ADP vs. MDB: Speed

[Neil]

I have a situation with an ODBC linked view in an Access 2000 MDB with a SQL
7 back end. The view is scrolling very slowly. However, if I open the view
in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the same,
but that the MDB was a more mature technology and less problematic than the
ADP technology. However, the speed difference I'm noticing with the ADP file
in regards to this view is significant and is very disconcerting re. using
an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced the
view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Steve Jorgensen]

The ways ADPs and MDBs use recordsets are very different, so sometimes one or
the other will be faster.

By default, the MDB opens a Dynaset which means it first opens a connection to
grab the list of keys for the records, then reads the actual records as needed
for display by doing individual selects of 10 records aby explicit key. This
can help speed when each row has a lot of data because only the rows that are
actually viewd will be read, not all of them. On the other hand, if the table
has a very large number of rows, Access will spend a lot of time in the
background reading the whole list of keys, and if the key lookup for each row
is slow for some reason, everything will be sluggish.

An ADP, a static recordset is normally used, and an absolute cap of 10,000
rows is applied, so if your recordset has more than that, you just won't get
all the rows. Static means in loads all the data at once, then you browse
through it in memeory. That's very fast once you load the data, but if each
row has a lot of data, especially memo fields and such, it can take a long
time to initially load.

I have a situation with an ODBC linked view in an Access 2000 MDB with a SQL
7 back end. The view is scrolling very slowly. However, if I open the view
in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the same,
but that the MDB was a more mature technology and less problematic than the
ADP technology. However, the speed difference I'm noticing with the ADP file
in regards to this view is significant and is very disconcerting re. using
an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced the
view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Sylvain Lafontaine]

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

If this doesn't help, then you will have to use an unbound form coupled with
SQL pass-through queries (or ADO objects) to resolve your speed problem with
MDB. Another solution could be to go with TS to simulate a high-speed LAN.

I don't know where you got the impression that MDB were about the same as
ADP in term of speed. It has been repeated a number of times that the use
of MDB' linked tables and views is only a workable solution for small
databases on a fast Lan.

S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL 7 back end. The view is scrolling very slowly. However, if I open the
view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the
same, but that the MDB was a more mature technology and less problematic
than the ADP technology. However, the speed difference I'm noticing with
the ADP file in regards to this view is significant and is very
disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Steve Jorgensen]

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

If this doesn't help, then you will have to use an unbound form coupled with
SQL pass-through queries (or ADO objects) to resolve your speed problem with
MDB. Another solution could be to go with TS to simulate a high-speed LAN.

I don't know where you got the impression that MDB were about the same as
ADP in term of speed. It has been repeated a number of times that the use
of MDB' linked tables and views is only a workable solution for small
databases on a fast Lan.

Frankly, I find that statement ludicrous. Many developers including myself
have had excelent results using MDBs as front-ends to various kinds of SQL
Server back-end for many years before there was such a thing as an ADP. When
MDBs are slow, the workarounds to fix it are far less arduous than the
workarounds required in ADPs to simply make them function in many cases.

 

[Neil]

The view in question only returns 1154 rows. So we're not talking a large
number here. And only returning 24 fields.

There was a modification recently where three additional fields were added
to the view, and that seemed to slow things down significantly. I'm not sure
if there's some boundary at around 24 fields, or if something else is going
on. But the linked view is *very* slow, taking several seconds just to bring
up the first screen, and then, whenever the scroll bar goes down by one,
several more seconds just to refresh. The ADP view, on the other hand, is
fast, with no delay at all, either in bringing up the data or in scrolling.

Neil

The ways ADPs and MDBs use recordsets are very different, so sometimes one
or
the other will be faster.

By default, the MDB opens a Dynaset which means it first opens a
connection to
grab the list of keys for the records, then reads the actual records as
needed
for display by doing individual selects of 10 records aby explicit key.
This
can help speed when each row has a lot of data because only the rows that
are
actually viewd will be read, not all of them. On the other hand, if the
table
has a very large number of rows, Access will spend a lot of time in the
background reading the whole list of keys, and if the key lookup for each
row
is slow for some reason, everything will be sluggish.

An ADP, a static recordset is normally used, and an absolute cap of 10,000
rows is applied, so if your recordset has more than that, you just won't
get
all the rows. Static means in loads all the data at once, then you browse
through it in memeory. That's very fast once you load the data, but if
each
row has a lot of data, especially memo fields and such, it can take a long
time to initially load.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL
7 back end. The view is scrolling very slowly. However, if I open the view
in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the
same,
but that the MDB was a more mature technology and less problematic than
the
ADP technology. However, the speed difference I'm noticing with the ADP
file
in regards to this view is significant and is very disconcerting re. using
an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the
view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Neil]

You may try to add a virtual index on your linked view:

http://support.microsoft.com/kb/q209123/

Yes, these are added when you first attach the view or table. When the
object doesn't have a primary key (as with views) Access prompts you for
which field(s) to use as pk. It then stores that information. You can't
update the data otherwise. So it's already there.

If this doesn't help, then you will have to use an unbound form coupled
with SQL pass-through queries (or ADO objects) to resolve your speed
problem with MDB.

As noted, the reason for not using pass-through is because it needs to be
updatable.

Another solution could be to go with TS to simulate a high-speed LAN.

What is "TS"?

I don't know where you got the impression that MDB were about the same as
ADP in term of speed. It has been repeated a number of times that the use
of MDB' linked tables and views is only a workable solution for small
databases on a fast Lan.

From discussions in this newsgroup.

Neil

S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL 7 back end. The view is scrolling very slowly. However, if I open the
view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable. Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front end for SQL Server, the impression I got was that both were about
the same, but that the MDB was a more mature technology and less
problematic than the ADP technology. However, the speed difference I'm
noticing with the ADP file in regards to this view is significant and is
very disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Sylvain Lafontaine]

TS = Terminal Server; you can also use Citrix. This is a quick fix for
getting a multi-user access to an Access' MDB file over the Internet or to
solve the possibility of corruption when you LAN network is not rock solid.
However, this solution come with a price ($).

With the use of unbound forms as the solution, you are responsible for
sending the modifications to the data back to the database. This will give
you the possibility to use the result of a read-only SQL pass-through in a
form but, obviously, with the obligation of having more coding work to be
done. Of course, some of this work can be partially automated. You will
find more information on that subject on books dealing with Access and
SQL-Server. (Personally, I prefer to use ADP but it has many bugs.)

By using the profiler on the SQL-Server, it is also possible that you will
see something that will give you the possibility of resolving the speed
problem of you linked views by having a better understanding of what Access
is doing when it communicates with the server.

S. L.

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

Yes, these are added when you first attach the view or table. When the
object doesn't have a primary key (as with views) Access prompts you for
which field(s) to use as pk. It then stores that information. You can't
update the data otherwise. So it's already there.

If this doesn't help, then you will have to use an unbound form coupled
with SQL pass-through queries (or ADO objects) to resolve your speed
problem with MDB.

As noted, the reason for not using pass-through is because it needs to be
updatable.

Another solution could be to go with TS to simulate a high-speed LAN.

What is "TS"?

I don't know where you got the impression that MDB were about the same as
ADP in term of speed. It has been repeated a number of times that the
use of MDB' linked tables and views is only a workable solution for small
databases on a fast Lan.

From discussions in this newsgroup.

Neil

S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL 7 back end. The view is scrolling very slowly. However, if I open the
view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable. Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front end for SQL Server, the impression I got was that both were about
the same, but that the MDB was a more mature technology and less
problematic than the ADP technology. However, the speed difference I'm
noticing with the ADP file in regards to this view is significant and is
very disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Sylvain Lafontaine]

Are you talking about the WAN or a LAN?

In the case of the WAN, all tests that I have done in the past indicate that
MDB files are much slower to access a SQL-Server backend. The use of linked
views will greatly reduce the performance hit but even with them, I don't
see the benefice of creating hundred of views instead of creating hundred of
stored procedures. If you want to get some decent speed over the internet,
there are a lot more of work to do using MDB than using ADP and even then,
I'm not really sure if the use of linked views will achieve the same level
of performance.

You are entitled to your opinion but all the tests that I have done in the
past clearly indicate that the use of MDB to access a SQL-Server over the
internet is only, at its best, a kludge.

For a LAN, the problem is of course much less severe but at the condition
that the network is not already overcrowded.

S. L.

 

[Steve Jorgensen]

Did you specify a field or set of fields to be used as the primary key for the
view when you created the link? If not, it will be slower, and will not be
updateable.

The view in question only returns 1154 rows. So we're not talking a large
number here. And only returning 24 fields.

There was a modification recently where three additional fields were added
to the view, and that seemed to slow things down significantly. I'm not sure
if there's some boundary at around 24 fields, or if something else is going
on. But the linked view is *very* slow, taking several seconds just to bring
up the first screen, and then, whenever the scroll bar goes down by one,
several more seconds just to refresh. The ADP view, on the other hand, is
fast, with no delay at all, either in bringing up the data or in scrolling.

Neil

The ways ADPs and MDBs use recordsets are very different, so sometimes one
or
the other will be faster.

By default, the MDB opens a Dynaset which means it first opens a
connection to
grab the list of keys for the records, then reads the actual records as
needed
for display by doing individual selects of 10 records aby explicit key.
This
can help speed when each row has a lot of data because only the rows that
are
actually viewd will be read, not all of them. On the other hand, if the
table
has a very large number of rows, Access will spend a lot of time in the
background reading the whole list of keys, and if the key lookup for each
row
is slow for some reason, everything will be sluggish.

An ADP, a static recordset is normally used, and an absolute cap of 10,000
rows is applied, so if your recordset has more than that, you just won't
get
all the rows. Static means in loads all the data at once, then you browse
through it in memeory. That's very fast once you load the data, but if
each
row has a lot of data, especially memo fields and such, it can take a long
time to initially load.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL
7 back end. The view is scrolling very slowly. However, if I open the view
in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the
same,
but that the MDB was a more mature technology and less problematic than
the
ADP technology. However, the speed difference I'm noticing with the ADP
file
in regards to this view is significant and is very disconcerting re. using
an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the
view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Steve Jorgensen]

Well, perhaps the reason for our difference of opinion is that I never thought
it was particularly appropriate to connect directly to a database server
across a WAN at all. I usually recommend using a terminal server or rewriting
the app as a Web application or some other kind of 3-tier application.

 

[Albert D. Kallal]

In previous discussions about using an MDB file vs. an ADP file as a front
end for SQL Server, the impression I got was that both were about the
same, but that the MDB was a more mature technology and less problematic
than the ADP technology. However, the speed difference I'm noticing with
the ADP file in regards to this view is significant and is very
disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the view's SQL below for reference.

Yes, a few things needs to cleared up here.

First, using a ADP with sql server is kind of like using a automatic truck
vs a truck with a standard shift. If you don't know trucks, and how to shift
gears, then obviously the automatic truck is going to be better. On the
other hand, an advanced driver will get the same performance out of the
standard truck....

If you look at the sql you posted, there is a number of tables involved.
If you just link a bunch of tables to sql server, and then tell ms-access to
"join" them together..you will often get poor performance. I mean, obviously
ms-access/JET has to pull data from multiple tables. With ODBC linked
tables, each table is *often* thought as a separate data source. With
a ADP, that sql is processed server side.

Remember, ms-access/JET has a difficult
time working with multiple ODBC DATA sources when you do a join on them. The
reason of course is that one table might be from Oracle, and the other might
be a local FoxPro table. When you join data through linked tables, you have
to remem ber what the Robot in Lost in space used to say:


"Danger ...Will Robison.....Danger"...

When you use a ADP, that whole sql statement is sent to sql server to be
processed.

So, of course, if you used a pass-through query, then both the ADP, and the
ODBC will performance the same.

However, you mentioned that you can't use a pass through. However, you STILL
are using a sql statement that have SEVERAL LINKED tables. ms-access is
going
to have to figure out those links for you!. This should not be a surprise if
you think about what is going on here. However, the simple solution here is
thus to simply create a view on sql server, and then link to that!

Doing this, you will get the same
performance again as the ADP.

So, the lesson here is that you simply have to be MORE conscience of sql
that joins tables together. You can often get away with at last one extra
joined table via link tables..but as a general rule, you have to build a
query
anyway, so, just built a view on the sql side..and you eliminate the
performance
problem.

So, our question is using a ADP going to be faster then a MDB with linked
tables?

answers: Yes, ADP will be faster if you don't pay attention to avoiding
bottle necks, and thinking about what is going on....

So, yes, you do need a bit more caution when using a mdb file and odbc
tables against sql server. Without question, a ADP allows you to be much
more lazy, as ALL
SQL is 100% executed on the sql server side, and thus it is MUCH harder to
screw things up. With a mdb/odbc linked tables, you need extra caution, and
extra effort to avoid bottle necks. In effect, the increased flexibility of
a
mdb/odbc setup means you have more rope and more room to hang yourself!!

However, with a small effort, and some caution, you can EASLEY get the same
performance with a mdb/odbc as you get with a
ADP.

 

[Albert D. Kallal]

Are you talking about the WAN or a LAN?

In the case of the WAN, all tests that I have done in the past indicate
that MDB files are much slower to access a SQL-Server backend.

The problem of slowness is not ms-access/jet, but that how the developer
uses sql server here.

When ms-access is used correctly, and thoughtfully by a developer, then the
limits of the application become that of sql server, and not ms-access at
al. There are companies out there with 1000 simultaneous ms-access users
hitting the same sql server database. using ms-access is no worse the using
VB6, c++ or any other ide. The ONLY differences here are that of poor
developers.

The use of linked views will greatly reduce the performance hit but even
with them, I don't see the benefice of creating hundred of views instead
of creating hundred of stored procedures.

HUH? You mean grabbing data from a link view vs a stored proc makes any
difference here? (it makes not ONE bit!!).

If you talking about some code that needs to update some data..then, sure,
by all means move the code from ms-access into a stored proc, but we are not
talking about bad development practices here.

Without question, execute sql on a JET based client through linked tables
needs caution. ANY time more then one table is involved, that sql should be
put on the server side, or pass through be used. If one follows this rule,
then 9 out 10 times, the odbc linked application will perform as good as the
ADP one.

The fact of the matter is that a native ole-db connection sql server vs a
odbc one has be thrashed out MANY TIMES. If I hit a database and ask the sql
server to return one record, both the ole-db, and a simply linked table in
ms-access both return one record, and produce approximate the same network
traffic.

If you want to get some decent speed over the internet, there are a lot
more of work to do using MDB than using ADP and even then, I'm not really
sure if the use of linked views will achieve the same level of
performance.

Linked views is the solution in this poster case. If the poster does this,
then no difference will be noticed. The problem here is not ms-access, but
users of ms-access who don't take the time to utilize, and effect use sql
server here.

You are entitled to your opinion but all the tests that I have done in the
past clearly indicate that the use of MDB to access a SQL-Server over the
internet is only, at its best, a kludge.

Compared to what? I know of people successfully using ms-access OVER DIAL UP
lines to sql server (you read that correctly!!). If you make the effort,
(and this is NO more effort then writing in VB6, or other tools, then you
get the same performance).

So, sure, if a person just lazily links multiple tables..and then tries to
build a local query based on all those linked tables..then you will not get
decent performance.

However, it is a myth that a ms-access odbc connection to sql server don't
work well. It will JUST as well as the other IDE's, and you get the same
performance....

Further, bound forms in ms-access can successful be used, but again, as long
as stupid things like opening a form to a table without some type of "where"
clause must be avoided. (I never do that in JET based solutions...let alone
sql server based ones anyway).

Again, the fact that SO many ms-access applications open up forms to a
table, and THEN let the user browse/search for a record is a HORRIBLE
design, and one that should be avoided.

So, it is not the fact of ms-access being bad, but the fact that it is SO
EASY to simply throw up a form with a large data set, and let the user "have
at it".

So, even bound forms can quite well be used over a wan.

The real problem here is bad practices...not ms-access...

 

[Sylvain Lafontaine]

I don't really understand your statement about poor developers: you are
telling me that if I forget about 90% (or 50, 60 or 70%, pick your number)
of the coding facilities of SQL-Server, I will be a better programmer?

I know that the use of linked views will provide some relief about the lack
of speed of linked ODBC tables; however, I don't see why this could be
considered as an advantage:

1) It will take as much time creating all the necessary views for each
form/sub-form/control using a join in their queries than it will take for
creating the relevant stored procedures.

2) When I will really need to use a stored procedure - for example for
having access to temporary tables, cursor, other stored procedures, etc. -
because of the underlying complexity of the request, I will have a pretty
leg if I've limited myself to the exclusive use of views because I'm using
ODBC linked tables.

(For obvious reasons, I won't comment on the possibility of using a sql
pass-through query in these cases.)

From what I can read from your post, it's like telling me that a car is as
good and as fast as another one for the same price, but that you have the
right to go in only half the city if you buy it. In my opinion, when you
have to pay the same price in working time (at the minimum), you should be
entitled to the same full capacity in programming capabilities and when the
price is higher, there should be more, not less, capabilities.

I don't see why limiting myself to the exclusive use of views and forgetting
about stored procedures will make me a better programmer but I you want to
go on this path, this is your right and your decision; not mine.

S. L.

 

[Neil]

Yes, there is a virtual primary key defined.

Did you specify a field or set of fields to be used as the primary key for
the
view when you created the link? If not, it will be slower, and will not
be
updateable.

The view in question only returns 1154 rows. So we're not talking a large
number here. And only returning 24 fields.

There was a modification recently where three additional fields were added
to the view, and that seemed to slow things down significantly. I'm not
sure
if there's some boundary at around 24 fields, or if something else is
going
on. But the linked view is *very* slow, taking several seconds just to
bring
up the first screen, and then, whenever the scroll bar goes down by one,
several more seconds just to refresh. The ADP view, on the other hand, is
fast, with no delay at all, either in bringing up the data or in
scrolling.

Neil

The ways ADPs and MDBs use recordsets are very different, so sometimes
one
or
the other will be faster.

By default, the MDB opens a Dynaset which means it first opens a
connection to
grab the list of keys for the records, then reads the actual records as
needed
for display by doing individual selects of 10 records aby explicit key.
This
can help speed when each row has a lot of data because only the rows
that
are
actually viewd will be read, not all of them. On the other hand, if the
table
has a very large number of rows, Access will spend a lot of time in the
background reading the whole list of keys, and if the key lookup for
each
row
is slow for some reason, everything will be sluggish.

An ADP, a static recordset is normally used, and an absolute cap of
10,000
rows is applied, so if your recordset has more than that, you just won't
get
all the rows. Static means in loads all the data at once, then you
browse
through it in memeory. That's very fast once you load the data, but if
each
row has a lot of data, especially memo fields and such, it can take a
long
time to initially load.


I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL
7 back end. The view is scrolling very slowly. However, if I open the
view
in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable.
Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front
end for SQL Server, the impression I got was that both were about the
same,
but that the MDB was a more mature technology and less problematic than
the
ADP technology. However, the speed difference I'm noticing with the ADP
file
in regards to this view is significant and is very disconcerting re.
using
an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the
view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Neil]

FWIW, in my case I'm testing the db on my laptop using MSDE, and the speed
difference is the same. So there isn't a WAN vs. LAN issue anyway. FWIW.

Neil

 

[Neil]

Mr. Kallal:

Perhaps you misread my original post, since you wrote:

"The problem of slowness is not ms-access/jet, but that how the developer
uses sql server here."

And:

"ANY time more then one table is involved, that sql should be put on the
server side, or pass through be used. If one follows this rule,
then 9 out 10 times, the odbc linked application will perform as good as
the ADP one."

And:

"Linked views is the solution in this poster case. If the poster does this,
then no difference will be noticed."

I say that you must have misread my original post, since linked views are
what are being used here; yet you offer them as a solution.

From my original post:

"I have a situation with an ODBC linked view in an Access 2000 MDB...."

Neil

 

[Neil]

TS = Terminal Server; you can also use Citrix. This is a quick fix for
getting a multi-user access to an Access' MDB file over the Internet or to
solve the possibility of corruption when you LAN network is not rock
solid. However, this solution come with a price ($).

Not an issue with connection. I'm using the db locally for development with
MSDE and have the same situation with the linked view being slow. Definitely
not a network issue.

With the use of unbound forms as the solution, you are responsible for
sending the modifications to the data back to the database. This will
give you the possibility to use the result of a read-only SQL pass-through
in a form but, obviously, with the obligation of having more coding work
to be done. Of course, some of this work can be partially automated. You
will find more information on that subject on books dealing with Access
and SQL-Server. (Personally, I prefer to use ADP but it has many bugs.)

Yes, I'm familiar with the approach. It would just be better to save the
development overhead. And, if one were to use unbound forms, then one might
as well just use VB.

By using the profiler on the SQL-Server, it is also possible that you will
see something that will give you the possibility of resolving the speed
problem of you linked views by having a better understanding of what
Access is doing when it communicates with the server.

Yeah, perhaps. The strange thing, as noted elsewhere in this thread, is that
it was fine until I added three new fields. So I don't know if something
needs to be optimized, or going from 21 to 24 fields really makes that much
of a difference.

Neil

S. L.

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

Yes, these are added when you first attach the view or table. When the
object doesn't have a primary key (as with views) Access prompts you for
which field(s) to use as pk. It then stores that information. You can't
update the data otherwise. So it's already there.

If this doesn't help, then you will have to use an unbound form coupled
with SQL pass-through queries (or ADO objects) to resolve your speed
problem with MDB.

As noted, the reason for not using pass-through is because it needs to be
updatable.

Another solution could be to go with TS to simulate a high-speed LAN.

What is "TS"?

I don't know where you got the impression that MDB were about the same
as ADP in term of speed. It has been repeated a number of times that
the use of MDB' linked tables and views is only a workable solution for
small databases on a fast Lan.

From discussions in this newsgroup.

Neil

S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with a
SQL 7 back end. The view is scrolling very slowly. However, if I open
the view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable. Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front end for SQL Server, the impression I got was that both were about
the same, but that the MDB was a more mature technology and less
problematic than the ADP technology. However, the speed difference I'm
noticing with the ADP file in regards to this view is significant and
is very disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've reproduced
the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Neil]

If you look at the sql you posted, there is a number of tables involved.

If you just link a bunch of tables to sql server, and then tell ms-access
to
"join" them together..you will often get poor performance.

Again, as noted in my other post, you misread my original post. The first
sentence in my post stated I was dealing with a linked view, and, before the
SQL I posted I said it was the view's SQL. The SQL is from a SQL view --
pure server side -- nothing done in Access except to link to the view and
display the data.

However, you mentioned that you can't use a pass through. However, you
STILL
are using a sql statement that have SEVERAL LINKED tables. ms-access is
going
to have to figure out those links for you!. This should not be a surprise
if
you think about what is going on here. However, the simple solution here
is
thus to simply create a view on sql server, and then link to that!

Which is what was done.

Doing this, you will get the same
performance again as the ADP.

Well, this gets us back to the original post: that is what was done; yet the
linked view in the MDB file is sluggish, taking a long time to scroll, and
the same linked view in the ADP file is quick. Both the MDB and ADP are
accessing a single view from SQL Server.

So, the lesson here is that you simply have to be MORE conscience of sql
that joins tables together. You can often get away with at last one extra
joined table via link tables..but as a general rule, you have to build a
query
anyway, so, just built a view on the sql side..and you eliminate the
performance
problem.

Apparently not -- at least not in this case.

In *theory* a view from SQL Server should perform the same in an ADP and
MDB, since the processing is done on the server side. But, as this situation
demonstrates, things are not always as simple as they appear in theory.

Oh, and before we go there, please note that the large-recordset issue has
already been addressed: there are only 1154 records returned by the view,
with 24 fields displayed.

So, our question is using a ADP going to be faster then a MDB with linked
tables?

answers: Yes, ADP will be faster if you don't pay attention to avoiding
bottle necks, and thinking about what is going on....

So, yes, you do need a bit more caution when using a mdb file and odbc
tables against sql server. Without question, a ADP allows you to be much
more lazy, as ALL
SQL is 100% executed on the sql server side, and thus it is MUCH harder to
screw things up. With a mdb/odbc linked tables, you need extra caution,
and
extra effort to avoid bottle necks. In effect, the increased flexibility
of
a
mdb/odbc setup means you have more rope and more room to hang yourself!!

However, with a small effort, and some caution, you can EASLEY get the
same
performance with a mdb/odbc as you get with a
ADP.

Well, I'm open to suggestions!

Neil

 

[Sylvain Lafontaine]

First, what are these three fields that have slowed down your application
and are Invtry.MImage and Invtry.HImage image (binary) fields?

Second, you should really take a look with the profiler. Don't forget that
we don't have your database in front of us and that it is quite possible
that only you will have the possibility of solving this problem.

S. L.

TS = Terminal Server; you can also use Citrix. This is a quick fix for
getting a multi-user access to an Access' MDB file over the Internet or
to solve the possibility of corruption when you LAN network is not rock
solid. However, this solution come with a price ($).

Not an issue with connection. I'm using the db locally for development
with MSDE and have the same situation with the linked view being slow.
Definitely not a network issue.

With the use of unbound forms as the solution, you are responsible for
sending the modifications to the data back to the database. This will
give you the possibility to use the result of a read-only SQL
pass-through in a form but, obviously, with the obligation of having more
coding work to be done. Of course, some of this work can be partially
automated. You will find more information on that subject on books
dealing with Access and SQL-Server. (Personally, I prefer to use ADP but
it has many bugs.)

Yes, I'm familiar with the approach. It would just be better to save the
development overhead. And, if one were to use unbound forms, then one
might as well just use VB.

By using the profiler on the SQL-Server, it is also possible that you
will see something that will give you the possibility of resolving the
speed problem of you linked views by having a better understanding of
what Access is doing when it communicates with the server.

Yeah, perhaps. The strange thing, as noted elsewhere in this thread, is
that it was fine until I added three new fields. So I don't know if
something needs to be optimized, or going from 21 to 24 fields really
makes that much of a difference.

Neil

S. L.

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

Yes, these are added when you first attach the view or table. When the
object doesn't have a primary key (as with views) Access prompts you for
which field(s) to use as pk. It then stores that information. You can't
update the data otherwise. So it's already there.

If this doesn't help, then you will have to use an unbound form coupled
with SQL pass-through queries (or ADO objects) to resolve your speed
problem with MDB.

As noted, the reason for not using pass-through is because it needs to
be updatable.

Another solution could be to go with TS to simulate a high-speed LAN.

What is "TS"?

I don't know where you got the impression that MDB were about the same
as ADP in term of speed. It has been repeated a number of times that
the use of MDB' linked tables and views is only a workable solution for
small databases on a fast Lan.

From discussions in this newsgroup.

Neil



S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with
a SQL 7 back end. The view is scrolling very slowly. However, if I open
the view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable. Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front end for SQL Server, the impression I got was that both were
about the same, but that the MDB was a more mature technology and less
problematic than the ADP technology. However, the speed difference I'm
noticing with the ADP file in regards to this view is significant and
is very disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've
reproduced the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))

 

[Neil]

MImage and HImage are two of the new fields, and are bit. The other new
field was AdCode, which is varchar.

First, what are these three fields that have slowed down your application
and are Invtry.MImage and Invtry.HImage image (binary) fields?

Second, you should really take a look with the profiler. Don't forget
that we don't have your database in front of us and that it is quite
possible that only you will have the possibility of solving this problem.

S. L.

TS = Terminal Server; you can also use Citrix. This is a quick fix for
getting a multi-user access to an Access' MDB file over the Internet or
to solve the possibility of corruption when you LAN network is not rock
solid. However, this solution come with a price ($).

Not an issue with connection. I'm using the db locally for development
with MSDE and have the same situation with the linked view being slow.
Definitely not a network issue.

With the use of unbound forms as the solution, you are responsible for
sending the modifications to the data back to the database. This will
give you the possibility to use the result of a read-only SQL
pass-through in a form but, obviously, with the obligation of having
more coding work to be done. Of course, some of this work can be
partially automated. You will find more information on that subject on
books dealing with Access and SQL-Server. (Personally, I prefer to use
ADP but it has many bugs.)

Yes, I'm familiar with the approach. It would just be better to save the
development overhead. And, if one were to use unbound forms, then one
might as well just use VB.

By using the profiler on the SQL-Server, it is also possible that you
will see something that will give you the possibility of resolving the
speed problem of you linked views by having a better understanding of
what Access is doing when it communicates with the server.

Yeah, perhaps. The strange thing, as noted elsewhere in this thread, is
that it was fine until I added three new fields. So I don't know if
something needs to be optimized, or going from 21 to 24 fields really
makes that much of a difference.

Neil

S. L.

You may try to add a virtual index on your linked view:
http://support.microsoft.com/kb/q209123/

Yes, these are added when you first attach the view or table. When the
object doesn't have a primary key (as with views) Access prompts you
for which field(s) to use as pk. It then stores that information. You
can't update the data otherwise. So it's already there.

If this doesn't help, then you will have to use an unbound form
coupled with SQL pass-through queries (or ADO objects) to resolve your
speed problem with MDB.

As noted, the reason for not using pass-through is because it needs to
be updatable.

Another solution could be to go with TS to simulate a high-speed LAN.

What is "TS"?

I don't know where you got the impression that MDB were about the same
as ADP in term of speed. It has been repeated a number of times that
the use of MDB' linked tables and views is only a workable solution
for small databases on a fast Lan.

From discussions in this newsgroup.

Neil



S. L.

I have a situation with an ODBC linked view in an Access 2000 MDB with
a SQL 7 back end. The view is scrolling very slowly. However, if I
open the view in an ADP file, it scrolls quickly.

I needed to use an ODBC link for the view because it needs to be
editable. Otherwise, I would have used a pass-through query.

In previous discussions about using an MDB file vs. an ADP file as a
front end for SQL Server, the impression I got was that both were
about the same, but that the MDB was a more mature technology and
less problematic than the ADP technology. However, the speed
difference I'm noticing with the ADP file in regards to this view is
significant and is very disconcerting re. using an MDB file.

Any thoughts/comments/suggestions would be appreciated. I've
reproduced the view's SQL below for reference.

Thanks,

Neil

SQL for view in question:

SELECT INVTRY.[Index], INVTRY.TITLE, INVTRY.AUTHILL1,
INVTRY.attFirstEdition, INVTRY.attSigned,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond, INVTRY.YRPUB,
INVTRY.PRICE, INVTRY.Web, INVTRY.Status,
INVTRY.WebStatusPending, INVTRY.ActivateDate,
INVTRY.DeactivateDate, INVTRY.WebAddedBatchID,
INVTRY.AllowDuplicate, INVTRY.WebAction,
INVTRY.WebActionPending, INVTRY.DateModified,
INVTRY.DateWebActionApplied, INVTRY.JIT, INVTRY.MImage,
INVTRY.HImage, INVTRY.AdCode,
CASE WHEN INVTRY.WebAddedBatchID IS NOT NULL
THEN - 1 ELSE 0 END AS OnWeb
FROM vwInventory_Dupes INNER JOIN
(WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web) ON
(vwInventory_Dupes.YearPub = INVTRY.YRPUB) AND
(vwInventory_Dupes.SignedCond = ISNULL(INVTRY.attSignedPD,
' ')) AND (vwInventory_Dupes.Signed = INVTRY.attSigned) AND
(vwInventory_Dupes.FirstEd = INVTRY.attFirstEdition) AND
(vwInventory_Dupes.Author = INVTRY.AUTHILL1) AND
(vwInventory_Dupes.TITLE = INVTRY.TITLE)
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))

SQL for vwInventory_Dupes, used as subquery:

SELECT INVTRY.TITLE, INVTRY.AUTHILL1 Author,
Cast(attFirstEdition AS tinyint) FirstEd,
Cast(attSigned AS tinyint) Signed,
ISNULL(INVTRY.attSignedPD, ' ') SignedCond,
INVTRY.YRPUB YearPub
FROM WebStatus INNER JOIN
(INVTRY INNER JOIN
tabStatus ON INVTRY.Status = tabStatus.Status) ON
WebStatus.WebStatus = INVTRY.Web
WHERE (((tabStatus.ForWeb) = 1) AND ((WebStatus.IncludeDupe)
= 1))
GROUP BY INVTRY.TITLE, INVTRY.AUTHILL1,
Cast(attFirstEdition AS tinyint), Cast(attSigned AS tinyint),
ISNULL(INVTRY.attSignedPD, ' '), INVTRY.YRPUB
HAVING (((COUNT(INVTRY.[INDEX])) > 1))