…. Which means that any full table scan is really going to be a full database scan, or alternately, a full index scan followed by nested lookups by… this mean the PBXT is going to have issues with full table scans and hence is probably not a good choice for…
Post: COUNT(*) for Innodb Tables
December 1, 2006 By 32 Comments
… from stored value. Innodb will however need to perform full table scan or full index scan because it does not have such counter, it also… same way both for MyISAM and Innodb tables by performing index rage scan. This can be faster or slower both for MyISAM…
Comment: COUNT(*) vs COUNT(col)
March 22, 2011 By 45 Comments
Hi, You’re looking at full index scan or full table scan in this case. Innodb has some protection from full table scan polluting cache, though it is done differently than using same page
Comment: COUNT(*) vs COUNT(col)
April 10, 2007 By 45 Comments
Hi, You’re looking at full index scan or full table scan in this case. Innodb has some protection from full table scan polluting cache, though it is done differently than using same page
Comment: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
The count(*) group by k could be optimized slightly by adding an index to k. That will at least give you a full index scan instead of a full table scan which can reduce io if the table is wide.
Comment: XtraDB feature: save / restore buffer pool
January 20, 2010 By 20 Comments
… take to warm the cache using conventional means, such as full table scans/full index scans on this hardware? And how does the TPC compare…
Post: Using UNION to implement loose index scan in MySQL
August 10, 2006 By 15 Comments
… retrived. Notice Using Where. There are even more bad news. Full rows will need to be read to check if zip… be done only by reading data from the index. MySQL can ether read index only for all rows, in this case you… cases when it is technically possible. For multiple key part indexes MySQL will only be able to use multiple keyparts if…
Post: A rule of thumb for choosing column order in indexes
June 5, 2009 By 15 Comments
… use to decide which columns should come first in an index. This is not specific to MySQL, it’s generally applicable to any database server with b-tree indexes. And there are a bunch of subtleties, but I will… with this query, which returns zero rows but does a full table scan. EXPLAIN says there are no possible_keys. SELECT * FROM…
Comment: Full table scan vs full index scan performance
November 23, 2012 By 15 Comments
Peter, Why not? But that would probably be lots of queries! So it should rather be ‘log queries using a full index scan but not using a covering index‘ 
Comment: Heikki Tuuri Innodb answers - Part I
October 30, 2007 By 19 Comments
…. Each part has its own LRU list. That is a full index scan will only wipe out the warm part of the keycache…
