[dba-SQLServer] SQL Log file usage

Jim Lawrence jlawrenc1 at shaw.ca
Thu Nov 1 14:30:15 CDT 2012


As far as I know, it is always faster, a lot faster, to insert data into
tables without indexes or keys. (Knew a system that took a week to insert
all the data but removing the keys first and inserting the data took less
than 3 hours) 

Jim

-----Original Message-----
From: dba-sqlserver-bounces at databaseadvisors.com
[mailto:dba-sqlserver-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Thursday, November 01, 2012 11:22 AM
To: Access Developers discussion and problem solving; Sqlserver-Dba
Subject: [dba-SQLServer] SQL Log file usage

I attempted to insert 150 million records into a table, from one database to
another.  The 
destination table was empty but had a bunch of indexes on it.  I ran out of
room on the log file 
disk and the process hung.

I ended up stripping off all of the indexes except the PK clustered index
and the insert used less 
than 1/2 of the previous log file size for the insert.  Furthermore the
build of the indexes as a 
second step is essentially not using the log file at all.

So the whole argument about "which is faster" also needs to include a
component about log file 
usage.  I have no idea which would have been faster - with or without the
indexes already in place - 
but in this case at least stripping off the indexes and building them after
the fact seems to make 
the whole process work without a (log file size) hitch.

-- 
John W. Colby
Colby Consulting

Reality is what refuses to go away
when you do not believe in it

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