Re: Tuple identifier (tid) - object identifiers

The tid is the page/offset of the tuple.  You can't really remove it
because it is a characteristic of the tuple, not really in each tuple.
Each page has a number, and each page has slots, so the page number/slot
number of the tuple is its tid.

However, there is a ctid element in the heap tuple header:

    ItemPointerData t_ctid;     /* current TID of this or newer tuple */

and that is used more make tid access easier and to chain tuples to
newer versions.  Not much saving there.

7.3 will reduce the typle header by 8 bytes, so there is progress being
made on tuple overhead reduction.

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Tourtounis Sotiris wrote:
>     In Postgres documentation there is a reference of the tid that is by
> default inserted for each tuple in the database where is it, which takes
> an extra  percent of the database's storage space.
>     It's referred that is of the general form:
> tid : <block number, tuple index within each block>
>     Is it possible afterwards the installation of Postgres to not have
> it on database's size. Or most important can we see its size (tid) per
> tuple or totally to the whole database (size of the block number , size
> of tuple index within each block)? Does it have some default values and
> which are those?Thanks you
>
>
>
>                                                  SWTHRHS TOYRTOYNHS
>                                                 (tourtoun@csd.uch.gr)
>
>
>
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