Cast text to bytea

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Hi,

I want to change a column from text to bytea; since it seems that alter
table can't change the column type, i have to add a temporary column and
copy the data from the old one to the new, delete the old and rename the
new.


But it seems that Postgres can't cast text to bytea:

 odem=> UPDATE forum_gtree SET gid2=gid::bytea;
 ERROR:  Cannot cast type text to bytea


The same with casting only:

 odem=> SELECT 'abc'::text::bytea;
 ERROR:  Cannot cast type text to bytea
 odem=> SELECT '\000'::text::bytea;
 ERROR:  Cannot cast type text to bytea


How can I do this?

encode/decode seems to handle only bytea data:

  http://www.postgresql.org/docs/current/interactive/functions-string.html


And in http://www.postgresql.org/docs/current/static/datatype-binary.html I
also found no solution -- perhaps I missed something?


Thanks && Ciao
  Alvar


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** Alvar C.H. Freude -- http://alvar.a-blast.org/
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