Mario Rigotti's List: oracle

• spiegazione sul delete cascade - Mario Rigotti on 2006-11-22

• versione lite e gratuita di oracle
  - Mario Rigotti on 2006-11-28

• aiuto su configurazione toad
  - Mario Rigotti on 2006-12-05

• interfacciare java con oracle pl-sql stored procedure
  - Mario Rigotti on 2008-02-22

• Some materialized views contain only joins and no aggregates, such as in Example 8-4, where a materialized view is created that joins the sales table to the times and customers tables. The advantage of creating this type of materialized view is that expensive joins will be precalculated.
• A materialized view log must be present for each detail table and the ROWID column must be present in each materialized view log.
• The rowids of all the detail tables must appear in the SELECT list of the materialized view query definition.
• To improve refresh performance, you should create indexes on the materialized view's columns that store the rowids of the fact table.
• You can create a nested materialized view on materialized views that contain joins only or joins and aggregates
• In the case of materialized views containing only joins using fast refresh, Oracle recommends that indexes be created on the columns that contain the rowids to improve the performance of the refresh operation.

4 more annotations...

• Concetti viste materializzate
  - Mario Rigotti on 2008-01-15

• registerO

• registerOutParameter
  - Mario Rigotti on 2007-09-17

• Interfaccia JDBC di Java
  - Mario Rigotti on 2007-09-17

• c'e' anche il pdf in alto a destra
  - Mario Rigotti on 2006-12-20

• help out an application that is continually closing and reopening cursors, you can monitor its effectiveness via two more statistics in v$sesstat. The statistic "session cursor cache hits" reflects the number

• To see if you've set OPEN_CURSORS high enough, monitor v$sesstat for the maximum opened cursors current. If your sessions are running close to the limit, up the value of OPEN_CURSORS.

    

  SQL> select max(a.value) as highest_open_cur, p.value as max_open_cur   2> from v$sesstat a, v$statname b, v$parameter p   3> where a.statistic# = b.statistic#    4> and b.name = 'opened cursors current'   5> and p.name= 'open_cursors'   6> group by p.value;  HIGHEST_OPEN_CUR MAX_OPEN_CUR ---------------- ------------             1953         2500
• If you set OPEN_CURSORS to a high value, this doesn't mean that every session will have that number of cursors open. Cursors are opened on an as-needed basis
• If you have an application session whose opened cursors current always increases to catch up with OPEN_CURSORS, then you've likely got a cursor leak in your application code: your application is opening cursors and not closing them when it's done.

2 more annotations...

• opened cursor
  - Mario Rigotti on 2006-12-13

• startup oracle 9
  - Mario Rigotti on 2006-12-13

• • A materialized view log must be present for each detail table and the ROWID column must be present in each materialized view log.

   
  •  

    The rowids of all the detail tables must appear in the SELECT list of the materialized view query definition.

   
  •  

    If there are no outer joins, you may have arbitrary selections and joins in the WHERE clause. However, if there are outer joins, the WHERE clause cannot have any selections. Further, if there are outer joins, all the joins must be connected by ANDs and must use the equality (=) operator.

   
  •  

    If there are outer joins, unique constraints must exist on the join columns of the inner table. For example, if you are joining the fact table and a dimension table and the join is an outer join with the fact table being the outer table, there must exist unique constraints on the join columns of the dimension table.