1, the drawbacks of redundancy index
Large number of redundant and useless index resulting in poor overall database performance, consumes a large amount of CPU and I / O overhead, the following specific performance:
a, consume large amounts of storage space (maintenance and management index segment)
b, an increase of DML completion time
c, a considerable amount of time statistical information (index) collected
d, structural verification time
f, increases the time required for recovery
2, a single index monitoring
a, for the monitoring of a single index, the following command can be done
alter index <INDEX_NAME> monitoring usage;
b, close monitoring of the index
alter index <INDEX_NAME> nomonitoring usage;
c, observation monitoring results (Query v $ object_usage view)
select * from v$object_usage
3, schema level index monitor (without user SYS)
a, direct execution of the script to open the index monitoring
robin@SZDB:~/dba_scripts/custom/sql> more idx_monitor_on.sql
SET HEADING OFF FEEDBACK OFF TERMOUT OFF ECHO OFF;
SET PAGESIZE 0;
SPOOL /tmp/mnt_idx.sql
SELECT 'ALTER INDEX ' || owner || '.' || index_name || ' MONITORING USAGE;' FROM dba_indexes
WHERE owner IN (SELECT username FROM dba_users WHERE account_status = 'OPEN')
AND owner NOT IN ('SYS', 'SYSTEM', 'PERFSTAT', 'MGMT_VIEW', 'MONITOR', 'SYSMAN', 'DBSNMP');
SPOOL OFF;
b, disabled index monitoring
robin@SZDB:~/dba_scripts/custom/sql> more idx_monitor_off.sql
SET HEADING OFF FEEDBACK OFF TERMOUT OFF ECHO OFF;
SET PAGESIZE 0;
SPOOL /tmp/un_mnt_idx.sql
SELECT 'ALTER INDEX ' || owner || '.' || index_name || ' NOMONITORING USAGE;' FROM dba_indexes
WHERE owner IN (SELECT username FROM dba_users WHERE account_status = 'OPEN')
AND owner NOT IN ('SYS', 'SYSTEM', 'PERFSTAT', 'MGMT_VIEW', 'MONITOR', 'SYSMAN', 'DBSNMP');
SPOOL OFF;
c, see the index monitoring results
set linesize 190
SELECT u.name owner,
io.name index_name,
t.name table_name,
DECODE (BITAND (i.flags, 65536), 0, 'NO', 'YES') monitoring,
DECODE (BITAND (ou.flags, 1), 0, 'NO', 'YES') used,
ou.start_monitoring start_monitoring,
ou.end_monitoring end_monitoring
FROM sys.user$ u, sys.obj$ io, sys.obj$ t, sys.ind$ i, sys.object_usage ou
WHERE i.obj# = ou.obj# AND io.obj# = ou.obj# AND t.obj# = i.bo#
AND u.user# = io.owner#
AND u.name=decode(upper('&input_owner'),'ALL',u.name,upper('&input_owner'));