Re: Documentation on pgdump(1) uses "regular expression" instead of "psql pattern"

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: mjf(at)mjf(dot)cz
Cc: pgsql-docs(at)lists(dot)postgresql(dot)org
Subject: Re: Documentation on pgdump(1) uses "regular expression" instead of "psql pattern"
Date: 2022-09-23 02:17:16
Message-ID: 2030443.1663899436@sss.pgh.pa.us
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PG Doc comments form <noreply(at)postgresql(dot)org> writes:
> the [1] uses term "regular expression" where "psql pattern" [2] should be
> used instead which
> may be misleading (and might cause even some harm in some edge usage
> cases).

> I therefor propose to improve the documentation by emphasizing (strongly)
> the fact that the
> "regular expression" is in fact (psql) "pattern" and have nothing to do with
> *common* regular
> expressions and therefor extra care should be taken when using them.

Hmm. I looked at this but I think that the existing wording is fine.
The definitions of the switches, earlier on the same page, correctly
state that they use psql-style patterns, and provide cross-references
to that documentation. Moreover, the context of this is that the
preceding example already uses shell-pattern notation:

To dump all schemas whose names start with east or west and end in
gsm, excluding any schemas whose names contain the word test:

$ pg_dump -n 'east*gsm' -n 'west*gsm' -N '*test*' mydb > db.sql

The same, using regular expression notation to consolidate the switches:

$ pg_dump -n '(east|west)*gsm' -N '*test*' mydb > db.sql

We could write something wishy-washy like "additional pattern-matching
notation", but the psql Patterns section specifically uses "regular
expression notation" to describe these extensions to normal shell
patterns, and that's completely correct because they *are* standard
regular expression notations. So I think being consistent with that
is more useful than writing something else. Also, we have five
cross-references to Patterns on that page already, so I don't think
a sixth would add much.

regards, tom lane

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