Documentation Home
MySQL 5.7 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 35.0Mb
PDF (A4) - 35.1Mb
PDF (RPM) - 34.1Mb
EPUB - 8.6Mb
HTML Download (TGZ) - 8.3Mb
HTML Download (Zip) - 8.4Mb
HTML Download (RPM) - 7.2Mb
Eclipse Doc Plugin (TGZ) - 9.2Mb
Eclipse Doc Plugin (Zip) - 11.3Mb
Man Pages (TGZ) - 200.1Kb
Man Pages (Zip) - 305.3Kb
Info (Gzip) - 3.3Mb
Info (Zip) - 3.3Mb
Excerpts from this Manual

MySQL 5.7 Reference Manual  /  ...  /  InnoDB Temporary Table Undo Logs

15.2.5 InnoDB Temporary Table Undo Logs

MySQL 5.7.2 introduces a new type of undo log for both normal and compressed temporary tables and related objects. This type of undo log is not a redo log, as temporary tables are not recovered during crash recovery and do not require redo logs. Temporary table undo logs are, however, used for rollback while the server is running. This special type of non-redo undo log benefits performance by avoiding redo logging I/O for temporary tables and related objects. Temporary table undo logs reside in the temporary tablespace. The default temporary tablespace file, ibtmp1, is located in the data directory by default and is always recreated on server startup. A user defined location for the temporary tablespace file can be specified by setting innodb_temp_data_file_path.

With this change, 32 rollback segments are now reserved for temporary table undo logs for transactions that modify temporary tables and related objects. This reduces the maximum number of rollback segments available for data-modifying transactions that generate undo records from 128 to 96, which reduces the limit on concurrent data-modifying transactions from 128K to 96K. For more information see Section 15.2.2, “InnoDB Multi-Versioning” and Section 15.6.7, “Limits on InnoDB Tables”.

User Comments
Sign Up Login You must be logged in to post a comment.