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by: Carlos Ibarra |
last post by:
In various places I have seen mentioned the importance of indexing
foreign keys to avoid table locks on the child table on parent
update/delete and full table scans when the constraint has action ON
DELETE CASCADE. For example, see
http://asktom.oracle.com/pls/ask/f?p=4950:8:10827638093976934265::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:292016138754,
However, if I have no index on the FKs, the only mention of full table
scans on the...
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by: Greg Stark |
last post by:
Hm, here's a query where the optimizer is choosing the wrong plan by far. I
think it boils down to it guessing wrong on how selective an rtree index is,
which I guess would be hard to predict.
Except if it guesses wrong by assuming it isn't selective it would be maybe
50% slower doing lots of index lookups instead of a more efficient full table
scan and join. If it guesses wrong by assuming it'll be very selective as it
is in this case...
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by: Zri Man |
last post by:
I'm relatively new to DB2 and was reasonably amused to see the REVERSE
SCAN availability for Indexes.
My assumptions are as follows:
DB2/UDB uses B-Tree for indexing by default and is likely the main
offering for Indexing within the DB.
Reverse Scans could possibly only happen on the the leaf node of
the index
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by: tlyczko |
last post by:
Hello Rob B posted this wonderful code in another thread,
http://groups.google.com/group/comp.lang.javascript/browse_thread/thread/c84d8538025980dd/6ead9d5e61be85f0#6ead9d5e61be85f0
I could not figure out how to reply to the thread per se using Google
Groups and so please forgive me for cutting and pasting (I emailed him
but he may not have time to check his email), and I am hoping someone
might be able to tell me how I can change this...
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by: teddysnips |
last post by:
Table DDL below:
The tables I have contain Timesheet information. Each row in the
tblTSCollected table contains an entry for an employee into the
timesheet system, specifically by scanning the barcode on their badge.
A whole bunch of business logic periodically attempts to "pair" these
into logically matched scans. For example, some employees will scan in
and out of a single place of work. For these there will be a row
written to...
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by: Claudio Grondi |
last post by:
Let's consider a test source code given at the very end of this posting.
The question is if Python allows somehow access to the bytes of the
representation of a long integer or integer in computers memory?
Or does Python hide such implementation details that deep, that there is
no way to get down to them?
The test code below shows, that extracting bits from an integer value n
is faster when using n&0x01 than when using n%2 and I...
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by: NEW2DB2 |
last post by:
Does the optimizer create a temporay table for the index that allows reverse scans ?
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by: BD |
last post by:
Hey, all.
Subject line says it all.
But for background:
I'm developing on UDB for Windows. The production application is on z/
OS.
I'm using some Quest tools (SQL Optimizer) to review some queries, and
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by: lovelyasha |
last post by:
i'm trying to print the children of a process backwards, but once i exit the for loop the children are getting printed as 0
for(i = 0; i < counter; i++)
{
switch(pid = fork())
{
case -1:
perror("Could not fork\n");
exit(1);
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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: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
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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,...
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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: 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: 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
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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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