…Innodb would implement command to preload table to Innodb buffer pool, which would simply go through .ibd file sequentially…TEXT fields. If you would like some non PRIMARY Indexes preloaded you can use something like…externally stored blobs will also scan Clustered key Anyway. Now, say you have bunch …
Comment: Full table scan vs full index scan performance
November 23, 2012 By 15 Comments
“When we are doing a full table scan, we are doing sequential reads,” No, we are not. It’s InnoDB storage engine, the data are stored in a B-Tree, by the primary key. There is no way to do a sequential table scan in InnoDB, a “table scan” is always an index scan, a scan by the primary key.
Comment: Full table scan vs full index scan performance
November 24, 2012 By 15 Comments
… will get fragmented rows. Freshly created Innodb table will most likely result in a lot of sequential reads. Though even in the most fragmented case there is a major difference in primary index scan vs other index scan. The data is at least “clustered” in primary key so you will…
Post: How many partitions can you have ?
December 5, 2009 By 19 Comments
… NOT NULL, `c` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY(c) ) ENGINE=InnoDB PARTITION BY RANGE(id) ( PARTITION p100000 VALUES LESS THAN… 1 to 1000 and loaded the table with 1000000 of sequential values from 1 to 1million (the C column was set… 1000 partitions – which is over 10x difference. Both MyISAM and Innodb are affected by this issue. The Update path for MyISAM…
Post: MySQL Partitioning - can save you or kill you
December 11, 2010 By 45 Comments
…) DEFAULT NULL, `data` bigint(20) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `uu` (`uu`), ) ENGINE=InnoDB The access pattern to this table is to… 32 – This allows to partition data to 32 partitions placing sequential ranges of 10M values in the same partition – very handy… will require physical IO and going down to the leaf key to verify such value does not exist, which reduced performance…
Post: What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
… having only row pointers together with key value – which are offsets for MyISAM and primary key values for Innodb or storing full data which…_buffer in the sorted order – it can be pretty much sequential if you’re lucky. The read_rnd_buffer_size is… see how it really impacts performance both for MyISAM and Innodb.
Comment: COUNT(*) vs COUNT(col)
April 26, 2007 By 45 Comments
…, Good point. It looks like a bug to me as Innodb automatically picks up “shorter” indexes while in practice even first… tables, because if you insert data in order primary key tree is often sequential while secondary indexes may be scattered having few sequential pages.
Comment: Full table scan vs full index scan performance
November 23, 2012 By 15 Comments
… is sequentially accessed or not. A FTS on InnoDB is a scan over the primary key. Scanning an entire table via the secondary key is a scan over the secondary key plus…
Post: ALTER TABLE: Creating Index by Sort and Buffer Pool Size
June 27, 2012 By 4 Comments
…sbtest” \G *************************** 1. row *************************** Name: sbtest Engine: InnoDB Version: 10 Row_format: Compact Rows:…_creation=1 which builds table with primary key only when creating a table and … because disks are not that bad with sequential IO, which is what file merge …
Post: My "hot" list for next InnoDB features
March 30, 2009 By 18 Comments
…InnoDB scalability problems seem fixed in InnoDB-plugin-1.0.3 and I expect InnoDB-plugin will run…into buffer_pool. You can use custom queries by primary / secondary key to “warm up” part of table, but…O. Implementing preload of full .ibd file with sequential read would be much better solution. This …
