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75 lines
2.9 KiB
C++
75 lines
2.9 KiB
C++
#pragma once
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#include <Core/Block.h>
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#include <Interpreters/Context_fwd.h>
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#include <Parsers/IAST_fwd.h>
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#include <Storages/SelectQueryInfo.h>
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#include <unordered_set>
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namespace DB
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{
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class NamesAndTypesList;
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namespace VirtualColumnUtils
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{
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/// Adds to the select query section `WITH value AS column_name`, and uses func
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/// to wrap the value (if any)
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///
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/// For example:
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/// - `WITH 9000 as _port`.
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/// - `WITH toUInt16(9000) as _port`.
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void rewriteEntityInAst(ASTPtr ast, const String & column_name, const Field & value, const String & func = "");
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/// Prepare `expression_ast` to filter block. Returns true if `expression_ast` is not trimmed, that is,
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/// `block` provides all needed columns for `expression_ast`, else return false.
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bool prepareFilterBlockWithQuery(const ASTPtr & query, ContextPtr context, Block block, ASTPtr & expression_ast);
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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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/// If `expression_ast` is passed, use it to filter block.
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void filterBlockWithQuery(const ASTPtr & query, Block & block, ContextPtr context, ASTPtr expression_ast = {});
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/// Extract from the input stream a set of `name` column values
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template <typename T>
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auto extractSingleValueFromBlock(const Block & block, const String & name)
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{
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std::unordered_set<T> 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<T>());
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return res;
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}
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NamesAndTypesList getPathAndFileVirtualsForStorage(NamesAndTypesList storage_columns);
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ASTPtr createPathAndFileFilterAst(const ASTPtr & query, const NamesAndTypesList & virtual_columns, const String & path_example, const ContextPtr & context);
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ColumnPtr getFilterByPathAndFileIndexes(const std::vector<String> & paths, const ASTPtr & query, const NamesAndTypesList & virtual_columns, const ContextPtr & context, ASTPtr filter_ast);
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template <typename T>
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void filterByPathOrFile(std::vector<T> & sources, const std::vector<String> & paths, const ASTPtr & query, const NamesAndTypesList & virtual_columns, const ContextPtr & context, ASTPtr filter_ast)
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{
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auto indexes_column = getFilterByPathAndFileIndexes(paths, query, virtual_columns, context, filter_ast);
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const auto & indexes = typeid_cast<const ColumnUInt64 &>(*indexes_column).getData();
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if (indexes.size() == sources.size())
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return;
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std::vector<T> filtered_sources;
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filtered_sources.reserve(indexes.size());
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for (auto index : indexes)
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filtered_sources.emplace_back(std::move(sources[index]));
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sources = std::move(filtered_sources);
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}
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void addRequestedPathAndFileVirtualsToChunk(
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Chunk & chunk, const NamesAndTypesList & requested_virtual_columns, const String & path, const String * filename = nullptr);
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}
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}
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