…value fetched from step 1, and when the buffer is full sort them by pk_column, and do a range … I have used TPC-H Query #10 and ran it on TPC-H dataset (InnoDB tables) with a Scale Factor of …the storage engine to perform the index record read and then to perform the MRR range scan on the PK. This …
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
… able to provide just 100 row lookups by index pr second. The difference is 10.000 times for our worse case scenario… in temporary table etc. Prefer full table scans to index accesses – For large data sets full table scans are often faster than range scans and other types of index lookups…
Post: InnoDB vs MyISAM vs Falcon benchmarks - part 1
January 8, 2007 By 117 Comments
… increment primary key and couple of extra indexes. CREATE TABLE IF NOT EXISTS `$tableName` ( `id` int(10) unsigned NOT NULL auto_increment, `name… key range lookup, same access types for primary key and full table scans. To highlight different properties of storage engines we tested ranges…
Post: Multiple column index vs multiple indexes
August 22, 2008 By 13 Comments
… couple of simple tables: CREATE TABLE `t1000idxmerge` ( `i` int(11) NOT NULL, `j` int(11) NOT NULL, `val` char(10) NOT NULL, KEY… not – Full table scan is performed and in this case turns to be faster than scanning 1/5th of the table using index. Also Full Table Scan is preferred…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
… for this benchmark. We have 4 tables: 1) Table with ENUM: CREATE TABLE cities_enum ( id int(10) unsigned NOT NULL auto_increment, state… read. For Full Table Scan operation difference often would be larger. It is also interesting to note performance of Innodb tables in this case… – traversing about same amount of rows full table scan performs about 25 times better than accessing rows via index (for the case when data…
Post: Long PRIMARY KEY for Innodb tables
October 3, 2006 By 8 Comments
…5) unsigned NOT NULL default ’0′, `size` int(10) unsigned NOT NULL default ’0′, `pathversion` … number of benefits – caching data and index in memory -so cached lookups are very…Full table scan for this table would also be slow as it is quite fragmented. Table however is not getting any table scans…
Post: PBXT benchmarks
April 8, 2007 By 14 Comments
… increment primary key and couple of extra indexes. CREATE TABLE IF NOT EXISTS `$tableName` ( `id` int(10) unsigned NOT NULL auto_increment, `name… key range lookup, same access types for primary key and full table scans. To highlight different properties of storage engines we tested ranges…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 93 Comments
… executed without scanning and sorting full result set, so it is important for it to use index – in this case index range scan will be… it is rare category large portion of table may be scanned to find 10 rows. So index on (category_id, date_created) will be…, if you do not have full where clause resolved by index is how many rows you need to scan to resolve order by…
Post: Multi Column indexes vs Index Merge
September 19, 2009 By 30 Comments
…look at some examples now: CREATE TABLE `idxtest` ( `i1` int(10) unsigned NOT NULL, `i2` int(10) unsigned NOT NULL, `val` varchar(…case of full table scan about 50 times more rows are scanned. This reflects very large performance difference between full table scan and access through the index, which…
Post: 3 ways MySQL uses indexes
September 12, 2009 By 27 Comments
… index MySQL will use the index… but it will only use A prefix for row lookups and scan whole A BETWEEN 5 AND 10… able to use full index for sorting (note MySQL may not select to use index for sort if you sort full table without a limit). However ORDER BY B or ORDER BY A, B DESC will not be able to use index…
