Re: -d option for pg_isready is broken

On Fri, Nov 15, 2013 at 9:01 PM, Fabrízio de Royes Mello
<fabriziomello(at)gmail(dot)com> wrote:
> On Wed, Nov 13, 2013 at 9:37 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>> handyrep(at)john:~/handyrep$ pg_isready --version
>> pg_isready (PostgreSQL) 9.3.1
>>
>> handyrep(at)john:~/handyrep$ pg_isready -h john -p 5432 -U postgres -d
>> postgres -q
>> pg_isready: missing "=" after "postgres" in connection info string
>>
>> handyrep(at)john:~/handyrep$ pg_isready --host=john --port=5432
>> --user=postgres --dbname=postgres
>> pg_isready: missing "=" after "postgres" in connection info string
>>
>> handyrep(at)john:~/handyrep$ pg_isready -h john -p 5432 -U postgres
>> john:5432 - accepting connections
>>
>> so apparently the -d option:
>>
>> a) doesn't work, and
>> b) doesn't do anything
>>
>> I suggest simply removing it from the utility.
>>
>> I'll note that the -U option doesn't appear to do anything relevant
>> either, but at least it doesn't error unnecessarily:
>>
>> handyrep(at)john:~/handyrep$ pg_isready -h john -p 5432 -U no_such_user
>> john:5432 - accepting connections
>>
>
> The attached patch fix it.

Well, there still seem to be some problems.

[rhaas pgsql]$ src/bin/scripts/pg_isready -d host=sgdasasg
/tmp:5432 - no attempt

I added some debugging instrumentation and it looks like there's a
problem with this code:

if (strcmp(def->keyword, "hostaddr") == 0 ||
strcmp(def->keyword, "host") == 0)

The problem is that we end up executing the code contained in that
block twice, once for host and once for hostaddr. Thus:

[rhaas pgsql]$ src/bin/scripts/pg_isready -d host=sgdasasg
def->keyword=host pghost_str=sgdasasg
def->keyword=hostaddr pghost_str=/tmp
def->keyword=port pgport_str=5432
/tmp:5432 - no attempt

Oops.

Nevertheless, that's kind of a separate problem, so we could address
in a separate commit. But even ignoring that, this still isn't right:
according to the fine documentation, -d will be expanded not only if
it contains an =, but also if it starts with a valid URI prefix. This
would break that documented behavior.

http://www.postgresql.org/docs/9.3/static/app-pg-isready.html

If you submit an updated patch, please fix the comment just above the
code you're changing to more accurately reflect what this does.

The number of bugs in pg_isready certainly seems out of proportion to
the surface area of the problem it solves. Whee!

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company