Re: TOAST versus VACUUM, or "missing chunk number 0 for toast value" identified

Excerpts from Tom Lane's message of vie oct 28 15:37:43 -0300 2011:

> The main concern I had about detoast before caching is the risk of
> circularity, ie, needing detoastable cache entries in order to figure
> out how to detoast.  But I think it's probably okay.  The current list
> of catalogs with toast tables is
> 
>  pg_attrdef
>  pg_constraint
>  pg_database
>  pg_db_role_setting
>  pg_description
>  pg_proc
>  pg_rewrite
>  pg_seclabel
>  pg_shdescription
>  pg_statistic
>  pg_trigger
> 
> Of these, only pg_proc is even conceivably consulted during a toast
> table fetch, and we can be sure that functions needed for such a fetch
> don't have toasted entries.  But we will have to be very wary of any
> future proposal for adding a toast table to pg_class, pg_index, etc.

BTW we had previous discussions about dropping pg_database's toast
table.  Maybe this is a good time to do it, even if there's no risk of
this bug (or the hypothetical circularity detoasting problem) showing up
there.

-- 
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
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