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Hello,
I write apllication(.NET 3.5 C#, SQL Server 2k8) (type ERP) with modules like: HRM, SCM, FRM, MRP.
It is multi user application.
I decide store all important data from DB in Dictionaries or List<t> ex. for INVOICE i create Dictionary<int,> etc.
To reduce connection with data base I have mechanism base on events to update specific data in my Dictionaries.
I chose this solution because I don't want once again fill my GridView from DataBase when one record has been changed by another user.
To synchronize my Dictionaries I want to use Query Notification and tracking changes mechanism (SQL Server 2008).
And all work fine but ....
Hypothetical situation.
I have for example 20 Dictionaries and any of this Dictionary have 2000-5000 elements.I fill it when the user logs on to an application.
How does it affect the weight of memory?
Is that way - casched Dictionaries - is a better solution then load all data (ex.Invoices) from data base when i need use it ?
Sorry for my English. It is not perfect.
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Such extensive caching is usually not required unless you have some tremendous load on your servers. Generally speaking, you should avoid caching as muc has possible because it adds an additional level of complexity that must be managed in addition to managing the data in the database. You greatly increase the risk of data corruption but caching everything all the time, because it is now your responsibility to make absolutely certain data integrity constraints are met, rather than letting an RDBMS do it for you. Not only that, you will indeed greatly increase your memory footprint, and that footprint will grow as the usage of your application grows to the point where you can't keep everything in memory at all times.
If you already have performance problems...then there are other ways to solve them...such as scaling out your hardware (better hardware, more servers, etc.) If you do not have performance problems yet, and are trying to preemptively solve possible performance problems...don't bother. It is difficult to predict what may cause performance problems, and caching isn't always the best solution, and should generally not be the first. You can gain much more in terms of performance improvements for less cost by adding hardware than by increasing the complexity of your code.
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Thank you for your answere.
Unfortunetlly I have this mechanism in my application and I'm done 2 modules. It is hard to change everythig in this moment.
But... is there a big problem if in my whole application with all modules I will be have maximum 100 000 rows in my whole tables in Data Base ?
I don't know that 100 000 records whether much, and how much it affects the load on the system ?
Because I want to sell this application with computer (notebook), my minimum requiments is:
- Core 2 Duo 2GHz,
- minimum 2GB RAM.
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I can't say exactly what the memory load would be. It entirely depends on the size of your records. If they are all maximum size (aprox 8000 bytes, barring varchar(max) columns), and factoring in .NET overhead, 100000 records will use approximately a gig of memory. That is JUST for the rows...that doesn't factor in any other memory used by your application. Assuming you want this application to work on 32bit systems, then you will really be pushing it, as each app in 32bit windows gets a maximum of 2Gb addressable memory space.
That aside, there are much deeper concerns than memory consumption here. You are trying to cache ALL of your data in memory. Its not as simple as sticking all your records in a collection. There are usually relationships between data, concurrent updates, general data integrity, etc. to worry about when you cache that much data. Despite the fact that you have already started development, I think you need to take a step back and really evaluate what caching all your data means to the long-term sustainability of your project. You may think that continuing on will save time and money...but you are just as likely to introduce some very complex scenarios due to your caching that will need to be addressed down the road, and that could cause your long-term costs to explode far beyond any short-term costs of reevaluating your approach.
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Thx for you answer.
Because I have 2 modules finshed from 4, I'll change the way of work with database during creation 2 new modules. In time I'll try to change everything, without simple dictionaries like for example types of invoices or types of education level.
What you suggesting as an alternative ??
I thought about :
- strong typed DataSet's,
- LINQ to SQL (but I read that is more slow then classic ADO.NET),
- Entity Framework,
- ADO.NET (mode non-connection),
- or something else ??
I'd like to just keep communicating with the database using stored procedures.
Overall, I am not afraid of new challenges and if I need I'll learn new technologies.
Thank you once again
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I would recommend LINQ to SQL. You can build a conceptual model with L2S, then add stored procedures that return objects from your model. You are still able to use SPs, but you are still able to strongly typed objects rather than data sets. L2S is not slow if you use it for what it is...an ORM. The SQL generated by L2S is actually very efficient. If you use it with procs, you won't really see any of the performance benefits...but, neither will you run into anything that could cause performance problems either (i.e. working with huge object graphs and their changes, which can get kind of hairy).
Entity Framework is premature. It has potential, but its up to Microsoft to realize that potential. Currently, EF is very intrusive and heavy. It will work great for non-distributed apps where the clien app is not separated from its business by web services or remoting. However, if there are web services separating your presentation from your domain, then EF is a real disaster.
There is another free ORM, called nHibernate. It came from the Java world, so it doesn't fit well with Microsoft standards, but it is one of the better ORM's out there. It still has some of the problems that EF does as it is a bit intrusive, however it does generally support POCO and PI, so its currently a better choice than EF if you want a real ORM.
Since you are currently looking to use stored procs, I would defintly go with L2S. Its the simplest solution that will get you the quickest results with procs.
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Ok, thx for your advice.
I'll try to learn LINQ to SQL.
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StreamWriter sw = new StreamWriter("D:\\Text.txt");
DataTable dt = new DataTable();
DataColumn dc = new DataColumn("ID", typeof(int));
dc.AllowDBNull = false;
dc.Unique = true;
dt.Columns.Add(dc);
dt.Columns.Add("FirstName", typeof(string));
dt.Columns.Add("LastName", typeof(string));
dt.Rows.Add(1, "Micael", "Macdonald");
dt.Rows.Add(2, "John", "Smith");
int length = dt.Columns.Count;
for (int i = 0; i < length; i++) {
sw.Write(dt.Columns[i]+" ");
}
foreach (DataRow dr in dt.Rows) {
sw.Write("\n" + dr[0] + " " + dr[1] + " " + dr[2]);
}
sw.Close();
StreamReader sr = new StreamReader("D:\\Text.txt");
a = sr.ReadLine();
while (a != null) {
Console.Write(a + "\n");
a = sr.ReadLine();
}
sr.Close();
well as you can see this code writes in file from DataTable and it works
now I want to put back this text from File to DataTable, columnames to Columns and rownames to Rows
what will you advise me, how i'll do it?
C# Developer
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You can use OleDB connection to both read and write datatables to text file. Have a look at this[^].
जय हिंद
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no i want to do this one, put back this columns and names to datatable
I have exercise
if you have any time plz post code
C# Developer
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West1989 wrote: I have exercise
if you have any time plz post code
There you go. This is not a way to learn.
Did you tried reading books or searching web? No one here has a "responsibility" to write code for anyone except themselves or their employers. You should do your homework on your own.
जय हिंद
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why dont you use XML instead of TEXT. You wont even need to write long code.
DataTable.WriteXml();
DataTable.ReadXml();
but if you want to do this with text file then instead of writing all Row's cell in a line, write each cell on each line. Because your string column can contains the splitting char.
eg
dt.Rows.Add(2, "John", "Smith Corner");
now when you split you will lose 'Corner'.
Plus do not use StreamWriter or StreamReader, both are slow. Try this
string[] maLines = new string[cols*rows];
for (int a=0;a<dt.rows.count;a++)>
{
maLines[a] = dt.Rows[a][0].ToString();
maLines[a+1] = dt.Rows[a][1].ToString();
}
File.WriteAllLines(filePath, maLines);
string readMaLines = File.ReadAllLines(filePath);
TVMU^P[[IGIOQHG^JSH`A#@`RFJ\c^JPL>;"[,*/|+&WLEZGc`AFXc!L
%^]*IRXD#@GKCQ`R\^SF_WcHbORY87֦ʻ6ϣN8ȤBcRAV\Z^&SU~%CSWQ@#2
W_AD`EPABIKRDFVS)EVLQK)JKQUFK[M`UKs*$GwU#QDXBER@CBN%
R0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-iTV.C\y<pjxsg-b$f4ia> -----------------------------------------------
128 bit encrypted signature, crack if you can
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What's the counterpart of this line of vb.net in C#:
Datagridview1.Item(1,iCtr).Value.ToString()
I have managed to do it in the following way:
Datagridview1.Rows[1].Cells[iCtr].Value.ToString();
But is the line of vb.net supported in C#?
If not then what's the alternative?
Regards.
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Why not run the code and check.
जय हिंद
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The exact C# equivalent of the VB line is Datagridview1[1, iCtr].Value.ToString();
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Thanx Mirko that's what I wanted. Regards.
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Hi,
how to get user name on which an NT Service is running?
And I don't mean the process user, 'cause I need that information even if the service is stopped.
Thanks.
modified on Thursday, March 19, 2009 12:50 PM
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Qbashi wrote: And I don't mean the process user, 'cause I need that information even if the service is stopped.
How are you going to get it if the service is not running? 
Yusuf
Oh didn't you notice, analogous to square roots, they recently introduced rectangular, circular, and diamond roots to determine the size of the corresponding shapes when given the area. Luc Pattyn[^]
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Yusuf wrote:
How are you going to get it if the service is not running?
Well, that was the problem you know... but the service is installed and even if it's not running we can get some informations about it.
I've solve the problem by getting ObjectName for service from registry.
You didn't have advice for me but I have one for you:
You should do something with that extra time you got, try picking your nose or something instead of writing nonhelpful replies.
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Qbashi wrote: Well, that was the problem you know... but the service is installed and even if it's not running we can get some informations about it.
alright, let us see how the genius dumbass of the day will solve it
Qbashi wrote: I've solve the problem by getting ObjectName for service from registry.
that does not tell you about the user who is running the service.
Qbashi wrote: You didn't have advice for me but I have one for you:
You should do something with that extra time you got, try picking your nose or something instead of writing nonhelpful replies.
oh yea, since I have extra time, for this for starters. F*** off dumb a**hole.
Yusuf
Oh didn't you notice, analogous to square roots, they recently introduced rectangular, circular, and diamond roots to determine the size of the corresponding shapes when given the area. Luc Pattyn[^]
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How about that! Another absolutely useless reply from you.
http://technet.microsoft.com/en-us/library/cc787581.aspx[^]
So I am really sorry that I've come up with that stupid solu... But no! Wait, just wait a minute. No I'm not! I was right! Muahahahahahaha 
So, dear Yusuf, I'll b**ch slap you any time any where.
Regards.
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Hi
How can we check the failure of windows service programatically. I have a windows service that elapses every 5 minutes and I need to check if the service is failed then restart it automatically in my code. I googled but I couldnt find the Failed Status for the windows service.
Any ideas please!
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I take failure as your service breaks ie exception. Correct me if I am wrong. If this is the case, then you need to rethink. An application that breaks every 5 minutes is not desirable.
जय हिंद
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The ServiceController[^] allows you to Start, Stop and check the running status of services.
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