feat: add utils to project exprs on rows to exps on partitions

src/iceberg/CMakeLists.txt

@@ -28,6 +28,7 @@ set(ICEBERG_SOURCES
     expression/inclusive_metrics_evaluator.cc
     expression/literal.cc
     expression/predicate.cc
+    expression/projections.cc
     expression/rewrite_not.cc
     expression/strict_metrics_evaluator.cc
     expression/term.cc

src/iceberg/expression/meson.build

@@ -26,6 +26,7 @@ install_headers(
         'inclusive_metrics_evaluator.h',
         'literal.h',
         'predicate.h',
+        'projections.h',
         'rewrite_not.h',
         'strict_metrics_evaluator.h',
         'term.h',

src/iceberg/expression/projections.cc

@@ -0,0 +1,244 @@
+/*
+ * 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 "iceberg/expression/projections.h"
+
+#include <memory>
+#include <vector>
+
+#include "iceberg/expression/expression.h"
+#include "iceberg/expression/expression_visitor.h"
+#include "iceberg/expression/expressions.h"
+#include "iceberg/expression/predicate.h"
+#include "iceberg/expression/rewrite_not.h"
+#include "iceberg/expression/term.h"
+#include "iceberg/partition_field.h"
+#include "iceberg/partition_spec.h"
+#include "iceberg/result.h"
+#include "iceberg/transform.h"
+#include "iceberg/util/macros.h"
+
+namespace iceberg {
+
+// Implementation detail - not exported
+class ProjectionVisitor : public ExpressionVisitor<std::shared_ptr<Expression>> {
+ public:
+  ~ProjectionVisitor() override = default;
+
+  ProjectionVisitor(const std::shared_ptr<PartitionSpec>& spec,
+                    const std::shared_ptr<Schema>& schema, bool case_sensitive)
+      : spec_(spec), schema_(schema), case_sensitive_(case_sensitive) {}
+
+  Result<std::shared_ptr<Expression>> AlwaysTrue() override { return True::Instance(); }
+
+  Result<std::shared_ptr<Expression>> AlwaysFalse() override { return False::Instance(); }
+
+  Result<std::shared_ptr<Expression>> Not(
+      const std::shared_ptr<Expression>& child_result) override {
+    return InvalidExpression("Project called on expression with a not");
+  }
+
+  Result<std::shared_ptr<Expression>> And(
+      const std::shared_ptr<Expression>& left_result,
+      const std::shared_ptr<Expression>& right_result) override {
+    return Expressions::And(left_result, right_result);
+  }
+
+  Result<std::shared_ptr<Expression>> Or(
+      const std::shared_ptr<Expression>& left_result,
+      const std::shared_ptr<Expression>& right_result) override {
+    return Expressions::Or(left_result, right_result);
+  }
+
+  Result<std::shared_ptr<Expression>> Predicate(
+      const std::shared_ptr<UnboundPredicate>& pred) override {
+    ICEBERG_ASSIGN_OR_RAISE(auto bound_pred, pred->Bind(*schema_, case_sensitive_));
+    if (bound_pred->is_bound_predicate()) {
+      auto bound_predicate = std::dynamic_pointer_cast<BoundPredicate>(bound_pred);
+      ICEBERG_DCHECK(
+          bound_predicate != nullptr,
+          "Expected bound_predicate to be non-null after is_bound_predicate() check");
+      return Predicate(bound_predicate);
+    }
+    return bound_pred;
+  }
+
+  Result<std::shared_ptr<Expression>> Predicate(
+      const std::shared_ptr<BoundPredicate>& pred) override {
+    return InvalidExpression("Bound predicates are not supported in projections");
+  }
+
+ protected:
+  const std::shared_ptr<PartitionSpec>& spec_;
+  const std::shared_ptr<Schema>& schema_;
+  bool case_sensitive_;
+
+  /// \brief Get partition fields that match the predicate's term.
+  std::vector<const PartitionField*> GetFieldsByPredicate(
+      const std::shared_ptr<BoundPredicate>& pred) const {
+    int32_t source_id;
+    switch (pred->term()->kind()) {
+      case Term::Kind::kReference: {
+        const auto& ref = pred->term()->reference();
+        source_id = ref->field().field_id();
+        break;
+      }
+      case Term::Kind::kTransform: {
+        const auto& transform =
+            internal::checked_pointer_cast<BoundTransform>(pred->term());
+        source_id = transform->reference()->field().field_id();
+        break;
+      }
+      default:
+        std::unreachable();
+    }
+
+    std::vector<const PartitionField*> result;
+    for (const auto& field : spec_->fields()) {
+      if (field.source_id() == source_id) {
+        result.push_back(&field);
+      }
+    }
+    return result;
+  }
+};
+
+ProjectionEvaluator::ProjectionEvaluator(std::unique_ptr<ProjectionVisitor> visitor)
+    : visitor_(std::move(visitor)) {}
+
+ProjectionEvaluator::~ProjectionEvaluator() = default;
+
+/// \brief Inclusive projection visitor.
+///
+/// Uses AND to combine projections from multiple partition fields.
+class InclusiveProjectionVisitor : public ProjectionVisitor {
+ public:
+  ~InclusiveProjectionVisitor() override = default;
+
+  InclusiveProjectionVisitor(const std::shared_ptr<PartitionSpec>& spec,
+                             const std::shared_ptr<Schema>& schema, bool case_sensitive)
+      : ProjectionVisitor(spec, schema, case_sensitive) {}
+
+  Result<std::shared_ptr<Expression>> Predicate(
+      const std::shared_ptr<BoundPredicate>& pred) override {
+    ICEBERG_DCHECK(pred != nullptr, "Predicate cannot be null");
+    // Find partition fields that match the predicate's term
+    auto partition_fields = GetFieldsByPredicate(pred);
+    if (partition_fields.empty()) {
+      // The predicate has no partition column
+      return AlwaysTrue();
+    }
+
+    // Project the predicate for each partition field and combine with AND
+    //
+    // consider (d = 2019-01-01) with bucket(7, d) and bucket(5, d)
+    // projections: b1 = bucket(7, '2019-01-01') = 5, b2 = bucket(5, '2019-01-01') = 0
+    // any value where b1 != 5 or any value where b2 != 0 cannot be the '2019-01-01'
+    //
+    // similarly, if partitioning by day(ts) and hour(ts), the more restrictive
+    // projection should be used. ts = 2019-01-01T01:00:00 produces day=2019-01-01 and
+    // hour=2019-01-01-01. the value will be in 2019-01-01-01 and not in 2019-01-01-02.
+    std::shared_ptr<Expression> result = True::Instance();
+    for (const auto* part_field : partition_fields) {
+      ICEBERG_ASSIGN_OR_RAISE(auto projected,
+                              part_field->transform()->Project(part_field->name(), pred));
+      if (projected != nullptr) {
+        result =
+            Expressions::And(result, std::shared_ptr<Expression>(projected.release()));
+      }
+    }
+
+    return result;
+  }
+
+ protected:
+};
+
+/// \brief Strict projection evaluator.
+///
+/// Uses OR to combine projections from multiple partition fields.
+class StrictProjectionVisitor : public ProjectionVisitor {
+ public:
+  ~StrictProjectionVisitor() override = default;
+
+  StrictProjectionVisitor(const std::shared_ptr<PartitionSpec>& spec,
+                          const std::shared_ptr<Schema>& schema, bool case_sensitive)
+      : ProjectionVisitor(spec, schema, case_sensitive) {}
+
+  Result<std::shared_ptr<Expression>> Predicate(
+      const std::shared_ptr<BoundPredicate>& pred) override {
+    ICEBERG_DCHECK(pred != nullptr, "Predicate cannot be null");
+    // Find partition fields that match the predicate's term
+    auto partition_fields = GetFieldsByPredicate(pred);
+    if (partition_fields.empty()) {
+      // The predicate has no matching partition columns
+      return AlwaysFalse();
+    }
+
+    // Project the predicate for each partition field and combine with OR
+    //
+    // consider (ts > 2019-01-01T01:00:00) with day(ts) and hour(ts)
+    // projections: d >= 2019-01-02 and h >= 2019-01-01-02 (note the inclusive bounds).
+    // any timestamp where either projection predicate is true must match the original
+    // predicate. For example, ts = 2019-01-01T03:00:00 matches the hour projection but
+    // not the day, but does match the original predicate.
+    std::shared_ptr<Expression> result = False::Instance();
+    for (const auto* part_field : partition_fields) {
+      ICEBERG_ASSIGN_OR_RAISE(auto projected, part_field->transform()->ProjectStrict(
+                                                  part_field->name(), pred));
+      if (projected != nullptr) {
+        result =
+            Expressions::Or(result, std::shared_ptr<Expression>(projected.release()));
+      }
+    }
+
+    return result;
+  }
+};
+
+Result<std::shared_ptr<Expression>> ProjectionEvaluator::Project(
+    const std::shared_ptr<Expression>& expr) {
+  // Projections assume that there are no NOT nodes in the expression tree. To ensure that
+  // this is the case, the expression is rewritten to push all NOT nodes down to the
+  // expression leaf nodes.
+  //
+  // This is necessary to ensure that the default expression returned when a predicate
+  // can't be projected is correct.
+  ICEBERG_ASSIGN_OR_RAISE(auto rewritten, RewriteNot::Visit(expr));
+  return Visit<std::shared_ptr<Expression>, ProjectionVisitor>(rewritten, *visitor_);
+}
+
+std::unique_ptr<ProjectionEvaluator> Projections::Inclusive(
+    const std::shared_ptr<PartitionSpec>& spec, const std::shared_ptr<Schema>& schema,
+    bool case_sensitive) {
+  auto visitor =
+      std::make_unique<InclusiveProjectionVisitor>(spec, schema, case_sensitive);
+  return std::unique_ptr<ProjectionEvaluator>(
+      new ProjectionEvaluator(std::move(visitor)));
+}
+
+std::unique_ptr<ProjectionEvaluator> Projections::Strict(
+    const std::shared_ptr<PartitionSpec>& spec, const std::shared_ptr<Schema>& schema,
+    bool case_sensitive) {
+  auto visitor = std::make_unique<StrictProjectionVisitor>(spec, schema, case_sensitive);
+  return std::unique_ptr<ProjectionEvaluator>(
+      new ProjectionEvaluator(std::move(visitor)));
+}
+
+}  // namespace iceberg

src/iceberg/expression/projections.h

@@ -0,0 +1,109 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+/// \file iceberg/expression/projections.h
+/// Utils to project expressions on rows to expressions on partitions.
+
+#include <memory>
+
+#include "iceberg/expression/expression.h"
+#include "iceberg/iceberg_export.h"
+#include "iceberg/partition_spec.h"
+#include "iceberg/result.h"
+#include "iceberg/type_fwd.h"
+
+namespace iceberg {
+
+/// \brief A class that projects expressions for a table's data rows into expressions on
+/// the table's partition values, for a table's partition spec.
+class ICEBERG_EXPORT ProjectionEvaluator {
+ public:
+  ~ProjectionEvaluator();
+
+  /// \brief Project the given row expression to a partition expression.
+  ///
+  /// \param expr an expression on data rows
+  /// \return an expression on partition data (depends on the projection)
+  Result<std::shared_ptr<Expression>> Project(const std::shared_ptr<Expression>& expr);
+
+ private:
+  friend class Projections;
+
+  /// \brief Create a ProjectionEvaluator.
+  ///
+  /// \param visitor The projection visitor to use
+  explicit ProjectionEvaluator(std::unique_ptr<class ProjectionVisitor> visitor);
+
+  std::unique_ptr<class ProjectionVisitor> visitor_;
+};
+
+/// \brief Utils to project expressions on rows to expressions on partitions.
+///
+/// There are two types of projections: inclusive and strict.
+///
+/// An inclusive projection guarantees that if an expression matches a row, the projected
+/// expression will match the row's partition.
+///
+/// A strict projection guarantees that if a partition matches a projected expression,
+/// then all rows in that partition will match the original expression.
+class ICEBERG_EXPORT Projections {
+ public:
+  /// \brief Creates an inclusive ProjectionEvaluator for the partition spec.
+  ///
+  /// An evaluator is used to project expressions for a table's data rows into expressions
+  /// on the table's partition values. The evaluator returned by this function is
+  /// inclusive and will build expressions with the following guarantee: if the original
+  /// expression matches a row, then the projected expression will match that row's
+  /// partition.
+  ///
+  /// Each predicate in the expression is projected using Transform::Project.
+  ///
+  /// \param spec a partition spec
+  /// \param case_sensitive whether the Projection should consider case sensitivity on
+  /// column names or not. Defaults to true (case sensitive).
+  /// \return an inclusive projection evaluator for the partition spec
+  static std::unique_ptr<ProjectionEvaluator> Inclusive(
+      const std::shared_ptr<PartitionSpec>& spec, const std::shared_ptr<Schema>& schema,
+      bool case_sensitive = true);
+
+  /// \brief Creates a strict ProjectionEvaluator for the partition spec.
+  ///
+  /// An evaluator is used to project expressions for a table's data rows into expressions
+  /// on the table's partition values. The evaluator returned by this function is strict
+  /// and will build expressions with the following guarantee: if the projected expression
+  /// matches a partition, then the original expression will match all rows in that
+  /// partition.
+  ///
+  /// Each predicate in the expression is projected using Transform::ProjectStrict.
+  ///
+  /// \param spec a partition spec
+  /// \param case_sensitive whether the Projection should consider case sensitivity on
+  /// column names or not. Defaults to true (case sensitive).
+  /// \return a strict projection evaluator for the partition spec
+  static std::unique_ptr<ProjectionEvaluator> Strict(
+      const std::shared_ptr<PartitionSpec>& spec, const std::shared_ptr<Schema>& schema,
+      bool case_sensitive = true);
+
+ private:
+  Projections() = default;
+};
+
+}  // namespace iceberg

src/iceberg/meson.build

@@ -50,6 +50,7 @@ iceberg_sources = files(
     'expression/inclusive_metrics_evaluator.cc',
     'expression/literal.cc',
     'expression/predicate.cc',
+    'expression/projections.cc',
     'expression/rewrite_not.cc',
     'expression/strict_metrics_evaluator.cc',
     'expression/term.cc',

src/iceberg/partition_spec.h

@@ -105,7 +105,6 @@ class ICEBERG_EXPORT PartitionSpec : public util::Formattable {
  private:
   /// \brief Create a new partition spec.
   ///
-  /// \param schema The table schema.
   /// \param spec_id The spec ID.
   /// \param fields The partition fields.
   /// \param last_assigned_field_id The last assigned field ID. If not provided, it will

src/iceberg/test/CMakeLists.txt

@@ -88,6 +88,7 @@ add_iceberg_test(expression_test
                  inclusive_metrics_evaluator_test.cc
                  inclusive_metrics_evaluator_with_transform_test.cc
                  predicate_test.cc
+                 projections_test.cc
                  strict_metrics_evaluator_test.cc)
 
 add_iceberg_test(json_serde_test