Bandwidth Required For ODBC Access

[Dominic Martin]

Hi,

I need to setup an ODBC link over our Internet connection between MS Access
(local) and a MySQL server (Remote - the local PC has the MySQL ODBC driver
installed). What kind of bandwidth requirements am I looking at? Will it
function over a 64k leased line? If this would be slow, could there be any
major impact on other uses such as web and email?

Regards,

Dominic

[Bernard Peek]

In message <c0************ *******@news.de mon.co.uk>, Dominic Martin
<do************ @dplm.co.uk> writes

Hi,

I need to setup an ODBC link over our Internet connection between MS Access
(local) and a MySQL server (Remote - the local PC has the MySQL ODBC driver
installed). What kind of bandwidth requirements am I looking at? Will it
function over a 64k leased line? If this would be slow, could there be any
major impact on other uses such as web and email?

It's certainly feasible to run an ODBC connection over a 64k link, and I
have done so. You haven't really given enough information to answer the
question. You need to know how many data requests will be issued and how
much data will have to be retrieved for each request.

You may need to consider the time distribution of the requests, will
they all occur at the same time? How long are the users willing to wait
for their data? What else will be using the line at the same time? Will
those users be prepared to wait for their data?


--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.

[Dominic Martin]

"Bernard Peek" <ba*@shrdlu.com > wrote in message

It's certainly feasible to run an ODBC connection over a 64k link, and I
have done so. You haven't really given enough information to answer the
question. You need to know how many data requests will be issued and how
much data will have to be retrieved for each request.

You may need to consider the time distribution of the requests, will
they all occur at the same time? How long are the users willing to wait
for their data? What else will be using the line at the same time? Will
those users be prepared to wait for their data?
Thank you for your response. The ODBC access will supplement web based
access, where the web server will be on the same local network as the MySQL
server. The web access will be used mostly for simple queries. The ODBC
access is to be used for more complex ad-hoc queries. So in answer to your
questions, only one person is ever likely to access the MySQL database via
ODBC at a time. The reports do not need to be done instantly, so time is not
too much of a worry.

I'm assuming that these are all good answers. What number of users and level
of data did you pass over the 64k link?

Dominic
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.

[Bernard Peek]

In message <c0************ *******@news.de mon.co.uk>, Dominic Martin
<do************ @dplm.co.uk> writes

"Bernard Peek" <ba*@shrdlu.com > wrote in message

It's certainly feasible to run an ODBC connection over a 64k link, and I
have done so. You haven't really given enough information to answer the
question. You need to know how many data requests will be issued and how
much data will have to be retrieved for each request.

You may need to consider the time distribution of the requests, will
they all occur at the same time? How long are the users willing to wait
for their data? What else will be using the line at the same time? Will
those users be prepared to wait for their data?

Thank you for your response. The ODBC access will supplement web based
access, where the web server will be on the same local network as the MySQL
server. The web access will be used mostly for simple queries. The ODBC
access is to be used for more complex ad-hoc queries. So in answer to your
questions, only one person is ever likely to access the MySQL database via
ODBC at a time. The reports do not need to be done instantly, so time is not
too much of a worry.

I'm assuming that these are all good answers. What number of users and level
of data did you pass over the 64k link?

You can work out the data capacity of the link by looking at the
structure of the tables returned and the number of records retrieved.
The number of users isn't important, just the amount of data they use.

That's very difficult to predict with ad hoc reports. Either the person
creating the reports needs to understand the bandwidth they have
available or you have to find a way of saving bandwidth. Have you
considered replicating the MySQL database to a local server?

--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.

[Larry Linson]

I have done some work on a database using ODBC over a 64K leased line. The
people paying the bills thought it was "acceptable ", but the actual users
thought it abominable. The users didn't find it acceptable until the lines
(one each to three separate user locations) were upgraded from 64KB to T-1
(which is about 1.5MB, as I recall).

A better-written application would have performed better, but the same
people paying the bills wouldn't pay for some obvious improvements, such as
opening the main/first form on a single record rather than on an entire
15,000 record table. But only parts of the app were so poorly
designed/implemented.

Larry Linson
Microsoft Access MVP

[User]

I have done so over ADSL lines (128k upload).

Adhoc queries that returned resonable amounts of data felt OK to me. The
important point is to send the query to the server and have it do the grunt
work - avoiding queries where raw data is returned to Access while it does
the grunt work. However the typical Access form performed substantially
worst - edge of usability.

When you try going long distances or overseas (large latency in the
internet - distance being defined as #routers, hops etc. as opposed to miles
per-se) then things become very bad, because by default Access does not take
care to minimize the amount of round-tripping. So the time is multiple
latency plus data transfer.
"Dominic Martin" <do************ @dplm.co.uk> wrote in message
news:c0******** ***********@new s.demon.co.uk.. .

Hi,

I need to setup an ODBC link over our Internet connection between MS Access (local) and a MySQL server (Remote - the local PC has the MySQL ODBC driver installed). What kind of bandwidth requirements am I looking at? Will it
function over a 64k leased line? If this would be slow, could there be any
major impact on other uses such as web and email?

Regards,

Dominic

[Dominic Martin]

"Bernard Peek" <ba*@shrdlu.com > wrote in message
news:I2******** ******@shrdlu.c om...

In message <c0************ *******@news.de mon.co.uk>, Dominic Martin
<do************ @dplm.co.uk> writes

"Bernard Peek" <ba*@shrdlu.com > wrote in message

It's certainly feasible to run an ODBC connection over a 64k link, and I have done so. You haven't really given enough information to answer the
question. You need to know how many data requests will be issued and how much data will have to be retrieved for each request.

You may need to consider the time distribution of the requests, will
they all occur at the same time? How long are the users willing to wait
for their data? What else will be using the line at the same time? Will
those users be prepared to wait for their data?
Thank you for your response. The ODBC access will supplement web based
access, where the web server will be on the same local network as the MySQLserver. The web access will be used mostly for simple queries. The ODBC
access is to be used for more complex ad-hoc queries. So in answer to yourquestions, only one person is ever likely to access the MySQL database viaODBC at a time. The reports do not need to be done instantly, so time is nottoo much of a worry.

I'm assuming that these are all good answers. What number of users and levelof data did you pass over the 64k link?

You can work out the data capacity of the link by looking at the
structure of the tables returned and the number of records retrieved.
The number of users isn't important, just the amount of data they use.

That's very difficult to predict with ad hoc reports. Either the person
creating the reports needs to understand the bandwidth they have
available or you have to find a way of saving bandwidth. Have you
considered replicating the MySQL database to a local server?

Yes, but the MySQL server is a hosted solution, so we're limited in the ways
that we can get hold of the data. It's either CSV copies of the tables or
the ODBC read only link to the live data. Apart from setting up a SQL server
locally, I'm not sure what else we would need to do. Are you suggesting that
the local SQL server would use ODBC just to make straight copies of the data
or that we would have to download and manually import the CSV files? Under
the latter, it is more likely that we would just import the CSV files
directly into MS Access.

When you say you can work out the data capacity of the link, is there a
rough formula that can be applied. i.e. a certain number of records from a
certain number of tables would require x amount of bandwidth?

Thank you for your continuing help.

Dominic
--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.

[Dominic Martin]

"User" <Us**@aol.com > wrote in message
news:OW******** ******@TK2MSFTN GP11.phx.gbl...

I have done so over ADSL lines (128k upload).

Adhoc queries that returned resonable amounts of data felt OK to me. The
important point is to send the query to the server and have it do the grunt work - avoiding queries where raw data is returned to Access while it does
the grunt work. However the typical Access form performed substantially
worst - edge of usability.
Thank you for your comments. How do you ensure that the query is sent to the
server to do the work and not have the raw data returned to Access? Is it
something that you have to build into the query?

Dominic

When you try going long distances or overseas (large latency in the
internet - distance being defined as #routers, hops etc. as opposed to miles per-se) then things become very bad, because by default Access does not take care to minimize the amount of round-tripping. So the time is multiple
latency plus data transfer.
"Dominic Martin" <do************ @dplm.co.uk> wrote in message
news:c0******** ***********@new s.demon.co.uk.. .

Hi,

I need to setup an ODBC link over our Internet connection between MS

Access

(local) and a MySQL server (Remote - the local PC has the MySQL ODBC

driver

installed). What kind of bandwidth requirements am I looking at? Will it
function over a 64k leased line? If this would be slow, could there be any major impact on other uses such as web and email?

Regards,

Dominic

[Bernard Peek]

In message <c0************ *******@news.de mon.co.uk>, Dominic Martin
<do************ @dplm.co.uk> writes

You can work out the data capacity of the link by looking at the
structure of the tables returned and the number of records retrieved.
The number of users isn't important, just the amount of data they use.

That's very difficult to predict with ad hoc reports. Either the person
creating the reports needs to understand the bandwidth they have
available or you have to find a way of saving bandwidth. Have you
considered replicating the MySQL database to a local server?
Yes, but the MySQL server is a hosted solution, so we're limited in the ways
that we can get hold of the data. It's either CSV copies of the tables or
the ODBC read only link to the live data. Apart from setting up a SQL server
locally, I'm not sure what else we would need to do. Are you suggesting that
the local SQL server would use ODBC just to make straight copies of the data
or that we would have to download and manually import the CSV files? Under
the latter, it is more likely that we would just import the CSV files
directly into MS Access.

MySQL supports replication, so that any changes to a master database are
automatically copied to a slave database. You would keep the master
database on the server and run all of your queries against the slave
kept on your own site. You need to talk to your hosting provider about
that, they may have other customers doing the same thing.

If your data changes slowly it may be OK to copy the data to CVS files
once per day and to copy them when the 64k bandwidth isn't being used
for anything else, perhaps overnight. That way you could run queries
against a database that is less than 24 hours old and not need to use
bandwidth during the day.

When you say you can work out the data capacity of the link, is there a
rough formula that can be applied. i.e. a certain number of records from a
certain number of tables would require x amount of bandwidth?

The amount of data to transfer depends on the size of the records. List
the fields in each table and determine the number of bytes required for
each of them. Multiply that by the number of records retrieved. Decide
how long it will take to transfer that data over a 64Kbit (8Kbyte) per
second link. Take account of other people using the same link for other
purposes.


--
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.