[CALCITE-7353] introduce Milvus adapter with scan and convention support

milvus/build.gradle.kts

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+/*
+ * 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.
+ */
+dependencies {
+    api(project(":core"))
+    api(project(":linq4j"))
+
+    implementation("io.milvus:milvus-sdk-java:2.5.13") {
+        exclude(group = "com.google.guava")
+    }
+
+    testImplementation(platform("org.junit:junit-bom:5.10.0"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+    testImplementation("org.testcontainers:testcontainers")
+}

milvus/src/main/java/org/apache/calcite/adapter/milvus/convention/MilvusRel.java

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+/*
+ * 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.
+ */
+package org.apache.calcite.adapter.milvus.convention;
+
+import org.apache.calcite.adapter.milvus.factory.MilvusTranslatableTable;
+import org.apache.calcite.plan.Convention;
+import org.apache.calcite.plan.RelOptTable;
+import org.apache.calcite.plan.volcano.RelSubset;
+import org.apache.calcite.rel.RelFieldCollation;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.type.RelDataType;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexNode;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Relational expression that uses Milvus calling convention.
+ */
+public interface MilvusRel extends RelNode {
+  void implement(Implementor implementor);
+
+  Convention CONVENTION = new Convention.Impl("MILVUS", MilvusRel.class);
+
+  /**
+   * Implementor for Milvus relational expressions.
+   */
+  class Implementor {
+    public final RexBuilder rexBuilder;
+
+    // scan
+    public RelOptTable table;
+    public MilvusTranslatableTable milvusTable;
+    public RelDataType rowType;
+    public Map<String, String> milvusOptions;
+
+    // filter
+    public RexNode filterCondition;
+
+    // project
+    public RelDataType projectRowType;
+    public List<RexNode> projects;
+
+    // vector search
+    public RexNode vectorDistanceExpr;
+    public Integer vectorDistanceFieldIndex;
+    public RelFieldCollation.Direction sortOrder;
+    public RexNode limit;
+
+    public Implementor(RexBuilder rexBuilder) {
+      this.rexBuilder = rexBuilder;
+    }
+
+    public void visitChild(int ordinal, RelNode input) {
+      assert ordinal == 0;
+
+      RelNode node = findMilvusRel(input);
+
+      if (!(node instanceof MilvusRel)) {
+        throw new IllegalStateException(
+            "Expected MilvusRel input but got "
+                + (node == null ? "null" : node.getClass().getName())
+                + " (original=" + input.getClass().getName() + ")");
+      }
+      ((MilvusRel) node).implement(this);
+    }
+  }
+
+  static RelNode findMilvusRel(RelNode input) {
+    RelNode node = input;
+    if (node instanceof RelSubset) {
+      final RelSubset subset = (RelSubset) node;
+      RelNode best = subset.getBest();
+      if (best != null) {
+        node = best;
+      } else {
+        // find first MilvusRel in the subset
+        for (RelNode r : subset.getRelList()) {
+          if (r instanceof MilvusRel) {
+            node = r;
+            break;
+          }
+        }
+      }
+    }
+    return node;
+  }
+}

milvus/src/main/java/org/apache/calcite/adapter/milvus/convention/MilvusToEnumerableConverter.java

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+/*
+ * 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.
+ */
+package org.apache.calcite.adapter.milvus.convention;
+
+import org.apache.calcite.adapter.enumerable.EnumerableRel;
+import org.apache.calcite.adapter.enumerable.EnumerableRelImplementor;
+import org.apache.calcite.adapter.enumerable.JavaRowFormat;
+import org.apache.calcite.adapter.enumerable.PhysType;
+import org.apache.calcite.adapter.enumerable.PhysTypeImpl;
+import org.apache.calcite.adapter.milvus.factory.MilvusTranslatableTable;
+import org.apache.calcite.adapter.milvus.operation.MilvusProjectExpression;
+import org.apache.calcite.linq4j.tree.BlockBuilder;
+import org.apache.calcite.linq4j.tree.Expression;
+import org.apache.calcite.linq4j.tree.Expressions;
+import org.apache.calcite.linq4j.tree.Types;
+import org.apache.calcite.plan.ConventionTraitDef;
+import org.apache.calcite.plan.RelOptCluster;
+import org.apache.calcite.plan.RelOptCost;
+import org.apache.calcite.plan.RelOptPlanner;
+import org.apache.calcite.plan.RelTraitSet;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.convert.ConverterImpl;
+import org.apache.calcite.rel.metadata.RelMetadataQuery;
+import org.apache.calcite.rel.type.RelDataType;
+import org.apache.calcite.rex.RexInputRef;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.schema.Schema;
+import org.apache.calcite.util.BuiltInMethod;
+import org.apache.calcite.util.Pair;
+
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * MilvusToEnumerableConverter converts a relational expression
+ * from Milvus calling convention to Enumerable calling convention.
+ */
+public class MilvusToEnumerableConverter
+    extends ConverterImpl
+    implements EnumerableRel {
+  protected MilvusToEnumerableConverter(
+      RelOptCluster cluster,
+      RelTraitSet traits,
+      RelNode input) {
+    super(cluster, ConventionTraitDef.INSTANCE, traits, input);
+  }
+
+  @Override public RelNode copy(RelTraitSet traitSet, List<RelNode> inputs) {
+    return new MilvusToEnumerableConverter(
+        getCluster(), traitSet, sole(inputs));
+  }
+
+  @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner,
+      RelMetadataQuery mq) {
+    return super.computeSelfCost(planner, mq).multiplyBy(.1);
+  }
+
+  @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
+    final BlockBuilder list = new BlockBuilder();
+    final MilvusRel.Implementor milvusImplementor =
+        new MilvusRel.Implementor(getCluster().getRexBuilder());
+    milvusImplementor.visitChild(0, getInput());
+
+    final Expression root = implementor.getRootExpression();
+    final Expression schema =
+        Expressions.call(root, BuiltInMethod.DATA_CONTEXT_GET_ROOT_SCHEMA.method);
+
+    // scan
+    final List<String> qualifiedTableName = milvusImplementor.table.getQualifiedName();
+    final Expression table = getScanInfo(qualifiedTableName, schema);
+    final Expression tableExpr =
+        Expressions.convert_(table, MilvusTranslatableTable.class);
+    // project
+    final RelDataType rowType = milvusImplementor.projectRowType != null
+        ? milvusImplementor.projectRowType
+        : getRowType();
+
+    final PhysType physType =
+        PhysTypeImpl.of(
+            implementor.getTypeFactory(), rowType,
+            pref.prefer(JavaRowFormat.ARRAY));
+
+    final List<RexNode> projects = milvusImplementor.projects;
+    List<Pair<Integer, MilvusProjectExpression>>
+        projectInfo = getProjectInfo(projects, rowType, milvusImplementor.rowType, physType);
+    final Expression projectInfoExpr =
+        list.append("projectRowTypeMapForEnumerator", expressionForProjectPairs(projectInfo));
+
+    Expression enumerable =
+        list.append(
+            "enumerable", Expressions.call(tableExpr,
+                "scan",
+                Expressions.constant(""),
+                projectInfoExpr));
+
+    list.add(Expressions.return_(null, enumerable));
+    return implementor.result(physType, list.toBlock());
+  }
+
+  private static Expression getScanInfo(List<String> qualifiedName,
+      Expression schema) {
+    final String schemaName = qualifiedName.size() > 1 ? qualifiedName.get(0) : null;
+    final String tableName = qualifiedName.get(qualifiedName.size() - 1);
+
+    Expression current = schema;
+
+    if (schemaName != null) {
+      current =
+          Expressions.call(current, BuiltInMethod.SCHEMA_GET_SUB_SCHEMA.method,
+              Expressions.constant(schemaName));
+      current = Expressions.convert_(current, Schema.class);
+    }
+
+    return Expressions.call(current,
+        BuiltInMethod.SCHEMA_GET_TABLE.method,
+        Expressions.constant(tableName));
+  }
+
+  private static List<Pair<Integer, MilvusProjectExpression>> getProjectInfo(List<RexNode> projects,
+      RelDataType rowType, RelDataType inputRowType, PhysType physType) {
+    List<Pair<Integer, MilvusProjectExpression>> projectInfo = new ArrayList<>();
+    if (projects != null) {
+      for (int i = 0; i < projects.size(); i++) {
+        RexNode project = projects.get(i);
+        Class<?> fieldClass = physType.fieldClass(i);
+        MilvusProjectExpression expr;
+
+        if (project instanceof RexInputRef) {
+          int inputIndex = ((RexInputRef) project).getIndex();
+          String originalFieldName = inputRowType.getFieldNames().get(inputIndex);
+          expr = new MilvusProjectExpression.InputField(originalFieldName, fieldClass);
+        } else if (project instanceof RexLiteral) {
+          RexLiteral literal = (RexLiteral) project;
+          expr = new MilvusProjectExpression.Constant(fieldClass, literal.getValue3());
+        } else {
+          throw new UnsupportedOperationException("Unsupported project type");
+        }
+        projectInfo.add(Pair.of(i, expr));
+      }
+    } else {
+      List<String> inputFields = rowType.getFieldNames();
+      for (int i = 0; i < inputFields.size(); i++) {
+        String fieldName = inputFields.get(i);
+        Class<?> fieldClass = physType.fieldClass(i);
+        projectInfo.add(
+            Pair.of(i,
+                new MilvusProjectExpression.InputField(fieldName, fieldClass)));
+      }
+    }
+    return projectInfo;
+  }
+
+  private Expression expressionForProjectExpression(MilvusProjectExpression expr) {
+    if (expr instanceof MilvusProjectExpression.InputField) {
+      String fieldName = ((MilvusProjectExpression.InputField) expr).getFieldName();
+      return Expressions.new_(MilvusProjectExpression.InputField.class,
+          Expressions.constant(fieldName),
+          Expressions.constant(expr.getClazz(), Class.class));
+    } else if (expr instanceof MilvusProjectExpression.Constant) {
+      Object value = ((MilvusProjectExpression.Constant) expr).getValue();
+      return Expressions.new_(MilvusProjectExpression.Constant.class,
+          Expressions.constant(expr.getClazz(), Class.class),
+          Expressions.constant(value));
+    } else if (expr instanceof MilvusProjectExpression.VectorScore) {
+      return Expressions.new_(MilvusProjectExpression.VectorScore.class,
+          Expressions.constant(expr.getClazz(), Class.class));
+    } else {
+      throw new AssertionError("Unknown expression type: " + expr);
+    }
+  }
+
+  private Expression expressionForProjectPairs(List<Pair<Integer, MilvusProjectExpression>> pairs) {
+    List<Expression> pairExpressions = new ArrayList<>();
+
+    for (Pair<Integer, MilvusProjectExpression> pair : pairs) {
+      Expression first = Expressions.constant(pair.left, Integer.class);
+      Expression second = expressionForProjectExpression(pair.right);
+      Type pairType = Types.of(Pair.class, Integer.class, MilvusProjectExpression.class);
+      Expression pairExpr = Expressions.new_(pairType, first, second);
+      pairExpressions.add(pairExpr);
+    }
+    return Expressions.call(BuiltInMethod.ARRAYS_AS_LIST.method,
+        Expressions.newArrayInit(Pair.class, pairExpressions));
+  }
+
+}

milvus/src/main/java/org/apache/calcite/adapter/milvus/convention/MilvusToEnumerableConverterRule.java

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+/*
+ * 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.
+ */
+package org.apache.calcite.adapter.milvus.convention;
+
+import org.apache.calcite.adapter.enumerable.EnumerableConvention;
+import org.apache.calcite.plan.RelOptRuleCall;
+import org.apache.calcite.plan.RelTraitSet;
+import org.apache.calcite.rel.RelNode;
+import org.apache.calcite.rel.convert.ConverterRule;
+
+/**
+ * Rule to convert a relational expression from
+ * {@link MilvusRel#CONVENTION Milvus calling convention} to
+ * {@link org.apache.calcite.adapter.enumerable.EnumerableConvention Enumerable calling convention}.
+ */
+public class MilvusToEnumerableConverterRule extends ConverterRule {
+  public static final MilvusToEnumerableConverterRule INSTANCE =
+      Config.INSTANCE
+          .withConversion(MilvusRel.class, MilvusRel.CONVENTION,
+              EnumerableConvention.INSTANCE, "MilvusToEnumerableConverterRule")
+          .withRuleFactory(MilvusToEnumerableConverterRule::new)
+          .toRule(MilvusToEnumerableConverterRule.class);
+
+  protected MilvusToEnumerableConverterRule(Config config) {
+    super(config);
+  }
+
+  @Override public RelNode convert(RelNode relNode) {
+    final RelTraitSet traitSet = relNode.getTraitSet()
+        .replace(getOutTrait());
+    return new MilvusToEnumerableConverter(relNode.getCluster(), traitSet,
+        relNode);
+  }
+
+  @Override public void onMatch(RelOptRuleCall call) {
+    final RelNode rel = call.rel(0);
+    if (rel.getConvention() == getOutTrait()) {
+      return;
+    }
+    final RelNode converted = convert(rel);
+    if (converted != null) {
+      call.transformTo(converted);
+    }
+  }
+}