From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
---|---|
To: | Jesper Krogh <jesper(at)krogh(dot)cc> |
Cc: | Divakar Singh <dpsmails(at)yahoo(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Postgres insert performance and storage requirement compared to Oracle |
Date: | 2010-10-27 18:51:23 |
Message-ID: | AANLkTimMSMcqkAY9jMi8UZKveY3YS-p-V60KckvtDB6g@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers pgsql-performance |
On Wed, Oct 27, 2010 at 2:42 PM, Jesper Krogh <jesper(at)krogh(dot)cc> wrote:
> On 2010-10-27 20:28, Merlin Moncure wrote:
>>
>> Postgres indexes are pretty compact, and oracle (internals I am not
>> familiar with) also has to do MVCC type management, so I am suspecting
>> your measurement is off (aka, operator error) or oracle is cheating
>> somehow by optimizing away storage requirements somehow via some sort
>> of tradeoff. However you still fail to explain why storage size is a
>> problem. Are planning to port oracle to postgres on a volume that is
>> 50% full? :-)
>>
>
> Pretty ignorant comment.. sorry ..
>
> But when your database approaches something that is not mainly
> fitting in memory, space directly translates into speed and a more
> compact table utillizes the OS-page cache better. This is both
> true for index and table page caching.
>
> And the more compact your table the later you hit the stage where
> you cant fit into memory anymore.
>
> .. but if above isn't issues, then your statements are true.
Yes, I am quite aware of how the o/s page cache works. All else being
equal, I more compact database obviously would be preferred. However
'all else' is not necessarily equal. I can mount my database on bzip
volume, that must make it faster, right? wrong. I understand the
postgres storage architecture pretty well, and the low hanging fruit
having been grabbed further layout compression is only going to come
as a result of tradeoffs.
Now, comparing oracle vs postgres, mvcc works differently because
oracle uses rollback logs while postgres maintains extra/old versions
in the heap. This will add up to big storage usage based on various
things, but should not so much be reflected via insert only test.
merlin
From | Date | Subject | |
---|---|---|---|
Next Message | Simon Riggs | 2010-10-27 19:10:58 | Re: max_wal_senders must die |
Previous Message | Steve Singer | 2010-10-27 18:51:02 | Re: Postgres insert performance and storage requirement compared to Oracle |
From | Date | Subject | |
---|---|---|---|
Next Message | Jon Nelson | 2010-10-27 18:52:05 | Re: temporary tables, indexes, and query plans |
Previous Message | Steve Singer | 2010-10-27 18:51:02 | Re: Postgres insert performance and storage requirement compared to Oracle |