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This article is to share with you about the use of hash join in MYSQL. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

In MYSQL's multi-table federated query, it is only nest loop's query method that makes MYSQL consistent is "ridiculed". Mysql will have HASH JOIN functionality after MYSQL 8.018, which is not new compared to other databases, but it is an epoch-making milestone for MYSQL.

Don't talk about the principle and so on, let's see the effect first. Set up two stored procedures to insert test data for C1 and C2 tables

Delimiter / /

CREATE PROCEDURE insert_c1 ()

BEGIN

DECLARE i int

DECLARE a varchar (20)

DECLARE b smallint

Set I = 1

Begin

WHILE i

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