to log or not to log

In summary :-
If nologging is specified on a table or tablespace all operations against a table will still be logged except

Alter table...move partition
alter table...split partition
alter index...split partition
alter index...rebuild
alter index...rebuild partition
create table...as select (CTAS)
create index
direct load with SQL*Loader
direct load INSERT (using APPEND)

with nologging specified


http://www.dbasupport.com/oracle/ora10g/managing_tables.shtml

parallel_max_servers

parallel_max_servers set the TOTAL maximum number of parallel processes that each server.


http://www.stanford.edu/dept/itss/docs/oracle/10g/server.101/b10736/usingpe.htm#i1008006

parallel, degrees and instances

create table
PARALLEL ( DEGREE DEFAULT INSTANCES DEFAULT )

The Degree 'default value' is worked out thus :-
number of CPUs (cores) * number_of_thread_per_cpu (from v$parameter)

Instances is the number of nodes in the RAC that you want it to use

We hit a problem with a query going 'massively paralle' because the server had 16 cpus
, the number_of_thread_per_cpu was2 and the number of nodes was 2
We therefore ended up with something close to 64 parallel processes.

unusable columns and exchange partitions

column mismatch during exchange may be caused by unusable columns.

http://itnewscast.com/ora14097-column-type-or-size-mismatch-alter-table-exchange-partition

PL/sql function and no_data_found

PL/SQL functions with a 'select col1 into v1 from table' line in them behave differently when they hit a no_data_found error (i.e. if the table is empty).
IF
you call the function like this .....
BEGIN
my_function;
END;
THEN
YOU get a no_data_found exception raised.


BUT
IF YOU CALL THE FUNCTION LIKE THIS....
SELECT my_function FROM dual;
THEN
It will not raise a no_data_found

see
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:317260900346187160

db link full spec

DROP DATABASE LINK "apollo";
CREATE DATABASE LINK "apollo"
connect TO xxxxxx
IDENTIFIED BY "xxxxxxx"
using '(DESCRIPTION =(ADDRESS_LIST =(ADDRESS=(PROTOCOL=tcp)(HOST=10.24.0.11)(PORT=1521)))(connect_data=(SID=MIS10G1)))';
SELECT * FROM dual@apollo

unix list directories only

ls -d */