On Tue, Jul 11, 2006 at 01:50:40AM +0300, Tzahi Fadida wrote:
> As i understand rowids, i.e ctids, are supposed to allow for fast access to 
> the tables. I don't see the rational, for example, when casting some 
> attributes, to blank the ctid. So it is not exactly the same, but it still 
> came from the same tuple. What will happen if for read only SPI queries
> it will not be blank?

Did you read the email Tom sent? 

I worked out the exact issue with your example btw. It's because of the
DROP COLUMN. After dropping the column the tuples on disk have 3
columns and you only asked for 2, so an extra step has to be taken.
This extra step copies the two values, creating a new tuple, which has
no CTID.

If you're tying yourself this tightly to the backend, maybe you should
just use index_beginscan/heap_beginscan/etc which return actual tuples.

Have a nice day,
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to 
> litigate.

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