Posted By: Anonymous
I am using MySQL in localhost as a “query tool” for performing statistics in R, that is, everytime I run a R script, I create a new database (A), create a new table (B), import the data into B, submit a query to get what I need, and then I drop B and drop A.
It’s working fine for me, but I realize that the ibdata file size is increasing rapidly, I stored nothing in MySQL, but the ibdata1 file already exceeded 100 MB.
I am using more or less default MySQL setting for the setup, is there a way for I can automatically shrink/purge the ibdata1 file after a fixed period of time?
ibdata1 isn’t shrinking is a particularly annoying feature of MySQL. The
ibdata1 file can’t actually be shrunk unless you delete all databases, remove the files and reload a dump.
But you can configure MySQL so that each table, including its indexes, is stored as a separate file. In that way
ibdata1 will not grow as large. According to Bill Karwin’s comment this is enabled by default as of version 5.6.6 of MySQL.
It was a while ago I did this. However, to setup your server to use separate files for each table you need to change
my.cnf in order to enable this:
As you want to reclaim the space from
ibdata1 you actually have to delete the file:
- Do a
mysqldumpof all databases, procedures, triggers etc except the
- Drop all databases except the above 2 databases
- Stop mysql
- Start mysql
- Restore from dump
When you start MySQL in step 5 the
ib_log files will be recreated.
Now you’re fit to go. When you create a new database for analysis, the tables will be located in separate
ibd* files, not in
ibdata1. As you usually drop the database soon after, the
ibd* files will be deleted.
You have probably seen this:
By using the command
ALTER TABLE <tablename> ENGINE=innodb or
OPTIMIZE TABLE <tablename> one can extract data and index pages from ibdata1 to separate files. However, ibdata1 will not shrink unless you do the steps above.
information_schema, that is not necessary nor possible to drop. It is in fact just a bunch of read-only views, not tables. And there are no files associated with the them, not even a database directory. The
informations_schema is using the memory db-engine and is dropped and regenerated upon stop/restart of mysqld. See https://dev.mysql.com/doc/refman/5.7/en/information-schema.html.