Re: [HACKERS] LONG

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Jan Wieck <wieck(at)debis(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] LONG
Date: 1999-12-13 02:38:15
Message-ID: 199912130238.VAA13410@candle.pha.pa.us
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> The solution I see is to give any out of line datum another
> Oid, that is part of it's header and stamped into the
> reference data. That way, the long attribute lookup can use
> SnapshotAny using this Oid, there can only be one that
> exists, so SnapshotAny is safe here and forces that only the
> visibility of the master tuple in the main table counts at
> all.

This is a great idea. Get rid of my use of the attribute number. Make
the varlena long value be:

long-bit|length|longrelid|longoid|longlen

No need for attno in there anymore.

Having a separate oid for the long value is great. You can then have
multiple versions of the long attribute in the long table and can
control when updating a tuple.

I liked Hiroshi's idea of allowing long values in an index by just
pointing to the long table. Seems that would work too. varlena access
routines make that possible.

--
Bruce Momjian | http://www.op.net/~candle
maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026

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