全表扫描 all: 走数据表:explain select * from ruozedata.testsalt; 走数据表:explain select /*+ INDEX(ruozedata.testsalt testsalt_idx) */ * from ruozedata.testsalt;【使用hint强制】
explain select date from my_schema.my_table where sex='2'; 范围扫描 走索引表:RANGE SCAN OVER MY_SCHEMA:MY_INDEX2 ['2'] 【如果建表默认一个region不加盐】 走索引表:RANGE SCAN OVER MY_SCHEMA:MY_INDEX2 [0,'2'] - [19,'2'] 【如果建表设定20个region】
explain select sex from my_schema.my_table where date='2020-05-31'; 走索引表:FULL SCAN OVER MY_SCHEMA.MY_INDEX 【如果建表默认一个region不加盐】全扫描 走索引表:RANGE SCAN OVER MY_SCHEMA:MY_INDEX [0] - [19] 【如果建表设定20个region】
alter table my_schema.my_table add col4 varchar(10);
upsert into my_schema.my_table(id, date,sex,col4) values (1,'2020-03-31','1','5');
走数据表:explain select sex from my_schema.my_table where col4='5'; 走数据表:explain select date,col4 from my_schema.my_table where sex='5'; 先走索引表查出rowkey再走数据表:explain select /*+ INDEX(my_schema.my_table my_index) */ date,col4 from my_schema.my_table where sex='5';
创建索引 CREATE LOCAL INDEX my_index ON my_schema.my_table(sex,date);
删除索引 DROP INDEX my_index ON my_schema.my_table;
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全表扫描 all: explain select * from my_schema.my_table; explain select /*+ INDEX(my_schema.my_table my_index) */ * from ruozedata.testsalt;
走index,RANGE SCAN explain select date from my_schema.my_table where sex=1; 走index,RANGE SCAN explain select date,col4 from my_schema.my_table where sex=1;
走index,RANGE SCAN explain select col4 from my_schema.my_table where sex=1;
强制,走index explain select /*+ INDEX(my_schema.my_table my_index) */ col4 from my_schema.my_table where sex=1;