On Thu, 2010-12-30 at 10:45 -0500, Tom Lane wrote:
Comments?
Thanks for working on this. I love the reuse of tuple flags; I can't
help feeling that opens up doors, just not sure how yet...
--
Simon Riggs http://www.2ndQuadrant.com/books/
PostgreSQL Development, 24x7 Support,
I had an epiphany about this topic, or actually two of them.
1. Whether or not you think there's a significant performance reason
to support hash right joins, there's a functionality reason. The
infrastructure for right join could just as easily do full joins.
And AFAICS, a hash full join would
On Thu, Dec 30, 2010 at 10:45 AM, Tom Lane t...@sss.pgh.pa.us wrote:
I had an epiphany about this topic, or actually two of them.
1. Whether or not you think there's a significant performance reason
to support hash right joins, there's a functionality reason. The
infrastructure for right
Robert Haas robertmh...@gmail.com writes:
On Thu, Dec 30, 2010 at 10:45 AM, Tom Lane t...@sss.pgh.pa.us wrote:
... But we only need one bit, so what about commandeering
an infomask bit in the tuple itself? For the initial implementation
I'd be inclined to take one of the free bits in
On Thu, Dec 30, 2010 at 11:50 PM, Robert Haas robertmh...@gmail.com wrote:
On Thu, Dec 30, 2010 at 10:45 AM, Tom Lane t...@sss.pgh.pa.us wrote:
I had an epiphany about this topic, or actually two of them.
1. Whether or not you think there's a significant performance reason
to support
Tom Lane t...@sss.pgh.pa.us writes:
I can't get all *that* excited about complicating hash joins as
proposed. The query is still fundamentally going to be slow because
you won't get out of having to seqscan the large table. The only way
to make it really fast is to not read all of the large
On Tue, Dec 28, 2010 at 5:13 AM, Jie Li jay23j...@gmail.com wrote:
Hi,
Please see the following plan:
postgres=# explain select * from small_table left outer join big_table using
(id);
QUERY PLAN
On Wed, 2010-12-29 at 07:17 -0500, Robert Haas wrote:
Here I have a puzzle, why not choose the small table to build hash table? It
can avoid multiple batches thus save significant I/O cost, isn't it?
Yeah, you'd think. Can you post a full reproducible test case?
It's not a bug, that's
Excerpts from Robert Haas's message of mié dic 29 09:17:17 -0300 2010:
On Tue, Dec 28, 2010 at 5:13 AM, Jie Li jay23j...@gmail.com wrote:
Hi,
Please see the following plan:
postgres=# explain select * from small_table left outer join big_table using
(id);
On Wed, Dec 29, 2010 at 7:34 AM, Simon Riggs si...@2ndquadrant.com wrote:
On Wed, 2010-12-29 at 07:17 -0500, Robert Haas wrote:
Here I have a puzzle, why not choose the small table to build hash table?
It
can avoid multiple batches thus save significant I/O cost, isn't it?
Yeah, you'd
Robert Haas robertmh...@gmail.com writes:
On Wed, Dec 29, 2010 at 7:34 AM, Simon Riggs si...@2ndquadrant.com wrote:
It's not a bug, that's the way it currently works. We don't need a test
case for that.
Oh, you're right. I missed the fact that it's a left join.
The only thing that struck me
- Original Message -
From: Alvaro Herrera alvhe...@commandprompt.com
To: Robert Haas robertmh...@gmail.com
Cc: Jie Li jay23j...@gmail.com; pgsql-hackers
pgsql-hackers@postgresql.org
Sent: Wednesday, December 29, 2010 8:39 PM
Subject: Re: [HACKERS] small table left outer join big table
- Original Message -
From: Robert Haas robertmh...@gmail.com
To: Simon Riggs si...@2ndquadrant.com
Cc: Jie Li jay23j...@gmail.com; pgsql-hackers
pgsql-hackers@postgresql.org
Sent: Wednesday, December 29, 2010 8:59 PM
Subject: Re: [HACKERS] small table left outer join big table
On Wed, Dec 29
- Original Message -
From: Tom Lane t...@sss.pgh.pa.us
To: Robert Haas robertmh...@gmail.com
Cc: Simon Riggs si...@2ndquadrant.com; Jie Li jay23j...@gmail.com;
pgsql-hackers pgsql-hackers@postgresql.org
Sent: Wednesday, December 29, 2010 10:59 PM
Subject: Re: [HACKERS] small table left
On Wed, 2010-12-29 at 09:59 -0500, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
On Wed, Dec 29, 2010 at 7:34 AM, Simon Riggs si...@2ndquadrant.com wrote:
It's not a bug, that's the way it currently works. We don't need a test
case for that.
Oh, you're right. I missed the
On Wed, Dec 29, 2010 at 3:58 PM, Simon Riggs si...@2ndquadrant.com wrote:
On Wed, 2010-12-29 at 09:59 -0500, Tom Lane wrote:
Robert Haas robertmh...@gmail.com writes:
On Wed, Dec 29, 2010 at 7:34 AM, Simon Riggs si...@2ndquadrant.com
wrote:
It's not a bug, that's the way it currently
Hi,
Please see the following plan:
postgres=# explain select * from small_table left outer join big_table using
(id);
QUERY PLAN
Hash Left Join (cost=126408.00..142436.98 rows=371
On Tue, Dec 28, 2010 at 5:13 AM, Jie Li jay23j...@gmail.com wrote:
Hi,
Please see the following plan:
postgres=# explain select * from small_table left outer join big_table
using (id);
QUERY PLAN
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