mysql执行计划实战分析(3)--模糊查询索引利用问题

目标

ddl

CREATE TABLE
    tbl_merchant
    (
        ID bigint NOT NULL AUTO_INCREMENT,
        CREATE_TIME DATETIME DEFAULT CURRENT_TIMESTAMP,
        LAST_UPDATE_TIME DATETIME DEFAULT CURRENT_TIMESTAMP,
        MERCHANT_NO VARCHAR(128) NOT NULL,
        MERCHANT_NAME VARCHAR(64) NOT NULL,
        CONTACT_NAME VARCHAR(64),
        CONTACT_PHONE VARCHAR(128),
        PLATFORM_KEY VARCHAR(2048),
        STATUS VARCHAR(32) NOT NULL,
        SHORT_NAME VARCHAR(128),
        MERCHANT_MODEL VARCHAR(128),
        CHECK_GROUP VARCHAR(32),
        PRIMARY KEY (ID),
        CONSTRAINT merchant_no_index UNIQUE (MERCHANT_NO),
        INDEX TBL_MERCHAN_CREATE_TIME_INDEX (CREATE_TIME),
        INDEX TBL_MERCHAN_LAST_UPDATE_TIME_INDEX (LAST_UPDATE_TIME)
    )
    ENGINE=InnoDB DEFAULT CHARSET=utf8;

分析举例

针对merchant_no进行sql

explain SELECT * FROM tbl_merchant where merchant_no like '512312312321132%';

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explain SELECT * FROM tbl_merchant where merchant_no like '%512312312321132';

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所以,模糊查询一样遵循左前缀原则,必须保证值左侧固定索引才生效