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55 lines
1.9 KiB
C++
55 lines
1.9 KiB
C++
#pragma once
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#include <Core/Block.h>
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#include <Processors/Formats/IRowInputFormat.h>
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#include <Formats/FormatSettings.h>
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#include <Common/HashTable/HashMap.h>
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namespace DB
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{
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class ReadBuffer;
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/** Stream for reading data in TSKV format.
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* TSKV is a very inefficient data format.
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* Similar to TSV, but each field is written as key=value.
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* Fields can be listed in any order (including, in different lines there may be different order),
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* and some fields may be missing.
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* An equal sign can be escaped in the field name.
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* Also, as an additional element there may be a useless tskv fragment - it needs to be ignored.
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*/
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class TSKVRowInputFormat : public IRowInputFormat
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{
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public:
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TSKVRowInputFormat(ReadBuffer & in_, Block header_, Params params_, const FormatSettings & format_settings_);
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String getName() const override { return "TSKVRowInputFormat"; }
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bool readRow(MutableColumns & columns, RowReadExtension &) override;
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bool allowSyncAfterError() const override { return true; }
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void syncAfterError() override;
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void resetParser() override;
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private:
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const FormatSettings format_settings;
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/// Buffer for the read from the stream the field name. Used when you have to copy it.
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String name_buf;
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/// Hash table matching `field name -> position in the block`. NOTE You can use perfect hash map.
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using NameMap = HashMap<StringRef, size_t, StringRefHash>;
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NameMap name_map;
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/// Set of columns for which the values were read. The rest will be filled with default values.
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std::vector<UInt8> read_columns;
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/// Set of columns which already met in row. Exception is thrown if there are more than one column with the same name.
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std::vector<UInt8> seen_columns;
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/// These sets may be different, because if null_as_default=1 read_columns[i] will be false and seen_columns[i] will be true
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/// for row like ..., non-nullable column name=\N, ...
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};
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}
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