minmax: fix copy index data in a wrong way (#8302) (#8305)

close #8301
pingcap · Nov 3, 2023 · 506b920 · 506b920
1 parent 1b60452
commit 506b920
Showing 1 changed file with 21 additions and 8 deletions.
diff --git a/dbms/src/Storages/DeltaMerge/Index/MinMaxIndex.cpp b/dbms/src/Storages/DeltaMerge/Index/MinMaxIndex.cpp
@@ -175,6 +175,7 @@ MinMaxIndexPtr MinMaxIndex::read(const IDataType & type, ReadBuffer & buf, size_
                                        + " vs. actual: " + std::to_string(bytes_read),
                                    Errors::DeltaTree::Internal);
     }
+    // NOLINTNEXTLINE (modernize-make-shared), std::make_shared does not support private constructor
     return MinMaxIndexPtr(new MinMaxIndex(has_null_marks, has_value_marks, std::move(minmaxes)));
 }
 
@@ -249,10 +250,13 @@ RSResult MinMaxIndex::checkNullableEqual(size_t pack_index, const Field & value,
         size_t pos = pack_index * 2;
         size_t prev_offset = pos == 0 ? 0 : offsets[pos - 1];
         // todo use StringRef instead of String
-        auto min = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        // When using String, we should use reinterpret_cast<const char *>(&chars[prev_offset]) instead of chars[prev_offset]
+        // so that it will call constructor `constexpr basic_string( const CharT* s, const Allocator& alloc = Allocator())`
+        // rather than `constexpr basic_string( size_type count, CharT ch, const Allocator& alloc = Allocator() );`
+        auto min = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         pos = pack_index * 2 + 1;
         prev_offset = offsets[pos - 1];
-        auto max = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        auto max = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         return RoughCheck::checkEqual<String>(value, type, min, max);
     }
     return RSResult::Some;
@@ -312,10 +316,13 @@ RSResult MinMaxIndex::checkEqual(size_t pack_index, const Field & value, const D
         size_t pos = pack_index * 2;
         size_t prev_offset = pos == 0 ? 0 : offsets[pos - 1];
         // todo use StringRef instead of String
-        auto min = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        // When using String, we should use reinterpret_cast<const char *>(&chars[prev_offset]) instead of chars[prev_offset]
+        // so that it will call constructor `constexpr basic_string( const CharT* s, const Allocator& alloc = Allocator())`
+        // rather than `constexpr basic_string( size_type count, CharT ch, const Allocator& alloc = Allocator() );`
+        auto min = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         pos = pack_index * 2 + 1;
         prev_offset = offsets[pos - 1];
-        auto max = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        auto max = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         return RoughCheck::checkEqual<String>(value, type, min, max);
     }
     return RSResult::Some;
@@ -378,10 +385,13 @@ RSResult MinMaxIndex::checkNullableGreater(size_t pack_index, const Field & valu
         size_t pos = pack_index * 2;
         size_t prev_offset = pos == 0 ? 0 : offsets[pos - 1];
         // todo use StringRef instead of String
-        auto min = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        // When using String, we should use reinterpret_cast<const char *>(&chars[prev_offset]) instead of chars[prev_offset]
+        // so that it will call constructor `constexpr basic_string( const CharT* s, const Allocator& alloc = Allocator())`
+        // rather than `constexpr basic_string( size_type count, CharT ch, const Allocator& alloc = Allocator() );`
+        auto min = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         pos = pack_index * 2 + 1;
         prev_offset = offsets[pos - 1];
-        auto max = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        auto max = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         return RoughCheck::checkGreater<String>(value, type, min, max);
     }
     return RSResult::Some;
@@ -441,10 +451,13 @@ RSResult MinMaxIndex::checkGreater(size_t pack_index, const Field & value, const
         size_t pos = pack_index * 2;
         size_t prev_offset = pos == 0 ? 0 : offsets[pos - 1];
         // todo use StringRef instead of String
-        auto min = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        // When using String, we should use reinterpret_cast<const char *>(&chars[prev_offset]) instead of chars[prev_offset]
+        // so that it will call constructor `constexpr basic_string( const CharT* s, const Allocator& alloc = Allocator())`
+        // rather than `constexpr basic_string( size_type count, CharT ch, const Allocator& alloc = Allocator() );`
+        auto min = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         pos = pack_index * 2 + 1;
         prev_offset = offsets[pos - 1];
-        auto max = String(chars[prev_offset], offsets[pos] - prev_offset - 1);
+        auto max = String(reinterpret_cast<const char *>(&chars[prev_offset]), offsets[pos] - prev_offset - 1);
         return RoughCheck::checkGreater<String>(value, type, min, max);
     }
     return RSResult::Some;