… test combinations. The details are below. Here is a brief context recap. There are two cases covered in the first post: single SELECT… from the equation. We ran tests on Dell PowerEdge R720 box and varied cpu combinations with taskset. The following chart shows a results comparison on a single-node (on the left) vs. two-node (on…
Comment: ORDER BY ... LIMIT Performance Optimization
September 15, 2007 By 100 Comments
… well because the random number is generated inside the query resulting with two different random numbers. This can be overcome by making… first problem. my choice was to combine the ORDER BY RAND() and the other one. SELECT * FROM (SELECT * FROM comments WHERE count > $number AND topic…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…combination…results mysql> select sum(total_lines) from dashboard_customer_sales ; +——————+ | sum(total_lines) | +——————+ | 155186550 | +——————+ 1 row in set (0.64 sec) mysql> select…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…SELECT non_key_column FROM tbl WHERE pk_column=val As you can see that the values returned from… small as compared to the combined size of the secondary key …see the difference in numbers. Benchmark results For the purpose of this benchmark… MRR is used then there are two separate calls made to the…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…’ll usually capture two of these. It looks …manual way.) The result looks like this: +———————————–+———————-+———————-+ | Variable_name | Value | Value…WHERE client IN (SELECT id FROM clients)” which is … broken into pieces, combined, or even eliminated …
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…how well Infobright community edition (ICE) performs in combination with Shard-Query. Data set It was …to conform to the new schema, and additionally two new test queries have been added. To … the “scale-out” results are the most striking. — Q4 SELECT Carrier, count(*) as c from ontime_fact JOIN dim…
Post: A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
…the following table which contains a combination of integer values. There …rows takes a second or two. mysql> show create table t2\G *************************** 1…. entire table to produce the result: mysql> select * from v2 where c1 = 10; +——+———-+ | c1 | count(*) | +——+———-+ | 10…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
…-server partitioning to use combined memory and a …select count(pad) from large; +————+ | count(pad) | +————+ | 31457280 | +————+ 1 row in set (4 min 58.63 sec) mysql> select count(pad) from… would be close to two full table scans (… in parallel and aggregate result sets. So if …
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
…” MySQL does not count it as access to two tables. In case of “real” access to the…results. What you can think about in this case is removing group by and aggregate functions. Then query would become “select * from… rows it scans 100x, for example by adding combined index. So what is the easy way to…
Comment: Multi Column indexes vs Index Merge
September 24, 2009 By 31 Comments
…checked this page two hours ago 
Anyway…combined index on (type_id, is_active, date_created). For this query: SELECT id, title, body FROM…result: ———————————– select_type: SIMPLE type: ref key: multi key_len: 7 ref: const,const,const rows: 104 Extra: Using where But for SELECT…
