… over the range 1..MAX(id)? Yes, there’s a risk if you have irregular distribution of matching rows that you’ll… table to count the movies per production year for each kind_id. It was more efficient in this case to force MySQL to scan the `title` table first, grouping by kind_id in index order. This made the first table in the…
Post: Understanding the maximum number of columns in a MySQL table
April 8, 2013 By 5 Comments
…: /* Hack to avoid bugs with small static rows in MySQL */ reclength=max(file->min_record_length(table_options),reclength); if (info_length+(ulong) create… number of columns in a MySQL table. So what’s the maximum number of columns in a MySQL table? Well.. I tried a few…_MAX_N_FIELDS – 3 = 1020, but we play safe here */ DBUG_RETURN(HA_ERR_TO_BIG_ROW); } Which is curiously gone from MySQL…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
…this benchmarks round, since reportedly Dimitri was using 8 tables with 1M rows each (about 2.1GB) for his tests, while …–forced-shutdown=1 –max-time=120 –max-requests=0 –percentile=99 –mysql-user=root –mysql-db=sbtest8t1M –mysql-table-engine=INNODB –mysql-socket=/tmp/mysql.sock –oltp-point…
Post: Benchmarking Percona Server TokuDB vs InnoDB
May 7, 2013 By 32 Comments
… compression on this dataset. We can easily fill TokuDB tables with 1bln of rows on this SSD, and projected InnoDB performance on… –oltp-table-size=10000 –mysql-user=root –oltp-tables-count=32 –mysql_table_engine=tokudb –oltp_auto_inc=on –max-time=18000 –report-interval=10 –max-requests…
Post: Virident vCache vs. FlashCache: Part 2
May 17, 2013 By 3 Comments
… tests were conducted with approximately 78GiB of data (32 tables, 10M rows each) and a 4GiB buffer pool. The cache…max-time=7200 –max-requests=0 –percentile=95 \ –mysql-user=root –mysql-socket=/tmp/mysql.sock –mysql-table-engine=innodb \ –oltp-read-only=off run The base MySQL…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
… to the amazing MySQL manual, especially the option and variable reference table. But just as…max_tmp_tablesblogpercona.commanual Max_used_connectionsblogpercona.commanual max_user_connectionsblogpercona.commanual max_write_lock_countblogpercona.commanual memlockblogpercona.commanual min_examined_row…
Post: Performance Schema tables stats
May 2, 2011 By 2 Comments
…tables. 1. table_io_waits_summary_by_table mysql> select * from table_io_waits_summary_by_table where OBJECT_NAME=’sbtest55′ G *************************** 1. row *************************** OBJECT_TYPE: TABLE…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…MAX_THREAD_INSTANCES | 1000 | 224 | | SOCKET | /tmp/mysql_sandbox5530.sock | /tmp/mysql_sandbox5610.sock | | INNODB_FILE_PER_TABLE…=on,inde | +—————————————————+——————————————+——————————————+ 56 rows in set (0…
Post: How much space does empty Innodb table take ?
December 16, 2008 By 7 Comments
…row size for table with one row: mysql> show table status like “test_innodb” \G *************************** 1. row *************************** Name: test_innodb Engine: InnoDB Version: 10 Row_format: Compact Rows…
Post: How much overhead is caused by on disk temporary tables
August 16, 2007 By 26 Comments
…) mysql> set global max_heap_table_size=1000000000; Query OK, 0 rows affected (0.00 sec) mysql> set global tmp_table_size=1000000000; Query OK, 0 rows… rows we have mysql> set max_heap_table_size=1000000000; Query OK, 0 rows affected (0.00 sec) mysql> set tmp_table_size=1000000000; Query OK, 0 rows…
