… buffer size used by MRR can be controlled by the variable read_rnd_buffer_size, while MariaDB introduces a different variable to control the MRR buffer size mrr_buffer_size. Both buffer sizes default to 256K in…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… the join_buffer_size increased to 6M, the query time was ~300s while when both the join_buffer_size and the read_rnd_buffer_size/mrr_buffer_size were set… 5.6 w/ join_buffer_size=6M & read_rnd_buffer_size=6M MariaDB 5.5 MariaDB 5.5 w/ join_buffer_size=6M & mrr_buffer_size=6M MariaDB 5.5…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So in the same way this blog post is aimed at a new optimizer enhancement Index Condition …
Post: What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
Looking for documentation for read_rnd_buffer_size you would find descriptions such as “The read_rnd_buffer_size is used after a sort, when reading rows in sorted…, when performs reading into read_rnd_buffer in the sorted order – it can be pretty much sequential if you’re lucky. The read_rnd_buffer_size is important…
Post: Are larger buffers always better ?
June 6, 2006 By 9 Comments
… quite unexpected improvements. sort_buffer_size – recently I worked with case which was running much faster with 32K sort_buffer_size, compared to 32M… and some 10 distinct c values. read_buffer_size and read_rnd_buffer_size – These are buffers used by MyISAM to perform reads, in different scenarios. So should we…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
… Handler_read_firstblogpercona.commanual Handler_read_keyblogpercona.commanual Handler_read_lastblogpercona.commanual Handler_read_nextblogpercona.commanual Handler_read_prevblogpercona.commanual Handler_read_rndblogpercona.commanual Handler_read_rnd_nextblogpercona… rand_seed2blogpercona.commanual range_alloc_block_sizeblogpercona.commanual read_buffer_sizeblogpercona.commanual read_onlyblogpercona.commanual read_rnd_buffer_sizeblogpercona.commanual relay_logblogpercona.commanual relay_log_indexblogpercona…
Comment: What exactly is read_rnd_buffer_size
April 1, 2009 By 4 Comments
[...] å¦å¤–ï¼Œå¢žåŠ read_rnd_buffer_size(3.2.3是record_rnd_buffer_size)的值对排åºçš„æ“作也有一点的好处，å‚è§ï¼šhttp://www.mysqlperformanceblog.com/2007/07/24/what-exactly-is-read_rnd_buffer_size/ [...]
Comment: What exactly is read_rnd_buffer_size
March 25, 2009 By 4 Comments
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Comment: MySQL 6.0 vs 5.1 in TPC-H queries
March 27, 2008 By 17 Comments
… Multi Range Read) is to perform range scan as follows: * Scan the index, collect the rowids in a buffer (of @@read_rnd_buff_size bytes… ‘sweep’. the expected improvement is that the full records are read sequentially which is faster than doing random disk probing. MRR…
Comment: What exactly is read_rnd_buffer_size
January 16, 2009 By 4 Comments
[...] MySQL Performance Blog: What exactly is read_rnd_buffer_size? [...]
