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What guarantees are there on the run-time complexity (Big-O) of LINQ methods?
...).
Distinct, GroupBy Join, and I believe also the set-aggregation methods (Union, Intersect and Except) use hashing, so they should be close to O(N) instead of O(N²).
Contains checks for an ICollection implementation, so it may be O(1) if the underlying collection is also O(1), such as a HashSet<...
Select first row in each GROUP BY group?
...mon problem can surprisingly be found in the one of most official sources, MySQL manual! See Examples of Common Queries :: The Rows Holding the Group-wise Maximum of a Certain Column.
How to debug Lock wait timeout exceeded on MySQL?
...al Locking and Mutex Information.
Here is a sample from one of my clients:
mysql> show engine innodb status\G
*************************** 1. row ***************************
Type: InnoDB
Name:
Status:
=====================================
110514 19:44:14 INNODB MONITOR OUTPUT
=================...
Library not loaded: libmysqlclient.16.dylib error when trying to run 'rails server' on OS X 10.6 wit
...his way you don't need to use install_name_tool every time you update your mysql
sudo ln -s /usr/local/mysql/lib/libmysqlclient.18.dylib /usr/lib/libmysqlclient.18.dylib
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MySQL error 2006: mysql server has gone away
...rver at my office to process some files and report the results to a remote MySQL server.
28 Answers
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新浪是如何分析处理32亿条实时日志的？ - 更多技术 - 清泛网 - 专注C/C++及内核技术
新浪是如何分析处理32亿条实时日志的？【编者的话】我从2014年初入职新浪后就开始接触实时日志分析相关的技术，主要是ELK（Elasticsearch、Logstash、Kibana），当时是学习+ELK优...【编者的话】我从2014年初入职新浪后就开始接触实...
MySQL: determine which database is selected?
After calling mysql_select_db to grab a database, is there any way to later output the name of the database that is currently selected? This seems very basic but I couldn't find anything on php.net or stackoverflow (all results are for "no database selected").
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Insert current date in datetime format mySQL
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If you're looking to store the current time just use MYSQL's functions.
mysql_query("INSERT INTO `table` (`dateposted`) VALUES (now())");
If you need to use PHP to do it, the format it Y-m-d H:i:s so try
$date = date('Y-m-d H:i:s');
mysql_query("INSERT INTO `table` (`datepo...
How can I tell when a MySQL table was last updated?
..."last updated the xx/xx/200x" with this date being the last time a certain mySQL table has been updated.
15 Answers
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access denied for load data infile in MySQL
I use MySQL queries all the time in PHP, but when I try
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