Re: CLUSTER syntax

edwards_at_garland.dnr.state.sc.us wrote:
>
> I am trying to figure out how to make the two tables below share the
> columns 'ucan_station_id' and 'station_sequence'.
>
> I am able to create to create the following cluster with no errors.
> However, any operations on the tables are extremely slow.
>
> What am I doing wrong?
>
>
>
> create cluster UCAN_NWS (jack number(10),jill number(2));
>
> CREATE TABLE climate.ucan_stations (
> ucan_station_id NUMBER(10,0) CONSTRAINT nn_ucan NOT NULL,
> station_sequence NUMBER(2,0) CONSTRAINT nn_sequence NOT NULL,
> station_name VARCHAR2(20))
> cluster UCAN_NWS (ucan_station_id,station_sequence);
>
> CREATE TABLE climate.nws_stations (
> ucan_station_id NUMBER(10,0) CONSTRAINT nn_nws not null,
> station_sequence NUMBER(2,0) CONSTRAINT nn_nwssequence NOT NULL,
> nws_station_id varchar2(16))
> cluster UCAN_NWS (ucan_station_id,station_sequence);
>
> create index ucancluster on cluster UCAN_NWS;

   If your operation is concerned about the ucan_station_id or station_sequence such as joining, you will gain performance. Otherwise, you will probably lose the performance because of the increase in number of scanned blocks.

---
Name   : Lun Wing San
Title  : Oracle Application Developer of Hong Kong Productivity Council
         Oracle Database Administrator and System Administrator of QRC
Phone  : (852)27885841