Oracle : Drop multiple partitions

问题

A table TMP has 5 partitions, namely P_1, P_2,....P_5. I need to drop some partitions of TMP; the partitions to drop are derived by another query.

Ex:

ALTER TABLE TMP DROP PARTITIONS (SELECT ... From ...  //expression to get partition names )

Let's say the SELECT statement returns P_1 & P_5. The part query of the ALTER statement above doesn't work. Is there any way to drop partitions with input from a SELECT statement?

回答1:

You can use dynamic sql in anonymous pl/sql block;

Begin
  for i in (select part_name from ...  //expression to get partition names) loop
    execute immediate 'ALTER TABLE TMP DROP PARTITION ' || i.part_name;
  end loop;
end;

For dropping multiple partitions on a go then;

declare
  v_part varchar(1000);
Begin
  select LISTAGG(partition_name, ', ') WITHIN GROUP (ORDER BY partition_name DESC)
  into v_part  
  from ...  //expression to get partition names;
  execute immediate 'ALTER TABLE TMP DROP PARTITION ' || v_part;
end;

回答2:

You'll need to use dynamic SQL. Something this:

begin
    for prec in (SELECT ... From ...  //expression to get partition names )
    loop
         execute immediate 'ALTER TABLE TMP DROP PARTITION '
             || prec.partition_name;
    end loop;
end;
/

Clearly you need to have complete faith that your query will return only the partitions you want to drop. Or equivalent faith in your Backup & Recover plans :)

Alternatively you can use a similar approach to generate a drop script which you can review before you run it.

回答3:

You have to use pl/sql block for dropping partitions from a table with select query. Use listagg for making a comma separated list.

 DECLARE
    var1 varchar2(50);
    BEGIN
    SELECT listagg(Partition_names) into var1  from table_name//expression to get partition names ;
    execute immediate 'alter table tmp drop PARTITION'||var1  ;
    END;

Example on listagg

select LISTAGG(partition_name,',') within group(order by table_name) as comma_list
 from ALL_TAB_PARTITIONS where TABLE_owner='OWNER' AND TABLE_NAME='TABLE_NAME'

回答4:

Maybe it's could somebody help.

This script drop all partitions for all partition tables for specific schema. I use it with clear DB with METADATA, for changing started (referencial) partition.

ALTER TABLE SCHEMA_1.TABLE_1
  SET INTERVAL ();
ALTER TABLE SCHEMA_1.TABLE_2
  SET INTERVAL ();
ALTER TABLE SCHEMA_1.TABLE_3
  SET INTERVAL ();  

set lines 100

set heading off

spool runme.sql

select 'ALTER TABLE ' || TABLE_OWNER || '.' || TABLE_NAME || ' DROP PARTITION ' || '"' || PARTITION_NAME || '";' from DBA_TAB_PARTITIONS 
where 
    TABLE_OWNER='SCHEMA_1'
--    and TABLE_NAME='TABLE_%' 
    and PARTITION_NAME LIKE 'SYS_P%'
    ;

@runme

ALTER TABLE SCHEMA_1.TABLE_1
  SET INTERVAL (NUMTOYMINTERVAL(1,'MONTH'));
ALTER TABLE SCHEMA_1.TABLE_1
  SET INTERVAL (NUMTOYMINTERVAL(1,'MONTH'));
ALTER TABLE SCHEMA_1.TABLE_3
  SET INTERVAL (NUMTOYMINTERVAL(1,'MONTH'));

Yes, the script is semi-manual, but I think it's more safety.

ALTER TABLE ... INTERVAL it's need for droping last partition.

Interval must be same that it was before

回答5:

You may use the following sql to generate DML for dropping multiple table partitions.

select 'ALTER TABLE ' || TABLE_OWNER || '.' || TABLE_NAME || ' DROP PARTITION ' || '"' || PARTITION_NAME || '";' from DBA_TAB_PARTITIONS 
where TABLE_NAME='%YOUR_PATTERN%'order by PARTITION_NAME;

来源：https://stackoverflow.com/questions/32110948/oracle-drop-multiple-partitions

标签

Oracle

database-partitioning

partition