Question

I have a table defined as such:

CREATE TABLE `_debug_log` (
  ...
) ENGINE=MyISAM AUTO_INCREMENT=896692 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci MAX_ROWS=100000 ROW_FORMAT=COMPRESSED;

I’d like to drop the MAX_ROWS option as it isn’t necessary for this table, but I do need to keep the existing data. Is there a way to unset this table option via an ALTER statement, or will I need to export the data, rebuild the table and then import the data back in? I checked the MySQL docs on MAX_ROWS, but it only says it requires a positive integer value and doesn’t say what the default value is or what a value of 0 might do.

Answer 1

For what it is worth:

CREATE TABLE `_debug_log` (
id int unsigned primary key auto_increment
) ENGINE=MyISAM AUTO_INCREMENT=896692 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci MAX_ROWS=100000 ROW_FORMAT=COMPRESSED;

SHOW CREATE TABLE _debug_log;

gives:

CREATE TABLE `_debug_log` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=896692 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci MAX_ROWS=100000 ROW_FORMAT=COMPRESSED

then:

alter table _debug_log max_rows = 0;

SHOW CREATE TABLE _debug_log;

gives:

CREATE TABLE `_debug_log` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=896692 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=COMPRESSED

I tried inserting some data before running the ALTER and after running the ALTER and it did not seem to be affected.

Furthermore, if you create the same table with the same options but exclude the MAX_ROWS option, insert the same data and then take a look at the resulting data in information_schema.tables the data is pretty much identical (obvious differences aside):