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From:Vladislav Vaintroub Date:December 15 2008 5:37pm
Subject:RE: Falcon Index Keys
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Common memcmp'rable index format is probably the best sweet spot of Falcon I
can think of, from developers point of view.
Considering binary representation while doing sort/search/key compression
was a big pain in the back for me at the time I have done it for various
archaic Adabas datatypes  (alphanumeric ASCII and EBCDIC , binary integer
types in big and little endian , Unicode(UTF8), packed, unpacked  and fixed
decimal, IEEE float and double)

I think I would not map all numbers to double though if I'd be doing that
from scratch ;) , it is a strange imprecise format.

> -----Original Message-----
> From: [mailto:falcon-
>] On Behalf Of Jim Starkey
> Sent: Monday, December 15, 2008 5:28 PM
> To: FalconDev
> Subject: Falcon Index Keys
> Falcon index keys are designed to compare naturally byte-wise so that
> index code doesn't need to worry about data types, multi-segment keys,
> and collation sequences.  The theory is that index processing involves
> a
> lot of comparisons, and making the comparisons as cheap as possible is
> the best strategy.  Collations and multi-segment handling both fluffy
> up
> the index, possibly to the extent that the strategy needs to be
> reviewed.
> An alternative I've used in Nimbus is to use EncodedDataStreams to
> encode index keys.  It requires more processing per comparison but the
> keys, particularly multi-segment keys, are smaller.  Prefix compression
> isn't as nice (but isn't an issue in Nimbus), which is a significant
> consideration.
> I'm not recommending that Falcon change key formats, particularly for
> this version.  But the issue is well worth periodic reconsideration.
> --
> Jim Starkey
> President, NimbusDB, Inc.
> 978 526-1376
> --
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Falcon Index KeysJim Starkey15 Dec
  • RE: Falcon Index KeysVladislav Vaintroub15 Dec
    • Re: Falcon Index KeysJim Starkey15 Dec
    • Re: Falcon Index KeysAnn W. Harrison15 Dec