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Insert into using concantenated index

Posted on 2013-06-25
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Last Modified: 2013-06-25
I have two tables:
SourceTable
-----------------
Name
ExpDate
Type
OtherStuff

MasterTable
-----------------
Name
ExpDate
Type

We would like to take the info from SourceTable to Master Table where the incoming three fields do not exist in Master.
We placed a concantenated index on Master for these fields thinking it would be faster somehow.  But it looks like we are forced to do something like:
Insert into MasterTable.....
where
 (Name || ExpDate || Type)  
Not in
(select  (Name || ExpDate || Type)  from MasterTable)

Seems like the index is really useless.
What's the fastest way to accomplish this?
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Comment
Question by:GNOVAK
  • 2
4 Comments
 
LVL 78

Accepted Solution

by:
slightwv (䄆 Netminder) earned 2000 total points
ID: 39275424
Given the information provided, I would start out with:

insert into master
select name, expdate, type from source
minus
select name, expdate, type from master
/
0
 
LVL 78

Assisted Solution

by:slightwv (䄆 Netminder)
slightwv (䄆 Netminder) earned 2000 total points
ID: 39275435
Probably better, use MERGE:

merge into master mas
using (
	select name, expdate, type from source
) src
on (
	src.name = mas.name and
	src.expdate = mas.expdate and
	src.type = mas.type
)
when not matched then
	insert (mas.name, mas.expdate, mas.type) values (src.name, src.expdate, src.type)
;

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Author Closing Comment

by:GNOVAK
ID: 39275666
Thanks ! Great examples.
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LVL 32

Expert Comment

by:awking00
ID: 39275670
Indexes improve performance when data is being retrieved. So, to do the inserts you should have an index on the source table. And there is no need for a concatenated index, just use a compound index. For example, create index src_idx on sourcetable(name, expdate, type). Any index on the mastertable would assist in query performance but actually reduce performance on the inserts. It is fairly normal to disable indexes on target tables during inserts and rebuilding them after inserts are completed.
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