…of id’s between 47000 and 50000 with no movies, but your random number…of performance, or of accuracy of randomness. The ORDER BY RAND() solution is known to have poor performance…columns in a compound index, then the order would matter, and it would have to match the order of columns…
Post: How number of columns affects performance ?
September 28, 2009 By 12 Comments
…does not depends on number of columns. Another interesting observation is access speed to different columns. the max(t1) and max(t99) were … mysql [localhost] {msandbox} (test) > select max(t1+0) from t99v1; +———–+ | max(t1+0) | +———–+ | 0 | +———–+ 1 row in set (3.26 sec) mysql…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
…gets a special column `mview$pk` …number of lines in the order_lines table, three orders of magnitude more quickly than COUNT(*). mysql…If you use MIN/MAX/COUNT_DISTINCT,…of SQL features not available with the incremental method, like ORDER BY or use of NOW(), it but still provides improved performance…
Post: Edge-case behavior of INSERT...ODKU
October 27, 2012 By 6 Comments
…performance that dropped through the floor (to the point of… defined first. So, MySQL checks our INSERT, …, which is the number of seconds in a day… the auto-increment max value, which is the…columns is almost never a good idea; it wastes half of the column‘s available range. Intuition, like the laws of…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
… to 2010′; mysql> use ontime1; Database changed mysql> show table status like…_length: 241 Data_length: 1616904192 Max_data_length: 0 Index_length:… list of columns to show (click show/hide to change the columns) That …number of nodes) php genconfig 20 > shards.ini Running the test For best performance…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…of the data, performance can be improved significantly: $ cat shards.ini [default] user=mysql db=ontime password= port=5029 column…performs about 6x better as the degree of parallelism is controlled by the number of…
Post: Improved InnoDB fast index creation
November 6, 2011 By 4 Comments
…performed a number of simple benchmarks. Let’s start with a table containing 4 million rows and one secondary key: mysql…mysql> SET profiling=1; Query OK, 0 rows affected (0.00 sec) mysql> ALTER TABLE t ADD COLUMN… Avg_row_length: 29 Data_length: 125452288 Max_data_length: 0 Index_length: 278839296 …
Post: What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
… pointer (typically physical) order. MySQL takes bunch of pointers from sort_buffer (… number of columns or there are long VARCHAR columns used – it takes only couple of UTF8…max_length_for_sort_data in its static presentation. We should do benchmarks sometime to see how it really impacts performance…
Post: Talking MySQL to Sphinx
April 19, 2009 By 4 Comments
…performance, we already know Sphinx is much faster than MySQL build in full text search. I was rather interested to look performance of…number of rows it needs to reach the LIMIT Sphinx mysql…Sphinx adds couple of extra columns to result set… rows in set (32.47 sec) MySQL mysql> select max(forum_id) as…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
…of thousands times per second. To verify this I tried doing “open table” test for only 10K out of 100K tables – the performance…of data recovery does not depends on amount of records which need to be applied just about number of…
