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#11
 
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Re: oracle indexes -
06-05-2008
, 03:21 PM
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? *Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. *But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...” http://www.signonsandiego.com/uniont...s_1n5nude.html
#12
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? *Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. *But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...” http://www.signonsandiego.com/uniont...s_1n5nude.html
#13
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? *Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. *But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...” http://www.signonsandiego.com/uniont...s_1n5nude.html
#14
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...”
http://www.signonsandiego.com/uniont...s_1n5nude.html
I had forgotten to mention Richard Foote's web site. It is excellent. Lots
of fantastic information there.
Jim
#15
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...”
http://www.signonsandiego.com/uniont...s_1n5nude.html
I had forgotten to mention Richard Foote's web site. It is excellent. Lots
of fantastic information there.
Jim
#16
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...”
http://www.signonsandiego.com/uniont...s_1n5nude.html
I had forgotten to mention Richard Foote's web site. It is excellent. Lots
of fantastic information there.
Jim
#17
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Hello, Say If I have a table with column a, and column b (say they are integers). Sometimes I will do a query with a where clause that just references column a. Sometimes I will do a query with a where clause that references both column a and b. Is there a need to create an index with a, and an index with a, b? Or will an index with a,b work for both of the above types of queries? I know in mysql if I have an index (a, b, c), then it is useful for queries referencing a or a,b or a, b,c. But, I am not as familiar with how Oracle indexes work. Thanks. |
performance tuning manual. You can also search http://tahiti.oracle.com
for the skip scan Jim mentioned, which answers your question.
Once you become comfortable with the basic concepts, you can delve
deeper in many places, especially http://richardfoote.wordpress.com/
(be sure and check out the index internals presentation).
jg
--
@home.com is bogus.
“I just don't understand why kids would do a stupid thing like
that...”
http://www.signonsandiego.com/uniont...s_1n5nude.html
I had forgotten to mention Richard Foote's web site. It is excellent. Lots
of fantastic information there.
Jim
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