| Global index [message #49953] |
Wed, 20 February 2002 05:06  |
orafan
Messages: 8
Registered: December 2001
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Junior Member |
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'Unique indexes on columns other than the partitioning columns must be global because unique local nonprefixed indexes whose key does not contain the partitioning key are not supported.'
I can not understand this, could anyone explain it in detail ?
Thank you!
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| Re: Global index [message #49959 is a reply to message #49953] |
Wed, 20 February 2002 11:29  |
Sanjay Bajracharya
Messages: 279
Registered: October 2001
Location: Florida
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Senior Member |
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Here is an example.
Table X has columns A, B, C, D
Partition is on column A
1. Local prefixed index Must have A in the first position with combination of other columns (eg. A,B,C or A,C,D or A,D)
2. Local nonprefixed index will have column A in any position except the first one (eg B,C,A or D,A)
LOCAL NONPREFIXED MUST HAVE 'A' BUT NOT IN THE FIRST POSITION.
3. Global index can have other columns except A (eg B,C or D)
Hope you got the picture.
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| Re: Global index [message #49995 is a reply to message #49959] |
Fri, 22 February 2002 03:17 |
orafan
Messages: 8
Registered: December 2001
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Junior Member |
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Sanjay,
Thank you for help. But IĦĦstill don't know why LOCAL NONPREFIXED INDEX must include A?
The definition of LOCAL NONPREFIXED INDEX doesn't require this. For example, index(B,C) is also a local nonprefixed index, I think.
How do you think about it?
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| Re: Global index [message #50001 is a reply to message #49995] |
Fri, 22 February 2002 09:04 |
Sanjay Bajracharya
Messages: 279
Registered: October 2001
Location: Florida
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Senior Member |
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In fact, I have to correct my definitions, as you are right. Exact from the book
"Local prefixed indexes - these are indexes such that the partition keys are on the leading edge of the index definition."
"Local non-prefixed indexes - these indexes do not have the partition key on the leading edge of their column list. The index may or may not contain the partition key column."
...
Thanks for pointing out my mistake.
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