Hi guys,
just a quick and probably stupid question. When I make a cluster
based on an index on a table, how can I remove it later? Should I
'create' a new one by using the primary key index?
Also, can I have more than 1 cluster on my table? Let me explain ...
can I put for instance the record with, let's say, age between 10 and 20
on a specific cluster, from 20 to 30 on another one, and so on?
Thank you
-Gabriele
---------------------------(end of broadcast)---------------------------
TIP 3: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to ma*******@postg resql.org so that your
message can get through to the mailing list cleanly 2 2502
After a long battle with technology,gb** ******@optusnet .com.au (Gabriele Bartolini), an earthling, wrote: just a quick and probably stupid question. When I make a cluster based on an index on a table, how can I remove it later? Should I 'create' a new one by using the primary key index?
There are two options:
1. If there is something more relevant to cluster on, you might
cluster on that instead.
2. If there is nothing relevant to cluster on, then you could leave
it alone.
In either case, as _further_ changes are made to the table, the
clustering is likely to lose its effect as new entries will not
necessarily be made in the order the clustering indicates.
Also, can I have more than 1 cluster on my table? Let me explain ... can I put for instance the record with, let's say, age between 10 and 20 on a specific cluster, from 20 to 30 on another one, and so on?
No, that idea doesn't make much sense.
CLUSTER reorganizes the table base based an index that you select.
You get to pick one index.
Mind you, if you created a functional index, you might get something
sort of like this.
I'm not sure of the ideal syntax for this, but let's say you made up
an index:
create index age_clusters on tbl1 (round(age, -1));
(Which might or might not resemble how you'd round AGE to the nearest
10 :-)).
Cluster on that index and you might get the desired result. But the
point is that you need to be able to express it as ONE index, not as 5
of them...
--
(reverse (concatenate 'string "gro.gultn" "@" "enworbbc") ) http://www3.sympatico.ca/cbbrowne/
Rule of Scarcity
"If it's not allocated by a market, then it's more expensive than
money."
-- Mark Miller
Hello.
At the site http://www.postgresql.org/docs/7.3/static/lo-libpq.html there is a description to manipulate
binary data with libpq. How can I do the same but with ECPG?
Thanks.
---------------------------(end of broadcast)---------------------------
TIP 8: explain analyze is your friend This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: superprad |
last post by:
If I have
ex: x = ,
,
,
]
what I want is a boundingbox over the region where we find clusters of
1's.So for instance in the above list first 3 roes and colums have 1's
so the area of that box is 3x3
so my final array should have an array of approx areas of clusters of
|
by: MissLivvy |
last post by:
I recently came across a database where the data are horizonally partitioned
into 4 tables. I'm not sure if this was a poor design choice, or if it was
done for valid performance reasons. The schema of the tables are essentially
the same, it's just that they are named differenly and the columns are named
differenlty to differentiate the data from a business usage perspective. The
tables could easily be combined inot one by adding a new...
|
by: psql-mail |
last post by:
hi,
I am becoming more and more convinced that in order to achieve the
required performance and scalability I need to split my data amoungst
many backend machines.
Ideally I would start with about 10 machine and have 1/10th of the data
on each. As the data set grows I would then buy additional machines to
spread the data over.
|
by: Jeff Boes |
last post by:
I'm sure this is a concept that's been explored here. I have a table
(fairly simple, just two columns, one of which is a 32-digit checksum)
with several million rows (currently, about 7 million). About a million
times a day we do
select * from my_table where md5 = ?
to verify presence or absence of the row, and base further processing on
that information.
|
by: Jane |
last post by:
In Oracle we can partition a table as follows. What is the equivalent in DB2?
CREATE TABLE sales_list
(salesman_id NUMBER(5),
salesman_name VARCHAR2(30),
sales_state VARCHAR2(20),
sales_amount NUMBER(10),
sales_date DATE)
PARTITION BY LIST(sales_state)
(
| |
by: Rajesh.............................. |
last post by:
What is the impact of using a nullable column vs a not nullable column
for partitioning a Union ALL View? I have a Union ALL View with ten
underlying tables unioned based on different values for a column
partition_id in these tables. Now, if I define this column as NOT NULL,
I notice that the loading this view is almost twice fast as if I had
defined it NULLABLE. Can anyone explain? What exactly is DB2 doing in
each of the case when...
|
by: shsandeep |
last post by:
DB2 V8.2 (not Viper yet and no range partitioning!!)
I have created a table T1 (col1, col2) with col1 as the primary key.
When I try to create a partitioning key on col2, it gives me error that it
should have all primary keys included.
So, I created table T1 again with col2 as the partitioning key.
Now, I do not have col1 as the primary key.
When I try to create col1 as the primary key, I get the following error:
1 The primary key, each...
|
by: Piero 'Giops' Giorgi |
last post by:
Hi!
I have a question:
I already have a DB that uses partitions to divide data in US
Counties, partitioned by state.
Can I use TWO levels of partitioning?
I mean... 3077 filegroups and 50 partition functions that address
|
by: simoncole |
last post by:
Hi there
Am just about to deploy a new application - one of those 'generic' database
types with very little Oracle specific functionality built in.
There is no referential integrity, and one sequence generator. All referential
integrity is maintained by the (java / JDBC) application.
I'm looking at using partitioning as the expected data volume is large (3TB).
A few good partitioning candidates have come to light, and we can range
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
| |
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
| |
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| |