[TOC]
索引管理
按特定數(shù)據(jù)結(jié)構(gòu)存儲(chǔ)的數(shù)據(jù)
索引類型
- 聚集索引骗炉、非聚集索引: 數(shù)據(jù)是否與索引存儲(chǔ)在一起
- 主鍵索引菩暗、輔助索引
- 稠密索引肴敛、稀疏索引: 是否索引了每一項(xiàng)數(shù)據(jù)
- B+ TREE璃哟、HASH缰猴、R TREE
- 簡(jiǎn)單索引产艾、組合索引
- 左前綴索引
- 覆蓋索引
創(chuàng)建索引
alter table table_test add index index_test1(name) ;
create index index_test2 on table_test(age);
刪除索引
drop index name on table_test ;
查看索引
SHOW {INDEX | INDEXES | KEYS}
{FROM | IN} tbl_name
[{FROM | IN} db_name]
[WHERE expr]
示例:
SHOW INDEX FROM mytable FROM mydb;
SHOW INDEX FROM mydb.mytable;
分析查詢語(yǔ)句執(zhí)行過程(explain)
···sql
EXPLAIN SHOW INDEX FROM mytable FROM mydb;