CHYT-636: Add minmax optimization with columnar statistics

* Changelog entry
  Type: feature
  Component: ytserver-clickhouse

Add optimization for better performance with min/max queries using columnar statistics from nodes.
commit_hash:e6d4f4e5fa25d5411a35c6e91780a364499740b7

2 files changed, 6 insertions, 5 deletions

diff --git a/yt/yt/client/table_client/columnar_statistics.cpp b/yt/yt/client/table_client/columnar_statistics.cpp
index 0b8904c2277..d14d8c66d34 100644
--- a/yt/yt/client/table_client/columnar_statistics.cpp
+++ b/yt/yt/client/table_client/columnar_statistics.cpp
@@ -28,31 +28,30 @@ TNamedColumnarStatistics& TNamedColumnarStatistics::operator+=(const TNamedColum
 
 namespace {
 
-constexpr size_t MaxStringValueLength = 100;
 constexpr auto NullUnversionedValue = MakeNullValue<TUnversionedValue>();
 
 //! Approximates long string values with shorter but lexicographically less ones. Other values are intact.
 TUnversionedOwningValue ApproximateMinValue(TUnversionedValue value)
 {
-    if (value.Type != EValueType::String || value.Length <= MaxStringValueLength) {
+    if (value.Type != EValueType::String || value.Length <= TColumnarStatistics::MaxStringValueLength) {
         value.Flags = EValueFlags::None;
         value.Id = 0;
         return value;
     }
-    return MakeUnversionedStringValue(value.AsStringBuf().SubString(0, MaxStringValueLength));
+    return MakeUnversionedStringValue(value.AsStringBuf().SubString(0, TColumnarStatistics::MaxStringValueLength));
 }
 
 //! Approximates long string values with shorter but lexicographically greater ones. Other values are intact.
 TUnversionedOwningValue ApproximateMaxValue(TUnversionedValue value)
 {
-    if (value.Type != EValueType::String || value.Length <= MaxStringValueLength) {
+    if (value.Type != EValueType::String || value.Length <= TColumnarStatistics::MaxStringValueLength) {
         value.Flags = EValueFlags::None;
         value.Id = 0;
         return value;
     }
 
     const char MaxChar = std::numeric_limits<unsigned char>::max();
-    auto truncatedStringBuf = value.AsStringBuf().SubString(0, MaxStringValueLength);
+    auto truncatedStringBuf = value.AsStringBuf().SubString(0, TColumnarStatistics::MaxStringValueLength);
 
     while (!truncatedStringBuf.empty() && truncatedStringBuf.back() == MaxChar) {
         truncatedStringBuf.remove_suffix(1);
diff --git a/yt/yt/client/table_client/columnar_statistics.h b/yt/yt/client/table_client/columnar_statistics.h
index 27af62003b6..b1cea44c642 100644
--- a/yt/yt/client/table_client/columnar_statistics.h
+++ b/yt/yt/client/table_client/columnar_statistics.h
@@ -54,6 +54,8 @@ struct TLargeColumnarStatistics
 //! TColumnarStatistics stores per-column statistics of data stored in a chunk/table.
 struct TColumnarStatistics
 {
+    static constexpr size_t MaxStringValueLength = 100;
+
     //! Per-column total data weight for chunks whose meta contains columnar statistics.
     std::vector<i64> ColumnDataWeights;
     //! Total weight of all write and delete timestamps.