復(fù)制代碼 代碼如下:
SELECT
height, /*Height of the B-Tree*/
blocks, /* Blocks in the index segment */
name, /*index name */
lf_rows, /* number of leaf rows in the index */
lf_blks, /* number of leaf blocks in the index */
del_lf_rows, /* number of deleted leaf rows in the index */
rows_per_key /* average number of rows per distinct key */
blk_gets_per_access /* consistent mode block reads (gets) */
FROM INDEX_STATS
WHERE NAME='INDEX_NAME';
復(fù)制代碼 代碼如下:
ANALYZE index INDEX_NAME VALIDATE STRUCTURE
HEIGHT:
This column refers to the height of the B-tree index, and it's usually at the 1, 2, or 3 level.
If large inserts push the index height beyond a level of 4, it's time to rebuild, which flattens the B-tree.
DEL_LF_ROWS:
This is the number of leaf nodes deleted due to the deletion of rows.
Oracle doesn't rebuild indexes automatically and, consequently, too many deleted leaf rows can lead to an unbalanced B-tree.
BLK_GETS_PER_ACCESS:
You can look at the BLK_GETS_PER_ACCESS column to see how much logical I/O it takes to retrieve data from the index. If this row shows a double-digit number, you should probably start rebuilding the index.
您可能感興趣的文章:- MSSQL 大量數(shù)據(jù)時(shí),建立索引或添加字段后保存更改提示超時(shí)的解決方法
- mssql 建立索引
- SQLSERVER全文目錄全文索引的使用方法和區(qū)別講解
- SQL_Server全文索引的使用實(shí)例演示
- mysql 添加索引 mysql 如何創(chuàng)建索引
- sqlserver 索引的一些總結(jié)
- SQL Server 索引介紹
- sqlserver索引的原理及索引建立的注意事項(xiàng)小結(jié)
- 用SQL建立索引的方法步驟
- MSSQL自動(dòng)重建出現(xiàn)碎片的索引的方法分享
