RWF LEN Caching hint?

Susan Genoray
Susan Genoray
in TREP APIs

The RFA documentation describes the RWF length as a caching hint:
RWFLEN A caching length hint associated with this field.

Does that mean, that also content is correctly cached even when it extends the RWF_LEN specification in the RDMFieldDictionary ?

Background: The MF PRICE type is usually defined with a length of 17. The RWF translation in the file is REAL64 with a length of 7.

But a length of 7 is not enough to hold all possible values (big numbers/high precision) in RWF encoding.

According to your below answer, all values are correctly encoded. But are these values also correctly cached?


Btw: the same documentation recommends to use a field length of 9 for custom REAL64 fields.

There are a couple of recommendations for custom FIDs:

FIELD Type:PRICE

Length:17

RWF Type: REAL

RWF Len: 9

Notes: REAL can represent values with fractional denominators, trailing zeros, or up to 14 decimal positions.

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Best Answer

  • LarryT
    LarryT
    Answer ✓

    What happens in the case that content exceeds the length in dictionary is it will be truncated and a warning will be logged in the ADH. Other caching components might be different but that is the logic for ADH and ADS.


    The size mismatch between Marketfeed and RWF is often a problem for custom applications. Size in the dictionary is the max size any field can be on IDN/ERT and not the max size a value can reach. This is done to limit memory use and improve caching performance.

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