From cef9eb80d9004b55887e3a88063fba8300b721f9 Mon Sep 17 00:00:00 2001
From: Anton Popov <anton@clickhouse.com>
Date: Tue, 3 Sep 2024 22:47:59 +0000
Subject: [PATCH] better checkpoints for ColumnString

---
 src/Columns/ColumnString.cpp | 17 +++++++++++++++++
 src/Columns/ColumnString.h   |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/src/Columns/ColumnString.cpp b/src/Columns/ColumnString.cpp
index 00cf3bd9c30..269c20397b4 100644
--- a/src/Columns/ColumnString.cpp
+++ b/src/Columns/ColumnString.cpp
@@ -240,6 +240,23 @@ ColumnPtr ColumnString::permute(const Permutation & perm, size_t limit) const
     return permuteImpl(*this, perm, limit);
 }
 
+ColumnCheckpointPtr ColumnString::getCheckpoint() const
+{
+    auto nested = std::make_shared<ColumnCheckpoint>(chars.size());
+    return std::make_shared<ColumnCheckpointWithNested>(size(), std::move(nested));
+}
+
+void ColumnString::updateCheckpoint(ColumnCheckpoint & checkpoint) const
+{
+    checkpoint.size = size();
+    assert_cast<ColumnCheckpointWithNested &>(checkpoint).nested->size = chars.size();
+}
+
+void ColumnString::rollback(const ColumnCheckpoint & checkpoint)
+{
+    offsets.resize_assume_reserved(checkpoint.size);
+    chars.resize_assume_reserved(assert_cast<const ColumnCheckpointWithNested &>(checkpoint).nested->size);
+}
 
 void ColumnString::collectSerializedValueSizes(PaddedPODArray<UInt64> & sizes, const UInt8 * is_null) const
 {
diff --git a/src/Columns/ColumnString.h b/src/Columns/ColumnString.h
index ec0563b3f00..c2371412437 100644
--- a/src/Columns/ColumnString.h
+++ b/src/Columns/ColumnString.h
@@ -194,6 +194,10 @@ public:
         offsets.resize_assume_reserved(offsets.size() - n);
     }
 
+    ColumnCheckpointPtr getCheckpoint() const override;
+    void updateCheckpoint(ColumnCheckpoint & checkpoint) const override;
+    void rollback(const ColumnCheckpoint & checkpoint) override;
+
     void collectSerializedValueSizes(PaddedPODArray<UInt64> & sizes, const UInt8 * is_null) const override;
 
     StringRef serializeValueIntoArena(size_t n, Arena & arena, char const *& begin) const override;