ClickHouse/dbms/src/Interpreters/Set.h

#pragma once

#include <shared_mutex>
#include <Core/Block.h>
#include <DataStreams/SizeLimits.h>
#include <DataTypes/IDataType.h>
#include <Interpreters/SetVariants.h>
#include <Interpreters/Context.h>
#include <Parsers/IAST.h>
#include <Storages/MergeTree/BoolMask.h>

#include <common/logger_useful.h>


namespace DB
{

struct Range;
class FieldWithInfinity;

class IFunctionBase;
using FunctionBasePtr = std::shared_ptr<IFunctionBase>;


/** Data structure for implementation of IN expression.
  */
class Set
{
public:
    /// 'fill_set_elements': in addition to hash table
    /// (that is useful only for checking that some value is in the set and may not store the original values),
    /// store all set elements in explicit form.
    /// This is needed for subsequent use for index.
    Set(const SizeLimits & limits, bool fill_set_elements)
        : log(&Logger::get("Set")),
        limits(limits), fill_set_elements(fill_set_elements)
    {
    }

    bool empty() const { return data.empty(); }

    /** Set can be created either from AST or from a stream of data (subquery result).
      */

    /** Create a Set from expression (specified literally in the query).
      * 'types' - types of what are on the left hand side of IN.
      * 'node' - list of values: 1, 2, 3 or list of tuples: (1, 2), (3, 4), (5, 6).
      * 'fill_set_elements' - if true, fill vector of elements. For primary key to work.
      */
    void createFromAST(const DataTypes & types, ASTPtr node, const Context & context);

    /** Create a Set from stream.
      * Call setHeader, then call insertFromBlock for each block.
      */
    void setHeader(const Block & header);

    /// Returns false, if some limit was exceeded and no need to insert more data.
    bool insertFromBlock(const Block & block);

    /** For columns of 'block', check belonging of corresponding rows to the set.
      * Return UInt8 column with the result.
      */
    ColumnPtr execute(const Block & block, bool negative) const;

    size_t getTotalRowCount() const { return data.getTotalRowCount(); }
    size_t getTotalByteCount() const { return data.getTotalByteCount(); }

    const DataTypes & getDataTypes() const { return data_types; }

    bool hasExplicitSetElements() const { return fill_set_elements; }
    Columns getSetElements() const { return { set_elements.begin(), set_elements.end() }; }

private:
    size_t keys_size = 0;
    Sizes key_sizes;

    SetVariants data;

    /** How IN works with Nullable types.
      *
      * For simplicity reasons, all NULL values and any tuples with at least one NULL element are ignored in the Set.
      * And for left hand side values, that are NULLs or contain any NULLs, we return 0 (means that element is not in Set).
      *
      * If we want more standard compliant behaviour, we must return NULL
      *  if lhs is NULL and set is not empty or if lhs is not in set, but set contains at least one NULL.
      * It is more complicated with tuples.
      * For example,
      *      (1, NULL, 2) IN ((1, NULL, 3)) must return 0,
      *  but (1, NULL, 2) IN ((1, 1111, 2)) must return NULL.
      *
      * We have not implemented such sophisticated behaviour.
      */

    /** The data types from which the set was created.
      * When checking for belonging to a set, the types of columns to be checked must match with them.
      */
    DataTypes data_types;

    Logger * log;

    /// Limitations on the maximum size of the set
    SizeLimits limits;

    /// Do we need to additionally store all elements of the set in explicit form for subsequent use for index.
    bool fill_set_elements;

    /// If in the left part columns contains the same types as the elements of the set.
    void executeOrdinary(
        const ColumnRawPtrs & key_columns,
        ColumnUInt8::Container & vec_res,
        bool negative,
        const PaddedPODArray<UInt8> * null_map) const;

    /// Collected elements of `Set`.
    /// It is necessary for the index to work on the primary key in the IN statement.
    std::vector<IColumn::WrappedPtr> set_elements;

    /** Protects work with the set in the functions `insertFromBlock` and `execute`.
      * These functions can be called simultaneously from different threads only when using StorageSet,
      *  and StorageSet calls only these two functions.
      * Therefore, the rest of the functions for working with set are not protected.
      */
    mutable std::shared_mutex rwlock;

    template <typename Method>
    void insertFromBlockImpl(
        Method & method,
        const ColumnRawPtrs & key_columns,
        size_t rows,
        SetVariants & variants,
        ConstNullMapPtr null_map,
        ColumnUInt8::Container * out_filter);

    template <typename Method, bool has_null_map, bool build_filter>
    void insertFromBlockImplCase(
        Method & method,
        const ColumnRawPtrs & key_columns,
        size_t rows,
        SetVariants & variants,
        ConstNullMapPtr null_map,
        ColumnUInt8::Container * out_filter);

    template <typename Method>
    void executeImpl(
        Method & method,
        const ColumnRawPtrs & key_columns,
        ColumnUInt8::Container & vec_res,
        bool negative,
        size_t rows,
        ConstNullMapPtr null_map) const;

    template <typename Method, bool has_null_map>
    void executeImplCase(
        Method & method,
        const ColumnRawPtrs & key_columns,
        ColumnUInt8::Container & vec_res,
        bool negative,
        size_t rows,
        ConstNullMapPtr null_map) const;
};

using SetPtr = std::shared_ptr<Set>;
using ConstSetPtr = std::shared_ptr<const Set>;
using Sets = std::vector<SetPtr>;


class IFunction;
using FunctionPtr = std::shared_ptr<IFunction>;

/// Class for checkInRange function.
class MergeTreeSetIndex
{
public:
    /** Mapping for tuple positions from Set::set_elements to
      * position of pk index and functions chain applied to this column.
      */
    struct KeyTuplePositionMapping
    {
        size_t tuple_index;
        size_t key_index;
        std::vector<FunctionBasePtr> functions;
    };

    MergeTreeSetIndex(const Columns & set_elements, std::vector<KeyTuplePositionMapping> && indexes_mapping_);

    size_t size() const { return ordered_set.at(0)->size(); }

    BoolMask checkInRange(const std::vector<Range> & key_ranges, const DataTypes & data_types);

private:
    Columns ordered_set;
    std::vector<KeyTuplePositionMapping> indexes_mapping;
};

}