[AccessD] "Not In" query speed

Hi John:

Other than it is the SLOWEST, most resource hungry query there is in the
world of SQL and even running a 'loop' usually is significantly faster.

In one particular situation when adding a huge amount of data, to a table,
creating a unique key (also not usually recommended when adding large
amounts of data) and testing for data collision errors produced a superior
result.

Jim  

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Monday, October 29, 2007 7:16 AM
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] "Not In" query speed

Does anyone have any information on the speed of a "not in" query?  That is
where an outer join to a table is used and then a filter set on the PK (or
any field really) of the outer joined table to discover all records "not in"
the outer joined table?

Is the speed the same as an inner join would have been?  Is there more
overhead because of the where clause?  

In other words, assume a table where there are 50K claim records in
tblClaim.  
Assume that there are 25K records in TblClaimLogged (exactly 1/2 the number
of records in tblClaim) and that each ClaimID is only in tblClaimLogged one
time.  

Now do an inner join to discover which records are IN tblClaimLogged.  
Now do an outer join to discover which records are NOT IN tblClaimLogged.  

Both queries should return exactly 25K records since exactly 1/2 of the
records in tblClaim are in tblClaimLogged, and each record can only be in
there once.

Do the two queries return the result sets in the same amount of time?

John W. Colby
Colby Consulting
www.ColbyConsulting.com 

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