…have a small buffer pool and a very large number of rows from table2 that do …_shipdate > ’1995-03-09′ group by l_orderkey, o_orderdate, o_shippriority order by revenue desc, o_orderdate LIMIT…on MariaDB 5.5 is slow as compared to MySQL 5.6. Next interesting thing are the last two columns of the table…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 93 Comments
…ORDER BY with LIMIT is most common use of ORDER BY in interactive applications with large data sets being sorted. On…ORDER BY in other table. Here is example when ORDER BY is done by second table which requires filesort: mysql…
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 139 Comments
…order…tables being small it would not slow things down too much. On other hand join of few large tables, which is completely disk bound can be very slow. One of the reasons elevating this problem in MySQL…
Post: Using index for ORDER BY vs restricting number of rows.
February 16, 2007 By 7 Comments
…can be filtered on, and there…order by to be fully indexed. An extra problem comes from the fact MySQL…order by price desc limit 10 \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table…as otherwise very large portion of … trickier to slow for complex searches…
Post: MySQL: Followup on UNION for query optimization, Query profiling
August 14, 2006 By 12 Comments
…become very slow if IN lists are large. Take 3 IN lists 1000 values each, on …slow: mysql> explain select * from people where age=18 order by last_online desc limit 10; +—-+————-+——–+——+—————+——+———+——-+——-+————-+ | id | select_type | table |…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
…large log file generated. Another thing that we normally do is set the variable log_slow…: No Tmp_table: No Tmp_table_on_disk: No # Filesort: No Filesort_on_disk: No…the underlying tables involved and the query execution plan used by MySQL. …format’) AND tr.object_id IN (733) ORDER BY t.name ASC\G Let’…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
…tables in MyISAM format in “mysql” database. Plus HEAP/MEMORY tables are used for temporary tables which may become MyISAM if they are large…slow query log or general log. flush, flush_time Flushing (closing) of tables…tables for Full Table Scan (read_buffer) and for reading rows in sorted order…
Post: Thinking about running OPTIMIZE on your Innodb Table ? Stop!
December 9, 2010 By 13 Comments
…large indexes which would get inserts in very random order, such as indexes on… mysql> select * from a order by id limit 10; +—-+——————————————+ | id…TABLES on Innodb table to ensure there is not ton of queries starting reading table…slow method of building indexes by…
Post: Database problems in MySQL/PHP Applications
August 11, 2006 By 12 Comments
…group tables by …MySQL Could be slow with Large Tables article. 5. The n+1 pattern This probably should rather be called Not using Join. This is typical error. On…table scans. Funny enough this is often not the problem in the beginning – if application is bought or custom ordered…
Post: Finding out largest tables on MySQL Server
February 4, 2008 By 24 Comments
…TABLES ORDER BY data_length + index_length DESC LIMIT 10; +————————————-+——–+——–+——–+————+———+ | concat(table_schema,’.',table…on information_schema can be rather slow if you have a lot of large tables. On…
