I haven't looked in great detail into why this is happpening, but it seems as though processNamePattern() doesn't handle ?'s correctly in the negative lookahead context correctly.

1) \dn [pattern] strips ?'s and replaces them with periods. This may be intentional (as the comment in describe.c suggests, converting input from shell-style wildcards gets converted into regexp notation), but is quite annoying. Ex:

test=# \dn foo(?!_log|_shadow)
********* QUERY **********
SELECT n.nspname AS "Name",
       u.usename AS "Owner"
FROM pg_catalog.pg_namespace n LEFT JOIN pg_catalog.pg_user u
       ON n.nspowner=u.usesysid
WHERE   (n.nspname NOT LIKE 'pg\\_temp\\_%' OR
                 n.nspname = (pg_catalog.current_schemas(true))[1])
      AND n.nspname ~ '^foo(.!_log|_shadow)$'
ORDER BY 1;
**************************

Which is incorrect, IMHO. Instead the last bit of the query should be:

AND n.nspname ~ '^foo(?!_log|_shadow)$'

2) This brings up a large deficiency with the way that \d? [pattern] handling is done in psql(1). It'd be slick if there was a way to have psql's pattern routine look at the first non-whitespace character or two to change change the structure of the query. Something like \dn !.*_shadow% would change the RE operator from ~ to !~ and \dn %bar% would translate to LIKE('bar%'). Doing the regexp equiv of !LIKE('%_shadow') isn't trivial because '^.*(?!_shadow)$' doesn't return the expected result for various reasons. Oh! This'd be a "gun pointed at foot" feature, but having the first character being an = would, without escaping, drop the remainder of the input directly into the query (ex: \dn =nspname != (LIKE('%_log') OR LIKE('%_shadow'))). Maybe a psql(1) variable that changes the behavior of the pattern queries from using an RE to a LIKE statement could also be a possibility. The more I think about this, a leading pipe could be used to pipe the output to a utility, so that \dn | egrep -v '(log|shadow) would work and would be the easiest solution.

Maybe a better "bug report" would be, what's the suggested way of doing:

n.nspname !~ '_(log|shadow)$'?

from a list pattern?

-sc

--
Sean Chittenden


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