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pravin madoori
New User
Joined: 29 Jan 2007
Posts: 25
Location: Hyderabad
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Would the performance of an update/delete query be the same when primary key is used & when index is used.
I know primary key is also an index however it's an unique index.So if i have below 2 queries, would there be any performance difference with respect to query execution.
1. Update table
set column = :value
where primary key = xxxxxxx;
1. Update table
set column = :value
where index= xxxxxxx;
Thanks in advance |
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dbzTHEdinosauer
Global Moderator
Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne
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Should be a FORUM Rule: No discussion over query's without an EXPLAIN.
only the OP knows his environment; stop wasting our time making us guess. |
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enrico-sorichetti
Superior Member
Joined: 14 Mar 2007
Posts: 10873
Location: italy
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the way You posed it, Your question does not make any sense
the where clause must specify a column name
| Code: |
select ......
where column_name = some_value |
"primary key" and "index" do not look like column names to me
running an explain will tell You more |
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nabarundas
New User
Joined: 21 Jun 2007
Posts: 28
Location: pune
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Hi proven madoori,
Could you plz tell me how you get the value of index and how you can use it in where clause? The index is an ordered set of pointers that refer to one or more key columns in a base table. By using the Primary key of table DB2 makes an INDEX(unique) for faster access.
As Dick & Enrico suggested plz reform your question clearly.
Regards,
Nabarun |
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vini_srcna
Active User
Joined: 26 May 2005
Posts: 178
Location: Copenhagen, Denmark
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No one can guess the SQL performance and its unpredictable.!!.
Explain is the only way. We are not more intelligent than EXPLAIN. |
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rpuhlman
New User
Joined: 11 Jun 2007
Posts: 80
Location: Columbus, Ohio
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| FWIW, I believe Pravin is substituting Primary and Index instead of the actual column names to stress his point and help differentiate his examples. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
Probably a mistake, but i'm going to establish that there is only one matching value for the "other key".
If this is the case, i believe then the queston is: "Will access by the primary key be better, worse, or the same as access by the "other key?".
As far as i know, the access would be the same. |
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