Re: [HACKERS] Are we losing momentum? - Mailing list pgsql-patches

I assume we agreed against adding a MySQL mode --- just verifying.

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Sean Chittenden wrote:
> > > That's a pretty reasonable thought. I work for a shop that sells
> > > Postgres support, and even we install MySQL for the Q&D ticket
> > > tracking system we recommend because we can't justify the cost to
> > > port it to postgres. If the postgres support were there, we would
> > > surely be using it.
> >
> > > How to fix such a situation, I'm not sure. "MySQL Compatability
> > > Mode," anyone? :-)
> >
> > What issues are creating a compatibility problem for you?
>
> I don't think these should be hacked into the backend/libpq, but I
> think it'd be a huge win to hack in "show *" support into psql for
> MySQL users so they can type:
>
>      SHOW (databases|tables|views|functions|triggers|schemas);
>
> I have yet to meet a MySQL user who understands the concept of system
> catalogs even though it's just the 'mysql' database (this irritates me
> enough as is)... gah, f- it: mysql users be damned, I have three
> developers that think that postgresql is too hard to use because they
> can't remember "\d [table name]" and I'm tired of hearing them bitch
> when I push using PostgreSQL instead of MySQL.  I have better things
> to do with my time than convert their output to PostgreSQL.  Here goes
> nothing...
>
> I've tainted psql and added a MySQL command compatibility layer for
> the family of SHOW commands (psql [-m | --mysql]).
>
>
> The attached patch does a few things:
>
> 1) Implements quite a number of SHOW commands (AGGREGATES, CASTS,
>    CATALOGS, COLUMNS, COMMENTS, CONSTRAINTS, CONVERSIONS, DATABASES,
>    DOMAINS, FUNCTIONS, HELP, INDEX, LARGEOBJECTS, NAMES, OPERATORS,
>    PRIVILEGES, PROCESSLIST, SCHEMAS, SEQUENCES, SESSION, STATUS,
>    TABLES, TRANSACTION, TYPES, USERS, VARIABLES, VIEWS)
>
>    SHOW thing
>    SHOW thing LIKE pattern
>    SHOW thing FROM pattern
>    SHOW HELP ON (topic || ALL);
>    etc.
>
>    Some of these don't have \ command eqiv's.  :( I was tempted to add
>    them, but opted not to for now, but it'd certainly be a nice to
>    have.
>
> 2) Implements the necessary tab completion for the SHOW commands for
>    the tab happy newbies/folks out there.  psql is more friendly than
>    mysql's CLI now in terms of tab completion for the show commands.
>
> 3) Few trailing whitespace characters were nuked
>
> 4) guc.c is now in sync with the list of available variables used for
>    tab completion
>
>
> Few things to note:
>
> 1) SHOW INDEXES is the same as SHOW INDEX, I think MySQL is wrong in
>    this regard and that it should be INDEXES to be plural along with
>    the rest of the types, but INDEX is preserved for compatibility.
>
> 2) There are two bugs that I have yet to address
>
>    1) SHOW VARIABLES doesn't work, but "SHOW [TAB][TAB]y" does
>    2) "SHOW [variable_of_choice];" doesn't work, but "SHOW
>       [variable_of_choice]\n;" does work... not sure where this
>       problem is coming from
>
> 3) I think psql is more usable as a result of this more verbose
>    syntax, but it's not the prettiest thing on the planet (wrote a
>    small parser outside of the backend or libraries: I don't want to
>    get those dirty with MySQL's filth).
>
> 4) In an attempt to wean people over to PostgreSQL's syntax, I
>    included translation tips on how to use the psql equiv of the SHOW
>    commands.  Going from SHOW foo to \d foo is easy, going from \d foo
>    to SHOW foo is hard and drives me nuts.  This'll help userbase
>    retention of newbies/converts.  :)
>
> 5) The MySQL mode is just a bounce layer that provides different
>    syntax wrapping exec_command() so it should provide little in the
>    way of maintenance headaches.  Some of the SHOW commands, however,
>    don't have \ couterparts, but once they do and that code is
>    centralized, this feature should come for zero cost.
>
> 6) As an administrator, I'd be interested in having an environment
>    variable that I could set that'd turn on MySQL mode for some of my
>    bozo users that way they don't complain if they forget the -m
>    switch.  Thoughts?
>
>
> I'll try and iron out the last of those two bugs/features, but at this
> point, would like to see this patch get wider testing/feedback.
> Comments, as always, are welcome.
>
> PostgreSQL_usability++
>
> -sc
>
> --
> Sean Chittenden

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