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by: jbm05 |
last post by:
Hi,
I'm curious about the computational complexity of a query I have. The
query contains multiple nested self left joins, starting with a simple
select, then doing a self left join with the results, then doing a self
left join with those results, etc. What puzzles me is that the time
required for the query seems to grow exponentially as I add additional
left joins, which I didn't expect. I expected the inner select to
return about 25...
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by: DG |
last post by:
Can all "joins" be mimicked via nested selects?
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by: charles |
last post by:
I've got maybe a stupid question, concerning the difference between a
simple select and a select for update ( otherwise identical ).
The plan for such selects - in a DPF enviropnment - are completely
different. Hash joins are used and the select without update returns
fairly quickly, while the select for update involves large nested loop
joins.
Am I missing some obvious point about why a hj would not be used in a
select for update?
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by: sql-db2-dba |
last post by:
We have DB2 UDB v8.1 fixpak3 on AIX 5. Production and Development
configuarations (at least for DB2) are identical albeit production is
a 2-way server while development has only one processor. Tables and
indexes have the same schema. In fact, the dev database was taken from
a prod backup recently. Size of the tables differ slightly. Yet, on a
given query (with 4 tables joined), it took 30-50 times longer to run
in prod than on development....
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by: Steve C |
last post by:
Hi,
I'm having problems constructing a nested join. It's quite complex, so
here's a simplfied example of the problem. Any thoughts on what I'm
doig wrong - or if I've got the whole approach wrong are welcome.
I've two tables :-
one is a contact table contacting name, addresses etc. Three of the
fields represent users - 'created by', 'last modified by' and 'owner'.
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by: tt40 |
last post by:
Anyone know how to prevent Access 2002 from automatically breaking all
the incorrect joins in a query and then automatically saving the broken
query?
This is what I would call stupid design behaviour...Access takes your
'broken' query and auto saves it as what I call a 'corrupt' query...
1. Rename some BE tables and attributes
2. Open your FE
3. Open a query in design view that you know to now have broken names
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by: alan_conoco |
last post by:
Hi all,
I am trying to delete a subset of records (identified using my
InsertRemovePairs query) from a table names TradesDone.
When I execute the nested SELECT on its own it returns the correct
records. When I execute is nested in the DELETE it tries to delete
everything in my database....
What have I missed??
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by: d.s. |
last post by:
I've got an app with two classes, and one class (InventoryInfoClass)
is an object within the other class (InventoryItem). I'm running into
problems with trying to access (get/set) a private variable within the
included class (InventoryInfo) from the "including" class
(InventoryItem).
Here's the code, trimmed down. I've included ********* at the start
of the first line that's blowing up on me. I'm sure others that try
to access the...
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by: LanaR |
last post by:
Hello,
one sql statement is causing severe performance issue. The problem occurs only in UDB environment, the same statemnt on the mainframe is running fine. I have an explain output from the sql. The statement itself is not that complicated, it is 3 selects and union all. Explain output is pretty big, but I could not find anything unusual. I'm new to db2 and I could be missing stuff. I am posting the explain output below and I really...
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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...
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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,...
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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...
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by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
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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...
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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();...
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by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
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by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
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by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
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