11 Left Outer Join in a query and Oracle error

Question

I have to create a sql query for a new report. The problem is that I have to do 11 Left Outer Join !!! Oh yes this is the bad part. When I execute the query Oracle generate this error :

ORA-01652: unable to extend temp segment by 128 in tablespace TEMP
01652. 00000 -  "unable to extend temp segment by %s in tablespace %s"
*Cause:    Failed to allocate an extent of the required number of blocks for
           a temporary segment in the tablespace indicated.
*Action:   Use ALTER TABLESPACE ADD DATAFILE statement to add one or more
           files to the tablespace indicated.

I am sure that this error is triggered because there are a lot of reocrds to handle. Do you have any advice that could help me please?

Thanks, Walloud

Answer 1

Are the results of the report aggregated in any way? If so, you may be able to break the query down into a number of stages and store the intermediate results rather than doing it a single hit. Without seeing the query itself and having a basic understanding of the domain and requirements it would be difficult to help further.

Answer 2

If it's not to do with aggregation, as ninesided mentions ...

Oracle 9i and below had a problem with outer joins, particularly with hash outer joins, that might be relevant -- until 10g the driving table for table_a = table_b(+) had to be table_a, and this could mean that an efficient hash join where table_a was smaller than table_b could not occur. The alternative often turned out to be a sort-merge, which could require a lot of temp storage.

The cure could be to upgrade from a version for which extended support ended three years ago ;)

Answer 3

Check your temporary tablespace settings. The temporary tablespace required to sort or hash a table is usually about the same as the segment size of that table. Find those numbers with a query like this:

select bytes/1024/1024/1024 GB, dba_segments.*
from dba_segments
where segment_name = '<table_name>';

Then compare it with the available temporary tablespace:

select free_space/1024/1024/1024 GB, dba_temp_free_space.*
from dba_temp_free_space;

If you are sorting or hashing a table larger than your temp space, the easiest solution is probably to add more space.

Also check if other processes are using up a lot of temp tablespace. Assuming an 8K block size:

select blocks * 8 * 1024 /1024/1024 MB, v$sort_usage.*
from gv$sort_usage;