[mythtv] State of play Re. DB support (MySQL versions, Postgresql etc.)

usleepless at gmail.com usleepless at gmail.com
Tue May 16 09:40:13 UTC 2006


> > The MythTV wiki at
> > http://www.mythtv.org/wiki/index.php/Feature_Wishlist_(Backend_Addons)
> > claims that adding SQLite or PostgreSQL support is on the wishlist.  Is
> > this no longer correct?
> sqlite would have been an option - except that initial testing showed it to
> be
> about 6x slower at the main scheduler query than mysql is.  Too slow.

well, that query is horrendous. on most dbms the function calls can be
slow, and there is a hell of a lot of implicit typecasting going on
there because of the lousy schema. and this horrendous query has to be
planned everytime it is executed. furthermore, the initial test may
have missed the index on the time-fields, seriously affecting

> I don't see the point of supporting one big database engine (mysql) as well
> as
> supporting another big database engine (postgres).

i my book, cross-platform development or crossdatabase development for
this particular matter, adds robustness and clarity. supporting
postgres is just a matter of removing mysql-isms and other bad code (
constantly calling query.size() for example ). don't forget the

> Doesn't really add any
> value that I can see except for people who are philosophically opposed to
> running mysql

see another comment on this list: some people have already a running
dbms, and don't want to run two of them.

>, and it adds considerably to the difficulty of development
> (having to test with both, etc).

you have a style-guide for the c++ code, it would be easy to add a
styleguide for the sql-code as well ( i whish there had been one ).
support for other dbms's may be labeled "beta" ( google-style ) as
another reader suggested.

it is a pitty that with the release of mysql back in the days,
everybody thinks they understand databases ....

anyway, the transition of mythtv to another database ( embedded or not
), will take as much energy as making it cross-dbms-compatible in the
first place.



> Isaac
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