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Convert MS Access DB (FE&BE) to Oracle

P: n/a
I need to convert a 17mb access 2000 db to Oracle and house it in a
Citrix farm. The issue: we have never converted an Access Db to Oracle
but can probably use Oracle's Workbench to assist with this. Also - the
citrix folks do not want us to keep the FE in Access as the queries and
other activities consume a lot of power. The users will be in 3
different offices across the globe all accessing the 1 Oracle DB in
Citrix.

Does anyone have any good ideas on how to do the following?
1) How to convert the Access 2000 db to Oracle?
2) What FE to use once the db is in oracle?
3) if we have to keep Access as the FE are there any good ways to limit
the drain on bandwidth and power that occurs with Access queries and
other activities in access?

Mar 1 '06 #1
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1) Read the Oracle requirements like length of table/column names, etc.
I've found that to be a pain. Oracle doesn't like lengths > 30 (I
believe).

a) There are a few applications on the WEB that can create the DDL
commands that create tables. IOW, read the Access table & create the
Oracle DDL commands (script). Then just run the script in Oracle to
create the tables. Then link the Oracle tables to the Access data file.
and use Access append queries to load the Oracle tables. Then get rid
of the links to both the Oracle and Access tables (see 2).

2) Use the Access front end. You can use SQL pass-thru queries - all
the processing goes on in the Oracle server instead of thrashing the
network. The bad news is you'll have to convert all your Access queries
into Oracle stored procedures or views.

3) See 2).
--
MGFoster:::mgf00 <at> earthlink <decimal-point> net
Oakland, CA (USA)

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eg*********@westernasset.com wrote:
I need to convert a 17mb access 2000 db to Oracle and house it in a
Citrix farm. The issue: we have never converted an Access Db to Oracle
but can probably use Oracle's Workbench to assist with this. Also - the
citrix folks do not want us to keep the FE in Access as the queries and
other activities consume a lot of power. The users will be in 3
different offices across the globe all accessing the 1 Oracle DB in
Citrix.

Does anyone have any good ideas on how to do the following?
1) How to convert the Access 2000 db to Oracle?
2) What FE to use once the db is in oracle?
3) if we have to keep Access as the FE are there any good ways to limit
the drain on bandwidth and power that occurs with Access queries and
other activities in access?

Mar 1 '06 #2

P: n/a
> Does anyone have any good ideas on how to do the following?
1) How to convert the Access 2000 db to Oracle?
Do you have a split database now? You can use the oracle import tools to
import each of the tables. You will likely have to setup some relationships
etc...but not too big a task.

2) What FE to use once the db is in oracle?
Gee, VB.net, C++, Java, Oracle PowerTools, gee...whatever tools your
developers are familiar with, and think are up to the task.

3) if we have to keep Access as the FE are there any good ways to limit
the drain on bandwidth and power that occurs with Access queries and
other activities in access?


There should not be a big drain here if things were done right in the first
place.

A few things are;

If you write your application in c++, or VB or in your case with ms-access,
in GENERAL the performance of all of these tools will BE THE SAME when you
use Oracle.

In other words...oracle is rather nice, and is a standard system used in the
IT industry.

However, before you convert..how well does your application run now?

We often see posts here that a application is too slow with one user. If the
application is too slow with one user..then what can one expect when they
try and run 10 users. That is now 10 times the requirements..

The other issue is how well is the database setup?

Further..how well are the forms designed?

How well does the application work with 5 users..and then when you jump to
10 users...how much a slow down to you notice?

A few things:

Having a table with 75k records is quite small. Lets assume you have 12
users. With a just a 100% file base system (jet), and no sql server, then
the performance of that system should really have screamed.

Before Microsoft started "really" selling sql server, they rated JET could
handle easily 50 users. We have credible reports here of people
running 100 users. however, in those cases everything must be
"perfect".

I have some applications out there with 50, or 60 HIGHLY related tables.
With 5 to 10 users on a network, response time is instant. I don't think any
form load takes more then one second. Many of those 60+ tables are highly
relational...several tables deep, and in the 50 to 75k records range.

So, with my 5 users..I see no reason why I can't scale to 15 users with
such small tables in the 75,000 record range.

If the application did not perform with such small tables of only 75k
records..then upsizing to sql server (or oracle) will do absolute nothing to
fix
performance issues. In fact, in the sql server newsgroups you see weekly
posts by people who find that upgrading to sql actually slowed things down.
I even seem some very cool numbers showing that some queries where actually
MORE EFFICIENT in terms of network use by JET then sql server.

My point here is that technology will NOT solve performance problems.
However, good designs that make careful use of limited bandwidth resources
is the key here. So, if the application was not written with good
performance in mind..then you kind are stuck with a poor design!

I mean, when using a JET file share, you grab a invoice from the 75k record
table..only the one record is transferred down the network with a file share
(and, sql server/oracle will also only transfer one record). So, at this
point, you
really will NOT notice any performance difference by upgrading to sql
server. There is no magic here.

Oracle is a robust and more scalable product then is JET. And, security,
backup and host of other reasons make sql server a good choice.
However, oracle will NOT solve a performance problem with dealing
with such small tables as 75k records

Of course, when efforts are made to utilize oracle server, then
significant advances in performance can be realized.

I will give a few tips...these apply when using ms-access as a file
share (without a server), or even odbc to sql server or oracle.

** Ask the user what they need before you load a form!

The above is so simple, but so often I see the above concept ignored.
For example, when you walk up to a instant teller machine, does it
download every account number and THEN ASK YOU what you want to do? In
access, it is downright silly to open up form attached to a table WITHOUT
FIRST asking the user what they want! So, if it is a customer invoice, get
the invoice number, and then load up the form with the ONE record (how can
one record be slow!). When done editing the record...the form is closed, and
you are back to the prompt ready to do battle with the next customer. You
can read up on how this "flow" of a good user interface works here (and this
applies to both JET, or sql server applications):

http://www.members.shaw.ca/AlbertKal...rch/index.html

My only point here is restrict the form to only the ONE record the user
needs. Of course, sub-forms, and details records don't apply to this rule,
but I am always dismayed how often a developer builds a nice form, attaches
it to a large table, and then opens it..and the throws this form attached to
some huge table..and then tells the users to go have at and have fun. Don't
we have any kind of concern for those poor users? Often, the user will not
even know how to search for something ! (so, prompt, and asking the user
also makes a HUGE leap forward in usability. And, the big bonus is reduced
network traffic too!...Gosh...better and faster, and less network
traffic....what more do we want!). And, then the application is thrown
out...you buy oracle..and your developer is not so dumb..and as a
HABIT restricts bandwidth use....(this is a learned skill).

** Don't use quires that require more then one linked table

(this ONLY applies to odbc to sql server, or oracle...you CAN and are FREE
to do this with a mdb JET file share..and also with ADP projects to sql
server).

When you use
ODBC, one table could be on the corporate server, and the other ODBC might
be a FoxPro table link 3 computers from the cubicle left of you. As a
result..JET
has a real difficult time joining these tables together..and JET can not
assume that the two tables are on the same box..and thus have the "box" join
the tables. Thus,while jet does it best..these types of joins can often be
real slow. The simple solution in these cases is to change the query to
view..and link to that. This is the least amount of work, and means the
joins occur on the server side. This also applies to combo boxes. Most
combos boxes has sql embedded in them. That sql has to be processed, and
then thrown to a linked odbc table. This is a bit sluggish. (a form can have
maybe one, or two combos..but after that ..it will start to load slow). So,
remove the sql from the combo box, build a view..and link the combo box
direct to that view (JUST USE the view name...the sort, and any sql need to
be in the view). The result is quite good combo box load performance. (and
again, not very much work. There are other approaches that can even speed
this up more..but we have to balanced the benefits VS. the amount of work
and coding. I don't think once should re-code all combo boxes to a call back
with a pass-through reocrdset..but that can be a solution also).

** Of course, if you do have sql with more then one table..then pass-though
is the best if using odbc. (again..this does NOT apply to a mdb JET file
share).

** You can continue to use bound forms..but as mentioned..restrict the form
to the one record you need. You can safely open up to a single invoice,a and
even continue to use the "where" clause of the openform. Bound forms are way
less work then un-bound forms...and performance is generally just is good
anyway when done right.

** Large loading of combo boxes. A combo box is good for about 100
entries. After that..you are torturing the user (what..they got to look
through 100's of entries). So, keep things like combo boxes down
to a min size. This is both faster..and MORE importantly it is
kinder to your users.

After all, at the end of the day..what we really want is to make
things easy for the users...and treat them well.. It seems that
treating the users well, and reducing the bandwidth
(amount of data) goes hand in hand. So, better applications
treat the users well..and run faster! (this is good news!)
For all tables, make sure a primary key (usually id), and a timestamp field
are exposed (ms-access uses the timestamp field to figure out "when", and
what was updated....).

--
Albert D. Kallal (Access MVP)
Edmonton, Alberta Canada
pl*****************@msn.com
http://www.members.shaw.ca/AlbertKallal
Mar 2 '06 #3

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