Re: Tuple data - Mailing list pgsql-hackers

From Michael Richards
Subject Re: Tuple data
Date
Msg-id 04e101c0679c$cb936ed0$0200a8c0@digitallis
Whole thread Raw
In response to Tuple data  ("Michael Richards" <miker@interchange.ca>)
Responses Re: Tuple data
List pgsql-hackers
> That's not right --- AFAIR there is no length in the tuple data.  You
> must use the length from the 'page item' pointer that points to this
> tuple if you want to know the total tuple length.

Oops, I meant attribute length...

> If you were testing with tables containing single varlena columns, then
> you may have seen the varlena datum's length word and taken it for total
> length of the tuple --- but it's only total length of that one column.

Yes, I obviously had assumed that this length was common to all types (I was
testing with varchars before).

I presume then that I get the sizes based on some system tables. What query
should I run to give me the layout (in the order it's on disk) and the size
of each non-varlen attribute?

> Your example dump looks like F24D 0000 is userid, FFFF FFFF is folderid,
> and 1300 0000 is the varlena length word for foldername.

This is correct.

thanks
-Michael



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