Re: PostgreSQL versus MySQL for GPS Data

On Thu, Mar 19, 2009 at 11:50 AM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> On Tue, Mar 17, 2009 at 5:25 AM, Juan Pereira
> <juankarlos(dot)openggd(at)gmail(dot)com> wrote:
>> Hello,
>>
>> The question is: Which DBMS do you think is the best for this kind of
>> application? PostgreSQL or MySQL?
>
> Another advantage pgsql has is that many ddl operations on tables do
> NOT require exclusive locks on those tables.  Creating indexes, adding
> / dropping columns in mysql will lock the whole table and adding
> dropping columns will rewrite the whole table.  In pgsql adding and
> dropping columns is almost immediate, and you can create indexes
> concurrently so that the table you're creating the index on is not
> locked.  This is a big deal on a large production system where index
> creation could take anywhere from several minutes to several hours.
>
> Note that almost all ddl is transactable as well, so testing big
> schema changes is much safer in pgsql, where you can rollback just
> about anything except create / drop database / tablespace.
>
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This is the nicest feature about postgresql by far. It almost
compensates the lack of in place upgrade.

merlin