/ doc / tocNamespace / ARCCore / PExact<TEnumType> / __TOCDet / Attribute

Attribute

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AssemblyName = ARCCore
ClassNamespace = ARCCore
ClassType = PExact0x003CTEnumType0x003E
Description = Very -MemoryConsumption- efficient alternative to -PRich-.0x000D0x000ATypically used to store entities like 'Customer', 'Product', 'Order' and so on0x000D0x000A0x000D0x000AHas some limitations in the sense that can only store an exact number of properties (assumed to come from one specific -PropertyKeyEnum-), and only use -PK- as key.0x000D0x000A0x000D0x000AValues are stored 'directly', that is, without packing inside a -PValue-. (in other words, values are unpacked as they are received (by call to -GetV-), and packed again (by -PackObjectForStorageInEntityObject-) before being sent.0x000D0x000AIf -PValueEmpty- is received from outside, it is treated as 'not-existing' (stored internally as null)0x000D0x000A0x000D0x000ANote that from 22 Jan 2022 PExact contains the following high performance alternatives to standard -PropertyAccess-:0x000D0x000A-SetPVDirect-, -GetPVDirect- and -TryGetPVDirect-.0x000D0x000AThis avoids the performance overhead of unpacking and packing as described above.0x000D0x000A0x000D0x000ATODO: The high-performance alternatives describes above TODO: are not described in -ARCDoc- yet (see -Documentator-).0x000D0x000ATODO: One could argue that they should make PExact perform faster than PRich (in addition to using less memory as already mentioned),0x000D0x000ATODO: but this has not been tested properly as of Jan 2022.0x000D0x000ATODO: (Initial evaluation did not show any dramatic change, or actually any change at all).0x000D0x000ATODO: It is possible that the necessary boxing / unboxing is what impacts performance most. For value types0x000D0x000ATODO: it could quite possibly be more efficient to actually store PValue directly, in order to avoid boxing / unboxing.0x000D0x000ATODO: https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/types/boxing-and-unboxing 0x000D0x000A0x000D0x000AUse this class as basis for your 'entity' classes when you know exact what you want to store in them and when you do not need to store any meta-data like -Cid-, -Created- for each property.0x000D0x000A0x000D0x000AThe only memory overhead of this class compared to a 'traditional' C# class (with ordinary properties) should be the overhead for the -Storage- array instance (24 extra bytes).0x000D0x000A(with the exception of boxing / unboxing for value types of course.).0x000D0x000A0x000D0x000ASee also -MemoryConsumption-.0x000D0x000A0x000D0x000ASee -ARCDoc-, class -Orange- for example implementation.0x000D0x000A0x000D0x000ANOTE: Metadata at the entity level, like -Cid- and -Created- is only 0x000D0x000ANOTE: allowed as long as corresponding enum-members for the specific generic type parameter EnumType exists.0x000D0x000A0x000D0x000ASee also -ICreated, a dummy interface signifying that implementing class has the ability to store (in-memory) metadata -Created-0x000D0x000A0x000D0x000ATODO: This class is currently (as of Mar 2021) unable to store properties of type IP, that is, when packing / unpacking is not needed.0x000D0x000ATODO: Some workarounds could be to explicit recognize PValue0x003CT0x003E / PValueEmpty as the ones to be unpacked, and0x000D0x000ATODO: store all other properties (of IP) directly.0x000D0x000A
Interfaces = IP0x003BIEnumerable0xoooo003CIKIP0xoooo003E0x003BIEnumerable
InterfacesDirectlyImplemented = IP0x003BIEnumerable0xoooo003CIKIP0xoooo003E0x003BIEnumerable
LongDescription = Some examples of advantages of this class compared to -PRich-:0x000D0x000A0x000D0x000AExample 1: A small sample of about 832 000 -PropertyStreamLine- with data for about 16 000 customers (three properties, first name, last name and email) and 43 000 payments (about 21 properties each).0x000D0x000A42% reduction in RAM usage and a 16% reduction in CPU time for initial reading of all data into memory.0x000D0x000ADataset occupied 43 MB on disk and 59 MB in RAM.0x000D0x000A(Note: Example given is without any speed performance improvement through avoiding the pack / unpack cycle. (see speed improvements done on Jan 17 2022))0x000D0x000A0x000D0x000A

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