ALTER TABLE t TRUNCATE PARTITION p UPDATE GLOBAL INDEXES;
Instead of “truncate”, we can also use “drop” or “delete”, depending on what kind of operation we need.
Truncate partition without invalidating indexes
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Category Archives: ORACLE
Killing Oracle Sessions
From http://www.oracle-base.com/articles/misc/killing-oracle-sessions.php
Identify the Session to be Killed
SELECT s.inst_id,
s.sid,
s.serial#,
p.spid,
s.username,
s.program
FROM gv$session s
JOIN gv$process p ON p.addr = s.paddr AND p.inst_id = s.inst_id
WHERE s.type != 'BACKGROUND';
ALTER SYSTEM KILL SESSION
ALTER SYSTEM KILL SESSION 'sid,serial#';
or
ALTER SYSTEM KILL SESSION 'sid,serial#' IMMEDIATE;
Optimize Oracle UNDO Parameters
From http://www.akadia.com/services/ora_optimize_undo.html:
Optimal Undo Retention:
SELECT d.undo_size/(1024*1024) "ACTUAL UNDO SIZE [MByte]",
SUBSTR(e.value,1,25) "UNDO RETENTION [Sec]",
ROUND((d.undo_size / (to_number(f.value) *
g.undo_block_per_sec))) "OPTIMAL UNDO RETENTION [Sec]"
FROM (
SELECT SUM(a.bytes) undo_size
FROM v$datafile a,
v$tablespace b,
dba_tablespaces c
WHERE c.contents = 'UNDO'
AND c.status = 'ONLINE'
AND b.name = c.tablespace_name
AND a.ts# = b.ts#
) d,
v$parameter e,
v$parameter f,
(
SELECT MAX(undoblks/((end_time-begin_time)*3600*24))
undo_block_per_sec
FROM v$undostat
) g
WHERE e.name = 'undo_retention'
AND f.name = 'db_block_size';
Calculate Needed UNDO Size for given Database Activity:
SELECT d.undo_size/(1024*1024) "ACTUAL UNDO SIZE [MByte]",
SUBSTR(e.value,1,25) "UNDO RETENTION [Sec]",
(TO_NUMBER(e.value) * TO_NUMBER(f.value) *
g.undo_block_per_sec) / (1024*1024)
"NEEDED UNDO SIZE [MByte]"
FROM (
SELECT SUM(a.bytes) undo_size
FROM v$datafile a,
v$tablespace b,
dba_tablespaces c
WHERE c.contents = 'UNDO'
AND c.status = 'ONLINE'
AND b.name = c.tablespace_name
AND a.ts# = b.ts#
) d,
v$parameter e,
v$parameter f,
(
SELECT MAX(undoblks/((end_time-begin_time)*3600*24))
undo_block_per_sec
FROM v$undostat
) g
WHERE e.name = 'undo_retention'
AND f.name = 'db_block_size';
How to get tablespace usage
Taken from here, originally by Michael Lehmann.
SELECT df.tablespace_name TABLESPACE, df.total_space TOTAL_SPACE,
fs.free_space FREE_SPACE, df.total_space_mb TOTAL_SPACE_MB,
(df.total_space_mb - fs.free_space_mb) USED_SPACE_MB,
fs.free_space_mb FREE_SPACE_MB,
ROUND(100 * (fs.free_space / df.total_space),2) PCT_FREE
FROM (SELECT tablespace_name, SUM(bytes) TOTAL_SPACE,
ROUND(SUM(bytes) / 1048576) TOTAL_SPACE_MB
FROM dba_data_files
GROUP BY tablespace_name) df,
(SELECT tablespace_name, SUM(bytes) FREE_SPACE,
ROUND(SUM(bytes) / 1048576) FREE_SPACE_MB
FROM dba_free_space
GROUP BY tablespace_name) fs
WHERE df.tablespace_name = fs.tablespace_name(+)
ORDER BY fs.tablespace_name;
How to change column data type
How to change column data type, to VARCHAR2 in this example:
ALTER TABLE <table_name> MODIFY (<column_name> VARCHAR2(20));
Note that data may be lost in this operation.
How to move a partitionated index to another tablespace
Change the index’s default tablespace, so it’ll create every new partition on the new tablespace:
ALTER INDEX <index_name> MODIFY DEFAULT ATTRIBUTES TABLESPACE <new_tablespace>;
Move the index’s partition to another tablespace:
ALTER INDEX <index_name> REBUILD PARTITION <partition_name> TABLESPACE <new_tablespace> NOLOGGING;