???Takes very long to do make table query

J

Jaylin

Would very much appreciate expert advice on why it takes a minute to run a
select query, but takes forever to do Make table query on the same set
 
D

David F Cox

One reason is that SELECT is probably using an index, whilst make table is
probably building one.
Another reason is that it takes longer to write records (and read-verify,
than it does to just read them.
Another reason is that writing records is probably a one at a time function,
whilst reading is often done as lock operation.
 
J

Jaylin

Dear Mr Cox

Thank you very much for your wise advice. Just wondering if there is anyway
I can make the query run faster?

Many thanks again
 
R

Rick Brandt

Jaylin said:
Would very much appreciate expert advice on why it takes a minute to run a
select query, but takes forever to do Make table query on the same set
Click to expand...

Are you going to the end of the SELECT query's Recordset? A SELECT query might
look "done", but it will show you a screen of data as soon as it has processed a
screen of data. A MakeTable query isn't done until it has processed every row.
Chances are the entire SELECT query takes just about as long if you force it to
process all rows.

There is a difference where the MakeTable actually has to write data to disk,
but you might be seeing more of a difference than what really exists.
 
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