Oracle 数据库：查找丢失的索引以进行性能调整

Question

我们目前正在进行数据库性能调优。 Oracle数据库有DMV Select查询来直接查找丢失的索引吗？

Microsoft SqlServer 有以下内容：https://blog.sqlauthority.com/2011/01/03/sql-server-2008-missing-index-script-download/

-- Missing Index Script
-- Original Author: Pinal Dave 
SELECT TOP 25
dm_mid.database_id AS DatabaseID,
dm_migs.avg_user_impact*(dm_migs.user_seeks+dm_migs.user_scans) Avg_Estimated_Impact,
dm_migs.last_user_seek AS Last_User_Seek,
OBJECT_NAME(dm_mid.OBJECT_ID,dm_mid.database_id) AS [TableName],
'CREATE INDEX [IX_' + OBJECT_NAME(dm_mid.OBJECT_ID,dm_mid.database_id) + '_'
+ REPLACE(REPLACE(REPLACE(ISNULL(dm_mid.equality_columns,''),', ','_'),'[',''),']','') 
+ CASE
WHEN dm_mid.equality_columns IS NOT NULL
AND dm_mid.inequality_columns IS NOT NULL THEN '_'
ELSE ''
END
+ REPLACE(REPLACE(REPLACE(ISNULL(dm_mid.inequality_columns,''),', ','_'),'[',''),']','')
+ ']'
+ ' ON ' + dm_mid.statement
+ ' (' + ISNULL (dm_mid.equality_columns,'')
+ CASE WHEN dm_mid.equality_columns IS NOT NULL AND dm_mid.inequality_columns 
IS NOT NULL THEN ',' ELSE
'' END
+ ISNULL (dm_mid.inequality_columns, '')
+ ')'
+ ISNULL (' INCLUDE (' + dm_mid.included_columns + ')', '') AS Create_Statement
FROM sys.dm_db_missing_index_groups dm_mig
INNER JOIN sys.dm_db_missing_index_group_stats dm_migs
ON dm_migs.group_handle = dm_mig.index_group_handle
INNER JOIN sys.dm_db_missing_index_details dm_mid
ON dm_mig.index_handle = dm_mid.index_handle
WHERE dm_mid.database_ID = DB_ID()
ORDER BY Avg_Estimated_Impact DESC
GO

Answer 1

这是一个很好的资源：https://www.dba-scripts.com/scripts/diagnostic-and-tuning/troubleshooting/find-missing-index/

如果大家有更多答案，欢迎留言

ACCEPT SCHEMA_NAME PROMPT 'Choose the schema to analyze:'

select * from (
  select 'the column ' || c.name || ' of the table ' || us.name || '.' || o.name || ' was used ' || u.equality_preds || ' times in an equality predicate and ' || u.equijoin_preds || ' times in an equijoin predicate and is not indexed' as colum_to_index
  from sys.col_usage$ u,
       sys.obj$ o,
       sys.col$ c,
       sys.user$ us
  where u.obj# = o.obj#
  and   u.obj# = c.obj#
  and   us.user# = o.owner#
  and   u.intcol# = c.col#
  and   us.name='&SCHEMA_NAME'
  and   c.name not in (select column_name from dba_ind_columns where index_owner ='&SCHEMA_NAME')
  and   (u.equality_preds > 100 OR u.equijoin_preds > 100)
  order by u.equality_preds+u.equijoin_preds desc)
WHERE rownum <11;

Answer 2

SET PAGESIZE 5000
SET LINESIZE 350
COLUMN INDEX_STATUS        FORMAT A10
COLUMN TABLE_NAME          FORMAT A30
COLUMN FOREIGNKEY_NAME     FORMAT A30
COLUMN FOREIGNKEY_COLUMNS  FORMAT A30
COLUMN INDEX_NAME          FORMAT A30
COLUMN INDEX_COLUMNS       FORMAT A30
SELECT
CASE
   WHEN B.TABLE_NAME IS NULL THEN
      'UNINDEXED'
   ELSE
      'INDEXED'
END AS INDEX_STATUS,
   A.TABLE_NAME      AS TABLE_NAME,
   A.CONSTRAINT_NAME AS FOREIGNKEY_NAME,
  A.FK_COLUMNS      AS FOREIGNKey_COLUMNS,
  B.INDEX_NAME      AS INDEX_NAME,
  B.INDEX_COLUMNS   AS INDEX_COLUMNS
FROM
(
   SELECT 
    A.TABLE_NAME,
   A.CONSTRAINT_NAME,
   LISTAGG(A.COLUMN_NAME, ',') WITHIN GROUP (ORDER BY A.POSITION) FK_COLUMNS
FROM ALL_CONS_COLUMNS A,   ALL_CONSTRAINTS B
WHERE   A.CONSTRAINT_NAME = B.CONSTRAINT_NAME
AND    B.CONSTRAINT_TYPE = 'R'
AND    A.OWNER =  '&&SCHEMA_NAME'
AND    A.OWNER = B.OWNER
GROUP BY 
   A.TABLE_NAME,    A.CONSTRAINT_NAME
) A
,(
SELECT 
   TABLE_NAME,
   INDEX_NAME,
   LISTAGG(C.COLUMN_NAME, ',') WITHIN GROUP (ORDER BY C.COLUMN_POSITION) INDEX_COLUMNS
FROM   ALL_IND_COLUMNS C
WHERE   C.INDEX_OWNER = '&&SCHEMA_NAME'
GROUP BY   TABLE_NAME,    INDEX_NAME
) B
WHERE   A.TABLE_NAME = B.TABLE_NAME(+)
AND    B.INDEX_COLUMNS(+) LIKE A.FK_COLUMNS || '%'
ORDER BY    1 DESC, 2;