From 296c6eec27ce116815c3ef1d518fefad37d46a61 Mon Sep 17 00:00:00 2001
From: Igor Bernstein <igorbernstein@google.com>
Date: Tue, 27 Oct 2026 18:02:11 -0400
Subject: [PATCH] fix(bigtable): pass cell value size to RowBuilder.startCell
 in RowBuilderShim

---
 .../internal/compat/ops/RowBuilderShim.java   |  2 +-
 .../bigtable/data/v2/models/RowAdapter.java   |  8 ++++-
 .../compat/ops/RowBuilderShimTest.java        | 31 +++++++++++++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShim.java b/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShim.java
index d360f8d09a41..adab5cdd00f8 100644
--- a/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShim.java
+++ b/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShim.java
@@ -77,7 +77,7 @@ static <RowT> RowT buildRowFromProto(RowAdapter<RowT> adapter, Row protoRow) {
               column.getQualifier(),
               cell.getTimestampMicros(),
               cell.getLabelsList(),
-              0);
+              cell.getValue().size());
           builder.cellValue(cell.getValue());
           builder.finishCell();
         }
diff --git a/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/models/RowAdapter.java b/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/models/RowAdapter.java
index 874529bbe1c6..c6eb320af6ac 100644
--- a/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/models/RowAdapter.java
+++ b/java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/data/v2/models/RowAdapter.java
@@ -59,7 +59,13 @@ interface RowBuilder<RowT> {
     /** Called to start a new row. This will be called once per row. */
     void startRow(ByteString key);
 
-    /** Called to start a new cell in a row. */
+    /**
+     * Called to start a new cell in a row.
+     *
+     * <p>Note: Unlike {@link com.google.bigtable.v2.ReadRowsResponse.CellChunk#getValueSize()},
+     * which is {@code 0} when a cell is not split across chunks, {@code size} is always the total
+     * byte size of the cell value.
+     */
     void startCell(
         String family, ByteString qualifier, long timestamp, List<String> labels, long size);
 
diff --git a/java-bigtable/google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShimTest.java b/java-bigtable/google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShimTest.java
index d59390ff88d0..8b8f01157fe6 100644
--- a/java-bigtable/google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShimTest.java
+++ b/java-bigtable/google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/internal/compat/ops/RowBuilderShimTest.java
@@ -160,4 +160,35 @@ void buildRowFromProto_multipleFamiliesAndCells_roundTrips() {
                     RowCell.create("f1", col, 1_000, ImmutableList.of("lbl"), val1),
                     RowCell.create("f2", col, 2_000, ImmutableList.of("lbl"), val2))));
   }
+
+  @Test
+  void buildRowFromProto_passesCellValueSizeToStartCell() {
+    ByteString key = ByteString.copyFromUtf8("key");
+    ByteString col = ByteString.copyFromUtf8("col");
+    ByteString val = ByteString.copyFromUtf8("hello-world");
+
+    Row proto =
+        Row.newBuilder()
+            .setKey(key)
+            .addFamilies(
+                com.google.bigtable.v2.Family.newBuilder()
+                    .setName("f1")
+                    .addColumns(
+                        com.google.bigtable.v2.Column.newBuilder()
+                            .setQualifier(col)
+                            .addCells(
+                                com.google.bigtable.v2.Cell.newBuilder()
+                                    .setTimestampMicros(1_000)
+                                    .setValue(val)
+                                    .addLabels("lbl"))))
+            .build();
+
+    RowBuilderShim.buildRowFromProto(adapter, proto);
+
+    verify(rowBuilder).startRow(key);
+    verify(rowBuilder).startCell("f1", col, 1_000L, ImmutableList.of("lbl"), val.size());
+    verify(rowBuilder).cellValue(val);
+    verify(rowBuilder).finishCell();
+    verify(rowBuilder).finishRow();
+  }
 }