On Jan 31, 2009, at 9:36 AM, Scott Marlowe wrote:
> On Sat, Jan 31, 2009 at 2:13 AM, Erik Jones <ejones@engineyard.com>
> wrote:
>>
>> On Jan 30, 2009, at 11:37 AM, durumdara wrote:
>
>>> - I can add/modify a table, or a field to a table without "full
>>> lock" on
>>> the table (like DBISAM restructure). Like in FireBird, where the
>>> "add field"
>>> change only the table description. I don't know that PG supports
>>> this way of
>>> the DB modifying.
>>
>> Nope. PostgreSQL is an all or nothing transactional database. I'd
>> never
>> heard of DBISAM before you mentioned it and have never used
>> Firebird. After
>> doing a little reading it turns out that if you plan to use
>> transactions at
>> all (which is very likely given even just the little you've
>> described about
>> the applications you're building) then you should realize that
>> altering
>> tables is not compatible with transactions and doing so will
>> automatically
>> commit any open transactions on the table.
>
> Are talking about pgsql or some other database? Everything in pgsql
> can be done in a transaction, except create / drop database /
> tablespace.
I was referring to DBISAM there.
>> Looking into Firebird I couldn't
>> find how it handles (or doesn't) that at all I but I did see that
>> it will
>> happily let you add a new not null column with no default to a
>> table by
>> writing nulls for the new attribute for any existing columns. That
>> already
>> makes me queasy.
>
> That's pretty much what pgsql does. Why does it make you queasy?
Another poster already beat me to answering this one so I'll not
repeat what they said.
Erik Jones, Database Administrator
Engine Yard
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