Oracle

Index

Show:

 select * from dba_ind_columns where lower(table_name) = '<table>'; -- you only change <table>

Create:

create index <indexName> on <table> (<column1>, <column2>, ...);

Drop with either

drop <indexName>;

or

alter table <table> drop constraint <indexName>;

Select

Samples:

 select * from <table> sample(0.1);

Select <n> rows:

select <field1>, <field2> from 
(select <field1>, <field2>, row_number() over (order by <field2>) r from items) 
where r between 1 and <n>;

Links

• Using EXPLAIN PLAN