… | 1 | 46.78110075 | ALTER TABLE test add column c char(32) default ‘dummy_text’ | +———-+————-+————————————————————-+…Note that ALTER is a multi-step process, the old …threads can get piled up waiting for table metadata lock bringing down the MySQL…
Post: Scaling problems still exist in MySQL 5.5 and Percona Server 5.5
May 20, 2011 By 11 Comments
… attention such as Sysbench and DBT2/TPC-C scale pretty well a they got a …mysql_execute_command,mysql_parse,dispatch_command,do_command,do_handle_one_conn ection,handle_one_connection,start_thread…get_clust_rec_for_mysql,row_search_for_mysql,ha_innobase::general_fetch,handler::read _multi_range_next,…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
… usage and performance of the splitter. It is multi-threaded(actually multi-process) and is able to hash split … avaialble data from 1988 to 2010′; mysql> use ontime1; Database changed mysql> show table status like ‘ontime_fact’G… all text on the page and then CTRL-C to copy it. Paste this into a text…
Post: Percona Testing: Innodb crash / recovery tests available
December 21, 2011 By Leave a Comment
…been created for the main MySQL branch. The MySQL at Facebook branch has…My attempts at copying the Facebook multi-threaded python load-generation code seemed … 20111221-142505 TEST_DEBUG C: master_checksum= ((‘test.C‘, 2978384584L),) | slave_checksum= ((‘test.C‘, …
Post: The perils of InnoDB with Debian and startup scripts
January 28, 2009 By 13 Comments
…client right now who has a hosted multi-tenanting application that keeps each customer … created in file btr0sea.c line 139 a writer (thread id 1158064464) has reserved …thread id 1159956816 starting index read, thread declared inside InnoDB 500 mysql tables in use 7, locked 0 MySQL thread…
Post: EC2/EBS single and RAID volumes IO benchmark
August 6, 2009 By 14 Comments
….large instance), and made: RAID0 on 2 volumes as: mdadm -C /dev/md0 –chunk=256 -n 2 -l 0 /dev/sdj…=$size prepare for threads in 1 4 8 16; do echo PARAMS $size $mode $threads > sysbench-size-$size-mode-$mode-threads-$threads ./sysbench –test… of course to get benefit from multi-threading IO in MySQL you need to use XtraDB or MySQL 5.4 ® However there may be…
Post: Air traffic queries in LucidDB
October 26, 2009 By 20 Comments
…thread, it took for me 15273 sec or 4.24h. In difference with other systems LucidDB support multi-threaded … 7.9 sec – Q2: SELECT “DayOfWeek”, count(*) AS c FROM otp.”ontime” WHERE “DepDelay”>10 AND “Year…, transform external data (there is even access to MySQL via JDBC driver) just in SQL queries (…
Post: Moving Subtrees in Closure Table Hierarchies
February 14, 2011 By 18 Comments
…find they need to store hierarchical data, such as threaded comments, personnel org charts, or nested bill-of-materials…path to D. That is, copying A-C, B-C, C-C and changing the right C to D gives A-D, …same table in a single query in MySQL. But we can use MySQL‘s multi-table DELETE syntax, to find …
Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes
July 25, 2012 By 6 Comments
…mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 868 Server version: 5.5.24 Copyright (c… brain? This is a dangerous setting in multi-master setup, but should simplify things in… 120723 23:45:30 [Note] WSREP: applier thread exiting (code:7) 120723 23:45:30 […
Post: MySQL Limitations Part 2: The Binary Log
October 23, 2010 By 11 Comments
… MySQL in certain circumstances (links: part 1). In the first part, I wrote about single-threaded …, hooray), and c) privileges and other changes to the non-InnoDB data in MySQL were handled … precedent for this among MySQL storage engines. And there is Galera’s multi-master synchronization technology…
