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RE: TOAST (was: BLOB)

From: "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp>
To: "Jan Wieck" <wieck(at)debis(dot)com>
Cc: <pgsql-sql(at)postgresql(dot)org>, "Philippe Gobin" <philippe(dot)gobin(at)fth(dot)net>
Subject: RE: TOAST (was: BLOB)
Date: 2000-04-21 06:50:48
Message-ID: 003501bfab5d$ece98b60$2801007e@tpf.co.jp (view raw or flat)
Thread:
Lists: pgsql-sql
> -----Original Message-----
> From: pgsql-sql-owner(at)hub(dot)org [mailto:pgsql-sql-owner(at)hub(dot)org]On Behalf
> Of Jan Wieck
> 
> > Hello
> >
> > I would like to know
> > - how to create under psql a BLOB field in sql language
> > - how store a value (and not a file) in sql language
> > - the maximum size of the BLOB field
> 
>     For  now  (and  7.0),  there  is no way to have rows >8K in a
>     regular table.
> 
>     But I'm actually making alot  of  progress  in  breaking  it.
>     Seems we'll get rid of this restriction in 7.1.
> 
>     To share some info with the other developers:
> 
>     I  experienced  some  trouble  with   occational   "Deadlock"
>     detections,  when  using  multiple processes hammering on the
>     toaster. But I was able to reproduce the same  error  with  a
>     plain  7.0  and  "text"  attributes (only far less frequent).
>     Seems there's  something  wrong  in  our  deadlock  detection
>     algorithm.
>

Does the trouble mean that "Deadlock" message was issued for
non-deadlock cases ?
  
>     Another  thing  is,  that  ISTM  that index's never shrink on
>     vacuum. One requirement of TOAST  is,  that  the  secondaries
>     tables  index-OID is remembered in the external reference, so
>     the ref can be  passed  around  in  the  entire  backend  and
>     whenever needed, it's real value can be fetched quickly by an
>     index scan. Thus, it's not possible to drop/recreate an index
>     on that right now. Seems we need a "REBUILD INDEX" utility or
>     the like.
>

REINDEX command could do it in a sense.
However current implementation couldn't guarantee the existence
of  proper index in case of abort. Proper implementation would
require the standard transactional control mechanism to handle
relation files such as new naming rule of relation files....

Regards.

Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp 

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