Perhaps Nickolay can expound on his reasoning?

My initial 2-cents -- pointer values do not belong in
a blob ID - in any form. Keep it as a non-platform-dependant
ID.

Dave

> -----Original Message-----
> From: Jim Starkey [mailto:jas@...]
> Sent: Saturday, January 31, 2004 9:41 AM
> To: Firebird Devel; Arch
> Subject: [Firebird-Architect] Architectural Divergence
>
>
> We have a major divergence between Vulcan and Nickolay's 64 bit work
> that needs to be addressed immediately.
>
> Blobs are passed over the API by blob_id, defined by the architecture to
> be an opaque 64 bit quantity. In practice, the engine used the blob id
> as a two 32 bit word structure. For existing blobs, the high order word
> contained the relation id and the low order word contained the physical
> record number of the blob. For newly created blobs, the high order word
> was zero, and the low order words a pointer to an internal blob object.
>
> Since a 64 bit address cannot be crammed into a 32 bit number, something
> has to give.
>
> Nickolay chose to make the second word of the blob id a union of a 32
> record number and pointer (64 bits). The alignment rules force the size
> of the structure to 128 bits.
>
> I chose to retain the 64 bit blob id structure for backward
> compatibility. For temporary blocks, I plan to use a 32 bit handle for
> the internal blob.
>
> What makes the issue urgent is the Gpre has been changed since I
> checkout Vulcan to generate the new structure, which is incompatible
> with Vulcan.
>
> I think it is very important to maintain the Firebird API during the
> transition and coexistence of 32 and 64 bit platforms. Gpre was
> designed and implemented to generate cross platform code so that post
> processed programs are themselves portable. Arbitrary changes to the
> API break this philosophy. It is important that we define and control
> our API to minimize cross platform difficulties. I think changing the
> definition of blob id with nearly 20 years worth of installed based is
> unwise.
>
> --
>
> Jim Starkey
> Netfrastructure, Inc.
> 978 526-1376
>
>
>
>
>
>
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