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71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
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#pragma once
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#include <Core/Types.h>
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#include <DataTypes/DataTypeNumberBase.h>
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class DateLUTImpl;
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namespace DB
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{
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/** Mixin-class that manages timezone info for timezone-aware DateTime implementations
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*
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* Must be used as a (second) base for class implementing IDateType-interface.
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*/
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class TimezoneMixin
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{
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public:
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explicit TimezoneMixin(const String & time_zone_name = "");
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TimezoneMixin(const TimezoneMixin &) = default;
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const DateLUTImpl & getTimeZone() const { return time_zone; }
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protected:
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bool has_explicit_time_zone;
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const DateLUTImpl & time_zone;
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const DateLUTImpl & utc_time_zone;
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};
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/** DateTime stores time as unix timestamp.
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* The value itself is independent of time zone.
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*
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* In binary format it is represented as unix timestamp.
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* In text format it is serialized to and parsed from YYYY-MM-DD hh:mm:ss format.
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* The text format is dependent of time zone.
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*
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* To cast from/to text format, time zone may be specified explicitly or implicit time zone may be used.
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*
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* Time zone may be specified explicitly as type parameter, example: DateTime('Europe/Moscow').
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* As it does not affect the internal representation of values,
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* all types with different time zones are equivalent and may be used interchangingly.
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* Time zone only affects parsing and displaying in text formats.
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*
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* If time zone is not specified (example: DateTime without parameter), then default time zone is used.
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* Default time zone is server time zone, if server is doing transformations
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* and if client is doing transformations, unless 'use_client_time_zone' setting is passed to client;
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* Server time zone is the time zone specified in 'timezone' parameter in configuration file,
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* or system time zone at the moment of server startup.
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*/
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class DataTypeDateTime final : public DataTypeNumberBase<UInt32>, public TimezoneMixin
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{
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public:
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explicit DataTypeDateTime(const String & time_zone_name = "");
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explicit DataTypeDateTime(const TimezoneMixin & time_zone);
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static constexpr auto family_name = "DateTime";
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const char * getFamilyName() const override { return family_name; }
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String doGetName() const override;
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TypeIndex getTypeId() const override { return TypeIndex::DateTime; }
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bool canBeUsedAsVersion() const override { return true; }
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bool canBeInsideNullable() const override { return true; }
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bool equals(const IDataType & rhs) const override;
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SerializationPtr doGetDefaultSerialization() const override;
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};
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}
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