VBA: Querying Access with Excel. Why so slow?

Question

I found this code online to query Access and input the data into excel (2003), but it is much slower than it should be:

Sub DataPull(SQLQuery, CellPaste)
Dim         


        

Answer 1

Since you're using Access 2003, use DAO instead, it will be faster with the Jet engine.

See http://www.erlandsendata.no/english/index.php?d=envbadacexportdao for sample code.

Note that you should never use the "As New" keyword, as it will lead to unexpected results.

Answer 2

Lots of formulas may reference the query. Try temporarially turning on manual calculate in the macro and turning it off when all of your queries are done updating.

This should speed it up a bit, but still doesn't fix the underlying problem.

Answer 3

I'm no expert, but I run almost exactly the same code with good results. One difference is that I use the Command object as well as the Connection object. Where you

Set RST = Con.Execute(SQLQuery)

I

Dim cmd As ADODB.Command
Set cmd.ActiveConnection = con
cmd.CommandText = SQLQuery
Set RST = cmd.Execute

I don't know if or why that might help, but maybe it will? :-)

Answer 4

I don't know if it will help, but I am using VBA and ADO to connect to an Excel spreadsheet.

It was retrieving records lightning-fast (<5 seconds), but then all of a sudden it was awfully slow (15 seconds to retrieve one record). This is what lead me to your post.

I realized I accidentally had the Excel file open myself (I had been editing it).

Once I closed it, all was lightening fast again.

Answer 5

I used your code and pulled in a table of 38 columns and 63780 rows in less than 7 seconds - about what I'd expect - and smaller recordsets completed almost instantaneously.

Is this the kind of performance you are experiencing? If so, it is consistent with what I'd expect with an ADO connection from Excel to an MDB back-end.

If you are seeing much slower performance than this then there must be some local environment conditions that are affecting things.

Answer 6

If you retrieve a lot of records, it would explain why the Range(CellPaste)takes so long. (If you execute the query in Access it wouldn't retrieve all the records, but if you do the CopyFromRecordset it requires all the records.)

There is a MaxRows parameter for CopyFromRecordset:

Public Function CopyFromRecordset ( _
    Data As Object, _
    <OptionalAttribute> MaxRows As Object, _
    <OptionalAttribute> MaxColumns As Object _
) As Integer

Try if settings this to a low value (like 10 or so) changes the performance.