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50 lines
1.5 KiB
C++
50 lines
1.5 KiB
C++
#pragma once
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#include <set>
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#include <Core/Block.h>
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#include <Parsers/IAST.h>
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namespace DB
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{
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class Context;
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class NamesAndTypesList;
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namespace VirtualColumnUtils
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{
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/// Calculate the minimum numeric suffix to add to the string so that it is not present in the set
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String chooseSuffix(const NamesAndTypesList & columns, const String & name);
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/// Calculate the minimum total numeric suffix to add to each string,
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/// so that none is present in the set.
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String chooseSuffixForSet(const NamesAndTypesList & columns, const std::vector<String> & names);
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/// Adds to the select query section `select column_name as value`
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/// For example select _port as 9000.
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void rewriteEntityInAst(ASTPtr ast, const String & column_name, const Field & value);
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/// Leave in the block only the rows that fit under the WHERE clause and the PREWHERE clause of the query.
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/// Only elements of the outer conjunction are considered, depending only on the columns present in the block.
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/// Returns true if at least one row is discarded.
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bool filterBlockWithQuery(const ASTPtr & query, Block & block, const Context & context);
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/// Extract from the input stream a set of `name` column values
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template <typename T1>
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std::multiset<T1> extractSingleValueFromBlock(const Block & block, const String & name)
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{
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std::multiset<T1> res;
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const ColumnWithTypeAndName & data = block.getByName(name);
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size_t rows = block.rows();
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for (size_t i = 0; i < rows; ++i)
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res.insert((*data.column)[i].get<T1>());
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return res;
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}
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}
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}
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