MSSQL SQL SERVER 인덱스 성능 개선

인덱스의 조각이 많이 난 인덱스와 테이블명을 조회한다.

SELECT -- TOP 10 -- 상위 10개만

            DB_NAME() AS DatabaseName

          , OBJECT_NAME(S.OBJECT_ID) AS TableName

          , I.NAME AS IndexName

          , ROUND(AVG_FRAGMENTATION_IN_PERCENT, 2) AS Fragmentation

 FROM SYS.DM_DB_INDEX_PHYSICAL_STATS(DB_ID(),NULL,NULL,NULL,NULL) AS S

 INNER JOIN SYS.INDEXES AS I

 ON S.OBJECT_ID = I.OBJECT_ID AND S.INDEX_ID = I.INDEX_ID

 WHERE S.DATABASE_ID = DB_ID('DB_NAME') -- 현재 데이터베이스

 AND I.NAME IS NOT NULL -- HEAP은 무시

 AND OBJECTPROPERTY(S.OBJECT_ID, 'IsMsShipped') = 0 -- 시스템 개체 무시

 ORDER BY Fragmentation DESC

 

Fragmentation (AVG_FRAGMENTATION_IN_PERCENT) 가 클수록 조각이 많이 나있는 상태

또는

DBCC SHOWCONTIG(테이블명)

이런경우 인덱스를 다시 구성하거나 REBUID 해서 조각난것을 다시 모을수있다.

DBCC DBREINDEX (테이블명, 인덱스명) -- 인덱스명을 생략하면 테이블의 모든인덱스를 수행

DBCC INDEXDEFRAG (데이터베이스명, 테이블명, 인덱스명) -- DB에 LOCK이 걸리지않는다

ALTER INDEX ALL ON 테이블명 REBUILD WITH (ONLINE = ON)

또는

데이터베이스에서 선언된 임계값 이상으로 조각화된 모든 인덱스에 조각 모음을 수행

/*Perform a 'USE <database name>' to select the database in which to run the script.*/
-- Declare variables
SET NOCOUNT ON;
DECLARE @tablename VARCHAR(255);
DECLARE @execstr   VARCHAR(400);
DECLARE @objectid  INT;
DECLARE @indexid   INT;
DECLARE @frag      DECIMAL;
DECLARE @maxfrag   DECIMAL;
  
-- Decide on the maximum fragmentation to allow for.
SELECT @maxfrag = 30.0;
  
-- Declare a cursor.
DECLARE tables CURSOR FOR
   SELECT TABLE_SCHEMA + '.' + TABLE_NAME
   FROM INFORMATION_SCHEMA.TABLES
   WHERE TABLE_TYPE = 'BASE TABLE';
  
-- Create the table.
CREATE TABLE #fraglist (
   ObjectName CHAR(255),
   ObjectId INT,
   IndexName CHAR(255),
   IndexId INT,
   Lvl INT,
   CountPages INT,
   CountRows INT,
   MinRecSize INT,
   MaxRecSize INT,
   AvgRecSize INT,
   ForRecCount INT,
   Extents INT,
   ExtentSwitches INT,
   AvgFreeBytes INT,
   AvgPageDensity INT,
   ScanDensity DECIMAL,
   BestCount INT,
   ActualCount INT,
   LogicalFrag DECIMAL,
   ExtentFrag DECIMAL);
  
-- Open the cursor.
OPEN tables;
  
-- Loop through all the tables in the database.
FETCH NEXT
   FROM tables
   INTO @tablename;
  
WHILE @@FETCH_STATUS = 0
BEGIN
-- Do the showcontig of all indexes of the table
   INSERT INTO #fraglist
   EXEC ('DBCC SHOWCONTIG (''' + @tablename + ''')
      WITH FAST, TABLERESULTS, ALL_INDEXES, NO_INFOMSGS');
   FETCH NEXT
      FROM tables
      INTO @tablename;
END;
  
-- Close and deallocate the cursor.
CLOSE tables;
DEALLOCATE tables;
  
-- Declare the cursor for the list of indexes to be defragged.
DECLARE indexes CURSOR FOR
   SELECT ObjectName, ObjectId, IndexId, LogicalFrag
   FROM #fraglist
   WHERE LogicalFrag >= @maxfrag
      AND INDEXPROPERTY (ObjectId, IndexName, 'IndexDepth') > 0;
  
-- Open the cursor.
OPEN indexes;
  
-- Loop through the indexes.
FETCH NEXT
   FROM indexes
   INTO @tablename, @objectid, @indexid, @frag;
  
WHILE @@FETCH_STATUS = 0
BEGIN
   PRINT 'Executing DBCC INDEXDEFRAG (0, ' + RTRIM(@tablename) + ',
      ' + RTRIM(@indexid) + ') - fragmentation currently '
       + RTRIM(CONVERT(varchar(15),@frag)) + '%';
   SELECT @execstr = 'DBCC INDEXDEFRAG (0, ' + RTRIM(@objectid) + ',
       ' + RTRIM(@indexid) + ')';
   EXEC (@execstr);
  
   FETCH NEXT
      FROM indexes
      INTO @tablename, @objectid, @indexid, @frag;
END;
  
-- Close and deallocate the cursor.
CLOSE indexes;
DEALLOCATE indexes;
  
-- Delete the temporary table.
DROP TABLE #fraglist;
GO

 

 

 

참조 : https://rohsstory.tistory.com/497 

참조 : https://learn.microsoft.com/ko-kr/sql/t-sql/database-console-commands/dbcc-indexdefrag-transact-sql?view=sql-server-ver16