It is a normal behaviour for parallel query since 7.3.4.
Even table on which index being created has degree > 1 (suppose dgree 4)and
you create an index on that table, it will create initialy 4 extents of
initial extent size in target tablespace as well as 4 in temp table space to
develop that index. However once this job is completed , it will merge into
one or number of extents as per your storage parameter in target tablespace.
It is true for both creation of index as well as rebuilding index.
Regards
Rafiq
Reply-To: [EMAIL PROTECTED]
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
Date: Mon, 09 Apr 2001 09:35:42 -0800
Lisa,
Regrettably I'm not kidding, and neither was OTS. I'm on HP-UX 10.20
Oracle
8.0.4.4.0. According to OTS this is the "normal" behavior for all versions
of
Oracle, on all platforms, that support parallel query. On a small index I
could
see one not noticing, but on what should be a 4 GB index one notices the
extra 4
GB that goes down the drain!
Dick Goulet
____________________Reply Separator____________________
Author: "Koivu; Lisa" <[EMAIL PROTECTED]>
Date: 4/9/2001 11:02 AM
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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-----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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<TITLE>RE: Parallel index builds can crash</TITLE>
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<BODY>
<P><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 encountered that type of behavior... I don't see what version/OS
you
are 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>From: [EMAIL PROTECTED] [<A
HREF="mailto:[EMAIL PROTECTED]">mailto:[EMAIL PROTECTED]</A>]</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>
<BR><FONT SIZE=2>Subject: Parallel index builds can crash</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 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, but it</FONT>
<BR><FONT SIZE=2>tried to create itself at 8 to 10 GB instead. Odd I
thought until this morning</FONT>
<BR><FONT SIZE=2>when I noticed that there was two temporary segments in the
target 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 size</FONT>
<BR><FONT SIZE=2>times the parallel setting. OOPS!!! :-( Someone
can
correct me if they 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 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 ORDER</FONT>
<BR><FONT SIZE=2>BY clause. The table is randomly sampled and a set of index
keys is found 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 key,</FONT>
<BR><FONT SIZE=2>ROWID pairs, and sends each pair to a process in a second
set
of query processes</FONT>
<BR><FONT SIZE=2>based on key. Each process in the second set sorts the keys
and
builds an 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 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 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 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 the</FONT>
<BR><FONT SIZE=2>storage of each of the
subindexes created by the query server 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 index</FONT>
<BR><FONT SIZE=2>creation because each process
starts
with an extent of 5MB. When the query</FONT>
<BR><FONT SIZE=2>coordinator process combines
the
sorted subindexes, some of the extents may</FONT>
<BR><FONT SIZE=2>be trimmed, and the resulting index may be
smaller than the requested 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
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>
<BR><FONT SIZE=2>them as temp segments. Thus, most of the time you receive
this
error, it 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 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 if </FONT>
<BR><FONT SIZE=2>it is not contiguous, Oracle cannot use it. Allocating
extents
requires that </FONT>
<BR><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>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2> </FONT>
<BR><FONT SIZE=2>Have you tried MetaLink? </FONT>
<BR><FONT SIZE=2>Search our technical libraries, create/review/update your
TARs
at: </FONT>
<BR><FONT SIZE=2><A HREF="http://metalink.oracle.com"
TARGET="_blank">http://metalink.oracle.com</A> </FONT>
</P>
<BR>
<P><FONT SIZE=2>-- </FONT>
<BR><FONT SIZE=2>Please see the official ORACLE-L FAQ: <A
HREF="http://www.orafaq.com"
TARGET="_blank">http://www.orafaq.com</A></FONT>
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<BR><FONT SIZE=2>Author: </FONT>
<BR><FONT SIZE=2> INET: [EMAIL PROTECTED]</FONT>
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