This tutorial is going to help you learning how to do basic database operations (CRUD - Create, Retrieve, Update and Delete) using JDBC (Java Database Connectivity) API. These CRUD operations are equivalent to the INSERT, SELECT, UPDATE and DELETE statements in SQL language. MySQL stored procedures, functions, and triggers are tempting constructs for application developers. However, as I discovered, there can be an impact on database performance when using MySQL stored routines. Not being entirely sure of what I was seeing during a customer visit, I set out to create some simple tests to measure the impact of triggers on database performance. The outcome might surprise you. Why Stored Routines Are Not Optimal Performance-Wise: Short Version Recently, I worked with a customer to profile the performance of triggers and stored routines. What I've learned about stored routines: 'dead' code (the code in a branch which will never run) can still significantly slow down the response time of a function/procedure/trigger. We will need to be careful to clean up what we do not need. Profiling MySQL Stored Functions Let's compare these four simple stored functions (in MySQL 5.7): Function 1 CREATE DEFINER=`root`@`localhost` FUNCTION `func1`() RETURNS int(11) BEGIN declare r int default 0; RETURN r; END This function simply declares a variable and returns it. ![]() It is a dummy function. Function 2 CREATE DEFINER=`root`@`localhost` FUNCTION `func2`() RETURNS int(11) BEGIN declare r int default 0; IF 1=2 THEN select levenshtein_limit_n('test finc', 'test func', 1000) into r; END IF; RETURN r; END This function calls another function, levenshtein_limit_n (calculates levenshtein distance). But wait: this code will never run — the condition IF 1=2 will never be true. So that is the same as function 1. Function 3 CREATE DEFINER=`root`@`localhost` FUNCTION `func3`() RETURNS int(11) BEGIN declare r int default 0; IF 1=2 THEN select levenshtein_limit_n('test finc', 'test func', 1) into r; END IF; IF 2=3 THEN select levenshtein_limit_n('test finc', 'test func', 10) into r; END IF; IF 3=4 THEN select levenshtein_limit_n('test finc', 'test func', 100) into r; END IF; IF 4=5 THEN select levenshtein_limit_n('test finc', 'test func', 1000) into r; END IF; RETURN r; END Here there are four conditions and none of these conditions will be true: there are 4 calls of 'dead' code. ****************************************************************************** November 25, 2001 Wolfenstein No CD Fixed EXE for Multi and Single play released for V1.0. All you need to do is move or copy the file 'mp_pakmaps0.pk3' into the /Main folder located where you installed Return to Castle Wolfenstein. Click to DownLoad Size = 2.8meg. You will see other *.pk3 files there as well. Return to castle wolfenstein full.
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