… recomended ? TEMP TABLES Current max_heap_table_size = 128 M Current tmp_table_size = 128 M Of 21559 temp tables, 44% were created on disk Perhaps you should increase your tmp_table_size and/or max_heap_table_size to reduce the number of disk-based temporary tables Note! BLOB and TEXT columns are…
Post: Innodb row size limitation
April 7, 2011 By 12 Comments
…blob-storage-in-innodb/ for further reference). It’s worth mentioning that this limit applies to the byte-size of…
Post: Data compression in InnoDB for text and blob fields
May 30, 2012 By 2 Comments
… than 16KB) TEXT fields off-page so we utilized the KEY_BLOCK_SIZE=16 directive. This means that each TEXT / BLOB field that exceeds… stored blobs provided substaintial advantages. Why did we choose a KEY_BLOCK_SIZE that is the same value of the InnoDB page size of 16KB? As the fine MySQL manual states: This setting may still be useful for tables with many long BLOB, VARCHAR or TEXT…
Post: Blob Storage in Innodb
February 9, 2010 By 13 Comments
… it. How blobs are stored in Innodb ? This depends on 3 factors. Blob size; Full row size and Innodb row …which is reasonable as you can store more of them. BLOBs can have prefix index but this no more… to note I use BLOB here in a very general term. From storage prospective BLOB, TEXT as well as…
Post: What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
… which are being length can be converted to fixed size (basically everything but BLOB/TEXT) MySQL can use read_rnd_buffer to optimize…_size is important (optimization works in following conditions): Row pointers are stored in the sort_buffer, not the whole data selected Blob/Text… mean there are some TEXT/BLOB columns among them. It would be used however if there is large number of columns or there…
Post: Recover BLOB fields
July 1, 2010 By 4 Comments
… types like BLOB, TEXT were not supported by Percona InnoDB Recovery Tool. The reason consists in a special way InnoDB stores BLOBs. An… field size. The highest bit of the offset is 1 if the field is stored in external pages (i.e. long BLOB field… QA tests. The complexity of BLOB fields brings prerequisites to successfully recover a record with BLOB : all pieces of the BLOB field must be reachable…
Post: How number of columns affects performance ?
September 28, 2009 By 12 Comments
… DEFAULT CHARSET=latin1 I populated each of the tables with 12M rows. Getting 7 bytes row size for first table and 101… format table with many columns. But is it because of large number of columns or dynamic format on its own is slave… populated (everything but TEXTs/BLOBs is fixed length when it is being processed). This conversion process depends on number of columns while for…
Post: MySQL Blob Compression performance benefits
January 11, 2008 By 17 Comments
… storing text of significant size in the table it often makes sense to keep it compressed. Unfortunately MySQL does not provide compressed BLOB/TEXT columns…. This choice of server side vs client size compression depends on the queries you have. If you just retrieve these BLOB/TEXT columns for…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
…: How InnoBD handles blobs/text fields (needs more info) According to the documentation, InnoDB put first 768 chars of each text/blob in the page and will allocate some space outside of the page. However: 1. if the total size of the row is less than 8100 bytes InnoDB will not allocate additional space for blobs, even if each blob is…
Post: Real-Life Use Case for "Barracuda" InnoDB File Format
April 23, 2008 By 11 Comments
… set of TEXT fields. We’ve been trying to optimize this server before by playing with various innodb parameters (including page size changes… to 8kb) new innodb plugin performs TEXT/BLOB/VARCHAR fields compression off-page so every large TEXT field could become as small as… for compressed page sizes: 1k, 4k and 8k. Results were not so different because most of our data was in TEXT fields and…
