Simple database migration method from MySQL to Redis

Moving a large table from mysql to redis, you will find that extracting, converting, or loading 1 row of data is unbearably slow. Here's a tip to get you out of trouble. The content generated by the mysql command line is passed directly to redis-cli in a "piped out" manner, bypassing the "middleware" so that both can achieve optimal speed when performing data operations.

An mysql table with about 8 million rows of data, which would have taken 90 minutes to import into redis, takes only two minutes with this method. Believe it or not, I do.

Mysql to Redis data protocols

The redis-cli command line tool has a batch insert mode, designed specifically for batch command execution. The first step is to format the content of the Mysql query into the data format available to redis-cli. here we go!

My statistics:

CREATE TABLE events_all_time (
 id int(11) unsigned NOT NULL AUTO_INCREMENT,
 action varchar(255) NOT NULL,
 count int(11) NOT NULL DEFAULT 0,
 PRIMARY KEY (id),
 UNIQUE KEY uniq_action (action)
);

The redis command to be executed in each line of data is as follows:

HSET events_all_time [action] [count]
Create an events_to_redis.sql file in accordance with the above redis command rules. The content of SQL is used to generate the redis data protocol format:

-- events_to_redis.sql

SELECT CONCAT(
 "*4\r\n",
 '$', LENGTH(redis_cmd), '\r\n',
 redis_cmd, '\r\n',
 '$', LENGTH(redis_key), '\r\n',
 redis_key, '\r\n',
 '$', LENGTH(hkey), '\r\n',
 hkey, '\r\n',
 '$', LENGTH(hval), '\r\n',
 hval, '\r'
)
FROM (
 SELECT
 'HSET' as redis_cmd,
 'events_all_time' AS redis_key,
 action AS hkey,
 count AS hval
 FROM events_all_time
) AS t

ok, execute with the following command:

mysql stats_db --skip-column-names --raw < events_to_redis.sql | redis-cli --pipe

Important mysql parameter description:

--raw: causes mysql not to convert newlines in field values. -- skip-column-names: causes each row of mysql output to contain no column names.