1 | #pragma once |
2 | |
3 | #include <set> |
4 | |
5 | #include <Core/Block.h> |
6 | #include <Parsers/IAST_fwd.h> |
7 | |
8 | |
9 | namespace DB |
10 | { |
11 | |
12 | class Context; |
13 | class NamesAndTypesList; |
14 | |
15 | |
16 | namespace VirtualColumnUtils |
17 | { |
18 | |
19 | /// Adds to the select query section `WITH value AS column_name`, and uses func |
20 | /// to wrap the value (if any) |
21 | /// |
22 | /// For example: |
23 | /// - `WITH 9000 as _port`. |
24 | /// - `WITH toUInt16(9000) as _port`. |
25 | void rewriteEntityInAst(ASTPtr ast, const String & column_name, const Field & value, const String & func = "" ); |
26 | |
27 | /// Leave in the block only the rows that fit under the WHERE clause and the PREWHERE clause of the query. |
28 | /// Only elements of the outer conjunction are considered, depending only on the columns present in the block. |
29 | /// Returns true if at least one row is discarded. |
30 | void filterBlockWithQuery(const ASTPtr & query, Block & block, const Context & context); |
31 | |
32 | /// Extract from the input stream a set of `name` column values |
33 | template <typename T> |
34 | std::multiset<T> extractSingleValueFromBlock(const Block & block, const String & name) |
35 | { |
36 | std::multiset<T> res; |
37 | const ColumnWithTypeAndName & data = block.getByName(name); |
38 | size_t rows = block.rows(); |
39 | for (size_t i = 0; i < rows; ++i) |
40 | res.insert((*data.column)[i].get<T>()); |
41 | return res; |
42 | } |
43 | |
44 | } |
45 | |
46 | } |
47 | |