bkietz commented on code in PR #37418:
URL: https://github.com/apache/arrow/pull/37418#discussion_r1352285524
##########
cpp/src/arrow/array/array_dict.cc:
##########
@@ -211,6 +212,105 @@ Result<std::shared_ptr<ArrayData>> TransposeDictIndices(
return out_data;
}
+struct CompactTransposeMapVistor {
+ const std::shared_ptr<ArrayData>& data;
+ arrow::MemoryPool* pool;
+ std::unique_ptr<Buffer> output_map;
+ std::shared_ptr<Array> out_compact_dictionary;
+
+ template <typename IndexArrowType>
+ Status CompactTransposeMapImpl() {
+ int64_t index_length = data->length;
+ int64_t dict_length = data->dictionary->length;
+ if (dict_length == 0) {
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ } else if (index_length == 0) {
+ ARROW_ASSIGN_OR_RAISE(out_compact_dictionary,
+ MakeEmptyArray(data->dictionary->type, pool));
+ ARROW_ASSIGN_OR_RAISE(output_map, AllocateBuffer(0, pool))
+ return Status::OK();
+ }
+
+ using CType = typename IndexArrowType::c_type;
+ const CType* indices_data = data->GetValues<CType>(1);
+ std::vector<bool> dict_used(dict_length, false);
+ CType dict_len = static_cast<CType>(dict_length);
+ int64_t dict_used_count = 0;
+ for (int64_t i = 0; i < index_length; i++) {
+ if (data->IsNull(i)) {
+ continue;
+ }
+
+ CType current_index = indices_data[i];
+ if (current_index < 0 || current_index >= dict_len) {
+ return Status::IndexError(
+ "Index out of bounds while compacting dictionary array: ",
current_index,
+ "(dictionary is ", dict_length, " long) at position ", i);
+ } else if (!dict_used[current_index]) {
+ dict_used[current_index] = true;
+ dict_used_count++;
+
+ if (dict_used_count == dict_length) {
+ // The dictionary is already compact, so just return here
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ }
+ }
+ }
+
+ using BuilderType = NumericBuilder<IndexArrowType>;
+ using arrow::compute::Take;
+ using arrow::compute::TakeOptions;
+ BuilderType dict_indices_builder(pool);
+ ARROW_ASSIGN_OR_RAISE(output_map,
+ AllocateBuffer(dict_length * sizeof(int32_t), pool));
+ int32_t* output_map_raw =
reinterpret_cast<int32_t*>(output_map->mutable_data());
Review Comment:
```suggestion
auto* output_map_raw = output_map->mutable_data_as<int32_t>();
```
##########
cpp/src/arrow/compute/kernels/vector_dictionary.cc:
##########
@@ -0,0 +1,213 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "arrow/array/array_base.h"
+#include "arrow/array/array_dict.h"
+#include "arrow/array/builder_primitive.h"
+#include "arrow/array/dict_internal.h"
+#include "arrow/compute/api_vector.h"
+#include "arrow/compute/kernels/common_internal.h"
+#include "arrow/result.h"
+
+namespace arrow {
+
+namespace compute {
+namespace internal {
+
+namespace {
+
+// Dictionary compaction implementation
+
+const FunctionDoc dictionary_compact_doc{
Review Comment:
The compute function should be removed
##########
cpp/src/arrow/array/array_dict.cc:
##########
@@ -211,6 +212,105 @@ Result<std::shared_ptr<ArrayData>> TransposeDictIndices(
return out_data;
}
+struct CompactTransposeMapVistor {
+ const std::shared_ptr<ArrayData>& data;
+ arrow::MemoryPool* pool;
+ std::unique_ptr<Buffer> output_map;
+ std::shared_ptr<Array> out_compact_dictionary;
+
+ template <typename IndexArrowType>
+ Status CompactTransposeMapImpl() {
+ int64_t index_length = data->length;
+ int64_t dict_length = data->dictionary->length;
+ if (dict_length == 0) {
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ } else if (index_length == 0) {
+ ARROW_ASSIGN_OR_RAISE(out_compact_dictionary,
+ MakeEmptyArray(data->dictionary->type, pool));
+ ARROW_ASSIGN_OR_RAISE(output_map, AllocateBuffer(0, pool))
+ return Status::OK();
+ }
+
+ using CType = typename IndexArrowType::c_type;
+ const CType* indices_data = data->GetValues<CType>(1);
+ std::vector<bool> dict_used(dict_length, false);
+ CType dict_len = static_cast<CType>(dict_length);
+ int64_t dict_used_count = 0;
+ for (int64_t i = 0; i < index_length; i++) {
+ if (data->IsNull(i)) {
+ continue;
+ }
+
+ CType current_index = indices_data[i];
+ if (current_index < 0 || current_index >= dict_len) {
+ return Status::IndexError(
+ "Index out of bounds while compacting dictionary array: ",
current_index,
+ "(dictionary is ", dict_length, " long) at position ", i);
+ } else if (!dict_used[current_index]) {
Review Comment:
```suggestion
}
if (dict_used[current_index]) continue;
```
##########
cpp/src/arrow/array/array_dict.cc:
##########
@@ -211,6 +212,105 @@ Result<std::shared_ptr<ArrayData>> TransposeDictIndices(
return out_data;
}
+struct CompactTransposeMapVistor {
+ const std::shared_ptr<ArrayData>& data;
+ arrow::MemoryPool* pool;
+ std::unique_ptr<Buffer> output_map;
+ std::shared_ptr<Array> out_compact_dictionary;
+
+ template <typename IndexArrowType>
+ Status CompactTransposeMapImpl() {
+ int64_t index_length = data->length;
+ int64_t dict_length = data->dictionary->length;
+ if (dict_length == 0) {
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ } else if (index_length == 0) {
+ ARROW_ASSIGN_OR_RAISE(out_compact_dictionary,
+ MakeEmptyArray(data->dictionary->type, pool));
+ ARROW_ASSIGN_OR_RAISE(output_map, AllocateBuffer(0, pool))
+ return Status::OK();
+ }
+
+ using CType = typename IndexArrowType::c_type;
+ const CType* indices_data = data->GetValues<CType>(1);
+ std::vector<bool> dict_used(dict_length, false);
+ CType dict_len = static_cast<CType>(dict_length);
+ int64_t dict_used_count = 0;
+ for (int64_t i = 0; i < index_length; i++) {
+ if (data->IsNull(i)) {
+ continue;
+ }
+
+ CType current_index = indices_data[i];
+ if (current_index < 0 || current_index >= dict_len) {
+ return Status::IndexError(
+ "Index out of bounds while compacting dictionary array: ",
current_index,
+ "(dictionary is ", dict_length, " long) at position ", i);
+ } else if (!dict_used[current_index]) {
+ dict_used[current_index] = true;
+ dict_used_count++;
+
+ if (dict_used_count == dict_length) {
Review Comment:
Checking here enables skipping the rest of the dictionary, which is good.
However I think it'd also be useful to detect usage of only a slice of the
dictionary. If you'd prefer not to handle that in this PR, please write a
follow up issue
##########
cpp/src/arrow/array/array_dict.cc:
##########
@@ -211,6 +212,105 @@ Result<std::shared_ptr<ArrayData>> TransposeDictIndices(
return out_data;
}
+struct CompactTransposeMapVistor {
+ const std::shared_ptr<ArrayData>& data;
+ arrow::MemoryPool* pool;
+ std::unique_ptr<Buffer> output_map;
+ std::shared_ptr<Array> out_compact_dictionary;
+
+ template <typename IndexArrowType>
+ Status CompactTransposeMapImpl() {
+ int64_t index_length = data->length;
+ int64_t dict_length = data->dictionary->length;
+ if (dict_length == 0) {
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ } else if (index_length == 0) {
+ ARROW_ASSIGN_OR_RAISE(out_compact_dictionary,
+ MakeEmptyArray(data->dictionary->type, pool));
+ ARROW_ASSIGN_OR_RAISE(output_map, AllocateBuffer(0, pool))
+ return Status::OK();
+ }
+
+ using CType = typename IndexArrowType::c_type;
+ const CType* indices_data = data->GetValues<CType>(1);
+ std::vector<bool> dict_used(dict_length, false);
+ CType dict_len = static_cast<CType>(dict_length);
+ int64_t dict_used_count = 0;
+ for (int64_t i = 0; i < index_length; i++) {
+ if (data->IsNull(i)) {
+ continue;
+ }
+
+ CType current_index = indices_data[i];
+ if (current_index < 0 || current_index >= dict_len) {
+ return Status::IndexError(
+ "Index out of bounds while compacting dictionary array: ",
current_index,
+ "(dictionary is ", dict_length, " long) at position ", i);
+ } else if (!dict_used[current_index]) {
+ dict_used[current_index] = true;
+ dict_used_count++;
+
+ if (dict_used_count == dict_length) {
+ // The dictionary is already compact, so just return here
+ output_map = nullptr;
+ out_compact_dictionary = nullptr;
+ return Status::OK();
+ }
+ }
+ }
+
+ using BuilderType = NumericBuilder<IndexArrowType>;
+ using arrow::compute::Take;
+ using arrow::compute::TakeOptions;
+ BuilderType dict_indices_builder(pool);
+ ARROW_ASSIGN_OR_RAISE(output_map,
+ AllocateBuffer(dict_length * sizeof(int32_t), pool));
+ int32_t* output_map_raw =
reinterpret_cast<int32_t*>(output_map->mutable_data());
+ int32_t current_index = 0;
+ for (CType i = 0; i < dict_len; i++) {
+ if (dict_used[i]) {
+ ARROW_RETURN_NOT_OK(dict_indices_builder.Append(i));
Review Comment:
Since we know the number of indices ahead of time, please presize the
Builder and use unsafeappend
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