1 | #pragma once |
2 | |
3 | #include <ext/shared_ptr_helper.h> |
4 | |
5 | #include <Common/OptimizedRegularExpression.h> |
6 | #include <Storages/IStorage.h> |
7 | |
8 | |
9 | namespace DB |
10 | { |
11 | |
12 | /** A table that represents the union of an arbitrary number of other tables. |
13 | * All tables must have the same structure. |
14 | */ |
15 | class StorageMerge : public ext::shared_ptr_helper<StorageMerge>, public IStorage |
16 | { |
17 | friend struct ext::shared_ptr_helper<StorageMerge>; |
18 | public: |
19 | std::string getName() const override { return "Merge" ; } |
20 | std::string getTableName() const override { return table_name; } |
21 | std::string getDatabaseName() const override { return database_name; } |
22 | |
23 | bool isRemote() const override; |
24 | |
25 | /// The check is delayed to the read method. It checks the support of the tables used. |
26 | bool supportsSampling() const override { return true; } |
27 | bool supportsPrewhere() const override { return true; } |
28 | bool supportsFinal() const override { return true; } |
29 | bool supportsIndexForIn() const override { return true; } |
30 | |
31 | /// Consider columns coming from the underlying tables |
32 | NameAndTypePair getColumn(const String & column_name) const override; |
33 | bool hasColumn(const String & column_name) const override; |
34 | |
35 | QueryProcessingStage::Enum getQueryProcessingStage(const Context &) const override; |
36 | |
37 | BlockInputStreams read( |
38 | const Names & column_names, |
39 | const SelectQueryInfo & query_info, |
40 | const Context & context, |
41 | QueryProcessingStage::Enum processed_stage, |
42 | size_t max_block_size, |
43 | unsigned num_streams) override; |
44 | |
45 | void rename(const String & /*new_path_to_db*/, const String & new_database_name, const String & new_table_name, TableStructureWriteLockHolder &) override |
46 | { |
47 | table_name = new_table_name; |
48 | database_name = new_database_name; |
49 | } |
50 | |
51 | |
52 | void checkAlterIsPossible(const AlterCommands & commands, const Settings & /* settings */) override; |
53 | |
54 | /// you need to add and remove columns in the sub-tables manually |
55 | /// the structure of sub-tables is not checked |
56 | void alter(const AlterCommands & params, const Context & context, TableStructureWriteLockHolder & table_lock_holder) override; |
57 | |
58 | bool mayBenefitFromIndexForIn(const ASTPtr & left_in_operand, const Context & query_context) const override; |
59 | |
60 | private: |
61 | String table_name; |
62 | String database_name; |
63 | String source_database; |
64 | OptimizedRegularExpression table_name_regexp; |
65 | Context global_context; |
66 | |
67 | using StorageListWithLocks = std::list<std::pair<StoragePtr, TableStructureReadLockHolder>>; |
68 | |
69 | StorageListWithLocks getSelectedTables(const String & query_id) const; |
70 | |
71 | StorageMerge::StorageListWithLocks getSelectedTables(const ASTPtr & query, bool has_virtual_column, bool get_lock, const String & query_id) const; |
72 | |
73 | template <typename F> |
74 | StoragePtr getFirstTable(F && predicate) const; |
75 | |
76 | DatabaseTablesIteratorPtr getDatabaseIterator(const Context & context) const; |
77 | |
78 | protected: |
79 | StorageMerge( |
80 | const std::string & database_name_, |
81 | const std::string & table_name_, |
82 | const ColumnsDescription & columns_, |
83 | const String & source_database_, |
84 | const String & table_name_regexp_, |
85 | const Context & context_); |
86 | |
87 | Block (const Names & column_names, const SelectQueryInfo & query_info, |
88 | const Context & context, QueryProcessingStage::Enum processed_stage); |
89 | |
90 | BlockInputStreams createSourceStreams(const SelectQueryInfo & query_info, const QueryProcessingStage::Enum & processed_stage, |
91 | const UInt64 max_block_size, const Block & , const StoragePtr & storage, |
92 | const TableStructureReadLockHolder & struct_lock, Names & real_column_names, |
93 | Context & modified_context, size_t streams_num, bool has_table_virtual_column, |
94 | bool concat_streams = false); |
95 | |
96 | void convertingSourceStream(const Block & , const Context & context, ASTPtr & query, |
97 | BlockInputStreamPtr & source_stream, QueryProcessingStage::Enum processed_stage); |
98 | }; |
99 | |
100 | } |
101 | |