… type with highest memory available, and memory is what really really matters. High-Memory Quadruple Extra …table = 1 ## Disabling query cache query_cache_size = 0 query_cache_type = 0 You can see that the buffer pool is… rate can be classified as large, because it varies between ~6.5k to ~12.5k …
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… same way this blog post is aimed at a new optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take a look briefly at what this enhancement actually is, and what is it aimed at. Index Condition Pushdown Traditional B-Tree…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… Loop Join to join two or more tables. What this means is that, select rows from first table participating in the joins are read… ran it on TPC-H dataset (InnoDB tables) with a Scale Factor of 2 (InnoDB dataset size ~5G). Note that query cache is disabled… is one number in MariaDB 5.5 that is quite large as compared to MySQL 5.6 and that is ‘Handler_mrr_init’. Is it…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
… lot of memory for table cache, especially if you’re using large blobs. It is easy to check though. Run “FLUSH TABLES” and see whenever… memory is allocated from OS you might not see “VSZ” going down. What you might see instead is flushing tables regularly or reducing table cache reduces…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… let’s take a look at what this optimization actually is and what benefits it brings. Multi Range Read With…key tuple, a point primary key lookup is made against base table, the number of these point primary….6 and MariaDB 5.5. Note that query cache is disabled during these benchmark runs and that the…
Post: MariaDB 5.3 is released as GA!
March 5, 2012 By 17 Comments
…learn more about where its features might be helpful to you. So what‘s new and great in…, and elimination of useless tables in joins Thread pooling and a segmented key cache for improved scalability That…the same or slightly different forms, so there is some subtlety to this list. For example, Percona…
Post: More on table_cache
November 26, 2009 By 7 Comments
…you’re better off with small table cache. What I have not checked though is how does table_cache (or table_open_cache in newer version) size … What does this tell us ? If you can fit your tables in table cache and eliminate (or almost eliminate) table cache misses it is best to size table_cache …
Post: table_cache negative scalability
November 16, 2009 By 23 Comments
… improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning caches is to get… problem is real and it is not fixed even in Performance focused MySQL 5.4. As we can see large table_cache (or table_open_cache_ values…
Post: SHOW OPEN TABLES - what is in your table cache
December 14, 2008 By 3 Comments
… what tables are in the table_cache this command is rather helpful to understand if there is activity on the given table. Just run “FLUSH TABLES mytable” and examine open tables later – if you see this table in table cache again chances are it is…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 27 Comments
…look counterintuitive because table is significantly smaller with ENUM or TINYINT but in fact it is quite expected – This is MyISAM table which is accessed via index…performance, while join performance degraded dramatically. Here is why: mysql> explain select SQL_NO_CACHE c.city from cities_join c …
