… MySQL does not provide compressed BLOB/TEXT columns (I would really love to have COMPRESSED attribute for the BLOB/TEXT columns which would make… seeks for row retrieval and a lot of space wasted. So compressing BLOB/TEXT you should also think about how many rows you will… performance gains were even better because much fewer rows required external storage now. The BLOB/TEXT column compression is not for all workloads…
Post: Dynamic row format for MEMORY tables
September 6, 2011 By 5 Comments
… release has one new feature: now MEMORY tables can have BLOB and TEXT columns, and VARCHAR columns will not waste space due… MySQL 5.0. Although this patch did not add the BLOB and TEXT support, it refactored the code to make it easier… the MEMORY tables with dynamic row format could be used instead: for schemas containing large VARCHARs, BLOB, TEXT. Unfortunately, enabling this feature is…
Post: Blob Storage in Innodb
February 9, 2010 By 13 Comments
… depends on 3 factors. Blob size; Full row size and Innodb row format. But before we look into how BLOBs are really stored lets… from each of the BLOBs on the row page itself. With two of 7KB blobs we will have one blob stored on the page… is worth to note I use BLOB here in a very general term. From storage prospective BLOB, TEXT as well as long VARCHAR…
Post: Innodb row size limitation
April 7, 2011 By 12 Comments
… installation). This limit is a consequence of InnoDB storing two rows on a page. If you’re using compression, however, you… binary, so for example, you should use a BLOB instead of a TEXT column for storage. You can find more information about… interesting things about overflow blob storage is that if the columns aren’t requested as part of a row-read, they don…
Post: Data compression in InnoDB for text and blob fields
May 30, 2012 By 2 Comments
… choice of ROW_FORMAT=COMPACT and ROW_FORMAT=REDUNDANT where InnoDB stored the first 768 bytes of variable length columns (BLOB, VARCHAR, TEXT) in… the KEY_BLOCK_SIZE=16 directive. This means that each TEXT / BLOB field that exceeds 16KB it would be stored in it… may still be useful for tables with many long BLOB, VARCHAR or TEXT columns, because such values often do compress well, and…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… a search. Please use this with care: you MUST use row-based binlogging and replication, and remember that the execution is… 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…
Post: What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
… row pointer storage is used and the fields which are being length can be converted to fixed size (basically everything but BLOB/TEXT…): Row pointers are stored in the sort_buffer, not the whole data selected Blob/Text columns are not selected A lot of rows are…_for_sort_data it would frequently mean there are some TEXT/BLOB columns among them. It would be used however if there…
Comment: Heikki Tuuri to answer your in depth Innodb questions
September 28, 2007 By 51 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 larger…
Post: Data Corruption, DRBD and story of bug
November 29, 2010 By 6 Comments
… in MySQL 5.0) In short, if you use big BLOBS ( TEXT, MEDIUMBLOB, etc) (that allocated in external segment in InnoDB), you… trash state just executing update on row with blob and rolling back transaction twice ( on the same row) The keywords that diagnose you… the end let me reiterate my points: – if you have BLOB/TEXT fields in your InnoDB-plugin schema, it is recommended to…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
… to be put to temporary tables – BLOB/TEXT columns are not supported with MEMORY … table | type | possible_keys | key | key_len | ref | rows | Extra | +—-+————-+——-+——+—————+——+———+——+———+—————–+ | 1 | SIMPLE | gt | ALL | NULL | NULL | NULL …
