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#pragma once
#include <optional>
#include <Columns/IColumn.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NOT_IMPLEMENTED;
}
/// Sort of a dictionary
class IColumnUnique : public IColumn
{
public:
using ColumnUniquePtr = IColumn::template immutable_ptr<IColumnUnique>;
using MutableColumnUniquePtr = IColumn::template mutable_ptr<IColumnUnique>;
/// Column always contains Null if it's Nullable and empty string if it's String or Nullable(String).
/// So, size may be greater than the number of inserted unique values.
virtual const ColumnPtr & getNestedColumn() const = 0;
/// The same as getNestedColumn, but removes null map if nested column is nullable.
virtual const ColumnPtr & getNestedNotNullableColumn() const = 0;
virtual bool nestedColumnIsNullable() const = 0;
virtual void nestedToNullable() = 0;
virtual void nestedRemoveNullable() = 0;
/// Returns array with StringRefHash calculated for each row of getNestedNotNullableColumn() column.
/// Returns nullptr if nested column doesn't contain strings. Otherwise calculates hash (if it wasn't).
/// Uses thread-safe cache.
virtual const UInt64 * tryGetSavedHash() const = 0;
size_t size() const override { return getNestedNotNullableColumn()->size(); }
/// Appends new value at the end of column (column's size is increased by 1).
/// Is used to transform raw strings to Blocks (for example, inside input format parsers)
virtual size_t uniqueInsert(const Field & x) = 0;
virtual size_t uniqueInsertFrom(const IColumn & src, size_t n) = 0;
/// Appends range of elements from other column.
/// Could be used to concatenate columns.
virtual MutableColumnPtr uniqueInsertRangeFrom(const IColumn & src, size_t start, size_t length) = 0;
struct IndexesWithOverflow
{
MutableColumnPtr indexes;
MutableColumnPtr overflowed_keys;
};
/// Like uniqueInsertRangeFrom, but doesn't insert keys if inner dictionary has more than max_dictionary_size keys.
/// Keys that won't be inserted into dictionary will be into overflowed_keys, indexes will be calculated for
/// concatenation of nested column (which can be got from getNestedColumn() function) and overflowed_keys.
virtual IndexesWithOverflow uniqueInsertRangeWithOverflow(const IColumn & src, size_t start,
size_t length, size_t max_dictionary_size) = 0;
/// Appends data located in specified memory chunk if it is possible (throws an exception if it cannot be implemented).
/// Is used to optimize some computations (in aggregation, for example).
/// Parameter length could be ignored if column values have fixed size.
virtual size_t uniqueInsertData(const char * pos, size_t length) = 0;
virtual size_t getDefaultValueIndex() const = 0; /// Nullable ? getNullValueIndex : getNestedTypeDefaultValueIndex
virtual size_t getNullValueIndex() const = 0; /// Throws if not nullable.
virtual size_t getNestedTypeDefaultValueIndex() const = 0; /// removeNullable()->getDefault() value index
virtual bool canContainNulls() const = 0;
virtual size_t uniqueDeserializeAndInsertFromArena(const char * pos, const char *& new_pos) = 0;
/// Returns dictionary hash which is SipHash is applied to each row of nested column.
virtual UInt128 getHash() const = 0;
const char * getFamilyName() const override { return "ColumnUnique"; }
TypeIndex getDataType() const override { return getNestedColumn()->getDataType(); }
void insert(const Field &) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method insert is not supported for ColumnUnique.");
}
void insertRangeFrom(const IColumn &, size_t, size_t) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method insertRangeFrom is not supported for ColumnUnique.");
}
void insertData(const char *, size_t) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method insertData is not supported for ColumnUnique.");
}
void insertDefault() override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method insertDefault is not supported for ColumnUnique.");
}
void popBack(size_t) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method popBack is not supported for ColumnUnique.");
}
void gather(ColumnGathererStream &) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method gather is not supported for ColumnUnique.");
}
const char * deserializeAndInsertFromArena(const char *) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method deserializeAndInsertFromArena is not supported for ColumnUnique.");
}
ColumnPtr index(const IColumn &, size_t) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method index is not supported for ColumnUnique.");
}
ColumnPtr cut(size_t, size_t) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method cut is not supported for ColumnUnique.");
}
ColumnPtr filter(const IColumn::Filter &, ssize_t) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method filter is not supported for ColumnUnique.");
}
void expand(const IColumn::Filter &, bool) override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method expand is not supported for ColumnUnique.");
}
ColumnPtr permute(const IColumn::Permutation &, size_t) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method permute is not supported for ColumnUnique.");
}
ColumnPtr replicate(const IColumn::Offsets &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method replicate is not supported for ColumnUnique.");
}
void getPermutation(IColumn::PermutationSortDirection, IColumn::PermutationSortStability,
size_t, int, IColumn::Permutation &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method getPermutation is not supported for ColumnUnique.");
}
void updatePermutation(PermutationSortDirection, PermutationSortStability,
size_t, int, Permutation &, EqualRanges &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method getPermutation is not supported for ColumnUnique.");
}
std::vector<MutableColumnPtr> scatter(IColumn::ColumnIndex, const IColumn::Selector &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method scatter is not supported for ColumnUnique.");
}
void updateWeakHash32(WeakHash32 &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method updateWeakHash32 is not supported for ColumnUnique.");
}
void updateHashFast(SipHash &) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method updateHashFast is not supported for ColumnUnique.");
}
void compareColumn(const IColumn &, size_t, PaddedPODArray<UInt64> *, PaddedPODArray<Int8> &, int, int) const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method compareColumn is not supported for ColumnUnique.");
}
bool hasEqualValues() const override
{
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Method hasEqualValues is not supported for ColumnUnique.");
}
/** Given some value (usually, of type @e ColumnType) @p value that is convertible to DB::StringRef, obtains its
* index in the DB::ColumnUnique::reverse_index hashtable.
*
* The reverse index (StringRef => UInt64) is built lazily, so there are two variants:
* - On the function call it's present. Therefore we obtain the index in O(1).
* - The reverse index is absent. We search for the index linearly.
*
* @see DB::ReverseIndex
* @see DB::ColumnUnique
*
* The most common example uses https://clickhouse.com/docs/en/sql-reference/data-types/lowcardinality/ columns.
* Consider data type @e LC(String). The inner type here is @e String which is more or less a contiguous memory
* region, so it can be easily represented as a @e StringRef. So we pass that ref to this function and get its
* index in the dictionary, which can be used to operate with the indices column.
*/
virtual std::optional<UInt64> getOrFindValueIndex(StringRef value) const = 0;
};
using ColumnUniquePtr = IColumnUnique::ColumnUniquePtr;
using MutableColumnUniquePtr = IColumnUnique::MutableColumnUniquePtr;
}
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