GROUP_CONCAT in MySQL… GROUP_CONCAT(expr) – This function returns a string result with the concatenated non-NULL values from a group. Where it can be useful? For example to get PHP array without looping inside PHP: CREATE TABLE services ( id INT UNSIGNED NOT NULL, client_id …
Post: Tokyo Tyrant - The Extras Part I : Is it Durable?
November 10, 2009 By 5 Comments
…a TC table ( an id, and…return false; } if(hdb->async && !tchdbflushdrp(hdb)){ HDBUNLOCKMETHOD(hdb); return false; } bool rv = tchdbmemsync(hdb, true); HDBUNLOCKMETHOD(hdb); return…functions periodically: -ext path : specify the script language extension file. -extpc name period : specify the function…
Post: Using any general purpose computer as a special purpose SIMD computer
May 16, 2011 By 5 Comments
… a function on a large amount of input. Often times, the same function … load data infile ‘/tmp/words’ into table words (chars); Query OK, 6033 rows…md5(reverse(word))] => ffc86c559e06009a743d891ce1e4fc4f [count(*)] => 512 ) 1427 rows returned (0.87930011749268s, 0.87229418754578s, 0.0070059299468994s…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
… *************************** 2. row *************************** mview_table_id: 28 mview_id: 21 mview_table_name: customers mview_table_schema: demo mview_table_alias: c mview….get_sql() function call. This function reads the meta-data stored in the Flexviews data dictionary. It returns the SQL which…
Post: A micro-benchmark of stored routines in MySQL
August 16, 2009 By 7 Comments
… select ….\G *************************** 1. row *************************** id: 1 select_type: PRIMARY table: ci type: ALL possible_keys: NULL key: NULL …rewrote it as a stored function. mysql> delimiter // mysql> create function speaks_english(c char(3)) returns integer deterministic > begin > …
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
… hash table by using values of the columns participating in the equijoin condition. The hash table is accessed by using a hash function… a large table with no WHERE clause The SQL used for this test together with its EXPLAIN output as returned by MySQL…) from one table with a large table The SQL used for this test together with its EXPLAIN output as returned by MySQL 5…
Comment: Database problems in MySQL/PHP Applications
August 11, 2006 By 13 Comments
… agree – regardless of what database is used, abstracting out core functionality usually means more portable code. You’re right that when…. Not using auto_increment functionality This is right. With some > exception however. For example Innodb tables do internal full table > lock if auto… so that the right number of rows are scanned and returned. SELECT * FROM articles INNER JOIN users ON users.id = articles…
Post: Testing MySQL column stores
August 16, 2010 By 15 Comments
…types of testing. The first focused on core functionality and compatibility of ICE (Infobright Community Edition) … would be “select avg(char_column) from table” where the column contains a mix of ascii…(*) from carsales.sales_fact” when run on InfiniDB returned a number that was higher than it …
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
… perform but as only actual rows which are found and returned up to the top level MySQL part for processing are… aggregate functions/group by and only to ones which examine one table only. What is about queries which query more than one table… by, distinct and aggregate functions are removed (A) – look at number of rows examined divided by number of tables in join (B…
Post: Full Text Search Webinar Questions Followup
August 24, 2012 By 5 Comments
… in the Sphinx Search indexes will be returned by Sphinx Search queries. Mike W. also asked:…but I assume the search would necessarily do table-scans. Jessy B. also asked: Q: Were …different, and has different requirements for the FT functionality. So one solution may include advanced features …
