of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized when it involves
multiple partitions.
- Dave
David Hau wrote:
I assume you're talking about the Fast Full Index Scan. This is used
when
Logical and Physical I/Os.
test it and hint your queries
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized
, it generally means my table(s) aren't properly analyzed.
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized
your queries
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized when it involves
multiple partitions.
- Dave
means my table(s) aren't properly analyzed.
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized when
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can be parallelized when it involves
multiple partitions.
- Dave
David Hau wrote
PROTECTED]
Date: 2004/01/27 Tue AM 11:14:27 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
This is where the access time of your disks (or SAN) makes a difference.
If your disks have really fast access time, then a random
PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Another situation where index full scans might be handy, would be where hash
joins are disabled and sorted output can be used for fast sort-merge join.
Btw, multiblock reads are available for regular index range and full scan
under
scans.
any ideas? I rarely ever find this to be an optimal index access method
for anything.
From: Tanel Poder [EMAIL PROTECTED]
Date: 2004/01/27 Tue AM 11:19:27 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Another
PROTECTED]
Sent by: [EMAIL PROTECTED]
01/27/2004 08:54 AM
Please respond to ORACLE-L
To:Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
cc:
Subject:Re: When does Oracle use 'Index Fast Scan'
This is where the access time of your disks (or SAN) makes a difference
and Physical I/Os.
test it and hint your queries
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/26 Mon PM 10:34:25 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
Correction: the Index Range Scan can
found that index_ffs typically incur higher logical I/Os that index range scans. so its not just access speeds.
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/27 Tue AM 11:54:26 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan
logical I/Os that index
range scans. so its not just access speeds.
From: David Hau [EMAIL PROTECTED]
Date: 2004/01/27 Tue AM 11:54:26 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
This is where the access time of your
AM 11:54:26 EST
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Subject: Re: When does Oracle use 'Index Fast Scan'
This is where the access time of your disks (or SAN) makes a difference.
If your disks have really fast access time, then a random-access
pattern would not cause much
I have found that the vast majority of time that
Oracle chooses this method, my statistics are stale and the query is
sub-optimal. One time, Oracle changed from a 'range scan' to this type of scan
with a FIRST_ROWS hint and this reduced performance.
This is just a full scan of the index,
I assume you're talking about the Fast Full Index Scan. This is used
when the index contains all the columns necessary to answer the query.
It's faster than a Full Table Scan because indexes are smaller than
entire rows, so a Fast Full Index Scan will scan fewer blocks than a
Full Table Scan.
Correction: the Index Range Scan can be parallelized when it involves
multiple partitions.
- Dave
David Hau wrote:
I assume you're talking about the Fast Full Index Scan. This is used
when the index contains all the columns necessary to answer the query.
It's faster than a Full Table Scan
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