導讀:1建站知識經常需要在Oracle中檢查是否需要重構索引，在此寫了個示例語句，有此需求的朋友可以參考下，希望對大家有所幫助如何seo優化推廣網站seo網站優化培訓。

復制代碼 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 ro網站建設哪家好ws 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;

復制代碼 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 網站建設多少錢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 h建設網站ow 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.相關如何seo優化推廣網站seo網站優化培訓。

關鍵詞標簽: 索引 重構