I use very big innodb tables.
When I delete a data size does not shrink from the table.
What should I do for the reduction of crush syndrome delete data?
OPTIMIZE TABLE won't shrink the disk size of the table unless you haveinnodb_file_per_table=ON;
If you did not already have it ON, turning it on will only increase disk usage. This is because you will be moving that table out of ibdata1 without doing anything to shrink ibdata1.
The only way to shrink ibdata1 is to dump all tables, remove ibdata1, then reload all tables. (Yuck!)
Use OPTIMIZE TABLE yourtablenameHERE; in this case:
After doing substantial insert, update, or delete operations on an InnoDB table that has its own .ibd file because it was created with the innodb_file_per_table option enabled. The table and indexes are reorganized, and disk space can be reclaimed for use by the operating system.
In the future when in doubt just google it.
Related
I have an innodb table with big table size (around 7GB),
I already delete about 80% of its rows,
The problem is the table size remains the same,
The innodb_file_per_table is ON,
How do I shrink the table size so it reflect the actual condition and save more disk space ?
It depends...
If you built the table with innodb_file_per_table=ON, then you can do OPTIMIZE TABLE now. (Be sure it is still ON.)
If =OFF, then the table is in the tablespace file ibdata1 and the only way to return the space to the OS is by dumping all tables, removing ibdata1, then reloading the dump. This is tedious and risky. Meanwhile, the free space created by the DELETEs will be used by future INSERTs, etc.
More discussion of big deletes.
I got the free space (fragmentation issues) in my information_Schema database.
Alert shows that there are 1500% free space in some tables like COLUMNS , ROUTINES.
I am worried how this is possible because i don't have any routines in my database and how i can optimize the information_schema because its memory based database and created on the starting of mysql service.
Also when i query "SHOW CREATE TABLE" on any of the information_schema table it gives me innodb as engine of these table, but i think it should be memory.
Any idea to optimize these tables without restart?
Thanks
When you have innodb_file_per_table = OFF, InnoDB tables are created in the system 'tablespace', ibdata1. It could be that you have created and manipulated a lot of tables there.
Data_free is a confusing term in SHOW CREATE TABLE and certain tables in information_schema...
For MyISAM tables, it is an accurate amount of the space that could be recovered from the .MYD file (but not the .MYI file).
For InnoDB it means one of 2 things...
If the table you are looking at was created with innodb_file_per_table = ON, then Data_free is some of the unused space. Often, not all of it can be recovered by any means.
If the table you are looking at was created with innodb_file_per_table = OFF, then Data_free is the free space in ibdata1. That free space will be used for new inserts and new tables, thereby decreasing Data_free. However, the size of ibdata1 cannot be shrunk, at least not without a lot of effort (dump everything, remove, reload).
I need your advice. Need to reclaim disk space on live server with minimum downtime. We are using:
mysql -- 5.5
innodb table per file -- on
Was a huge table(70% insers/30% deletes -- it means that sometimes we delete rows from this table), this table was dropped with "drop table" command, as we expect, mysql didn't release disk space to OS, but now we need to release free space. OPTIMIZE command is possible way -- but now we don't 100% sure if we will have enough free space on disk to do this command, because previous table was huge. But in mysql documentation written:
You can run OPTIMIZE TABLE to compact or recreate a file-per-table tablespace. When you run an OPTIMIZE TABLE, InnoDB creates a new .ibd file with a temporary name, using only the space required to store actual data. When the optimization is complete, InnoDB removes the old .ibd file and replaces it with the new one.
I highlighted confusing moment in documentation, does it means, that "OPTIMIZE dropped_table;" will use only space for data that really needed, for this situation there is no actual data if we drop table early ?
If the table was created when innodb_file_per_table was OFF, then the table was written to ibdata1, and the space is not returned to the OS by DROP TABLE.
If it had been ON, then there would be a .ibd file. Did you see that file before the DROP? Does it still exist? (It should not still exist.)
When DROP removes the .ibd file, there is a slight lag (depending on the OS) while waiting for the data to be actually freed up by the OS. du and/or df reflects this lag.
OPTIMIZE TABLE will copy the table to tmpdir (I think), then drop the old table and play RENAME games. This requires extra space -- enough for a compete copy of the table. Assuming you really have a .ibd file, it will create another .ibd file (with a temp name) and shuffle files. If tmpdir points to a different "filesystem", the shuffle will involve a copy, not just a move.
If I have not explained things adequately, please provide more details -- actual commands you are proposing, size of table in question, whether the .ibd exists, etc.
I have some large InnoDB databases, close to 1TB.
In order to free up some space while working on an alternative storage, I deleted some unused InnoDB indexes hoping that it would free up some space.
It freed nothing.
As it's InnoDB, will the engine use the empty allocated space for further inserts and indexing?
InnoDB stores data in a tablespace. By default, there is one single tablespace and data of all the databases is stored in one file. This file has data dictionary, tables, as well as indexes in it. There is a global parameter innodb_data_file_path that defines this tablespace file. It has a syntax like ibdata1:256M:autoextend, this means at the beginning a file of size 256 MB will be created and then whenever the data size exceeds this, the file will be auto-extended. The innodb_autoextend_increment variable defines in MB's that by how much each increment should be.
How you will get your Index Space?
You should first backup all InnoDB tables and change setting in my.ini/my.cnf as innodb_file_per_table and restart MySQL server.
Now import those tables now each table will have it's own tablespace which can shrink size on deleting a table.
These are possible workarounds:
Separate Files per Table: InnoDB provides this option where data (data + indexes) for each table can be stored in a separate file through a global variable innodb_file_per_table.
Fixed Tablespace size: One way to work around with the tablespace file size problems is to fix the tablespace size (remove autoextend) to an extrapolated value. So, when you hit the limit, you know it is time to cleanup.
Move to MyISAM: For all the tables (or even databases), for which you feel data is not that critical to have transactions et al, move them to MyISAM.
Answer here: https://stackoverflow.com/a/8932289/82114
If you don't use innodb_file_per_table, reclaiming disk space is possible, but quite tedious, and requires a significant amount of downtime.
The "How To" can be found here: http://dev.mysql.com/doc/refman/5.6/en/innodb-data-log-reconfiguration.html
Be sure to also retain a copy of your schema in your dump.
Currently, you cannot remove a data file from the system tablespace.
To decrease the system tablespace size, use this procedure:
Use mysqldump to dump all your InnoDB tables.
Stop the server.
Remove all the existing tablespace files, including the ibdata and
ib_log files. If you want to keep a backup copy of the information,
then copy all the ib* files to another location before the removing
the files in your MySQL installation.
Remove any .frm files for InnoDB tables.
Configure a new tablespace.
Restart the server.
Import the dump files.
You should reorganize the InnoDB infrastructure. Why? Because ibdata1 never shrinks. With innodb_file_per_table disabled, it will bloat ibdata1 in a hurry? Aside from data and indexes, what lives in ibdata1?
Data dictionary
Double write buffer (handles Background Page Writes)
Insert Buffer (andles Changes to Secondary Indexes)
Rollback Segments
Undo Tablespace
That being said, you need to migrate your data out, delete all InnoDB relayed files, and reload with two things:
innodb_file_per_table enabled
bigger transaction logs
I wrote up how to do this back on Oct 29, 2010 : Howto: Clean a mysql InnoDB storage engine?
Going forward you could alwsy shrink individual InnoDB tables. For example, to shrink mydb.mytable:
ALTER TABLE mydb.mytable ENGINE=InnoDB;
My ibdata1 file for MySQL database grew to about 32GB over time. Recently I deleted about 10GB of data from my databases (and restarted mysql for good measure), but the file won't shrink. Is there any way to reduce the size of this file
The file size of InnoDB tablespaces will never reduce automatically, no matter how much data you delete.
What you could do, although it is a lot of effort, is to create one tablespace for every table by setting
innodb_file_per_table
The long part about this is, that you need to export ALL DATA from the mysql server (setting up a new server would be easier) and then reimport the data. Instead of one single ibdata1 file which holds the data for each and every table, you will find a lot of files called tablename.ibd which hold the data only for one single table.
Afterwards:
When you then delete a lot of data from tables, you can let mysql recreate the data-file by issuing
alter table <tablename> engine=myisam;
to switch to MyIsam (and have the InnoDB data file for this table deleted) and then
alter table <tablename> engine=innodb;
to recreate the table.
Unless you set innodb_file_per_table, ibdata1 holds all InnoDB tables plus undo.
This file never shrinks.
To shrink it, you should (at your own risk):
Backup and drop all InnoDB tables in all databases
Delete the file manually
Reinitialize InnoDB storage (by restarting mysqld) and
Restore the tables from backup.
If you set innodb_file_per_table, you'll still have to do this to reclaim the space, but in this case you'll be able to do this on per-table basis, without affecting the other tables.
Note that the undo is still held in ibdata, even with innodb_file_per_table set.
Adding, Removing, or Resizing InnoDB Data and Log Files
Run optimize table your_db.your_table; sql request
or use mysql workbench migration wizard and it will create database copy with reduced size