Ugh. Guess you'll have to reduce the initial size and minextents to try to minimize
the wasted space. It's an art, not a science.... 8-)
>>> [EMAIL PROTECTED] 04/09/01 01:53PM >>>
Lisa,
What do you mean "lie & claim not to"? I have one EVERY day.
BTW: Tim, it's initial xxx by minextents x. I had minextents 4, ended up with
8. Made a real mess of sorts, except now the index is 50% empty. The behavior
did not make sense since I've user parallel in table creations in the past to
speed matters up & this behavior was not displayed. It appears to be a
peculiarity with indexes.
And: Lisa, the parallel slaves divy up the work by rowid's if you look at the
cursor their executing it will say "where rowid < :1" or "where rowid > :1". In
this case the parallel turds build two indexes, one on the top half & the other
on the bottom half & then join them at the root point. Pretty slick, except in
my case it took 18+ hours on each run.
Dick Goulet
____________________Reply Separator____________________
Author: "Koivu; Lisa" <[EMAIL PROTECTED]>
Date: 4/9/2001 9:10 AM
On a partitioned table? If you have a slave for each partition, how would
this be wrong? Or, less slaves than partitions?
It was pounded into my head not to use parallel with non-partitioned tables
because without partitions the slaves would not know how to divy up the
work. Seemed to me that it should be smart enough to split it up by
extents, but what do I know. Any comments?
I never did claim to be that incredibly bright and I did burn quite a few
brain cells over the weekend. Forgive my ignorance, people ! We all have
our days and then there are those of us who lie and claim not to.
-----Original Message-----
Sent: Monday, April 09, 2001 12:55 PM
To: Multiple recipients of list ORACLE-L
Well, duh, of course you're going to get 12 pieces, each of initial xxx
size. How else can it do a parallel creation? Seems pretty intuitive to
me...but then, I'm a pretty smart guy!
8-)
>>> [EMAIL PROTECTED] 04/09/01 11:55AM >>>
Hello Dick,
YOU ARE KIDDING. I've done this many times in the past and never
encountered that type of behavior... I don't see what version/OS you are
running? Was the table partitioned?
And, back by popular demand, is my highly overrated signature
Lisa Rutland Koivu
Oracle Database Administrator
[EMAIL PROTECTED]
NeoMedia
2201 Second St., Suite 600
Fort Myers, FL 33901, USA
Phone: 941-337-3434
Fax: 941-337-3668
www.neom.com <http://www.neom.com>
www.paperclick.com <http://www.paperclick.com>
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Enter Your PaperClick Code Here!
-----Original Message-----
Sent: Monday, April 09, 2001 11:41 AM
To: Multiple recipients of list ORACLE-L
To ALL,
Over the weekend I've been trying to rebuild a VERY large index on a
data
warehouse table. Well in an attempt to get faster processing I invoked the
parallel option, but the index failed for the one reason I could not easily
figure out. I expected the index to be 4 to 5 GB in size when completed,
but it
tried to create itself at 8 to 10 GB instead. Odd I thought until this
morning
when I noticed that there was two temporary segments in the target
tablespace.
I submitted a TAR to OTS for an explanation (Attached). Basically if you do
your index builds in parallel one should expect them to be the estimated
size
times the parallel setting. OOPS!!! :-( Someone can correct me if they
know
otherwise, but I don't remember seeing this in any of the documentation.
BTW: The final index size, now that it did successfully complete, is twice
what
I expected (parallel 2).
Dick Goulet
____________________Forward Header_____________________
Author: [EMAIL PROTECTED] (Oracle Support)
Date: 4/9/2001 10:33 AM
Hello Richard,
Creating Indexes in Parallel
Parallel index creation works in much the same way as a table scan with an
ORDER
BY clause. The table is randomly sampled and a set of index keys is found
that
equally divides the index into the same number of pieces as the degree of
parallelism(DOP). A first set of query processes scans the table, extracts
key,
ROWID pairs, and sends each pair to a process in a second set of query
processes
based on key. Each process in the second set sorts the keys and builds an
index
in the usual fashion.
After all index pieces are built, the parallel coordinator simply
concatenates
the pieces (which are ordered) to form the final index.
Parallel local index creation uses a single server set. Each server process
in
the set is assigned a table partition to scan, and
for which to build an index partition. Because half as many server processes
are
used for a given DOP, parallel local index
creation can be run with a higher DOP.
Note:
When creating an index in parallel, the STORAGE clause refers to
the
storage of each of the subindexes created by the query server
processes.
Therefore, an index created with an INITIAL
of 5MB and a DOP of 12 consumes at least 60MB of storage during
index
creation because each process starts with an extent of 5MB. When the
query
coordinator process combines the sorted subindexes, some of the extents
may
be trimmed, and the resulting index may be smaller than the requested
60MB.
ORA-1652
>From version 7.x, we can create certain objects in parallel, or
unrecoverable.
In order for Oracle to accomplish this, temporary segments are created that
eventually become a permanent part of the object, yet Oracle still refers to
them as temp segments. Thus, most of the time you receive this error, it
will
be referring to the tablespace the object is going to be created in.
Do the following query to find out if you're out of extents:
select max(blocks), max (bytes) from sys.dba_free_space
where tablespace_name = '<tablespace in error message>';
For example, The above query may return:
SQL> blocks bytes
6143 12,580,864
Notice that the biggest CONTIGUOUS block of free space is only 6143 blocks
and
Oracle needs a contiguous block of free space of 6144 to create an object.
You may have a lot of free space in separate blocks in your tablespace, but
if
it is not contiguous, Oracle cannot use it. Allocating extents requires that
there be a contiguous block of free space.
SOLUTION:
1. Add a datafile to the tablespace
2. Adjust the storage parameters of the object you are trying to create.
Parameters to look at: initial extent, next extent, pct increase.
3. If you have a lot of free space in that tablespace, but the it is
very fragmented, you may want to consider rebuilding the tablespace.
4. Enable AUTOEXTEND for the datafile
- Also, Please review<Note:100492.1>Via metalink (Metalink - - >technical
library- - >reach with note#)
Title: ORA-01652: estimate space needed to create index
- Also further researched and found:<Bug:377439.-P>
Abstract: INDEX BUILD FAIL WITH PARALLEL DEGREE > 1
- is there any ora-7445 and core dump file in udump directory?
- is there an internal error (ora-600) trace file?
Please update the tar via metalink.
Thank you,
Oracle Support Services.
Have you tried MetaLink?
Search our technical libraries, create/review/update your TARs at:
http://metalink.oracle.com
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Author: Tim Sawmiller
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">
<META NAME="Generator" CONTENT="MS Exchange Server version 5.5.2653.12">
<TITLE>RE: Parallel index builds can crash</TITLE>
</HEAD>
<BODY>
<P><FONT SIZE=2>On a partitioned table? If you have a slave for each
partition, how would this be wrong? Or, less slaves than
partitions?</FONT></P>
<P><FONT SIZE=2>It was pounded into my head not to use parallel with
non-partitioned tables because without partitions the slaves would not know how
to divy up the work. Seemed to me that it should be smart enough to split
it up by extents, but what do I know. Any comments?</FONT></P>
<P><FONT SIZE=2>I never did claim to be that incredibly bright and I did burn
quite a few brain cells over the weekend. Forgive my ignorance, people
! We all have our days and then there are those of us who lie and claim
not to.</FONT></P>
<BR>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Tim Sawmiller [<A
HREF="mailto:[EMAIL PROTECTED]">mailto:[EMAIL PROTECTED]</A>]</FONT>
<BR><FONT SIZE=2>Sent: Monday, April 09, 2001 12:55 PM</FONT>
<BR><FONT SIZE=2>To: Multiple recipients of list ORACLE-L</FONT>
<BR><FONT SIZE=2>Subject: RE: Parallel index builds can crash</FONT>
</P>
<BR>
<P><FONT SIZE=2>Well, duh, of course you're going to get 12 pieces, each of
initial xxx size. How else can it do a parallel creation? Seems
pretty intuitive to me...but then, I'm a pretty smart guy!</FONT></P>
<P><FONT SIZE=2> 8-)</FONT>
</P>
<P><FONT SIZE=2>>>> [EMAIL PROTECTED] 04/09/01 11:55AM
>>></FONT>
<BR><FONT SIZE=2>Hello Dick, </FONT>
</P>
<P><FONT SIZE=2>YOU ARE KIDDING. I've done this many times in the past and
never</FONT>
<BR><FONT SIZE=2>encountered that type of behavior... I don't see what
version/OS you are</FONT>
<BR><FONT SIZE=2>running? Was the table partitioned?</FONT>
</P>
<P><FONT SIZE=2>And, back by popular demand, is my highly overrated
signature</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>Lisa Rutland Koivu</FONT>
<BR><FONT SIZE=2>Oracle Database Administrator</FONT>
<BR><FONT SIZE=2>[EMAIL PROTECTED] </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> NeoMedia</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>2201 Second St., Suite 600</FONT>
<BR><FONT SIZE=2>Fort Myers, FL 33901, USA</FONT>
<BR><FONT SIZE=2>Phone: 941-337-3434</FONT>
<BR><FONT SIZE=2>Fax: 941-337-3668</FONT>
<BR><FONT SIZE=2>www.neom.com <<A HREF="http://www.neom.com"
TARGET="_blank">http://www.neom.com</A>> </FONT>
<BR><FONT SIZE=2>www.paperclick.com <<A HREF="http://www.paperclick.com"
TARGET="_blank">http://www.paperclick.com</A>> </FONT>
<BR><FONT SIZE=2>www.qode.com <<A HREF="http://www.qode.com"
TARGET="_blank">http://www.qode.com</A>> </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>P a p e r C l i c k . c o m <<A
HREF="http://www.paperclick.com/home.htm"
TARGET="_blank">http://www.paperclick.com/home.htm</A>> </FONT>
<BR><FONT SIZE=2> </FONT>
</P>
<BR>
<P><FONT SIZE=2> Enter Your PaperClick Code Here!</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> </FONT>
</P>
<BR>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>Sent: Monday, April 09, 2001 11:41 AM</FONT>
<BR><FONT SIZE=2>To: Multiple recipients of list ORACLE-L</FONT>
</P>
<BR>
<P><FONT SIZE=2>To ALL,</FONT>
</P>
<P><FONT SIZE=2> Over the weekend I've been trying to rebuild
a VERY large index on a</FONT>
<BR><FONT SIZE=2>data</FONT>
<BR><FONT SIZE=2>warehouse table. Well in an attempt to get faster
processing I invoked the</FONT>
<BR><FONT SIZE=2>parallel option, but the index failed for the one reason I
could not easily</FONT>
<BR><FONT SIZE=2>figure out. I expected the index to be 4 to 5 GB in size
when completed,</FONT>
<BR><FONT SIZE=2>but it</FONT>
<BR><FONT SIZE=2>tried to create itself at 8 to 10 GB instead. Odd I
thought until this</FONT>
<BR><FONT SIZE=2>morning</FONT>
<BR><FONT SIZE=2>when I noticed that there was two temporary segments in the
target</FONT>
<BR><FONT SIZE=2>tablespace. </FONT>
<BR><FONT SIZE=2>I submitted a TAR to OTS for an explanation (Attached).
Basically if you do</FONT>
<BR><FONT SIZE=2>your index builds in parallel one should expect them to be the
estimated</FONT>
<BR><FONT SIZE=2>size</FONT>
<BR><FONT SIZE=2>times the parallel setting. OOPS!!! :-( Someone can
correct me if they</FONT>
<BR><FONT SIZE=2>know</FONT>
<BR><FONT SIZE=2>otherwise, but I don't remember seeing this in any of the
documentation.</FONT>
</P>
<P><FONT SIZE=2>BTW: The final index size, now that it did successfully
complete, is twice</FONT>
<BR><FONT SIZE=2>what</FONT>
<BR><FONT SIZE=2>I expected (parallel 2).</FONT>
</P>
<P><FONT SIZE=2>Dick Goulet</FONT>
</P>
<P><FONT SIZE=2>____________________Forward Header_____________________</FONT>
<BR><FONT SIZE=2>Author: [EMAIL PROTECTED] (Oracle Support)</FONT>
<BR><FONT SIZE=2>Date: 4/9/2001 10:33
AM</FONT>
</P>
<P><FONT SIZE=2> Hello Richard,</FONT>
</P>
<P><FONT SIZE=2>Creating Indexes in Parallel</FONT>
</P>
<P><FONT SIZE=2>Parallel index creation works in much the same way as a table
scan with an</FONT>
<BR><FONT SIZE=2>ORDER</FONT>
<BR><FONT SIZE=2>BY clause. The table is randomly sampled and a set of index
keys is found</FONT>
<BR><FONT SIZE=2>that</FONT>
<BR><FONT SIZE=2>equally divides the index into the same number of pieces as the
degree of</FONT>
<BR><FONT SIZE=2>parallelism(DOP). A first set of query processes scans the
table, extracts</FONT>
<BR><FONT SIZE=2>key,</FONT>
<BR><FONT SIZE=2>ROWID pairs, and sends each pair to a process in a second set
of query</FONT>
<BR><FONT SIZE=2>processes</FONT>
<BR><FONT SIZE=2>based on key. Each process in the second set sorts the keys and
builds an</FONT>
<BR><FONT SIZE=2>index</FONT>
<BR><FONT SIZE=2>in the usual fashion.</FONT>
<BR><FONT SIZE=2>After all index pieces are built, the parallel coordinator
simply</FONT>
<BR><FONT SIZE=2>concatenates</FONT>
<BR><FONT SIZE=2>the pieces (which are ordered) to form the final index. </FONT>
</P>
<P><FONT SIZE=2>Parallel local index creation uses a single server set. Each
server process</FONT>
<BR><FONT SIZE=2>in</FONT>
<BR><FONT SIZE=2>the set is assigned a table partition to scan, and</FONT>
<BR><FONT SIZE=2>for which to build an index partition. Because half as many
server processes</FONT>
<BR><FONT SIZE=2>are</FONT>
<BR><FONT SIZE=2>used for a given DOP, parallel local index</FONT>
<BR><FONT SIZE=2>creation can be run with a higher DOP. </FONT>
</P>
<P><FONT SIZE=2> Note:
</FONT>
</P>
<P><FONT SIZE=2> When
creating an index in parallel, the STORAGE clause refers to</FONT>
<BR><FONT SIZE=2>the</FONT>
<BR><FONT SIZE=2>storage of each of the
subindexes created by the query server</FONT>
<BR><FONT SIZE=2>processes.</FONT>
<BR><FONT SIZE=2>Therefore, an index created with an INITIAL</FONT>
<BR><FONT SIZE=2> of 5MB
and a DOP of 12 consumes at least 60MB of storage during</FONT>
<BR><FONT SIZE=2>index</FONT>
<BR><FONT SIZE=2>creation because each process starts
with an extent of 5MB. When the</FONT>
<BR><FONT SIZE=2>query</FONT>
<BR><FONT SIZE=2>coordinator process combines the
sorted subindexes, some of the extents</FONT>
<BR><FONT SIZE=2>may</FONT>
<BR><FONT SIZE=2>be trimmed, and the resulting index may be
smaller than the requested</FONT>
<BR><FONT SIZE=2>60MB. </FONT>
</P>
<BR>
<P><FONT SIZE=2>ORA-1652</FONT>
<BR><FONT SIZE=2>From version 7.x, we can create certain objects in parallel,
or</FONT>
<BR><FONT SIZE=2>unrecoverable. </FONT>
<BR><FONT SIZE=2>In order for Oracle to accomplish this, temporary segments are
created that </FONT>
<BR><FONT SIZE=2>eventually become a permanent part of the object, yet Oracle
still refers to</FONT>
</P>
<P><FONT SIZE=2>them as temp segments. Thus, most of the time you receive this
error, it</FONT>
<BR><FONT SIZE=2>will </FONT>
<BR><FONT SIZE=2>be referring to the tablespace the object is going to be
created in. </FONT>
</P>
<P><FONT SIZE=2>Do the following query to find out if you're out of extents:
</FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> select max(blocks), max (bytes) from
sys.dba_free_space </FONT>
<BR><FONT SIZE=2> where tablespace_name =
'<tablespace in error message>'; </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>For example, The above query may return:</FONT>
<BR><FONT SIZE=2> SQL> blocks bytes </FONT>
<BR><FONT SIZE=2>
6143 12,580,864 </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>Notice that the biggest CONTIGUOUS block of free space is only
6143 blocks</FONT>
<BR><FONT SIZE=2>and </FONT>
<BR><FONT SIZE=2>Oracle needs a contiguous block of free space of 6144 to create
an object. </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>You may have a lot of free space in separate blocks in your
tablespace, but</FONT>
<BR><FONT SIZE=2>if </FONT>
<BR><FONT SIZE=2>it is not contiguous, Oracle cannot use it. Allocating extents
requires that</FONT>
</P>
<P><FONT SIZE=2>there be a contiguous block of free space. </FONT>
</P>
<BR>
<P><FONT SIZE=2>SOLUTION: </FONT>
<BR><FONT SIZE=2>1. Add a datafile to the tablespace </FONT>
<BR><FONT SIZE=2>2. Adjust the storage parameters of the object you are trying
to create. </FONT>
<BR><FONT SIZE=2> Parameters to look at: initial extent, next
extent, pct increase. </FONT>
<BR><FONT SIZE=2>3. If you have a lot of free space in that tablespace, but the
it is </FONT>
<BR><FONT SIZE=2> very fragmented, you may want to consider
rebuilding the tablespace. </FONT>
<BR><FONT SIZE=2>4. Enable AUTOEXTEND for the datafile </FONT>
</P>
<BR>
<P><FONT SIZE=2> </FONT>
</P>
<P><FONT SIZE=2> - Also, Please review<Note:100492.1>Via
metalink (Metalink - - >technical</FONT>
<BR><FONT SIZE=2>library- - >reach with note#)</FONT>
<BR><FONT
SIZE=2>Title: &
nbsp; ORA-01652: estimate space needed to create index</FONT>
</P>
<BR>
<BR>
<BR>
<P><FONT SIZE=2> - Also further researched and found:<Bug:377439.-P>
</FONT>
<BR><FONT SIZE=2>Abstract: INDEX BUILD FAIL
WITH PARALLEL DEGREE > 1</FONT>
</P>
<BR>
<BR>
<P><FONT SIZE=2> - is there any ora-7445 and core dump file in udump
directory?</FONT>
<BR><FONT SIZE=2> - is there an internal error (ora-600) trace file?</FONT>
</P>
<P><FONT SIZE=2>Please update the tar via metalink.</FONT>
<BR><FONT SIZE=2> Thank you,</FONT>
<BR><FONT SIZE=2>Oracle Support Services.</FONT>
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Sawmiller
INET: [EMAIL PROTECTED]
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