表的索引可以给数据检索提升效率，但是也给表的增删改操作带来代价。本文我们将关注，索引数量对INSERT操作的影响。
结论
索引数的新增会造成INSERT操作效率下降，约每增一个索引会降低10%效率。
实验数据
可以看到0个索引的效率是7个索引效率的一倍。
测试环境
见《Mysql使用中的性能优化——搭建Mysql的监测服务》
测试代码
DROP DATABASE IF EXISTS testdb;
CREATE DATABASE IF NOT EXISTS testdb;
USE testdb;DROP TABLE IF EXISTS test_insert_src;
CREATE TABLE test_insert_src (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_0_index;
CREATE TABLE test_insert_0_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_1_index;
CREATE TABLE test_insert_1_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_2_index;
CREATE TABLE test_insert_2_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_3_index;
CREATE TABLE test_insert_3_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_4_index;
CREATE TABLE test_insert_4_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_5_index;
CREATE TABLE test_insert_5_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_6_index;
CREATE TABLE test_insert_6_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32)),INDEX name5_index (name5(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_7_index;
CREATE TABLE test_insert_7_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32)),INDEX name5_index (name5(32)),INDEX name6_index (name6(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_8_index;
CREATE TABLE test_insert_8_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32)),INDEX name5_index (name5(32)),INDEX name6_index (name6(32)),INDEX name7_index (name7(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_9_index;
CREATE TABLE test_insert_9_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32)),INDEX name5_index (name5(32)),INDEX name6_index (name6(32)),INDEX name7_index (name7(32)),INDEX name8_index (name8(32))
) engine=InnoDB;DROP TABLE IF EXISTS test_insert_10_index;
CREATE TABLE test_insert_10_index (id SERIAL PRIMARY KEY,name TEXT,name1 TEXT,name2 TEXT,name3 TEXT,name4 TEXT,name5 TEXT,name6 TEXT,name7 TEXT,name8 TEXT,name9 TEXT,INDEX name_index (name(32)),INDEX name1_index (name1(32)),INDEX name2_index (name2(32)),INDEX name3_index (name3(32)),INDEX name4_index (name4(32)),INDEX name5_index (name5(32)),INDEX name6_index (name6(32)),INDEX name7_index (name7(32)),INDEX name8_index (name8(32)),INDEX name9_index (name9(32))
) engine=InnoDB;DROP PROCEDURE IF EXISTS test_insert_proc_batch_bulk;
DELIMITER //
CREATE PROCEDURE test_insert_proc_batch_bulk(IN name TEXT, IN fromNum INT, IN toNum INT)
BEGINDECLARE i INT DEFAULT fromNum;DECLARE j INT DEFAULT 0;DECLARE new_names TEXT DEFAULT '';DECLARE nameList TEXT DEFAULT '';SET @sql = 'INSERT INTO test_insert_src (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) VALUES ';WHILE i < toNum DOSET nameList = '';SET j = 0;while j < 10 DOSET new_names = CONCAT(name, i, "_", j);IF j = 0 THENSET nameList = CONCAT(nameList, '"', new_names, '"');ELSESET nameList = CONCAT(nameList, ',"', new_names, '"');END IF;SET j = j + 1;END WHILE;SET i = i + 1;SET @sql = CONCAT(@sql, '(', nameList, '),');END WHILE;SET @sql = LEFT(@sql, LENGTH(@sql) - 1);PREPARE stmt FROM @sql;EXECUTE stmt;DEALLOCATE PREPARE stmt;COMMIT;
END //
DELIMITER ;DROP PROCEDURE IF EXISTS test_insert_proc_batch;
DELIMITER //
CREATE PROCEDURE test_insert_proc_batch(IN name TEXT, IN count INT, IN step INT)
BEGINDECLARE i INT DEFAULT 0;WHILE i < count DOCALL test_insert_proc_batch_bulk(name, i, i + step);SET i = i + step;END WHILE;COMMIT;
END //
DELIMITER ;TRUNCATE TABLE test_insert_src;
CALL test_insert_proc_batch('test', 1000000, 5000);TRUNCATE TABLE test_insert_0_index;
INSERT INTO test_insert_0_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src; TRUNCATE TABLE test_insert_1_index;
INSERT INTO test_insert_1_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_2_index;
INSERT INTO test_insert_2_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_3_index;
INSERT INTO test_insert_3_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_4_index;
INSERT INTO test_insert_4_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_5_index;
INSERT INTO test_insert_5_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_6_index;
INSERT INTO test_insert_6_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_7_index;
INSERT INTO test_insert_7_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_8_index;
INSERT INTO test_insert_8_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_9_index;
INSERT INTO test_insert_9_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;TRUNCATE TABLE test_insert_10_index;
INSERT INTO test_insert_10_index (name, name1, name2, name3, name4, name5, name6, name7, name8, name9) SELECT name, name1, name2, name3, name4, name5, name6, name7, name8, name9 FROM test_insert_src;
