2018-07-20 10:00:56 +00:00
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#pragma once
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#include <DataTypes/DataTypeString.h>
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#include <Storages/ColumnsDescription.h>
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#include <Storages/IStorage.h>
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#include <ext/shared_ptr_helper.h>
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2020-01-24 15:32:17 +00:00
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#include <Processors/Sources/SourceFromSingleChunk.h>
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#include <Processors/Pipe.h>
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2018-07-20 10:00:56 +00:00
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namespace DB
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{
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2018-07-20 15:59:11 +00:00
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2018-07-20 10:00:56 +00:00
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class Context;
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2018-07-20 15:59:11 +00:00
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/** Base class for system tables whose all columns have String type.
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*/
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2018-07-20 10:00:56 +00:00
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template <typename Self>
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2018-07-23 16:10:57 +00:00
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class IStorageSystemOneBlock : public IStorage
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2018-07-20 10:00:56 +00:00
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{
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protected:
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2018-07-24 14:28:56 +00:00
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virtual void fillData(MutableColumns & res_columns, const Context & context, const SelectQueryInfo & query_info) const = 0;
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2018-07-20 10:00:56 +00:00
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public:
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2019-12-03 16:25:32 +00:00
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IStorageSystemOneBlock(const String & name_) : IStorage({"system", name_})
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2018-07-20 10:00:56 +00:00
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{
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2020-06-15 16:55:33 +00:00
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StorageInMemoryMetadata metadata_;
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metadata_.setColumns(ColumnsDescription(Self::getNamesAndTypes()));
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setInMemoryMetadata(metadata_);
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2018-07-20 10:00:56 +00:00
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}
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2020-06-15 19:08:58 +00:00
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Pipes read(
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const Names & column_names,
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2020-06-16 15:51:29 +00:00
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const StorageMetadataPtr & metadata_snapshot,
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2018-07-24 14:28:56 +00:00
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const SelectQueryInfo & query_info,
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const Context & context,
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2018-09-08 11:29:23 +00:00
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QueryProcessingStage::Enum /*processed_stage*/,
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2018-07-20 10:00:56 +00:00
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size_t /*max_block_size*/,
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unsigned /*num_streams*/) override
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{
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2020-06-17 14:32:25 +00:00
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metadata_snapshot->check(column_names, getVirtuals());
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2018-07-20 10:00:56 +00:00
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2020-06-16 15:51:29 +00:00
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Block sample_block = metadata_snapshot->getSampleBlock();
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2018-07-20 15:59:11 +00:00
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MutableColumns res_columns = sample_block.cloneEmptyColumns();
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2018-07-24 14:28:56 +00:00
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fillData(res_columns, context, query_info);
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2018-07-20 10:00:56 +00:00
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2020-01-24 15:32:17 +00:00
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UInt64 num_rows = res_columns.at(0)->size();
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Chunk chunk(std::move(res_columns), num_rows);
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2020-01-24 15:42:31 +00:00
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Pipes pipes;
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pipes.emplace_back(std::make_shared<SourceFromSingleChunk>(sample_block, std::move(chunk)));
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return pipes;
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2018-07-20 10:00:56 +00:00
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}
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};
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2018-07-20 15:59:11 +00:00
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2018-07-20 10:00:56 +00:00
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}
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