How to compress columns in MySQL?

Question

I have a table which stores e-mail correspondences. Every time someone replies, the whole body of the trail is also included and saved into the database (and I need it that way because the amount of application level changes to rectify that are going to be too high).

The size of the mail text column is 10000. But, I am having trouble storing text more than that. As I am not sure, how many correspondences can occur, I don't know what a good number will be for the column.

The engine is InnoDB. Can I use some kind of columnar compression technique in MySQL to avoid increasing the size of the column?

And, what if I go ahead and increase the varchar column to, say, 20000. The table has about 2 million records. Will that be a good thing to do?

Answer 1

You are probably looking for MySQL COMPRESS() and UNCOMPRESS() function to compress data for storage and retrieval respectively.

Also look at InnoDB Compression Usage.

Answer 2

This answer is specific to Percona

Percona introduced a compressed column format a while ago. That you can use on CREATE or ALTERs

CREATE TABLE test_compressed (
    id INT NOT NULL PRIMARY KEY,
    value MEDIUMTEXT COLUMN_FORMAT COMPRESSED
 );

Reference: https://www.percona.com/doc/percona-server/5.7/flexibility/compressed_columns.html