Re: Dawn doesn't like 1NF

From: Laconic2 <laconic2_at_comcast.net>
Date: Sat, 16 Oct 2004 07:27:49 -0400
Message-ID: <qfSdnRkiTNZZmOzcRVn-2g_at_comcast.com>


"Marshall Spight" <mspight_at_dnai.com> wrote in message news:hl0cd.188364$wV.92433_at_attbi_s54...
> There are only two areas of complexity in equality: identity and
> precision. Identity disappears completely if you don't allow pointers
> in the language.

Could you say a little more about this? I don't think I quite got your point.

BTW, there was (is) this datatype in DEC Rdb/VMS called BLOBS (informally). The formal name was "segmented strings" or something like that. But they were strings of bytes, not strings of characters. I don't know whether or not that's what Dawn's referring to when she talks about strings.

Segmented strings were stored one segment at a time, chained together by pointers. The value stored in the record that represents the table row was a pointer to the first variable. This is clearly non-relational, but it allowed you to store files inside the database, and subject them to the ACID of a DBMS.

The test for equality in BLOBS was bizarre: if two values pointed at the same BLOB, then they were equal. If they pointed at different BLOBS, then they were unequal, even if the two BLOBS were equal, bit for bit! The builders of Rdb warned you: only use BLOBS if you know what you are doing!

Is the bizarre test for equality in DEC Rdb/VMS BLOBS related to your point about identity and pointers? Received on Sat Oct 16 2004 - 13:27:49 CEST

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