… code in question that comes into play around the maximum number of columns is this: /* Hack to avoid bugs with small static rows in MySQL */ reclength=max(file->min_record_length(table_options…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
…in both MySQL 5.6 and MariaDB 5.5. You can read more about BKA in MySQL 5.6 here and BKA in…rows with table t2. This step is called the build step. After the hash table has been created, rows from table…the maximum possible benefit is when size of both the buffers is increased appropriately. Also in …
Post: AUTO_INCREMENT and MERGE TABLES
September 11, 2008 By Leave a Comment
… | | 3 | +—+ 3 rows in set (0.00 sec) So you can see merge table behaves quite smart. Even though the maximum value in table a2 was… | +—+ 2 rows in set (0.00 sec) As you see newly inserted row got value 3, which is maximum value which remained in the table plus… rows in set (0.00 sec) mysql> select * from a2; Empty set (0.00 sec) mysql> flush tables; Query OK, 0 rows affected (0.00 sec) mysql…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
… tuple r in the build input R Add to the in-memory hash table If the size of the hash table equals the maximum in-memory… scanning the table lineitem (right operand) in both test cases. Since in Test B we have a limited set of rows in the supplier table (left… of rows in the table orders (left operand), and so MySQL 5.5 prefers to do a PRIMARY index scan of the table orders resulting in…
Post: Edge-case behavior of INSERT...ODKU
October 27, 2012 By 6 Comments
…in which they were defined, and the PRIMARY KEY is always going to be considered as being defined first. So, MySQL…table is the same as what I’ve used in my demonstration table – INT UNSIGNED. Do the math. The maximum…think; the original customer table in question had less than 500K rows in it. Using …
Post: Fighting MySQL Replication Lag
September 22, 2008 By 7 Comments
… rows ? Use Query Chopping – this can be running update/delete with LIMIT in the loop, controlling maximum amount of values per batch in multiple row… body LIKE “%cheap rolex%”; This query will perform full table scan in MySQL 5.0 (even if there are no spam posts) which… use query chopping and run update in chunks if application allows it. In MySQL 5.1 with row level replication you will not have…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
… embarrassing and the maximum degree of parallelism …mysql> select min(id),max(id) from words; +———+———+ | min(id) | max(id) | +———+———+ | 1 | 3088896 | +———+———+ 1 row in set (0.00 sec) How to factor numbers create table…
Post: Innodb row size limitation
April 7, 2011 By 12 Comments
… for a given row on a single database page. Innodb has a limit for the maximum row size, which … more information about this functions here. Split the table in a way that you don’t have more … choose XML as format and you use MySQL‘s built in functions for handling this data. This approach, however…
Post: Tuning InnoDB Concurrency Tickets
May 24, 2010 By 5 Comments
… row affected (0.00 sec) mysql> SELECT * FROM test_table; — 1 Ticket Used +——+ | id | +——+ | 1 | +——+ 1 row in set (0.00 sec) mysql> INSERT INTO test_table… lookups would be blocked until the 900-row-SELECT statements complete execution. With a maximum value of 4,294,967,295 this…
Post: TMP_TABLE_SIZE and MAX_HEAP_TABLE_SIZE
January 19, 2007 By 17 Comments
… table after which it will be converted to MyISAM. To make things more confusing this is not what you would read in MySQL…_table_size system variable to impose a maximum size on MEMORY tables. For individual tables, you can also specify a MAX_ROWS table option in the CREATE TABLE…@ted.mysql.internal +6 -0 BUG #4291 fix: new configuration option “disk-tmp-table-size” introduced to set maximum expected on-disk temporary table…
