
try (TableWriter writer = Table.writeArrowIPCChunked(options, consumer)) {
writer.write(table0);