feat(bigtable): add column-mapping value transformations

Add a generic columnTransforms parameter for mapping column_family:column
pairs to value transformers. Proto decode and column transforms share
a unified TRANSFORMED_VALUE output path in BigQuery.

Supported transforms:
- BIG_ENDIAN_UINT64_TIMESTAMP_MS: 8-byte big-endian int64 → timestamp

Architecture: ValueTransformer interface + ValueTransformerRegistry with
two-level family→column map for O(1) lookup without per-element string
concatenation. Transform priority: proto decode first, then columnTransforms.

Includes proto decode parameters, options, pipeline wiring, BigQueryUtils
formatter integration, and tests for both features.

Author: MattiasMTS

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/options/BigtableChangeStreamToBigQueryOptions.java

@@ -149,4 +149,85 @@ public interface BigtableChangeStreamToBigQueryOptions
   String getDlqDirectory();
 
   void setDlqDirectory(String value);
+
+  @TemplateParameter.GcsReadFile(
+      order = 11,
+      optional = true,
+      description = "Cloud Storage path to the proto schema file",
+      helpText =
+          "The Cloud Storage location of the self-contained proto schema file. "
+              + "For example, gs://path/to/my/file.pb. This file can be generated with the "
+              + "--descriptor_set_out flag of the protoc command. The --include_imports flag "
+              + "guarantees that the file is self-contained. When set along with "
+              + "fullProtoMessageName, the pipeline decodes matching cell values as protobuf "
+              + "messages and writes them as JSON to BigQuery.")
+  @Default.String("")
+  String getProtoSchemaPath();
+
+  void setProtoSchemaPath(String value);
+
+  @TemplateParameter.Text(
+      order = 12,
+      optional = true,
+      regexes = {"^.+([a-zA-Z][a-zA-Z0-9_]+\\.?)+[a-zA-Z0-9_]$"},
+      description = "Full proto message name",
+      helpText =
+          "The full proto message name. For example, package.name.MessageName, "
+              + "where package.name is the value provided for the package statement "
+              + "and not the java_package statement.")
+  @Default.String("")
+  String getFullProtoMessageName();
+
+  void setFullProtoMessageName(String value);
+
+  @TemplateParameter.Text(
+      order = 13,
+      optional = true,
+      description = "Column family containing proto values",
+      helpText =
+          "The Bigtable column family containing protobuf-encoded values to decode. "
+              + "Required when protoSchemaPath is set.")
+  @Default.String("")
+  String getProtoColumnFamily();
+
+  void setProtoColumnFamily(String value);
+
+  @TemplateParameter.Text(
+      order = 14,
+      optional = true,
+      description = "Column qualifier containing proto values",
+      helpText =
+          "The Bigtable column qualifier containing protobuf-encoded values to decode. "
+              + "Required when protoSchemaPath is set.")
+  @Default.String("")
+  String getProtoColumn();
+
+  void setProtoColumn(String value);
+
+  @TemplateParameter.Boolean(
+      order = 15,
+      optional = true,
+      description = "Preserve proto field names in JSON output",
+      helpText =
+          "When set to true, preserves original proto field names (snake_case) in the "
+              + "JSON output. When set to false, uses lowerCamelCase. Defaults to false.")
+  @Default.Boolean(false)
+  Boolean getPreserveProtoFieldNames();
+
+  void setPreserveProtoFieldNames(Boolean value);
+
+  @TemplateParameter.Text(
+      order = 16,
+      optional = true,
+      description = "Column value transforms",
+      helpText =
+          "A comma-separated list of column value transformations in the format "
+              + "column_family:column:TRANSFORM_TYPE. Matched cell values are transformed "
+              + "before writing to BigQuery. Supported types: BIG_ENDIAN_UINT64_TIMESTAMP_MS "
+              + "(8-byte big-endian unsigned 64-bit integer as Unix epoch milliseconds, "
+              + "converted to a timestamp string).")
+  @Default.String("")
+  String getColumnTransforms();
+
+  void setColumnTransforms(String value);
 }

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/templates/bigtablechangestreamstobigquery/BigtableChangeStreamsToBigQuery.java

@@ -36,6 +36,8 @@
 import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.model.Mod;
 import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.model.ModType;
 import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.schemautils.BigQueryUtils;
+import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.schemautils.ProtoDecoder;
+import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.schemautils.ValueTransformerRegistry;
 import com.google.cloud.teleport.v2.transforms.DLQWriteTransform;
 import com.google.cloud.teleport.v2.utils.BigtableSource;
 import java.util.ArrayList;
@@ -182,6 +184,38 @@ public static PipelineResult run(BigtableChangeStreamToBigQueryOptions options)
 
     BigQueryUtils bigQuery = new BigQueryUtils(sourceInfo, destinationInfo);
 
+    ProtoDecoder protoDecoder = null;
+    boolean hasProtoSchema = !StringUtils.isBlank(options.getProtoSchemaPath());
+    boolean hasProtoMessage = !StringUtils.isBlank(options.getFullProtoMessageName());
+    boolean hasProtoColumnFamily = !StringUtils.isBlank(options.getProtoColumnFamily());
+    boolean hasProtoColumn = !StringUtils.isBlank(options.getProtoColumn());
+
+    if (hasProtoSchema || hasProtoMessage || hasProtoColumnFamily || hasProtoColumn) {
+      if (!hasProtoSchema || !hasProtoMessage || !hasProtoColumnFamily || !hasProtoColumn) {
+        throw new IllegalArgumentException(
+            "When using protobuf decoding, all of protoSchemaPath, fullProtoMessageName, "
+                + "protoColumnFamily, and protoColumn must be specified.");
+      }
+      protoDecoder =
+          new ProtoDecoder(
+              options.getProtoSchemaPath(),
+              options.getFullProtoMessageName(),
+              options.getProtoColumnFamily(),
+              options.getProtoColumn(),
+              options.getPreserveProtoFieldNames());
+      LOG.info(
+          "Proto decoding enabled for {}.{} using message type {}",
+          options.getProtoColumnFamily(),
+          options.getProtoColumn(),
+          options.getFullProtoMessageName());
+    }
+
+    ValueTransformerRegistry transformerRegistry =
+        ValueTransformerRegistry.parse(options.getColumnTransforms());
+    if (transformerRegistry != null) {
+      LOG.info("Column transforms enabled: {}", options.getColumnTransforms());
+    }
+
     Pipeline pipeline = Pipeline.create(options);
     DeadLetterQueueManager dlqManager = buildDlqManager(options);
 
@@ -213,7 +247,9 @@ public static PipelineResult run(BigtableChangeStreamToBigQueryOptions options)
     PCollection<TableRow> changeStreamMutationToTableRow =
         dataChangeRecord.apply(
             "ChangeStreamMutation To TableRow",
-            ParDo.of(new ChangeStreamMutationToTableRowFn(sourceInfo, bigQuery)));
+            ParDo.of(
+                new ChangeStreamMutationToTableRowFn(
+                    sourceInfo, bigQuery, protoDecoder, transformerRegistry)));
 
     Write<TableRow> bigQueryWrite =
         BigQueryIO.<TableRow>write()
@@ -324,10 +360,18 @@ private static String getBigQueryProjectId(BigtableChangeStreamToBigQueryOptions
   static class ChangeStreamMutationToTableRowFn extends DoFn<ChangeStreamMutation, TableRow> {
     private final BigtableSource sourceInfo;
     private final BigQueryUtils bigQuery;
-
-    ChangeStreamMutationToTableRowFn(BigtableSource source, BigQueryUtils bigQuery) {
+    private final ProtoDecoder protoDecoder;
+    private final ValueTransformerRegistry transformerRegistry;
+
+    ChangeStreamMutationToTableRowFn(
+        BigtableSource source,
+        BigQueryUtils bigQuery,
+        ProtoDecoder protoDecoder,
+        ValueTransformerRegistry transformerRegistry) {
       this.sourceInfo = source;
       this.bigQuery = bigQuery;
+      this.protoDecoder = protoDecoder;
+      this.transformerRegistry = transformerRegistry;
     }
 
     @ProcessElement
@@ -339,7 +383,7 @@ public void process(@Element ChangeStreamMutation input, OutputReceiver<TableRow
         Mod mod = null;
         switch (modType) {
           case SET_CELL:
-            mod = new Mod(sourceInfo, input, (SetCell) entry);
+            mod = new Mod(sourceInfo, input, (SetCell) entry, protoDecoder, transformerRegistry);
             break;
           case DELETE_CELLS:
             mod = new Mod(sourceInfo, input, (DeleteCells) entry);

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/templates/bigtablechangestreamstobigquery/model/Mod.java

@@ -23,6 +23,8 @@
 import com.google.cloud.bigtable.data.v2.models.DeleteFamily;
 import com.google.cloud.bigtable.data.v2.models.Range.BoundType;
 import com.google.cloud.bigtable.data.v2.models.SetCell;
+import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.schemautils.ProtoDecoder;
+import com.google.cloud.teleport.v2.templates.bigtablechangestreamstobigquery.schemautils.ValueTransformerRegistry;
 import com.google.cloud.teleport.v2.utils.BigtableSource;
 import com.google.common.collect.Maps;
 import com.google.protobuf.ByteString;
@@ -49,6 +51,8 @@ public final class Mod implements Serializable {
 
   private static final String PATTERN_FORMAT = "yyyy-MM-dd HH:mm:ss.SSSSSS";
 
+  public static final String TRANSFORMED_VALUE = "TRANSFORMED_VALUE";
+
   private static final ThreadLocal<ObjectMapper> OBJECT_MAPPER =
       ThreadLocal.withInitial(ObjectMapper::new);
 
@@ -79,6 +83,38 @@ public Mod(BigtableSource source, ChangeStreamMutation mutation, SetCell setCell
     this.changeJson = convertPropertiesToJson(propertiesMap);
   }
 
+  public Mod(
+      BigtableSource source,
+      ChangeStreamMutation mutation,
+      SetCell setCell,
+      ProtoDecoder protoDecoder,
+      ValueTransformerRegistry transformerRegistry) {
+    this(mutation.getCommitTimestamp(), ModType.SET_CELL);
+
+    Map<String, Object> propertiesMap = Maps.newHashMap();
+    setCommonProperties(propertiesMap, source, mutation);
+    setSpecificProperties(propertiesMap, setCell);
+
+    if (protoDecoder != null || transformerRegistry != null) {
+      String qualifierStr = setCell.getQualifier().toStringUtf8();
+      byte[] valueBytes = setCell.getValue().toByteArray();
+      String transformed = null;
+
+      if (protoDecoder != null && protoDecoder.matches(setCell.getFamilyName(), qualifierStr)) {
+        transformed = protoDecoder.decode(valueBytes);
+      }
+      if (transformed == null && transformerRegistry != null) {
+        transformed =
+            transformerRegistry.transform(setCell.getFamilyName(), qualifierStr, valueBytes);
+      }
+      if (transformed != null) {
+        propertiesMap.put(TRANSFORMED_VALUE, transformed);
+      }
+    }
+
+    this.changeJson = convertPropertiesToJson(propertiesMap);
+  }
+
   public Mod(BigtableSource source, ChangeStreamMutation mutation, DeleteCells deleteCells) {
     this.commitTimestampNanos = mutation.getCommitTimestamp().getNano();
     this.commitTimestampSeconds = mutation.getCommitTimestamp().getEpochSecond();

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/templates/bigtablechangestreamstobigquery/schemautils/BigEndianTimestampTransformer.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2023 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.templates.bigtablechangestreamstobigquery.schemautils;
+
+import java.nio.ByteBuffer;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Transforms an 8-byte big-endian 64-bit integer representing Unix epoch milliseconds into a
+ * BigQuery-compatible timestamp string.
+ */
+public class BigEndianTimestampTransformer implements ValueTransformer {
+
+  private static final long serialVersionUID = 1L;
+  private static final Logger LOG = LoggerFactory.getLogger(BigEndianTimestampTransformer.class);
+  private static final DateTimeFormatter FORMATTER =
+      DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSS").withZone(ZoneId.of("UTC"));
+
+  @Override
+  public String transform(byte[] bytes) {
+    if (bytes == null || bytes.length != 8) {
+      LOG.warn(
+          "Expected 8 bytes for big-endian uint64 timestamp, got {}",
+          bytes == null ? "null" : bytes.length);
+      return null;
+    }
+    try {
+      long millis = ByteBuffer.wrap(bytes).getLong();
+      return FORMATTER.format(Instant.ofEpochMilli(millis));
+    } catch (Exception e) {
+      LOG.warn("Failed to decode big-endian timestamp: {}", e.getMessage());
+      return null;
+    }
+  }
+}

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/templates/bigtablechangestreamstobigquery/schemautils/BigQueryUtils.java

@@ -94,10 +94,12 @@ public class BigQueryUtils implements Serializable {
     FORMATTERS.put(
         ChangelogColumn.VALUE_STRING,
         (bq, chg) -> {
+          if (chg.has(Mod.TRANSFORMED_VALUE)) {
+            return chg.getString(Mod.TRANSFORMED_VALUE);
+          }
           if (!chg.has(ChangelogColumn.VALUE_BYTES.name())) {
             return null;
           }
-
           String valueEncoded = chg.getString(ChangelogColumn.VALUE_BYTES.name());
           return bq.convertBase64ToString(valueEncoded);
         });

v2/googlecloud-to-googlecloud/src/main/java/com/google/cloud/teleport/v2/templates/bigtablechangestreamstobigquery/schemautils/ValueTransformer.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2023 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.templates.bigtablechangestreamstobigquery.schemautils;
+
+import java.io.Serializable;
+
+/** Transforms a Bigtable cell value from raw bytes to a string representation for BigQuery. */
+public interface ValueTransformer extends Serializable {
+
+  /**
+   * Transforms raw cell value bytes to a string for BigQuery.
+   *
+   * @param bytes the raw cell value bytes
+   * @return the transformed string, or null if transformation fails
+   */
+  String transform(byte[] bytes);
+}