be/src/format_v2/column_mapper_nested.cpp

Source
// 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 "format_v2/column_mapper_nested.h"

#include <algorithm>
#include <cstdint>
#include <memory>
#include <optional>
#include <utility>

#include "common/cast_set.h"
#include "common/exception.h"
#include "core/assert_cast.h"
#include "core/data_type/data_type_nullable.h"
#include "core/data_type/data_type_struct.h"
#include "core/data_type/primitive_type.h"
#include "exprs/vexpr.h"
#include "format_v2/expr/cast.h"
#include "gen_cpp/Exprs_types.h"

namespace doris::format {

namespace {

static bool is_cast_expr(const VExprSPtr& expr) {
    return dynamic_cast<const Cast*>(expr.get()) != nullptr;
}

static bool is_signed_integer_type(PrimitiveType type) {
    switch (type) {
    case TYPE_TINYINT:
    case TYPE_SMALLINT:
    case TYPE_INT:
    case TYPE_BIGINT:
    case TYPE_LARGEINT:
        return true;
    default:
        return false;
    }
}

static int primitive_integer_width(PrimitiveType type) {
    switch (type) {
    case TYPE_TINYINT:
        return 1;
    case TYPE_SMALLINT:
        return 2;
    case TYPE_INT:
        return 4;
    case TYPE_BIGINT:
        return 8;
    case TYPE_LARGEINT:
        return 16;
    default:
        return 0;
    }
}

static bool is_decimal_type(PrimitiveType type) {
    switch (type) {
    case TYPE_DECIMAL32:
    case TYPE_DECIMAL64:
    case TYPE_DECIMALV2:
    case TYPE_DECIMAL128I:
    case TYPE_DECIMAL256:
        return true;
    default:
        return false;
    }
}

static bool is_order_preserving_safe_cast(const DataTypePtr& from_type,
                                          const DataTypePtr& to_type) {
    if (from_type == nullptr || to_type == nullptr) {
        return false;
    }
    const auto from_nested_type = remove_nullable(from_type);
    const auto to_nested_type = remove_nullable(to_type);
    if (from_nested_type->equals(*to_nested_type)) {
        return true;
    }

    const auto from_primitive_type = from_nested_type->get_primitive_type();
    const auto to_primitive_type = to_nested_type->get_primitive_type();
    if (is_signed_integer_type(from_primitive_type) && is_signed_integer_type(to_primitive_type)) {
        return primitive_integer_width(to_primitive_type) >=
               primitive_integer_width(from_primitive_type);
    }
    if (from_primitive_type == TYPE_FLOAT && to_primitive_type == TYPE_DOUBLE) {
        return true;
    }
    if (is_decimal_type(from_primitive_type) && is_decimal_type(to_primitive_type)) {
        return from_nested_type->get_scale() == to_nested_type->get_scale() &&
               to_nested_type->get_precision() >= from_nested_type->get_precision();
    }
    return false;
}

static bool parse_struct_child_selector(const VExprSPtr& expr, StructChildSelector* selector) {
    DORIS_CHECK(selector != nullptr);
    if (expr == nullptr || !expr->is_literal()) {
        return false;
    }
    const Field field = literal_field(expr);
    switch (field.get_type()) {
    case TYPE_STRING:
    case TYPE_CHAR:
    case TYPE_VARCHAR:
        selector->by_name = true;
        selector->name = std::string(field.as_string_view());
        return true;
    case TYPE_BOOLEAN:
        selector->by_name = false;
        selector->ordinal = field.get<TYPE_BOOLEAN>() ? 1 : 0;
        return selector->ordinal > 0;
    case TYPE_TINYINT:
        selector->by_name = false;
        if (field.get<TYPE_TINYINT>() <= 0) {
            return false;
        }
        selector->ordinal = cast_set<size_t>(field.get<TYPE_TINYINT>());
        return true;
    case TYPE_SMALLINT:
        selector->by_name = false;
        if (field.get<TYPE_SMALLINT>() <= 0) {
            return false;
        }
        selector->ordinal = cast_set<size_t>(field.get<TYPE_SMALLINT>());
        return true;
    case TYPE_INT:
        selector->by_name = false;
        if (field.get<TYPE_INT>() <= 0) {
            return false;
        }
        selector->ordinal = cast_set<size_t>(field.get<TYPE_INT>());
        return true;
    case TYPE_BIGINT:
        selector->by_name = false;
        if (field.get<TYPE_BIGINT>() <= 0) {
            return false;
        }
        selector->ordinal = cast_set<size_t>(field.get<TYPE_BIGINT>());
        return true;
    default:
        return false;
    }
}

static bool extract_nested_struct_path(const VExprSPtr& expr, NestedStructPath* path) {
    DORIS_CHECK(path != nullptr);
    if (!is_struct_element_expr(expr)) {
        return false;
    }

    // Process for element_at(struct, 'field') or element_at(struct, 1) expression.
    StructChildSelector selector;
    if (!parse_struct_child_selector(expr->children()[1], &selector)) {
        return false;
    }

    const auto& parent = expr->children()[0];
    if (parent->is_slot_ref()) {
        const auto* slot_ref = assert_cast<const VSlotRef*>(parent.get());
        path->root_global_index = slot_ref_global_index(*slot_ref);
        path->selectors.clear();
        path->selectors.push_back(std::move(selector));
        return true;
    }

    // Process for element_at(element_at(struct<struct>, 'field'), 'field') or
    // element_at(element_at(struct<struct>, 1), 1) expression.
    if (!extract_nested_struct_path(parent, path)) {
        return false;
    }
    path->selectors.push_back(std::move(selector));
    return true;
}

static bool extract_nested_struct_path_for_pruning(const VExprSPtr& expr, NestedStructPath* path) {
    DORIS_CHECK(path != nullptr);
    // Simple `ELEMENT_AT`
    if (extract_nested_struct_path(expr, path)) {
        return true;
    }

    // `ELEMENT_AT` with `CAST`
    if (!is_cast_expr(expr) || expr->get_num_children() != 1) {
        return false;
    }
    const auto& child = expr->children()[0];
    if (!is_order_preserving_safe_cast(child->data_type(), expr->data_type())) {
        return false;
    }
    // A safe widening cast is null-preserving and keeps the comparison ordering of the nested
    // primitive leaf, so file-layer pruning can target the original leaf statistics. The row-level
    // filter still evaluates the original cast expression after read.
    return extract_nested_struct_path_for_pruning(child, path);
}

static const ColumnDefinition* resolve_file_child(const std::vector<ColumnDefinition>& children,
                                                  const StructChildSelector& selector) {
    if (selector.by_name) {
        const auto child_it = std::ranges::find_if(children, [&](const ColumnDefinition& child) {
            return child.name == selector.name;
        });
        return child_it == children.end() ? nullptr : &*child_it;
    }
    if (selector.ordinal == 0 || selector.ordinal > children.size()) {
        return nullptr;
    }
    return &children[selector.ordinal - 1];
}

static const DataTypeStruct* struct_type_or_null(const DataTypePtr& type) {
    if (type == nullptr) {
        return nullptr;
    }
    const auto nested_type = remove_nullable(type);
    if (nested_type->get_primitive_type() != TYPE_STRUCT) {
        return nullptr;
    }
    return assert_cast<const DataTypeStruct*>(nested_type.get());
}

static std::optional<int32_t> struct_child_index(const ColumnMapping& mapping,
                                                 const StructChildSelector& selector) {
    const auto* struct_type = struct_type_or_null(mapping.table_type);
    if (struct_type == nullptr) {
        return std::nullopt;
    }
    if (selector.by_name) {
        const auto position = struct_type->try_get_position_by_name(selector.name);
        if (!position.has_value()) {
            return std::nullopt;
        }
        return cast_set<int32_t>(*position);
    }
    if (selector.ordinal == 0 || selector.ordinal > struct_type->get_elements().size()) {
        return std::nullopt;
    }
    return cast_set<int32_t>(selector.ordinal - 1);
}

// Get the global child index for a child mapping. If the mapping's table type is struct, resolve
// the child index by the child mapping's table column name; otherwise, use the fallback child index.
static int32_t child_mapping_global_index(const ColumnMapping& mapping,
                                          const ColumnMapping& child_mapping,
                                          size_t fallback_child_idx) {
    const auto* struct_type = struct_type_or_null(mapping.table_type);
    if (struct_type == nullptr) {
        return cast_set<int32_t>(fallback_child_idx);
    }
    const auto position = struct_type->try_get_position_by_name(child_mapping.table_column_name);
    DORIS_CHECK(position.has_value()) << "Cannot find child '" << child_mapping.table_column_name
                                      << "' in table type " << mapping.table_type->get_name();
    return cast_set<int32_t>(*position);
}

static const ColumnMapping* resolve_mapped_child(const ColumnMapping& mapping,
                                                 int32_t global_child_index) {
    for (size_t child_idx = 0; child_idx < mapping.child_mappings.size(); ++child_idx) {
        const auto& child_mapping = mapping.child_mappings[child_idx];
        if (child_mapping_global_index(mapping, child_mapping, child_idx) == global_child_index) {
            return &child_mapping;
        }
    }
    return nullptr;
}

enum class NestedProjectionResolveResult {
    RESOLVED,
    NOT_REPRESENTED,
    MISSING_FILE_CHILD,
};

// Resolve a table-side nested struct path through the existing ColumnMapping tree and build the
// corresponding file-local projection. For example, if table column `s` has children
// `{a, renamed_b}` and file column `s` has children `{a, b}`, the filter path
// `struct_element(s, 'renamed_b')` is resolved to the file projection `s -> b` by following the
// child mapping instead of matching the table child name against the file schema. Return
// MISSING_FILE_CHILD when ColumnMapping explicitly says a table child is absent from this file; in
// that case callers must not fall back to schema-name lookup, because Iceberg can drop a field and
// later add a different field with the same name.
static NestedProjectionResolveResult resolve_nested_projection_with_mapping(
        const NestedStructPath& path, const std::vector<ColumnMapping>& mappings,
        LocalColumnIndex* root_projection) {
    DORIS_CHECK(root_projection != nullptr);
    *root_projection = {};
    if (path.selectors.empty()) {
        return NestedProjectionResolveResult::NOT_REPRESENTED;
    }
    const auto mapping_it = std::ranges::find_if(mappings, [&](const ColumnMapping& mapping) {
        return mapping.global_index == path.root_global_index;
    });
    if (mapping_it == mappings.end() || !mapping_it->file_local_id.has_value()) {
        return NestedProjectionResolveResult::NOT_REPRESENTED;
    }

    *root_projection = LocalColumnIndex::partial_local(*mapping_it->file_local_id);
    auto* current_projection = root_projection;
    const auto* current_mapping = &*mapping_it;

    // Traverse the ColumnMapping tree according to the table-side struct selectors and emit the
    // corresponding file-local child ids. A missing child mapping means this predicate-only path
    // may need schema fallback; an existing child mapping without a file id means the table child
    // is genuinely absent from this file and must stay above the file reader.
    for (size_t selector_idx = 0; selector_idx < path.selectors.size(); ++selector_idx) {
        const auto global_child_index =
                struct_child_index(*current_mapping, path.selectors[selector_idx]);
        if (!global_child_index.has_value()) {
            *root_projection = {};
            return NestedProjectionResolveResult::NOT_REPRESENTED;
        }
        const auto* child_mapping = resolve_mapped_child(*current_mapping, *global_child_index);
        if (child_mapping == nullptr) {
            *root_projection = {};
            return NestedProjectionResolveResult::NOT_REPRESENTED;
        }
        if (!child_mapping->file_local_id.has_value()) {
            *root_projection = {};
            return NestedProjectionResolveResult::MISSING_FILE_CHILD;
        }

        auto child_projection = LocalColumnIndex::partial_local(*child_mapping->file_local_id);
        child_projection.project_all_children = selector_idx + 1 == path.selectors.size();
        current_projection->children.push_back(std::move(child_projection));
        current_projection = &current_projection->children.back();
        current_mapping = child_mapping;
    }
    return NestedProjectionResolveResult::RESOLVED;
}

static bool table_root_is_struct(const ColumnMapping& mapping) {
    return struct_type_or_null(mapping.table_type) != nullptr;
}

static const std::vector<ColumnDefinition>& scan_file_children(const ColumnMapping& mapping) {
    return !mapping.projected_file_children.empty() ? mapping.projected_file_children
                                                    : mapping.original_file_children;
}

static bool collect_file_child_names_from_projection(const std::vector<ColumnDefinition>& children,
                                                     const LocalColumnIndex& projection,
                                                     std::vector<std::string>* file_child_names,
                                                     std::vector<DataTypePtr>* file_child_types) {
    DORIS_CHECK(file_child_names != nullptr);
    DORIS_CHECK(file_child_types != nullptr);
    const auto child_it = std::ranges::find_if(children, [&](const ColumnDefinition& child) {
        return child.file_local_id() == projection.local_id();
    });
    if (child_it == children.end()) {
        return false;
    }
    file_child_names->push_back(child_it->name);
    file_child_types->push_back(child_it->type);
    if (projection.children.empty()) {
        return true;
    }
    if (projection.children.size() != 1) {
        return false;
    }
    return collect_file_child_names_from_projection(child_it->children, projection.children[0],
                                                    file_child_names, file_child_types);
}

} // namespace

SplitLocalFileLiteral::SplitLocalFileLiteral(const DataTypePtr& file_type, const Field& file_field,
                                             DataTypePtr original_type, Field original_field)
        : VLiteral(file_type, file_field),
          _original_type(std::move(original_type)),
          _original_field(std::move(original_field)) {}

GlobalIndex slot_ref_global_index(const VSlotRef& slot_ref) {
    DORIS_CHECK(slot_ref.column_id() >= 0);
    return GlobalIndex(cast_set<size_t>(slot_ref.column_id()));
}

bool is_struct_element_expr(const VExprSPtr& expr) {
    if (expr == nullptr || expr->get_num_children() != 2) {
        return false;
    }
    const auto& function_name = expr->fn().name.function_name;
    if (function_name == "struct_element") {
        return true;
    }
    if (function_name != "element_at") {
        return false;
    }
    const auto& parent_type = expr->children()[0]->data_type();
    return parent_type != nullptr &&
           remove_nullable(parent_type)->get_primitive_type() == TYPE_STRUCT;
}

Field literal_field(const VExprSPtr& literal_expr) {
    DORIS_CHECK(literal_expr != nullptr);
    DORIS_CHECK(literal_expr->is_literal());
    const auto* literal = dynamic_cast<const VLiteral*>(literal_expr.get());
    DORIS_CHECK(literal != nullptr);
    Field field;
    literal->get_column_ptr()->get(0, field);
    return field;
}

bool resolve_nested_struct_path_for_file(const NestedStructPath& path,
                                         const std::vector<ColumnMapping>& mappings,
                                         ResolvedNestedStructPath* resolved,
                                         bool require_scan_projection) {
    DORIS_CHECK(resolved != nullptr);
    *resolved = {};
    const auto mapping_it = std::ranges::find_if(mappings, [&](const ColumnMapping& mapping) {
        return mapping.global_index == path.root_global_index;
    });
    if (mapping_it == mappings.end() || !mapping_it->file_local_id.has_value() ||
        path.selectors.empty()) {
        return false;
    }

    // Prefer ColumnMapping over schema-name lookup. This is the only path that can correctly
    // localize renamed Iceberg fields: a table filter `element_at(s, 'renamed_b')` must become a
    // file filter on physical child `b`, even if the old file type is `STRUCT<b ...>`.
    const auto mapping_result =
            resolve_nested_projection_with_mapping(path, mappings, &resolved->file_projection);
    if (mapping_result == NestedProjectionResolveResult::MISSING_FILE_CHILD) {
        return false;
    }
    if (mapping_result == NestedProjectionResolveResult::NOT_REPRESENTED) {
        if (!table_root_is_struct(*mapping_it)) {
            return false;
        }
        LocalColumnIndex child_projection;
        if (!build_file_child_projection_from_schema(mapping_it->original_file_children,
                                                     path.selectors, &child_projection)
                     .ok() ||
            child_projection.local_id() < 0) {
            return false;
        }
        resolved->file_projection = LocalColumnIndex::partial_local(*mapping_it->file_local_id);
        resolved->file_projection.children.push_back(std::move(child_projection));
    }

    if (resolved->file_projection.children.size() != 1) {
        *resolved = {};
        return false;
    }
    // When rewriting the final localized element_at chain, it executes on the file column produced
    // by this scan, so the intermediate return types must match the projected file shape, not the
    // full historical file schema. Example:
    //   SELECT s.c WHERE element_at(element_at(s, 'b'), 'cc') LIKE 'NestedC%'
    // reads only b.cc and c; the inner element_at(s, 'b') returns Struct(cc), not
    // Struct(cc, new_dd).
    //
    // Earlier projection collection also calls this resolver before filter-only children have been
    // merged into the scan projection. That phase only needs the file path, so it still resolves
    // names/types from the original file schema.
    const auto& child_source = require_scan_projection ? scan_file_children(*mapping_it)
                                                       : mapping_it->original_file_children;
    if (!collect_file_child_names_from_projection(
                child_source, resolved->file_projection.children[0], &resolved->file_child_names,
                &resolved->file_child_types) ||
        resolved->file_child_names.size() != path.selectors.size() ||
        resolved->file_child_types.size() != path.selectors.size()) {
        *resolved = {};
        return false;
    }
    return true;
}

bool resolve_nested_struct_expr_for_file(const VExprSPtr& expr,
                                         const std::vector<ColumnMapping>& mappings,
                                         ResolvedNestedStructPath* resolved) {
    DORIS_CHECK(resolved != nullptr);
    NestedStructPath path;
    if (!extract_nested_struct_path(expr, &path)) {
        *resolved = {};
        return false;
    }
    return resolve_nested_struct_path_for_file(path, mappings, resolved, true);
}

// Collect nested struct leaf references that can be turned into file-reader projections. For
// example, from `s.a > 1 AND element_at(s, 'b') = 2`, this records two paths rooted at `s`:
// `s -> a` and `s -> b`. Non-struct expressions are traversed recursively, while a recognized
// struct path is emitted once so the caller can merge it into the scan projection for that
// top-level file column.
void collect_nested_struct_paths(const VExprSPtr& expr, std::vector<NestedStructPath>* paths) {
    DORIS_CHECK(paths != nullptr);
    if (expr == nullptr) {
        return;
    }
    NestedStructPath path;
    if (extract_nested_struct_path_for_pruning(expr, &path)) {
        paths->push_back(std::move(path));
        return;
    }
    for (const auto& child : expr->children()) {
        collect_nested_struct_paths(child, paths);
    }
}

std::vector<const ColumnMapping*> present_child_mappings_in_file_order(
        const std::vector<ColumnMapping>& child_mappings) {
    std::vector<const ColumnMapping*> result;
    result.reserve(child_mappings.size());
    for (const auto& child_mapping : child_mappings) {
        if (child_mapping.file_local_id.has_value()) {
            result.push_back(&child_mapping);
        }
    }
    std::ranges::sort(result, [](const ColumnMapping* lhs, const ColumnMapping* rhs) {
        DORIS_CHECK(lhs->file_local_id.has_value());
        DORIS_CHECK(rhs->file_local_id.has_value());
        return *lhs->file_local_id < *rhs->file_local_id;
    });
    return result;
}

// Build the nested child projection under a top-level file column by walking file schema children
// directly. The returned projection does not include the root column id; callers attach it under a
// `LocalColumnIndex::partial_local(root_id)` when merging into the scan request.
Status build_file_child_projection_from_schema(const std::vector<ColumnDefinition>& children,
                                               std::span<const StructChildSelector> selectors,
                                               LocalColumnIndex* projection) {
    DORIS_CHECK(projection != nullptr);
    if (selectors.empty()) {
        return Status::InvalidArgument("Nested struct selector path is empty");
    }
    const auto* child = resolve_file_child(children, selectors.front());
    if (child == nullptr) {
        return Status::OK();
    }
    *projection = LocalColumnIndex::local(child->file_local_id());
    projection->project_all_children = selectors.size() == 1;
    projection->children.clear();
    if (selectors.size() == 1) {
        return Status::OK();
    }
    if (child->children.empty() ||
        remove_nullable(child->type)->get_primitive_type() != TYPE_STRUCT) {
        *projection = LocalColumnIndex {};
        return Status::OK();
    }
    LocalColumnIndex child_projection;
    RETURN_IF_ERROR(build_file_child_projection_from_schema(child->children, selectors.subspan(1),
                                                            &child_projection));
    if (child_projection.local_id() < 0) {
        *projection = LocalColumnIndex {};
        return Status::OK();
    }
    projection->children.push_back(std::move(child_projection));
    return Status::OK();
}

} // namespace doris::format

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Created: 2026-07-25 15:41