Dokumentation af Access

mener det er 255 brugere...

Teoretiskt 255 brukere, 10-20 brukere er mer reelt.
Det kommer ann på antal poster,spøringer osv.

This quesition has been up a number of times! as a couple of user say here there is a theoretical max of 255. In the real world it will be less. I have applications runing with 50 or more users without problem!

An appliction using Access as a database should close the connection to the datbase as soon as it has done what it wants (read/Write). If the database is designed correctly and we are NOT talking about great amounts of data then connections should be open for lets say 30 seconds! If we say that we only can manage 25 connections at one time then we are talking about 50 a minute and thats 3000 an hour,
72000 in a day!

Quite often programmers don not close connections as soon as possible which is only going to give problems.

What I am saying is IF the database is designed correctly AND with mulit users in mind then Access can manage FAR more users than many say. (Thats their bad programming they can blame!)

Jeg kørte for et par år siden et projekt (ca 50 tabeller, db størrelse 5 MB) med 3 samtidige brugere. Det gik totalt i vasken, og vi måtte skifte databasen ud med en professionel db. Vi anvendte databasen fra forskellige netværk, og oplevede at pga transmissionstider på de enkelte netværk blev svartiderne håbløst lange. Man kan sikkert koble 10-12 brugere på samtidig, men kun hvis alt andet er veltrimmet og db'en er lille. Med mere komplekse db's kan man opleve en grænse på 2-3 brugere.

Terry> Access er udviklet og markedsført som et værktøj til den helt almindelige bruger der ikke nødvendigvis har en masse teori og erfaring i bagagen. Derfor synes jeg det er lige en tand for stift at kalde access brugergruppen for håbløse programmører.

Jeg har selv prøvet at koble et par samtidige brugere på access, men jeg var mere intereseret i noget konkret at henføre til i mit projekt, jeg tænkte at det kunne være nogen af jer havde læst/set nogle tests af db på nettet eller i blade, jeg kunne bruge.....

hansk>This sums it all up, (Thats their bad programming they can blame!)
I have been programming for over 15 years and I KNOW what I see! I have almost NEVER seen one access prgram which takes into account locking. What would you call it if it isnt bad programming in a multi user environment, forgetfulness? I have alos seen numerous web applications where connections are left open, this is doomed to give problems where its possible to jump from one web to another without logging off.
Access is intended as a mulit users system and if used correctly is just that.

Jeg er helt enig med Terry. Er en Access database struktureret fornuftigt, kan den faktisk yde ganske pænt. Dog er 255 samtidige brugere MEGET teoretsk :)

thanks nonog>But 255 users at the same instance in time is also theoretical :o)

If we COULD manage 255 at one time and a database action such as select or update only took 30 seconds then we are talking 734400 in one day and if I was expecting so many then I thing I would be able to afford SQL :o)

Nu vil jeg nødig afbryde jeres ellers meget interesante diskussion, men for at vende tilbage til spørgsmålet, er der så nogen af jer der kender til konkrete tests af access. Meget gerne et link. Så jeg har noget dokumentation til mit projekt. Jeg har desværre ikke selv mulighed for at lave et forsøg med 255 brugere!!!!!

skriv til rrt@wagged.com der vil du kunne få den hjælp du har brug for...

tomniels> Microsoft STATE 255 in their documentation and I am sure they can give a demonstration using 255 users.

terry> Jeg er heltt enig i dine betragtninger omkring god og dårlig programmeringsskik. I de 25 år jeg har arbejdet indenfor området har jeg set meget af hvert. Det jeg prøver at sige er: Hvis man tuner en folkevogn kan man få den til at køre bedre end en ferrari som er dårligt tunet. Men hvis man sælger et produkt som access til millioner af brugere kan man som udgangspunkt ikke forvente at den almindelige bruger er nogen ørn til at tune programmet. Men en helt simpel database med kun 1 tabel med ganske få forekomster, hvor tingene er lavet på en fornuftig måde kan måske håndtere et par hundrede brugere.
Så mon ikke det korrekte svar på dette spørgsmål er at det helt kommer an på 1: størrelsen af databasen, 2: Kompleksiteten af databasen, 3: anvendt programmerings måde.

Yes I agree, and that would also be the case for other database systems too, although other systems may be more "kind" :o)

Tusind Tak for alle jeres indlæg, men jeg har imidlertidig selv fundet de informantioner jeg har brug for, bl.a. takket være flg. link: http://groups.google.com/groups?hl=da&threadm=98o4ir%24rpf4%40bornews.inprise.com&rnum=9&prev=/groups%3Fq%3Dinterbase%2Bvs.%2Baccess%26hl%3Dda%26selm%3D98o4ir%2524rpf4%2540bornews.inprise.com%26rnum%3D9

Hey tomniels>That was a comparison between two different databases. That does NOT conclude a thing! It deosnt give you ANY concrete documentaion at ALL on what Access can or can not!
I could also have gave an example where I have an appliction with over 50 users. But you would obvioulsy believe what I say!

But you would obvioulsy NOT believe what I say!

Hej Terry,

Du virker som om du har god styr på din ACCESS. Derfor får du lige et par ekstra spørgsmål med på vejen her:

Hvis du har en database med kun 3-4 ACCESS tabeller, som ikke er bundet op af relationer (ikke kompleks), gør det så nogen forskel på hvor mange brugere der kan køre samtidig?

Og gør det nogen forskel hvis en enkelt tabel indeholder f.eks. 1000 forekomster? Er ACCESS gearet til det?

Du nævner 30 sek. som et eksempel på en "database action" - mener du her den tid fra forespørgslen bliver sendt til databasen og til connectionen lukkes? Det kan godt være det er mig der misforstår dig, men hvordan kan det tage 30 sek?

Actually its the number of connections which is important. Access DOES allow 255 but in the real world it IS far less. I think I read in a previous question you placed that thomasjepsen mentioned a connection only needs to be open for a VERY SHORT time. This will (should) only be a matter of seconds! So it is VERY unlikely that you will get many users reading from the database at the same time.

At the moment there are 335 users logged into eksperten. This DOES NOT mean that they all have a connection opened. It only means that they have logged in and are maybe only reading/write information. Only when they press the Send button, or do some other action to read or write to the database does (should) a connection get opened. So in fact there may only be 10-20 connections opened at once.

1000 records is not many at all, but it depends on how much data is in each. Access has a limit of 2 GB for each database. But if your tables arent related then you could have one table in each database = (3-4)*2Gb

When I say 30 seconds then this was ONLY an example, and I VERY MUCH doubt that it will be open that long, as I mentioned previosuly.

In the example I gave above 10/05-2002 15:51:56 this was a simple example to explain that many connections (read/write access) to the dB can be made. Any I'm sure this can be far greater than the example if the application is put together correctly.

Hope that helps

If you understand database principles then I would NOT be afraid of goin gover to MySQL or MS SQL. But MS SQL generally costs money if you want a web provider supplying this. I have one with Azero which I find quite cheap and stable.