… are cases when MySQL will allocate a lot of memory for table cache, especially if you’re using large blobs. It is… might look at how it uses MySQL to identify potential causes. Is it working with large blobs ? Using user variables ? Prepared Statements… and fixed. This is where your MySQL Support contract can be handy. Conclusion Understanding where MySQL can allocate memory can help us…
Post: MySQL Blob Compression performance benefits
January 11, 2008 By 17 Comments
… compressed. Unfortunately MySQL does not provide compressed BLOB/TEXT columns (I would really love to have COMPRESSED attribute for the BLOB/TEXT columns…) it also makes data easier to work with with console MySQL tools. Some people get best of both worlds by taking COMPRESS/UNCOMPRESS functions from the MySQL code and having them work on the application side as…
Post: Blob Storage in Innodb
February 9, 2010 By 13 Comments
… bytes of the BLOB may look strange, especially as MySQL internally has no optimizations to read portions of the blob – it is either… to beware with Innodb BLOB storage is the fact external blob pages are not shared among the blobs. Each blob, even if it has… in XtraDB 
So BLOB storage was not very efficient in REDUNDANT (MySQL 4.1 and below) and COMPACT (MySQL 5.0 and above…
Post: Bug#12704861
November 20, 2011 By 1 Comment
… in MySQL 5.1.60. I’ll repeat here the full documentation from the release notes: “InnoDB Storage Engine: Data from BLOB… issue in tablespace extension. If the request to allocate a BLOB page leads to the tablespace being extended, crash recovery could… of a mini-transaction allocated (nonfree=TRUE) before storing the BLOBs, or freed (nonfree=FALSE) before committing the mini-transaction. btr…
Post: Recover BLOB fields
July 1, 2010 By 4 Comments
…=latin1 Here COMPACT format is used, which is default in MySQL >= 5.1. The record consists of four parts: Offsets. Effectively… brings prerequisites to successfully recover a record with BLOB : all pieces of the BLOB field must be reachable by pointers. That means… values format. BLOBs are printed in a hex form – 0ACD86… To upload the table back you should utilize UNHEX function: mysql> LOAD…
Post: Dynamic row format for MEMORY tables
September 6, 2011 By 3 Comments
… in the MEMORY storage engine (also known as HEAP) in MySQL has been one of the long-standing limitations caused by… not supported by the engine. This is true for all MySQL versions, including the latest 5.6 development tree as of…-VARCHAR support for MEMORY tables for MySQL 5.0. Although this patch did not add the BLOB and TEXT support, it refactored…
Post: How is join_buffer_size allocated?
July 5, 2010 By 9 Comments
When examining MySQL configuration, we quite often want to know how various buffer …_count) 14185 { … snip … 14268 cache->length=length+blobs*sizeof(char*); 14269 cache->blobs=blobs; 14270 *blob_ptr=0; /* End sequentel */ 14271 size=max(thd…
Comment: Blob Storage in Innodb
February 10, 2010 By 13 Comments
… blob, innodb will need to allocate 25 GB of memory to satisfy this query. See: http://mysqlinsights.blogspot.com/2009/01/mysql-blobs-and-memory-allocation.html The people at pbxt have created a solution for their storage engine using a streaming blob protocol, but this requires a change to mysql client as far as i know…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
… me the question how should they estimate memory consumption by MySQL Server in given configuration. What is the formula they could… to be impractical. Here is why: List of rarely considered MySQL Server Memory Requirements Thread buffers can be allocated more than… have unbound memory requirements retriving result sets from remove queries. Blobs may require 3x time of memory. This is important if…
Post: Percona Server 5.5.15-21.0
August 31, 2011 By 9 Comments
… available here and from the Percona Software Repositories). Based on MySQL 5.5.15, including all the bug fixes in it… milestone at Launchpad. Improvements Improved MEMORY Storage Engine As of MySQL 5.5.15, a Fixed Row Format (FRF) is still…, TEXT and BLOB fields in MEMORY tables. This implementation is based on the Dynamic Row Format (DFR) introduced by the mysql-heap…
