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

Bruce Momjian wrote:

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

We agreed that applications that need schema information are much better
off using the schema views.


Jan

>
> ---------------------------------------------------------------------------
>
> 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
>
> [ Attachment, skipping... ]
>
>>
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