How to retrieve a comment/description from a table

[Marcus Claesson]

Hello!
This psql command is very straight forward and promising:
COMMENT ON mytable IS 'This is my table.';

But how can I retrieve the particular comment from that table again?
Using \d+ gives you all the tables with their comments. I want a special
one.

And if that is not possible, can the \d+ results be obtained from a
system table or so?

Thanks,
Marcus


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[Darren Ferguson]

\d+ mytable will give you the comments for it

For system tables just do

\d+ pg_** substitute ** for system table name

HTH

Post by Marcus Claesson
Hello!
COMMENT ON mytable IS 'This is my table.';
But how can I retrieve the particular comment from that table again?
Using \d+ gives you all the tables with their comments. I want a special
one.
And if that is not possible, can the \d+ results be obtained from a
system table or so?
Thanks,
Marcus
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[Marcus Claesson]

Post by Darren Ferguson
\d+ mytable will give you the comments for it

This only gives me the same information as if I wrote '\d mytable', plus an
empty description column. I couldn't see my comment anywhere.

What I wish is to retrieve the comment with a sql question, which would work
if the '\d+ information' could be found in an actual table somewhere.

Regards,
Marcus


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[Tom Lane]

Post by Marcus Claesson
What I wish is to retrieve the comment with a sql question, which would work
if the '\d+ information' could be found in an actual table somewhere.

The descriptions are kept in pg_description. Although you can just do
"select from pg_description", the recommended retrieval method is the
obj_description() function. See
http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/functions-misc.html
http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/catalog-pg-description.html

regards, tom lane

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[Peter Gibbs]

Post by Marcus Claesson
What I wish is to retrieve the comment with a sql question, which would work
if the '\d+ information' could be found in an actual table somewhere.

select obj_description(oid, 'pg_class')
from pg_class
where relname = 'tablename';
--
Peter Gibbs
EmKel Systems



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[Stephan Szabo]

Post by Marcus Claesson

Post by Darren Ferguson
\d+ mytable will give you the comments for it

This only gives me the same information as if I wrote '\d mytable', plus an
empty description column. I couldn't see my comment anywhere.
What I wish is to retrieve the comment with a sql question, which would work
if the '\d+ information' could be found in an actual table somewhere.

If you start psql with -E it will show you the queries it's running for
those backslash commands.

I believe \d+ table gives you column descriptions in that description
column.


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