Re: [HACKERS] XIDTAG ???

> Why both
> 
>     int           pid;
>     TransactionId xid;
> 
> are used in XIDTAG?
> 
> lock.c:
>  *                                      normal lock     user lock
>  *
>  *      lockmethod                      1               2
>  *      tag.relId                       rel oid         0
>                                         ^^^^^^^^^^^^^^^^^
> Due to this, user-lock LOCKTAG is always different from
> normal-lock tag and so XIDTAG.lock is different also.
> 
>  *      tag.ItemPointerData.ip_blkid    block id        lock id2
>  *      tag.ItemPointerData.ip_posid    tuple offset    lock id1
>  *      xid.pid                         0               backend pid
>  *      xid.xid                         xid or 0        0
> 
> Why not get rid of XIDTAG.xid and use XIDTAG.pid equal
> to backend pid for both lock methods?

Probably no reason for the transaction id.  I don't remember that being
used at all.

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