… as I recall, innodb allocates memory for the entire blob to be returned to the user. So imagine a blob that is 1 GB in size and you have 25 conncurrent requests for such a sized blob, innodb will need to allocate 25 GB of memory to satisfy this query. See: http://mysqlinsights.blogspot.com/2009/01/mysql-blobs…
Post: Real-Life Use Case for "Barracuda" InnoDB File Format
April 23, 2008 By 11 Comments
… trying to optimize this server before by playing with various innodb parameters (including page size changes) but at the end of… with DYNAMIC row format InnoDB was able to keep an entire PRIMARY index in memory (TEXT and BLOB fields are stored off… to compress 16kb pages down to 8kb) new innodb plugin performs TEXT/BLOB/VARCHAR fields compression off-page so every large TEXT…
Post: Should you move from MyISAM to Innodb ?
January 12, 2009 By 59 Comments
… size is close to memory size), generally slower writes, slower blob handling, concurrency issues, problems dealing with very large number of… but instantly break upon upgrading to Innodb. Features The MyISAM features which forbid moving to Innodb are typically Full Text Search and…) for logging. Innodb Needs Tuning As a final note about MyISAM to Innodb migration I should mention about Innodb tuning. Innodb needs tuning. Really…
Post: Innodb Performance Optimization Basics
November 1, 2007 By 75 Comments
… for more details, check out detailed guide on tuning innodb buffer pool innodb_log_file_size – This depends on your recovery speed… good performance innodb_log_buffer_size=4M 4M is good for most cases unless you’re piping large blobs to Innodb in this case increase it a bit. innodb_flush_log_at_trx_commit=2…
Post: Data Recovery Toolkit for InnoDB Version 0.1 Released
November 26, 2007 By 6 Comments
… processed InnoDB page has been reassigned to another table and/or was partially destroyed Supports all MySQL data types except BLOBs, SETs… more links to information resources related to InnoDB data structures and recovery procedures. The commercial Innodb Data Recovery services are available from…
Post: Percona Testing: Innodb crash / recovery tests available
December 21, 2011 By Leave a Comment
Not everyone may know this, but there are precious few innodb crash recovery tests available. Some folks have noticed this and…). The team at Percona has been known to tinker with Innodb now and again, and were also very interested in having… incident, but I also haven’t dug into partitions or blobs >: ) If you’d like to try these out yourself, they…
Comment: When should you store serialized objects in the database?
January 21, 2010 By 47 Comments
Somewhat related to this, MySQL needs a storage engine that is crash safe and good at storing blobs. InnoDB is not it. Maybe PBXT is.
Post: Bug#12704861
November 20, 2011 By 1 Comment
… here the full documentation from the release notes: “InnoDB Storage Engine: Data from BLOB columns could be lost if the server crashed… are into InnoDB internals: The fix of Bug#12612184 broke crash recovery. When a record that contains off-page columns (BLOBs) is… clustered index pages unavailable to the BLOB allocation. This function is also a likely culprit of InnoDB hangs that were observed when…
Comment: Blob Storage in Innodb
February 10, 2010 By 13 Comments
… table status like “comptest” \G *************************** 1. row *************************** Name: comptest Engine: InnoDB Version: 10 Row_format: Compressed Rows: 1 Avg_row_length… than 1MB blob takes about 1.5M this is because space allocation for BLOB happens as well as for other innodb segments – allocation happens in 16K pages for a first few pages and when space is allocated in 1MB blobs. Which…
Comment: Heikki Tuuri to answer your in depth Innodb questions
September 28, 2007 By 51 Comments
… than 8100 bytes InnoDB will not allocate additional space for blobs, even if each blob is larger than 768. 2. InnoDB will allocate additional space outside of the page for _each_ blob (if we have 8 blobs 8xN bytes will be allocated) Question: How much space InnoDB allocates for each blob outside of…
