Re: extensible external toast tuple support

On Fri, Jun 28, 2013 at 9:23 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Jun 27, 2013 at 12:56 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> Please find attached the next version of the extensible toast
>> support. There basically are two changes:
>>
>> * handle indirect toast tuples properly in heap_tuple_fetch_attr
>> and related places
>> * minor comment adjustments
>
> It looks to me like you need to pass true, rather than false, as the
> first argument to TrapMacro:
>
> +#define VARTAG_SIZE(tag) \
> + ((tag) == VARTAG_INDIRECT ? sizeof(varatt_indirect) : \
> + (tag) == VARTAG_ONDISK ? sizeof(varatt_external) : \
> + TrapMacro(false, "unknown vartag"))
>
> Still looking at the rest of this.

Why does toast_insert_or_update() need to go through all the
rigamarole in toast_datum_differs()? I would have thought that it
could simply treat any external-indirect value as needing to be
detoasted and retoasted, since the destination is the disk anyhow.

Do you see external-indirect values getting used for anything other
than logical replication? Is there code to do so anywhere?

--
Robert Haas
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