fix: eager source row fetching logic

v2/googlecloud-to-neo4j/src/main/java/com/google/cloud/teleport/v2/neo4j/templates/GoogleCloudToNeo4j.java

@@ -81,7 +81,6 @@
 import org.neo4j.importer.v1.targets.RelationshipTarget;
 import org.neo4j.importer.v1.targets.Target;
 import org.neo4j.importer.v1.targets.TargetType;
-import org.neo4j.importer.v1.targets.Targets;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -275,6 +274,10 @@
                     Entry::getKey, mapping(Entry::getValue, Collectors.<PCollection<?>>toList())));
     var sourceRows = new ArrayList<PCollection<?>>(importSpecification.getSources().size());
     var targetRows = new HashMap<TargetType, List<PCollection<?>>>(targetCount());
+    var allActiveTargets =
+        importSpecification.getTargets().getAll().stream()
+            .filter(Target::isActive)
+            .collect(toList());
     var allActiveNodeTargets =
         importSpecification.getTargets().getNodes().stream()
             .filter(Target::isActive)
@@ -283,40 +286,42 @@
     ////////////////////////////
     // Process sources
     for (var source : importSpecification.getSources()) {
+      String sourceName = source.getName();
+      var activeSourceTargets =
+          allActiveTargets.stream()
+              .filter(target -> target.getSource().equals(sourceName))
+              .collect(toList());
+      if (activeSourceTargets.isEmpty()) {
+        return;
+      }
 
       // get provider implementation for source
       Provider provider = ProviderFactory.of(source, targetSequence);
       provider.configure(optionsParams);
       PCollection<Row> sourceMetadata =
           pipeline.apply(
-              String.format("Metadata for source %s", source.getName()), provider.queryMetadata());
+              String.format("Metadata for source %s", sourceName), provider.queryMetadata());
       sourceRows.add(sourceMetadata);
       Schema sourceBeamSchema = sourceMetadata.getSchema();
       processingQueue.addToQueue(
-          ArtifactType.source, false, source.getName(), defaultActionContext, sourceMetadata);
-      PCollection<Row> nullableSourceBeamRows = null;
+          ArtifactType.source, false, sourceName, defaultActionContext, sourceMetadata);
 
       ////////////////////////////
-      // Optimization: if single source query, reuse this PCollection rather than write it again
-      boolean targetsHaveTransforms = ModelUtils.targetsHaveTransforms(importSpecification, source);
-      if (!targetsHaveTransforms || !provider.supportsSqlPushDown()) {
+      // Optimization: if some of the current source's targets either
+      // - do not alter the source query (i.e. define no transformations)
+      // - or the source provider does not support SQL pushdown
+      // then the source PCollection can be defined here and reused across all the relevant targets
+      PCollection<Row> nullableSourceBeamRows = null;
+      if (!provider.supportsSqlPushDown()
+          || activeSourceTargets.stream()
+              .anyMatch(target -> !ModelUtils.targetHasTransforms(target))) {
         nullableSourceBeamRows =
             pipeline
-                .apply("Query " + source.getName(), provider.querySourceBeamRows(sourceBeamSchema))
+                .apply("Query " + sourceName, provider.querySourceBeamRows(sourceBeamSchema))
                 .setRowSchema(sourceBeamSchema);
       }
 
-      String sourceName = source.getName();
-
-      ////////////////////////////
-      // Optimization: if we're not mixing nodes and edges, then run in parallel
-      // For relationship updates, max workers should be max 2.  This parameter is job configurable.
-
-      ////////////////////////////
-      // No optimization possible so write nodes then edges.
-      // Write node targets
-      List<NodeTarget> nodeTargets =
-          getActiveTargetsBySourceAndType(importSpecification, sourceName, TargetType.NODE);
+      List<NodeTarget> nodeTargets = getTargetsByType(activeSourceTargets, TargetType.NODE);
       for (NodeTarget target : nodeTargets) {
         TargetQuerySpec targetQuerySpec =
             new TargetQuerySpecBuilder()
@@ -327,7 +332,7 @@
         String nodeStepDescription =
             targetSequence.getSequenceNumber(target)
                 + ": "
-                + source.getName()
+                + sourceName
                 + "->"
                 + target.getName()
                 + " nodes";
@@ -371,7 +376,7 @@
       ////////////////////////////
       // Write relationship targets
       List<RelationshipTarget> relationshipTargets =
-          getActiveTargetsBySourceAndType(importSpecification, sourceName, TargetType.RELATIONSHIP);
+          getTargetsByType(activeSourceTargets, TargetType.RELATIONSHIP);
       for (var target : relationshipTargets) {
         var targetQuerySpec =
             new TargetQuerySpecBuilder()
@@ -383,14 +388,14 @@
                 .endNodeTarget(
                     findNodeTargetByName(allActiveNodeTargets, target.getEndNodeReference()))
                 .build();
-        PCollection<Row> preInsertBeamRows;
         String relationshipStepDescription =
             targetSequence.getSequenceNumber(target)
                 + ": "
-                + source.getName()
+                + sourceName
                 + "->"
                 + target.getName()
                 + " edges";
+        PCollection<Row> preInsertBeamRows;
         if (ModelUtils.targetHasTransforms(target)) {
           preInsertBeamRows =
               pipeline.apply(
@@ -439,12 +444,12 @@
       ////////////////////////////
       // Custom query targets
       List<CustomQueryTarget> customQueryTargets =
-          getActiveTargetsBySourceAndType(importSpecification, sourceName, TargetType.QUERY);
+          getTargetsByType(activeSourceTargets, TargetType.QUERY);
       for (Target target : customQueryTargets) {
         String customQueryStepDescription =
             targetSequence.getSequenceNumber(target)
                 + ": "
-                + source.getName()
+                + sourceName
                 + "->"
                 + target.getName()
                 + " (custom query)";
@@ -455,6 +460,8 @@
             processingQueue.waitOnCollections(
                 target.getDependencies(), customQueryStepDescription));
 
+        // note: nullableSourceBeamRows is guaranteed to be non-null here since custom query targets
+        // cannot define source transformations
         PCollection<Row> blockingReturn =
             nullableSourceBeamRows
                 .apply(
@@ -581,15 +588,10 @@
   }
 
   @SuppressWarnings("unchecked")
-  private <T extends Target> List<T> getActiveTargetsBySourceAndType(
-      ImportSpecification importSpecification, String sourceName, TargetType targetType) {
-    Targets targets = importSpecification.getTargets();
-    return targets.getAll().stream()
-        .filter(
-            target ->
-                target.getTargetType() == targetType
-                    && target.isActive()
-                    && sourceName.equals(target.getSource()))
+  private <T extends Target> List<T> getTargetsByType(
+      List<Target> activeSourceTargets, TargetType targetType) {
+    return activeSourceTargets.stream()
+        .filter(target -> target.getTargetType() == targetType)
         .map(target -> (T) target)
         .collect(toList());
   }

v2/googlecloud-to-neo4j/src/main/java/com/google/cloud/teleport/v2/neo4j/utils/ModelUtils.java

@@ -21,7 +21,6 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Objects;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -38,8 +37,6 @@
 import net.sf.jsqlparser.statement.select.PlainSelect;
 import org.apache.beam.sdk.schemas.Schema;
 import org.apache.commons.lang3.StringUtils;
-import org.neo4j.importer.v1.ImportSpecification;
-import org.neo4j.importer.v1.sources.Source;
 import org.neo4j.importer.v1.targets.Aggregation;
 import org.neo4j.importer.v1.targets.EntityTarget;
 import org.neo4j.importer.v1.targets.NodeTarget;
@@ -58,12 +55,6 @@ public class ModelUtils {
   private static final Pattern variablePattern = Pattern.compile("(\\$([a-zA-Z0-9_]+))");
   private static final Logger LOG = LoggerFactory.getLogger(ModelUtils.class);
 
-  public static boolean targetsHaveTransforms(ImportSpecification jobSpec, Source source) {
-    return jobSpec.getTargets().getAll().stream()
-        .filter(target -> target.isActive() && Objects.equals(target.getSource(), source.getName()))
-        .anyMatch(ModelUtils::targetHasTransforms);
-  }
-
   public static boolean targetHasTransforms(Target target) {
     if (target.getTargetType() == TargetType.QUERY) {
       return false;

v2/googlecloud-to-neo4j/src/test/java/com/google/cloud/teleport/v2/neo4j/templates/SyntheticFieldsIT.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2025 Google LLC
+ *
+ * Licensed 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 com.google.cloud.teleport.v2.neo4j.templates;
+
+import static com.google.cloud.teleport.v2.neo4j.templates.Connections.jsonBasicPayload;
+import static com.google.cloud.teleport.v2.neo4j.templates.Resources.contentOf;
+import static org.apache.beam.it.truthmatchers.PipelineAsserts.assertThatResult;
+
+import com.google.cloud.teleport.metadata.TemplateIntegrationTest;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import org.apache.beam.it.common.PipelineLauncher.LaunchConfig;
+import org.apache.beam.it.common.PipelineLauncher.LaunchInfo;
+import org.apache.beam.it.common.PipelineOperator.Result;
+import org.apache.beam.it.common.TestProperties;
+import org.apache.beam.it.common.utils.ResourceManagerUtils;
+import org.apache.beam.it.gcp.TemplateTestBase;
+import org.apache.beam.it.neo4j.Neo4jResourceManager;
+import org.apache.beam.it.neo4j.conditions.Neo4jQueryCheck;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@Category(TemplateIntegrationTest.class)
+@TemplateIntegrationTest(GoogleCloudToNeo4j.class)
+@RunWith(JUnit4.class)
+public class SyntheticFieldsIT extends TemplateTestBase {
+
+  private Neo4jResourceManager neo4jClient;
+
+  @Before
+  public void setup() {
+    neo4jClient =
+        Neo4jResourceManager.builder(testName)
+            .setAdminPassword("letmein!")
+            .setHost(TestProperties.hostIp())
+            .build();
+  }
+
+  @After
+  public void tearDown() {
+    ResourceManagerUtils.cleanResources(neo4jClient);
+  }
+
+  @Test
+  // TODO: generate bigquery data set once import-spec supports value interpolation
+  public void importsStackoverflowUsers() throws IOException {
+    String spec = contentOf("/testing-specs/synthetic-fields/spec.yml");
+    gcsClient.createArtifact("spec.yml", spec);
+    gcsClient.createArtifact("neo4j-connection.json", jsonBasicPayload(neo4jClient));
+
+    LaunchConfig.Builder options =
+        LaunchConfig.builder(testName, specPath)
+            .addParameter("jobSpecUri", getGcsPath("spec.yml"))
+            .addParameter("neo4jConnectionUri", getGcsPath("neo4j-connection.json"));
+    LaunchInfo info = launchTemplate(options);
+
+    Result result =
+        pipelineOperator()
+            .waitForCondition(
+                createConfig(info),
+                Neo4jQueryCheck.builder(neo4jClient)
+                    .setQuery("MATCH (u:User) RETURN count(u) AS count")
+                    .setExpectedResult(List.of(Map.of("count", 10L)))
+                    .build(),
+                Neo4jQueryCheck.builder(neo4jClient)
+                    .setQuery(
+                        "MATCH (l:Letter) WITH DISTINCT toUpper(l.char) AS char ORDER BY char ASC RETURN collect(char) AS chars")
+                    .setExpectedResult(
+                        List.of(Map.of("chars", List.of("A", "C", "G", "I", "J", "T", "W"))))
+                    .build());
+    assertThatResult(result).meetsConditions();
+  }
+}

v2/googlecloud-to-neo4j/src/test/resources/testing-specs/synthetic-fields/spec.yml

@@ -0,0 +1,45 @@
+version: '1'
+sources:
+  - type: bigquery
+    name: so_users
+    # once value interpolation is supported by import-spec, this public data set query
+    # will be replaced by a query against a generated test bigquery data set
+    query: |-
+      SELECT id, display_name
+      FROM 
+        `bigquery-public-data.stackoverflow.users`
+      ORDER BY id ASC
+      LIMIT 10
+targets:
+  nodes:
+    - name: users
+      source: so_users
+      write_mode: merge
+      labels: [User]
+      source_transformations:
+        aggregations:
+          - expression: max(id)
+            field_name: max_id
+      properties:
+        - source_field: id
+          target_property: id
+        - source_field: display_name
+          target_property: name
+        - source_field: max_id
+          target_property: max_id
+      schema:
+        key_constraints:
+          - name: key_user_id
+            label: User
+            properties: [id]
+  queries:
+    # here we just need a custom query from the same source as another node/rel target that defines transformations
+    - name: user_name_starts_with
+      depends_on:
+        - users
+      source: so_users
+      query: |-
+        UNWIND $rows AS row 
+        MATCH (user:User {id: row.id})
+        MERGE (letter:Letter {char: left(user.name, 1)})
+        CREATE (user)-[:NAME_STARTS_WITH]->(letter)