Scara Maccai wrote:
>> Be sure to include an ORDER BY clause.
> Isn't it going to be much slower?
It might be; you'd have to test to know for sure.
> The important thing is that most of the records are stored "close"
> enough one to the other in the right order.
Then, yeah, it might not
> Be sure to include an ORDER BY clause. For
> example, if someone else starts a query which the planner
> determines
> is best handled with a table scan, and that is still
> running when you
> issue your INSERT/SELECT, your query will join the current
> scan at
> it's point of progress, and "wra
Scara Maccai wrote:
> - create table mytable as select * from where time
> (this gets all the data of last month ordered in the
> "almost" correct order, because all the single tables were
> clustered)
Be sure to include an ORDER BY clause. Without that, there is no
guarantee that even two
Hi all,
>On Wed, Jul 15, 2009 at 10:36 PM, Scott Marlowe
>wrote:
I'd love to see it.
>
> +1 for index organized tables
>
>--Scott
+1 also for me...
I am currently working for a large customer who is migrating his main
application towards PostgreSQL, this application currently using DB2 an
> As Kevin said, there's no guarantee that tuples will be
> read back
> in the order you inserted them.
Ok, didn't know that
> A better option you might consider is to use a separate
> table for the
> re-ordered tuples.
> You could even do this using partitions
Problem is I'm already using par
> You might be better off
> with a CLUSTER on
> some index.
I can't: table is too big, can't lock it for minutes; that's why I wanted to
cluster it "one day at a time".
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ISTR that is the approach that MSSQL follows.
Storing the full tuple in an index and not even having a data only
page
would also be an interesting approach to this (and perhaps simpler
than a
separate index file and data file if trying to keep the data in the
order of
the index).
--
S
According to the books online http://msdn.microsoft.com/en-us/library/ms177443.aspx
:
"In a clustered index, the leaf nodes contain the data pages of the
underlying table."
Which agrees with your assertion.
From a performance perspective, it DOES work very well. Which is why
I keep h
Is there any interest in adding that (continual/automatic cluster
order maintenance) to a future release?
On Wed, Jul 15, 2009 at 8:33 PM, Scott Carey wrote:
> If you have a lot of insert/update/delete activity on a table fillfactor can
> help.
>
> I don’t believe that postgres will try and mainta
On 7/16/09 5:27 PM, "Greg Stark" wrote:
> On Fri, Jul 17, 2009 at 1:02 AM, Scott Carey wrote:
>> Indexes would point to a heap page for normal tables and clustered index
>> pages for clustered tables. When new versions of data come in, it may point
>> to new clustered index pages, just like the
On Fri, Jul 17, 2009 at 1:02 AM, Scott Carey wrote:
> Indexes would point to a heap page for normal tables and clustered index
> pages for clustered tables. When new versions of data come in, it may point
> to new clustered index pages, just like they currently get modified to point
> to new heap
On 7/16/09 1:49 PM, "Greg Stark" wrote:
> On Thu, Jul 16, 2009 at 9:06 PM, Scott Carey wrote:
>> Keep the old page around or a copy of it that old transactions reference?
>> Just more Copy on Write.
>> How is that different from a nested loop on an index scan/seek currently?
>> Doesn't an old tr
Hi Scott,
Which fillfactor is better 70, 80 or another value?
Thanks.
Thanks
On Thu, Jul 16, 2009 at 3:33 AM, Scott Carey wrote:
> If you have a lot of insert/update/delete activity on a table fillfactor can
> help.
>
> I don’t believe that postgres will try and maintain the table in the cluste
> Scara Maccai wrote:
>
>> What am I doing wrong?
I didn't exactly follow the full sequence but it sounded like what's
happening is that Postgres is noticing all these empty pages from
earlier deletes and reusing that space. That's what it's designed to
do. As Kevin said, there's no guarantee tha
On Thu, Jul 16, 2009 at 9:06 PM, Scott Carey wrote:
> Keep the old page around or a copy of it that old transactions reference?
> Just more Copy on Write.
> How is that different from a nested loop on an index scan/seek currently?
> Doesn't an old transaction have to reference an old heap page thro
Scara Maccai wrote:
> What am I doing wrong?
> [function which uses INSERT/UPDATE/DELETE statements to try to force
> order of rows in heap]
You seem to be assuming that the rows will be in the table in the
sequence of your inserts. You might be better off with a CLUSTER on
some index. (The
On 7/16/09 12:46 PM, "Greg Stark" wrote:
> On Thu, Jul 16, 2009 at 8:18 PM, Scott Carey wrote:
>> " Each index row in the nonclustered index contains the nonclustered key
>> value and a row locator. This locator points to the data row in the
>> clustered index or heap having the key value."
>>
On Thu, Jul 16, 2009 at 8:18 PM, Scott Carey wrote:
> " Each index row in the nonclustered index contains the nonclustered key
> value and a row locator. This locator points to the data row in the
> clustered index or heap having the key value."
>
> That sort of model should work with MVCC and even
Yes, it seems as though the whole tuple is entirely in the index if it is
clustered.
From :
http://msdn.microsoft.com/en-us/library/ms177484.aspx
" Each index row in the nonclustered index contains the nonclustered key
value and a row locator. This locator points to the data row in the
clustered
Scott Carey wrote:
> I could be wrong, but I think MSSQL only keeps the data specified in
> the index in the index, and the remaining columns in the data.
Unless it has changed recently, an MS SQL Server clustered index is
the same as the Sybase implementation: all data for the tuple is
stored
I could be wrong, but I think MSSQL only keeps the data specified in the
index in the index, and the remaining columns in the data.
That is, if there is a clustered index on a table on three columns out of
five, those three columns in the index are stored in the index, while the
other two are in a
Either true Index Organized Tables or Clustered Indexes would be very useful
for a variety of table/query types. The latter seems more difficult with
Postgres' MVCC model since it requires data to be stored in the index that
is authoritative.
Storing the full tuple in an index and not even having
> +1 for index organized tables
+1
I have a table:
CREATE TABLE mytab
(
"time" timestamp without time zone NOT NULL,
ne_id integer NOT NULL,
values integer,
CONSTRAINT mytab_pk PRIMARY KEY (ne_id, "time"),
CONSTRAINT mytab_ne_id_key UNIQUE ("time", ne_id)
}
The table is written eve
On Wed, Jul 15, 2009 at 10:36 PM, Scott Marlowe wrote:
> I'd love to see it.
+1 for index organized tables
--Scott
I'd love to see it.
On Wed, Jul 15, 2009 at 8:17 PM, Justin Pitts wrote:
> Is there any interest in adding that (continual/automatic cluster
> order maintenance) to a future release?
>
> On Wed, Jul 15, 2009 at 8:33 PM, Scott Carey wrote:
>> If you have a lot of insert/update/delete activity on a
If you have a lot of insert/update/delete activity on a table fillfactor can
help.
I don't believe that postgres will try and maintain the table in the cluster
order however.
On 7/15/09 8:04 AM, "Ibrahim Harrani" wrote:
Hi,
thanks for your suggestion.
Is there any benefit of setting fillfac
Hi,
thanks for your suggestion.
Is there any benefit of setting fillfactor to 70 or 80 on this table?
On Wed, Jun 24, 2009 at 8:42 PM, Scott Marlowe wrote:
> As another poster pointed out, you cluster on ONE index and one index
> only. However, you can cluster on a multi-column index.
>
--
S
As another poster pointed out, you cluster on ONE index and one index
only. However, you can cluster on a multi-column index.
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Clustering reorganizes the layout of a table according to
the ordering of a SINGLE index. This will place items that
are adjacent in the index adjacent in the heap. So you need
to cluster on the index that will help the locality of
reference for the queries which will benefit you the most.
Executio
Hello,
I have a table like following. To increase the performance of this
table, I would like to create CLUSTER.
First, Which index should I use on this table for CLUSTER?
Secondly, Can I create multiple CLUSTER on the same table?
I will appreciate, if you can suggest other options to increase
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