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423 lines
16 KiB
C++
423 lines
16 KiB
C++
#pragma once
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#include <variant>
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#include <optional>
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#include <shared_mutex>
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#include <deque>
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#include <vector>
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#include <Parsers/ASTTablesInSelectQuery.h>
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#include <Interpreters/IJoin.h>
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#include <Interpreters/AggregationCommon.h>
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#include <Interpreters/RowRefs.h>
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#include <Common/Arena.h>
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#include <Common/ColumnsHashing.h>
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#include <Common/HashTable/HashMap.h>
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#include <Common/HashTable/FixedHashMap.h>
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#include <Storages/TableLockHolder.h>
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#include <Common/logger_useful.h>
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#include <Columns/ColumnString.h>
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#include <Columns/ColumnFixedString.h>
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#include <QueryPipeline/SizeLimits.h>
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#include <Core/Block.h>
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#include <Storages/IStorage_fwd.h>
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#include <Interpreters/IKeyValueEntity.h>
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namespace DB
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{
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class TableJoin;
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namespace JoinStuff
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{
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/// Flags needed to implement RIGHT and FULL JOINs.
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class JoinUsedFlags
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{
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using RawBlockPtr = const Block *;
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using UsedFlagsForBlock = std::vector<std::atomic_bool>;
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/// For multiple dijuncts each empty in hashmap stores flags for particular block
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/// For single dicunct we store all flags in `nullptr` entry, index is the offset in FindResult
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std::unordered_map<RawBlockPtr, UsedFlagsForBlock> flags;
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bool need_flags;
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public:
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/// Update size for vector with flags.
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/// Calling this method invalidates existing flags.
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/// It can be called several times, but all of them should happen before using this structure.
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template <JoinKind KIND, JoinStrictness STRICTNESS>
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void reinit(size_t size_);
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template <JoinKind KIND, JoinStrictness STRICTNESS>
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void reinit(const Block * block_ptr);
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bool getUsedSafe(size_t i) const;
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bool getUsedSafe(const Block * block_ptr, size_t row_idx) const;
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template <bool use_flags, bool multiple_disjuncts, typename T>
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void setUsed(const T & f);
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template <bool use_flags, bool multiple_disjunct>
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void setUsed(const Block * block, size_t row_num, size_t offset);
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template <bool use_flags, bool multiple_disjuncts, typename T>
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bool getUsed(const T & f);
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template <bool use_flags, bool multiple_disjuncts, typename T>
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bool setUsedOnce(const T & f);
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};
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}
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/** Data structure for implementation of JOIN.
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* It is just a hash table: keys -> rows of joined ("right") table.
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* Additionally, CROSS JOIN is supported: instead of hash table, it use just set of blocks without keys.
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*
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* JOIN-s could be of these types:
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* - ALL × LEFT/INNER/RIGHT/FULL
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* - ANY × LEFT/INNER/RIGHT
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* - SEMI/ANTI x LEFT/RIGHT
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* - ASOF x LEFT/INNER
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* - CROSS
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*
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* ALL means usual JOIN, when rows are multiplied by number of matching rows from the "right" table.
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* ANY uses one line per unique key from right table. For LEFT JOIN it would be any row (with needed joined key) from the right table,
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* for RIGHT JOIN it would be any row from the left table and for INNER one it would be any row from right and any row from left.
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* SEMI JOIN filter left table by keys that are present in right table for LEFT JOIN, and filter right table by keys from left table
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* for RIGHT JOIN. In other words SEMI JOIN returns only rows which joining keys present in another table.
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* ANTI JOIN is the same as SEMI JOIN but returns rows with joining keys that are NOT present in another table.
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* SEMI/ANTI JOINs allow to get values from both tables. For filter table it gets any row with joining same key. For ANTI JOIN it returns
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* defaults other table columns.
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* ASOF JOIN is not-equi join. For one key column it finds nearest value to join according to join inequality.
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* It's expected that ANY|SEMI LEFT JOIN is more efficient that ALL one.
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*
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* If INNER is specified - leave only rows that have matching rows from "right" table.
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* If LEFT is specified - in case when there is no matching row in "right" table, fill it with default values instead.
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* If RIGHT is specified - first process as INNER, but track what rows from the right table was joined,
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* and at the end, add rows from right table that was not joined and substitute default values for columns of left table.
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* If FULL is specified - first process as LEFT, but track what rows from the right table was joined,
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* and at the end, add rows from right table that was not joined and substitute default values for columns of left table.
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*
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* Thus, LEFT and RIGHT JOINs are not symmetric in terms of implementation.
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*
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* All JOINs (except CROSS) are done by equality condition on keys (equijoin).
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* Non-equality and other conditions are not supported.
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*
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* Implementation:
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*
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* 1. Build hash table in memory from "right" table.
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* This hash table is in form of keys -> row in case of ANY or keys -> [rows...] in case of ALL.
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* This is done in insertFromBlock method.
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*
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* 2. Process "left" table and join corresponding rows from "right" table by lookups in the map.
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* This is done in joinBlock methods.
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*
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* In case of ANY LEFT JOIN - form new columns with found values or default values.
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* This is the most simple. Number of rows in left table does not change.
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*
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* In case of ANY INNER JOIN - form new columns with found values,
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* and also build a filter - in what rows nothing was found.
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* Then filter columns of "left" table.
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*
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* In case of ALL ... JOIN - form new columns with all found rows,
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* and also fill 'offsets' array, describing how many times we need to replicate values of "left" table.
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* Then replicate columns of "left" table.
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*
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* How Nullable keys are processed:
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*
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* NULLs never join to anything, even to each other.
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* During building of map, we just skip keys with NULL value of any component.
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* During joining, we simply treat rows with any NULLs in key as non joined.
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*
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* Default values for outer joins (LEFT, RIGHT, FULL):
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*
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* Behaviour is controlled by 'join_use_nulls' settings.
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* If it is false, we substitute (global) default value for the data type, for non-joined rows
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* (zero, empty string, etc. and NULL for Nullable data types).
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* If it is true, we always generate Nullable column and substitute NULLs for non-joined rows,
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* as in standard SQL.
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*/
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class HashJoin : public IJoin
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{
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public:
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HashJoin(std::shared_ptr<TableJoin> table_join_, const Block & right_sample_block, bool any_take_last_row_ = false);
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const TableJoin & getTableJoin() const override { return *table_join; }
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/** Add block of data from right hand of JOIN to the map.
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* Returns false, if some limit was exceeded and you should not insert more data.
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*/
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bool addJoinedBlock(const Block & block, bool check_limits) override;
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void checkTypesOfKeys(const Block & block) const override;
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/** Join data from the map (that was previously built by calls to addJoinedBlock) to the block with data from "left" table.
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* Could be called from different threads in parallel.
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*/
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void joinBlock(Block & block, ExtraBlockPtr & not_processed) override;
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/// Check joinGet arguments and infer the return type.
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DataTypePtr joinGetCheckAndGetReturnType(const DataTypes & data_types, const String & column_name, bool or_null) const;
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/// Used by joinGet function that turns StorageJoin into a dictionary.
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ColumnWithTypeAndName joinGet(const Block & block, const Block & block_with_columns_to_add) const;
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bool isFilled() const override { return from_storage_join; }
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JoinPipelineType pipelineType() const override
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{
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/// No need to process anything in the right stream if hash table was already filled
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if (from_storage_join)
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return JoinPipelineType::FilledRight;
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/// Default pipeline processes right stream at first and then left.
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return JoinPipelineType::FillRightFirst;
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}
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/** For RIGHT and FULL JOINs.
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* A stream that will contain default values from left table, joined with rows from right table, that was not joined before.
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* Use only after all calls to joinBlock was done.
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* left_sample_block is passed without account of 'use_nulls' setting (columns will be converted to Nullable inside).
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*/
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std::shared_ptr<NotJoinedBlocks> getNonJoinedBlocks(
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const Block & left_sample_block, const Block & result_sample_block, UInt64 max_block_size) const override;
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/// Number of keys in all built JOIN maps.
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size_t getTotalRowCount() const final;
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/// Sum size in bytes of all buffers, used for JOIN maps and for all memory pools.
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size_t getTotalByteCount() const final;
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bool alwaysReturnsEmptySet() const final;
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JoinKind getKind() const { return kind; }
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JoinStrictness getStrictness() const { return strictness; }
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const std::optional<TypeIndex> & getAsofType() const { return asof_type; }
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ASOFJoinInequality getAsofInequality() const { return asof_inequality; }
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bool anyTakeLastRow() const { return any_take_last_row; }
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const ColumnWithTypeAndName & rightAsofKeyColumn() const;
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/// Different types of keys for maps.
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#define APPLY_FOR_JOIN_VARIANTS(M) \
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M(key8) \
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M(key16) \
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M(key32) \
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M(key64) \
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M(key_string) \
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M(key_fixed_string) \
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M(keys128) \
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M(keys256) \
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M(hashed)
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/// Used for reading from StorageJoin and applying joinGet function
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#define APPLY_FOR_JOIN_VARIANTS_LIMITED(M) \
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M(key8) \
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M(key16) \
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M(key32) \
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M(key64) \
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M(key_string) \
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M(key_fixed_string)
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enum class Type
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{
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EMPTY,
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CROSS,
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#define M(NAME) NAME,
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APPLY_FOR_JOIN_VARIANTS(M)
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#undef M
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};
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/** Different data structures, that are used to perform JOIN.
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*/
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template <typename Mapped>
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struct MapsTemplate
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{
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using MappedType = Mapped;
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std::unique_ptr<FixedHashMap<UInt8, Mapped>> key8;
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std::unique_ptr<FixedHashMap<UInt16, Mapped>> key16;
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std::unique_ptr<HashMap<UInt32, Mapped, HashCRC32<UInt32>>> key32;
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std::unique_ptr<HashMap<UInt64, Mapped, HashCRC32<UInt64>>> key64;
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std::unique_ptr<HashMapWithSavedHash<StringRef, Mapped>> key_string;
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std::unique_ptr<HashMapWithSavedHash<StringRef, Mapped>> key_fixed_string;
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std::unique_ptr<HashMap<UInt128, Mapped, UInt128HashCRC32>> keys128;
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std::unique_ptr<HashMap<UInt256, Mapped, UInt256HashCRC32>> keys256;
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std::unique_ptr<HashMap<UInt128, Mapped, UInt128TrivialHash>> hashed;
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void create(Type which)
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{
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switch (which)
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{
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case Type::EMPTY: break;
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case Type::CROSS: break;
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#define M(NAME) \
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case Type::NAME: NAME = std::make_unique<typename decltype(NAME)::element_type>(); break;
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APPLY_FOR_JOIN_VARIANTS(M)
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#undef M
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}
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}
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size_t getTotalRowCount(Type which) const
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{
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switch (which)
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{
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case Type::EMPTY: return 0;
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case Type::CROSS: return 0;
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#define M(NAME) \
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case Type::NAME: return NAME ? NAME->size() : 0;
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APPLY_FOR_JOIN_VARIANTS(M)
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#undef M
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}
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UNREACHABLE();
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}
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size_t getTotalByteCountImpl(Type which) const
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{
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switch (which)
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{
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case Type::EMPTY: return 0;
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case Type::CROSS: return 0;
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#define M(NAME) \
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case Type::NAME: return NAME ? NAME->getBufferSizeInBytes() : 0;
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APPLY_FOR_JOIN_VARIANTS(M)
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#undef M
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}
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UNREACHABLE();
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}
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size_t getBufferSizeInCells(Type which) const
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{
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switch (which)
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{
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case Type::EMPTY: return 0;
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case Type::CROSS: return 0;
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#define M(NAME) \
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case Type::NAME: return NAME ? NAME->getBufferSizeInCells() : 0;
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APPLY_FOR_JOIN_VARIANTS(M)
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#undef M
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}
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UNREACHABLE();
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}
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};
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using MapsOne = MapsTemplate<RowRef>;
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using MapsAll = MapsTemplate<RowRefList>;
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using MapsAsof = MapsTemplate<AsofRowRefs>;
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using MapsVariant = std::variant<MapsOne, MapsAll, MapsAsof>;
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using RawBlockPtr = const Block *;
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using BlockNullmapList = std::deque<std::pair<RawBlockPtr, ColumnPtr>>;
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struct RightTableData
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{
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Type type = Type::EMPTY;
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bool empty = true;
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std::vector<MapsVariant> maps;
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Block sample_block; /// Block as it would appear in the BlockList
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BlocksList blocks; /// Blocks of "right" table.
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BlockNullmapList blocks_nullmaps; /// Nullmaps for blocks of "right" table (if needed)
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/// Additional data - strings for string keys and continuation elements of single-linked lists of references to rows.
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Arena pool;
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};
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using RightTableDataPtr = std::shared_ptr<RightTableData>;
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/// We keep correspondence between used_flags and hash table internal buffer.
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/// Hash table cannot be modified during HashJoin lifetime and must be protected with lock.
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void setLock(TableLockHolder rwlock_holder)
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{
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storage_join_lock = rwlock_holder;
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}
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void reuseJoinedData(const HashJoin & join);
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RightTableDataPtr getJoinedData() const { return data; }
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bool isUsed(size_t off) const { return used_flags.getUsedSafe(off); }
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bool isUsed(const Block * block_ptr, size_t row_idx) const { return used_flags.getUsedSafe(block_ptr, row_idx); }
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private:
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template<bool> friend class NotJoinedHash;
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friend class JoinSource;
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std::shared_ptr<TableJoin> table_join;
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const JoinKind kind;
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const JoinStrictness strictness;
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/// This join was created from StorageJoin and it is already filled.
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bool from_storage_join = false;
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bool any_take_last_row; /// Overwrite existing values when encountering the same key again
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std::optional<TypeIndex> asof_type;
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const ASOFJoinInequality asof_inequality;
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/// Right table data. StorageJoin shares it between many Join objects.
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/// Flags that indicate that particular row already used in join.
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/// Flag is stored for every record in hash map.
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/// Number of this flags equals to hashtable buffer size (plus one for zero value).
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/// Changes in hash table broke correspondence,
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/// so we must guarantee constantness of hash table during HashJoin lifetime (using method setLock)
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mutable JoinStuff::JoinUsedFlags used_flags;
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RightTableDataPtr data;
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std::vector<Sizes> key_sizes;
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/// Block with columns from the right-side table.
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Block right_sample_block;
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/// Block with columns from the right-side table except key columns.
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Block sample_block_with_columns_to_add;
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/// Block with key columns in the same order they appear in the right-side table (duplicates appear once).
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Block right_table_keys;
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/// Block with key columns right-side table keys that are needed in result (would be attached after joined columns).
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Block required_right_keys;
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/// Left table column names that are sources for required_right_keys columns
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std::vector<String> required_right_keys_sources;
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Poco::Logger * log;
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/// Should be set via setLock to protect hash table from modification from StorageJoin
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/// If set HashJoin instance is not available for modification (addJoinedBlock)
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TableLockHolder storage_join_lock = nullptr;
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void dataMapInit(MapsVariant &);
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const Block & savedBlockSample() const { return data->sample_block; }
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/// Modify (structure) right block to save it in block list
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Block structureRightBlock(const Block & stored_block) const;
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void initRightBlockStructure(Block & saved_block_sample);
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template <JoinKind KIND, JoinStrictness STRICTNESS, typename Maps>
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void joinBlockImpl(
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Block & block,
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const Block & block_with_columns_to_add,
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const std::vector<const Maps *> & maps_,
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bool is_join_get = false) const;
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void joinBlockImplCross(Block & block, ExtraBlockPtr & not_processed) const;
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static Type chooseMethod(JoinKind kind, const ColumnRawPtrs & key_columns, Sizes & key_sizes);
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bool empty() const;
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};
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}
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