Partial Index Usage Performance Question

#31

On Mon, 6 Oct 2008 08:14:30 -0700 (PDT), digory <digory (AT) gmx (DOT) net>
wrote:

Quote:

Hi

I have a table T with columns A, B, C and an index I over all three
columns. Further, I have a query which uses columns A and B, but not
C, i.e.

SELECT * FROM T WHERE a = ? AND b = ?

I gather Oracle is able to use index I even though the last column is
not used. My question is the following: If I write a query like

SELECT * FROM T WHERE a = ? AND b = ? AND c = ?

with a condition for C that, for the data in T, is known to be true
always, will that query be generally slower or faster than the one
above, or is there no difference in performance, or does it depend on
the complexity of the index?

Thanks for a little insight,
Peter

Answers to a question like this one typically depend on posting a
database version.
You were too lazy to do so.
No answer is possible.

--
Sybrand Bakker
Senior Oracle DBA

#32

On Mon, 6 Oct 2008 08:14:30 -0700 (PDT), digory <digory (AT) gmx (DOT) net>
wrote:

Quote:

Hi

I have a table T with columns A, B, C and an index I over all three
columns. Further, I have a query which uses columns A and B, but not
C, i.e.

SELECT * FROM T WHERE a = ? AND b = ?

I gather Oracle is able to use index I even though the last column is
not used. My question is the following: If I write a query like

SELECT * FROM T WHERE a = ? AND b = ? AND c = ?

with a condition for C that, for the data in T, is known to be true
always, will that query be generally slower or faster than the one
above, or is there no difference in performance, or does it depend on
the complexity of the index?

Thanks for a little insight,
Peter

Answers to a question like this one typically depend on posting a
database version.
You were too lazy to do so.
No answer is possible.

--
Sybrand Bakker
Senior Oracle DBA

#33

On Mon, 6 Oct 2008 08:14:30 -0700 (PDT), digory <digory (AT) gmx (DOT) net>
wrote:

Quote:

Hi

I have a table T with columns A, B, C and an index I over all three
columns. Further, I have a query which uses columns A and B, but not
C, i.e.

SELECT * FROM T WHERE a = ? AND b = ?

I gather Oracle is able to use index I even though the last column is
not used. My question is the following: If I write a query like

SELECT * FROM T WHERE a = ? AND b = ? AND c = ?

with a condition for C that, for the data in T, is known to be true
always, will that query be generally slower or faster than the one
above, or is there no difference in performance, or does it depend on
the complexity of the index?

Thanks for a little insight,
Peter

Answers to a question like this one typically depend on posting a
database version.
You were too lazy to do so.
No answer is possible.

--
Sybrand Bakker
Senior Oracle DBA

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Partial Index Usage Performance Question

comp.databases.oracle.misc comp.databases.oracle.misc

Re: Partial Index Usage Performance Question - 10-14-2008 , 11:34 AM

Re: Partial Index Usage Performance Question - 10-14-2008 , 11:34 AM

Re: Partial Index Usage Performance Question - 10-14-2008 , 11:34 AM