C / C++ / MFC

14-Feb-07 23:18

Hi,
in the app i'm writing i need to collect data from various sources,every hour.I want the user to be capable of consulting these data through graphs,and most of all, to consult all the data acquired up to now.So i need to load all the data at every app start.

Now,i would like to ask you about a good way to store and quickly load data.I mean,i know i can store data in a text file,but i'm concerned about how long it will take to load this huge archive text file after some years....

C^hris L^osinger15-Feb-07 1:55

C^hris L^osinger

15-Feb-07 1:55

what about a database ?

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Accius15-Feb-07 2:33

15-Feb-07 2:33

This is the a good point,actually the one i was looking for,but i had no idea cause i have few experience of that and so i asked to more expert people.

Sorry about this following silly question,but as i told i'm a newbie in that:can a database solve my problems?

Thanks for the reply,by the way!

C^hris L^osinger15-Feb-07 2:43

C^hris L^osinger

15-Feb-07 2:43

Accius wrote:
can a database solve my problems?

yes.

their whole reason for existing is to store large amounts of data in ways that make it easy to access and update that data.

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Accius15-Feb-07 2:54

15-Feb-07 2:54

OK.
Just a last question:how about the time to load the database,when it has grown a lot?Will it be better than the simple text file loading?

toxcct15-Feb-07 3:01

toxcct

15-Feb-07 3:01

to "load" the database ?

you access a database records through SQL requests...

if the database get too huge, you can indexate some table columns that are used often to query data

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C^hris L^osinger15-Feb-07 3:02

C^hris L^osinger

15-Feb-07 3:02

you should only load the data that you actually need, when you need it. if you need to read everything into memory, then a database won't help you.

databases help organize data so you can get the relevant parts of the data when you need them, quickly.

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Accius15-Feb-07 3:28

15-Feb-07 3:28

Ok,again i thank you.
You helped me a lot

Accius15-Feb-07 5:58

15-Feb-07 5:58

By the way...
Can i add database support in a dialog based application i've already written?
Or have i got to make a new application?

Hamid_RT15-Feb-07 2:20

Hamid_RT

15-Feb-07 2:20

Do you want to use of Sql Server or Access you said every hour does data voluminous?

WhiteSky

toxcct15-Feb-07 2:34

toxcct

15-Feb-07 2:34

WhiteSky wrote:
Sql Server or Access

why don't you propose Oracle also in your list ? oh, yeah, MS Centric.
but know that Access is not a database Poke tongue | ;-P

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Hamid_RT15-Feb-07 2:43

Hamid_RT

15-Feb-07 2:43

But why I must suggest Oracle I preference use of Sql Server(products of Misrosoft) Big Grin | :-D

WhiteSky

toxcct15-Feb-07 2:45

toxcct

15-Feb-07 2:45

i've been using both, but for very huge databases, MS SQL Server does strange things somethings (weird execution paths, way slow than oracle for same scheme...)

The problem of Oracle is the non friendly administration tools. MS produces good stuff for this ; but the main purpose behind that is the database, no ?
then my choice is done (i repeat, for huge databases !)

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Problem in using COM

RajiRaghu14-Feb-07 23:14

14-Feb-07 23:14

I have a tbl for COM application.

In the header file of the application - initInstance(),
CoInitializeEx(NULL,COINIT_MULTITHREADED); is called.

In the Dialog (normal MFC) creatinstance is called.
The classID is passed to the createinstance.

Then,

BOOL Ret = AfxConnectionAdvise(
<punksrc>,
DIID__IEvents ,
GetIDispatch(FALSE), //get the IDispatch assocaiated with Mainframe...
FALSE, //donod addref
&m_dwCookie);//cookie to break connection later...
}

But, while calling the above method, exception is trown in AfxConnectionAdvise.

Thanks

Thanks
Raji

prasad_som15-Feb-07 0:55

15-Feb-07 0:55

RajiRaghu wrote:
GetIDispatch(FALSE), //get the IDispatch assocaiated with Mainframe...
FALSE, //donod addref
&m_dwCookie);//cookie to break connection later...
}

Are you sure GetIDDispatch here is retunring non-NULL ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

RajiRaghu15-Feb-07 1:17

15-Feb-07 1:17

m_pControl.CreateInstance("8fea0f92-1975-4a13-af9b-5666583843db");
m_pMonitor.CreateInstance("b4c8b90e-11c8-4f8b-81a0-a6bcb53d5c2a");

The first parameter of AfxConnectionAdvise - pUnkSrc is 0x00000000
pUnkSink - is not null.
- pUnkSink 0x0012fe34 IUnknown *
- [COleDispatchImpl] {...} COleDispatchImpl
- IDispatch {...} IDispatch
- IUnknown {...} IUnknown
- __vfptr 0x7c15957c const COleDispatchImpl::`vftable' *
[0] 0x7c2e5f80 COleDispatchImpl::QueryInterface(const _GUID &, void * *) *
[1] 0x7c2e5f40 COleDispatchImpl::AddRef(void) *
[2] 0x7c2e5f60 COleDispatchImpl::Release(void)

Thanks
Raji

prasad_som15-Feb-07 1:29

15-Feb-07 1:29

RajiRaghu wrote:
The first parameter of AfxConnectionAdvise - pUnkSrc is 0x00000000

That may be cause of exception.

Prasad
Notifier using ATL | Operator new[],delete[][^]

RajiRaghu15-Feb-07 1:31

15-Feb-07 1:31

The first parameter is from
m_pControl.CreateInstance("8fea0f92-1975-4a13-af9b-5666583843db");
m_pMonitor.CreateInstance("b4c8b90e-11c8-4f8b-81a0-a6bcb53d5c2a");

means that createInstance failed?

Please suggest altenatives..

Thanks
Raji

prasad_som15-Feb-07 1:46

15-Feb-07 1:46

May be seeing complete relevent code can thorugh some light.

Prasad
Notifier using ATL | Operator new[],delete[][^]

RajiRaghu15-Feb-07 18:36

15-Feb-07 18:36

improrted the tlb file with the path. .tlh got created.

but in createinstance, HRESULT returns "Invalid Class String" is returned.

Is anything need to be registered? Is this is the problem with the application unaware of the tlb file?

Any clues please.

Thanks
Raji

prasad_som15-Feb-07 18:45

15-Feb-07 18:45

RajiRaghu wrote:
but in createinstance, HRESULT returns "Invalid Class String" is returned

This resons may come because of following reaosns,
1. Either you have not registered your component using regsvr32.
2. You are using wrong class id to instanciate object.

Prasad
Notifier using ATL | Operator new[],delete[][^]

RajiRaghu15-Feb-07 19:00

15-Feb-07 19:00

Created an application where the .tbl file is included.

The corresponding .dll is in the library path.

Did not register any .dll.

Thanks
Raji

prasad_som15-Feb-07 19:03