What are some of the methods/techniques experienced SQL developers use to determine if a particular SQL query will scale well as load increases, rows in associated tables increase etc.
I'm having issues with one of my servers taking a long time to look up host names.
This is an Ubuntu 12.04 box, so I've tried following the new resolvconf directives.
In my /etc/network/interfaces file, I defined my name servers like this:
auto eth0
iface eth0 inet static
address someaddress
netmask 255.255.255.0
gateway 198.58.103.1
dns-nameservers 74.14.179.5 72.14.188.5
In my /etc/resolv.conf, I see these name servers, like this:
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 74.14.179.5
nameserver 72.14.188.5
On another box, I edited the resolv.conf directly as directed by my hosts' setup help files. It looks like this:
domain members.linode.com
search members.linode.com
nameserver 72.14.179.5
nameserver 72.14.188.5
options rotate
This second box has no issues with host name look ups and responds quite quickly.
Could not having the domain and search directives make my look ups slow? By slow, I mean it's taking anywhere from 5 to 15 seconds to find the IP address of a host.
I use SQL Server 2000.
Suppose I have two tables like the following:
Area
----------------------------------
ID| Name | HierarchyLevel
----------------------------------
1 | World | 1
2 | America| 2
3 | Europe | 2
4 | Africa | 2
5 | USA | 3
and
AreaHierarchy
------------------------
ID | ParentID | ChildID
------------------------
1 | 1 | 2
2 | 1 | 3
3 | 1 | 4
4 | 2 | 5
where
AreaHierarchy.ParentID and AreaHierarchy.ChildID are FKs of Area.ID
How can I find the nth parent of USA?
Is it possible without looping?
Probably not.
I've been handed a rather large, old, and crusty Access 2000/2003 database to clean up. I'll need to rename a number of tables and fields, but need to do so in a way that doesn't break existing queries. (Fortunately, there are no macros, forms, or reports to worry about.)
I've heard there are some commercial tools to make this job easier, but only found one (http://www.rickworld.com/products.html).
Can anyone recommend this software, or any alternatives?
I'm building a simple web application that is mainly going to be displaying small tables of data back to the user. The problem is I can't do design to save my life. I need a simple web 2.0 style template that is CSS/HTML compliant. I know about http://themeforest.net and http://www.oswd.org/. Just wondering if there are any other sites that have a good selection of templates suitable for web apps.
I have multiple webservers which use many small files to created dynamic web pages. Caching the web pages isn't an option. The webserver also performs writes so I need a synchronous filesystem.
I'm looking to maximise performance as it's my understanding that small files is the weakness (to varying degreess) of a cluster filesystem over ethernet.
Currently I'm using Centos 5.5, 64 bit.
Since it's only about 300MB of data, I'm looking at mdadm using RAID-1 with the GNBD and a local hard disk using the "--write-mostly" option so the reads are done using the local hard disk.
Is this possible?
If so, is there any advantage to making it a tmpfs disk instead of a local hard disk?
Or will the files on the local hard disk just get cached in RAM anyway so I won't see a performance gain by using tmpfs, assuming there's enough RAM available?
Say I have 2 tables whose structures are as follows:
tableA
id | A1 | A2
tableB
id | tableA_id (foreign key) | B1
Entries in A have a one-to-many relationship with entries in B. What kind of query operation would I need to achieve "something like this: select all objects from table B where A1="foo""? Basically, apply a query on tableA and from those result, find corresponding dependent objects in tableB
When I set up a tunnel using dynamic forwarding (ssh -D), which side is running the SOCKS proxy? That is, is the proxy running on the local end (client) or the remote end (server)?
Here's the situation: I want to set up several tunnels chained together using -L. Should the -D tunnel be the last one in the chain or the first one?
Edit: I found the answer to the second paragraph on Super User (the -D tunnel should be at the remotest end). But I'd still like to know where the proxy code is running.
I have a CentOS 6 machine running on our network which has a simple LAMP installation on it.
I have some files there which I would want to access through other Windows PC which I am able to do so using the IP address of the CentOS machine.
Since the IP address of the CentOS machine also could be dynamic I would want to connect to it using the computer / host name
But I am not able to do so using the computer / host name of the CentOS machine.
Can someone help me point out what I may be missing and help me out to resolve this?
Hi,
I am loading data for tests in tables using xml and ndbunit.But,for a table having computed column,I am having problem.I get this error
The column "xyz" cannot be modified because it is either a computed column or is the result of a UNION operator.
I have modified the INSERT and UPDATE commands(removed the computed column) of sqladapter in xsd file,but still face the issue.
thanks
I am trying to run an application on a Windows Server 2008 R2 machine from a Windows Server 2003 R2 machine using a batch file with the following line of code in a batch file:
psexec \\nightmachine -u DOMAIN\User -p Password -i "C:\FilePath\Application.exe" argument1 argument2
The application fails to run correctly when started using psexec, but the application will run correctly if I have logged into the nightmachine with the same user and started it from its file path via cmd. I have been able to get hold of the error returned in the application from its log and the exception returned is the following:
System.DllNotFoundException: Unable to load DLL 'rasapi32.dll': A dynamic link library (DLL) initialization routine failed. (Exception from HRESULT: 0x8007045A)
After searching for that error code on the net, there are a lot of posts saying that this is caused by file corruption, but I cant see why that would be the case as the application will run normally when not being run from psexec. (the user is an administrator on both machines)
Can anyone please help me on this? If any more information is needed to help solve this issue then please ask and I will do my best to post it.
Is there a way to specify the database engine to be used for fixtures in CakePHP test fixtures? Some of my models depend on database transactions, and I would like to write some tests for their correct behavior. Currently I'm simply auto-importing the schema, but the tables get created with MySQL's standard MyISAM engine, which doesn't support transactions.
class FooFixture extends CakeTestFixture {
public $name = 'Foo';
public $import = 'Foo';
public $records = array(...);
}
Is there any way to export a Microsoft SQL Server database to an sql script?
I'm looking for something which behaves similarly to mysqldump, taking a database name, and producing a single script which will recreate all the tables, stored procedures, reinsert all the data etc.
I've seen http://vyaskn.tripod.com/code.htm#inserts, but I ideally want something to recreate everything (not just the data) which works in a single step to produce the final script.
Can we do this query without subqueries?
SELECT login, post_n,
(SELECT SUM(vote) FROM votes WHERE votes.post_n=posts.post_n)AS votes,
(SELECT COUNT(comments.post_n) FROM comments WHERE comments.post_n=posts.post_n)AS comments_count
FROM users, posts
WHERE posts.id=users.id AND (visibility=2 OR visibility=3)
ORDER BY date DESC LIMIT 0, 15
tables:
Users: id, login
Posts: post_n, id, visibility
Votes: post_n, vote
id — it`s user id, Users the main table.
I'm trying to build a system where access to certain resources (file shares) in Windows Server, is limited not only by the username (in a Active Directory domain), but also by the client machine. So far, I haven't found a good way to do this; adding the computer account to the DACL is apparently not the way to do it.
Windows Server 2012 supports this with Dynamic Access Control, but this method requires all clients to be Windows 8, it seems, with no way to use this with Windows 7 clients.
Is there a supported way to do this? (or alternatively, add support for device authorization with Windows 7).
I am currently html encoding all user entered text before inserting/updating a db table record. The problem is that on any subsequent updates, the previously encoded string is reencoded. This endless loop is starting to eat up alot of column space in my tables. I am using parameterized queries for all sql statements but am wondering would it be safe to just let the .NET Framework handle this part without the HTML Encoding?
Im using c# windows form application. I have a database with many tables. Each table has several columns. I need to populate the combo box with the column names for a selected table.
I read:
Cannot connect to ec2 instance
http://stackoverflow.com/questions/5635640/cannot-ssh-into-amazon-ec2-instance
Amazon EC2 instance ssh problems
etc...
But could not fix it: suddenly (after a year of service, no changes on my winscp settings) it gives me "network error connection timed out" (im using ec2-user) (also from the amazon console).
Log FILE: http://pastebin.com/vNq6YQvN
All Sites that run on it run fine
port 22 is allowed (never changed it) (security group)
using the correct ec2-user and domain
via my winscp / putty i can connect to other hosting (via ssh)
update: SOLVED. I spend 2 days without looking at my own IP address .... (since it did not change the past 3 years....). Your comments made the spark in my brain. thank you so much. (and only now i find dozens of discussions from angry users that the static addresses from my provider are changed to dynamic ones: http://gathering.tweakers.net/forum/list_messages/1501005/12 ...)
I have a VPS server running in the cloud. Fully automated server image upgrade/downgrade(by RAM/HDD plans).
The problem is that server upgrade/downgrade takes time and involves total unavailability during this period(up to 30 minutes).
Goal: during this downtime server my website(http://mydomain.here) from different server with some message like "Under construction".
How can I do this?
--
mydomain.here is hosted on godaddy and uses its DNS(If I call it right). It's pointing with A-record to my VPS's IP address now.
Change in these DNS settings will take more than 30minutes, so it's not an option. How can I find mode "dynamic" DNS? What should I learn?
There are three tables in my db ITEM_MASTER, PRICE_MASTER, COMP_MASTER
ITEM_MASTER
STORE_CODE ITEM_CODE ITEM_DESC
011 914004 desccc
PRICE_MASTER
STORE_CODE ITEM_CODE COMP_CODE
011 914004 01
011 914004 02
011 914004 03
011 914004 04
COMP_MASTER
COMP_CODE COMP_DESC STORE_CODE
01 comp1 011
02 comp2 011
03 comp3 011
04 comp4 011
I want to get all these for an ITEM_CODE in single query
STORE_CODE ITEM_CODE ITEM_DESC COMP_DESC1 COMP_DESC2 COMP_DESC3 COMP_DESC4
011 914004 desccc comp1 comp2 comp3 comp4
How can i write a oracle SQL query for this??
How do I print the indicated div (without manually disabling all other content on the page)?
I want to avoid a new preview dialog, so crating a new window with this content is not useful...
The page contains a couple of tables, one of them contains the div I want to print - the table is styled with visual styles for the web, that should not be shown in print....
I have an HTML page with lot of tables. Among that I have a table with the following format
<table><tr><td class="myclass">..</td></tr>
<tr><td class="myclass">..</td></tr></table>
How can I get the object of this table using the class selector in jquery?
Hi,
I have 2 database:
production and to test.
Production should have the same fields and tables like testdatabase.
is there any software, or script to show difference between this two databases?
i have two tables with images that parts of them are transparent and i want
to ignore mouse interactions (especially clicking) on these parts and assign the
click to the image in the other table that below.
(i hope you understand because english is not my native language.)
thanks..