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Home -> Community -> Mailing Lists -> Oracle-L -> FW: Identifying Redundant Indexes
Ah, yes, Jeff has restored my memory (below). If your application does
not use bind variables, then you have many more "distinct" SQL
statements than you actually *should* have. ...Which is another reason
that collecting the SQL is such an important step. If you do it with too
simple of a matching algorithm, then you're accidentally giving yourself
(and your system) way too much work. For example, SELECT ID FROM T WHERE
LNAME='Smith' and SELECT ID FROM T WHERE LNAME='Jones' should really be
regarded as one distinct statement.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101, Jan 7-9 Knoxville
-----Original Message-----
Sent: Monday, December 23, 2002 1:06 PM
To: 'Cary Millsap'
That approach would work as long as you can predict the number of distinct statements over the observation interval. If you can predict the number of distinct statements, then you can attempt to size the tablespace. If you cannot predict the volume, then you risk filling the tablespace where the outlines are stored. The most common cause for not being able to predict is an application's lack of use of bind variables in its statements.
I haven't tested the scenario of create_stored_outlines=true and the outline cannot be stored because of some error such as 'table cannot be extended'.
I would hope that it would ignore the insert error but without a test it would be somewhat risky. Especially since the creations would be most likely be executed on a production instance.
Jeff Holt - An O2 bottle, an O2 bottle! My password for an O2 bottle!
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events at http://www.hotsos.com/events/index.html
-----Original Message-----
Sent: Mon, Dec 23, 2002 09:40
To: ORACLE-L_at_fatcity.com
We assessed this and discarded the option, and now I can't remember why (I'll get back to you after I ask Jeff Holt, who did the study). At best, using stored outlines is a replacement only for steps 2 and 4. The really hard part is step 1.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101, Jan 7-9 Knoxville
-----Original Message-----
John.Hallas_at_vodafone.co.uk
Sent: Monday, December 23, 2002 6:14 AM
To: Multiple recipients of list ORACLE-L
Cary,
I assume that using stored outlines will achieve No 2 in your list.
Would
that not be an easier approach?
If you altered the system to have CREATE_STORED_OUTLINES=true and ran
for a
period when all scripts are likely to be run, say a month so that all
month-end processing was completed, and then check the
OUTLN.OL$HINTS.HINT_TEXT column with a query such as the following.
1 select hint_text from outln.ol$hints 2* where substr(hint_text,1,5) = 'INDEX' SQL> / HINT_TEXT
-----Original Message-----
Sent: 23 December 2002 05:59
To: Multiple recipients of list ORACLE-L
Mark,
The way we do it is by what you might call extreme brute force:
Like I said, it's a "big hammer" method, but it has its reliability advantages, and the only step that we haven't automated is #6. (I'm assuming that you already have a valid test system as described in #3.) The tool we use that does steps 2, 4, and 5 is called Project Laredo (www.hotsos.com/products/laredo).
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101, Jan 7-9 Knoxville
-----Original Message-----
Richard
Sent: Sunday, December 22, 2002 10:54 PM
To: Multiple recipients of list ORACLE-L
Dear List,
Firstly - Merry Christmas to those who have not already departed for the holiday season.
I'm currently doing some investigation based around indexes and would
like
everyone's opinion: What is everyone's preferred approach to identify
redundant (as in "never used by Oracle") indexes? I believe Oracle 9
might
have a feature to set a flag on objects and then check back later to see
if
they have been accessed however we're still stuck on 8.1.7.4 (Solaris).
Some of my thoughts include:
Obviously we are searching for indexes to remove and identifying those
which aren't queried over a set period of time would be good candidates
for
a starting point. Any advice you might have would be greatly
appreciated.
Regards,
Mark.
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mark Richard INET: mrichard_at_transurban.com.au Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Cary Millsap INET: cary.millsap_at_hotsos.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: <John.Hallas_at_vodafone.co.uk INET: John.Hallas_at_vodafone.co.uk Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Cary Millsap INET: cary.millsap_at_hotsos.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Mon Dec 23 2002 - 13:53:59 CST
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