Re: RFC: replace pg_stat_activity.waiting with something more descriptive

On 2015-07-21 13:11:36 +0300, Ildus Kurbangaliev wrote:
>  
>  /*
>   * Top-level transactions are identified by VirtualTransactionIDs comprising
> diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
> index cff3b99..55b0687 100644
> --- a/src/include/storage/lwlock.h
> +++ b/src/include/storage/lwlock.h
> @@ -58,6 +58,9 @@ typedef struct LWLock
>  #ifdef LOCK_DEBUG
>      struct PGPROC *owner;        /* last exlusive owner of the lock */
>  #endif
> +
> +    /* LWLock group, initialized as -1, calculated in first acquire */
> +    int group;
>  } LWLock;

I'd very much like to avoid increasing the size of struct LWLock. We
have a lot of those and I'd still like to inline them with the buffer
descriptors. Why do we need a separate group and can't reuse the
tranche?  That might require creating a few more tranches, but ...?

Andres