… not in the form they are currently implemented in MySQL 5.0 Only SQL as a Language Which is ancient ugly for… Messages MySQL Parser is in general far from perfect when it comes to error handling. “You have an error in your SQL… help to Improve MySQL Performance. For DBT2 benchmarks we’ve tried a while back MySQL 5.0 was about 10% slower than 4.1…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
…as run by the native database interface (MySQL): mysql> select word, md5(word), md5(reverse(word)),…overhead, a single threaded operation may be slower than the same operation on the native database…six branches are combined with this. — AGGREGATION SQL: SELECT `word`,`md5(word)`,SUM(`count(*)`) AS `…
Post: TPC-H Run on MySQL 5.1 and 6.0
April 10, 2008 By 16 Comments
… MySQL 5.1 time so if it is less than 1 MySQL 6.0 is faster if more than 1 slower: Query MySQL 5.0.23 MySQL… close and MySQL 6.0 is even significantly slower than 5.1 for number of queries. Honestly I expected more from MySQL 6.0… site. For example These Are results recently published for Microsoft SQL Server. Of course this is much more powerful system but…
Post: Using UNION to implement loose index scan in MySQL
August 10, 2006 By 15 Comments
… name | +———————————-+ | 888ba838661aff00bbbce114a2a22423 | +———————————-+ 1 row in set (0.06 sec) mysql> SELECT SQL_NO_CACHE name FROM people WHERE age …covers 5 rows is hundreds of times slower than single row ? If MySQL Optimizer would handle this case …
Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown
March 14, 2013 By 2 Comments
… the time to execute than the same “SELECT one_indexed_column” query in MySQL 5.6.10…., the actual number of rows read at SQL layer is actually very different from the “…slower? It seems that whenever the covering index technique is available, this is always preferred over the ICP optimization: mysql…
Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
January 24, 2008 By 30 Comments
… slower, we’ll take those records starting from record #10000 making MySQL to discard first 10000 records. 1) Results for ENUM: select SQL… great example of the case when Innodb is much faster than MyISAM for Read load. The other surprise could be almost… performance, while join performance degraded dramatically. Here is why: mysql> explain select SQL_NO_CACHE c.city from cities_join c JOIN…
Post: Using GROUP BY WITH ROLLUP for Reporting Performance Optimization
September 17, 2007 By 14 Comments
… and I find it quite inconvenient whenever it is MySQL limitation or SQL Standard. This would be extremely useful feature and I… considerable penalty associalted with GROUP BY WITH ROLLUP in MySQL – it is significantly slower than standard group by even though the only thing it needs to do is maintain an extra count. So if MySQL…
Comment: Mystery Performance Variance with MySQL Restarts
February 28, 2013 By 18 Comments
… database instance, same server. I run the same batch of sql queries on all 4 schemas and get constant performance on… after I restart MySQL, it’s not the same schema that is slower. But there is always 1 schema slower than the 3 others… on the slower one (41 sec). And as I said, if I restart MySQL, there is always one schema that is slower than the…
Post: How does MySQL Replication really work?
January 9, 2013 By 9 Comments
… are covered pretty well in the MySQL manual here. Put simply, the events… diffs if you will But other than that, I won’t be going… copying of replication events is a slower element of the replication. There could…” from the master. 2. SQL thread The second process – SQL thread – reads events from…
Comment: Four ways to optimize paginated displays
September 25, 2008 By 27 Comments
…the first 10 rows in milliseconds. If you add SQL_COUNT_FOUND_ROWS to your query though, the …faster this way. From what I can tell, the MYSQL optimizer doesn’t take the limit clause into account …faster at these high offset limit clauses, but still slower than a low offset). If the data you want is…
