From: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Possible typo in create_policy.sgml |
Date: | 2015-01-30 08:27:52 |
Message-ID: | CAEZATCWyyxFH5dZoFM5AmsXgc0CyC10cycBNvOLEptppjtY2DQ@mail.gmail.com |
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Lists: | pgsql-hackers |
On 30 January 2015 at 03:40, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> * Robert Haas (robertmhaas(at)gmail(dot)com) wrote:
>> On Thu, Jan 29, 2015 at 9:04 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>> > A policy grants the ability to SELECT, INSERT, UPDATE, or DELETE rows
>> > which match the relevant policy expression. Existing table rows are
>> > checked against the expression specified via USING, while new rows
>> > that would be created via INSERT or UPDATE are checked against the
>> > expression specified via WITH CHECK. When a USING expression returns
>> > false for a given row, that row is not visible to the user. When a WITH
>> > CHECK expression returns false for a row which is to be added, an error
>> > occurs.
>>
>> Yeah, that's not bad. I think it's an improvement, in fact.
>
Yes I like that too. My main concern was that we should be describing
policies in terms of permitting access to the table, not limiting
access, because of the default-deny policy, and this new text clears
that up.
One additional quibble -- it's misleading to say "expression returns
false" here (and later in the check_expression parameter description)
because if the expression returns null, that's also a failure. So it
ought to be "false or null", but perhaps it could just be described in
terms of rows matching the expression, with a separate note to say
that a row only matches a policy expression if that expression returns
true, not false or null.
Regards,
Dean
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