…In my case here is the properties file in use for my Percona Server…count of columns, row counts, and comments — a great way for a high level overview of the table sizes and an easy way to…how do they compare with SchemaSpy? Feel free to…
Post: Debugging problems with row based replication
May 6, 2010 By 12 Comments
… to play with: select count(*) from t1; +———-+ | count(*) | +———-+ | 65536 | +———-+ 1 row in …rows are missing, and the one in particular that the server is trying to find is c1=1, but how…rows -v”. This omits any base64 output and instead replaces the output with semi-valid SQL…
Post: Shard-Query adds parallelism to queries
November 15, 2010 By 18 Comments
…to demonstrate how much improvement could be made to…server, but it has enough resources to answer queries in parallel, then it can be used to add parallelism to queries which use IN…SQL via ShardQuery and it prints the results. Test #1 This set of queries tests the most basic aggregation (count…
Post: Four ways to optimize paginated displays
September 24, 2008 By 27 Comments
… link. And usually, show how many items are in the whole list and how many pages of results…count, you either a) use SQL_CALC_FOUND_ROWS (see our post on this) or b) execute a separate SELECT to count the rows…acceptable in many.) These suggestions can take a lot of work off the database server …
Post: Is it query which needs to be optimized ?
March 6, 2007 By 9 Comments
…COUNT 5-10 times faster, sometimes more. This however still works up to certain number of rows in result set, with results set of 100.000+ it becomes pretty inefficient. There is surely SQL_CALC_FOUND_ROWS…
Post: How is join_buffer_size allocated?
July 5, 2010 By 9 Comments
…in special cases. A join buffer is allocated to cache rows from each table in…to the question about how the buffer is allocated. Its meaning is actually “minimum join buffer size.” Here’s the code, in sql/sql…tables,uint table_count) 14185 { … snip … …to an interesting possibility to run the server…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…how to get it. Most distributed engines work with rows. They break the queries up into the lowest level sets possible (rows…IN (2009) GROUP BY 1 ORDER BY NULL ) — AGGREGATION SQL: SELECT `origin_airport_id`, SUM(`count(*)`) AS `count…
Post: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
…in the table: mysql> select count(*), count(distinct UniqueCarrier) from dim_flightG *************************** 1. row *************************** count(*): 58625 count(distinct UniqueCarrier): 29 1 row in…SQL script was fed to…to about 2GB total data. then spread over six servers). Due to…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…count” and “signal count” show how actively innodb uses internal sync array – how frequently slots are allocated in it and how…in queue 1 read views open inside InnoDB Main thread process no. 10099, id 88021936, state: waiting for server activity Number of rows…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…to 2010 1 row in…to copy it. Paste this into a text file on shard1 called “/tmp/servers.txt” and run the following commands: $ cat servers…count(*) from ontime_fact;” | ./run_query Array ( [count(*)] => 135125787 ) 1 rows…
