PostgreSQL solves the shortest path

Some businesses need to solve the shortest path. A pgrouting plug-in in PostgreSQL has algorithms related to calculating the shortest path built in.Here's an example Table definition postgres=# \d testpath Table "public.testpath" Column | Type | Collation | Nullable | Default --------+---------+-----------+----------+-------- ...

Posted on Sun, 26 Apr 2020 19:41:13 -0700 by astoller

MyBatis level 1 cache implementation details and precautions

Introduction to L1 cache In the process of application running, it is possible for us to execute multiple SQL queries with the same query conditions in a database session. MyBatis provides the scenario of optimizing the first level cache. If the SQL statements are the same, the first level cache will be hit first, so as to avoid directly queryi ...

Posted on Sun, 26 Apr 2020 09:08:44 -0700 by Vince889

Mybatis source detailed series -- mybatis usage and details you don't know

brief introduction This is Mybatis In the fourth part of the blog series, I intended to explain the configuration, mapper and dynamic sql of mybatis in detail, but Official Chinese document of Mybatis The introduction of this part has been detailed enough, which can be referred to directly if necessary. So, I'll extend some other features or u ...

Posted on Sat, 25 Apr 2020 21:58:23 -0700 by alsal

PLSQL syntax (variable, if,loop,cursor,exception)

1. Grammar Break executable method saved on the database server for other developers to call It can effectively reduce the data interaction between database and server, improve efficiency and reduce bandwidth consumption Syntax format: declare -- define part, save variable, reference variable, record exception begin -- logical processing ...

Posted on Sat, 25 Apr 2020 07:58:39 -0700 by gplaurin

java jdbc ResultSet results are assigned to Java objects through java reflection

In the case of unconformity framework, when using jdbc to read data from the database, we have to get and set one by one, which is not only tedious but also not concise. So we write a tool class using java reflection mechanism, so it is not so troublesome to use jdbc to get data from the database. Because in many cases there is more than one p ...

Posted on Fri, 24 Apr 2020 09:23:25 -0700 by trace

Some situations that need aliasing in Python programming

Function aliasing is just an application scenario of aliasing, and there are several places where aliasing is used. This note will summarize all kinds of aliases I have encountered. Scenario A: pseudonym when importing When importing other modules, the direct pseudonym is the simple version, which is quite commonly used by me. There are even so ...

Posted on Thu, 23 Apr 2020 01:54:51 -0700 by hdpt00

Fault analysis | effectively solve the timeout problem of MySQL row lock waiting [recommended collection]

By xuty Source: original contribution *Aikesheng is produced by the open source community. The original content cannot be used without authorization. Please contact the editor for reprint and indicate the source. 1, Background #### 20191219 10:10:10,234 | com.alibaba.druid.filter.logging.Log4jFilter.statementLogError(Log4jFilter.java:152) ...

Posted on Tue, 21 Apr 2020 02:02:36 -0700 by oyse

freecplus framework MySQL database operation

1, Source code description Freecplus is a C/C + + open source framework under Linux system. Please go to the C language technology network (www.freecplus.net) to download the source code. This paper introduces the use of connection and sqlstatement classes to operate MySQL database in freecplus framework. The declaration file of the class is f ...

Posted on Mon, 20 Apr 2020 09:34:46 -0700 by dkoolgeek

JDBC mysql large data streaming read

Summarize some problems and solutions in the use of mysql driver to help customers to generate reports next week. Because the logic of report generation needs to read a lot of data from the database and process it in memory, then generate a lot of summary data and write it to the database. The basic process is read - > process - > write.A ...

Posted on Fri, 17 Apr 2020 10:19:16 -0700 by sebthib55

Issue 02: Art of MySQL data type - large object field

I've shared one before MySQL big object example , let's talk about the advantages and disadvantages of large objects and the use scenarios in detail today. We divided MySQL's large object types into TEXT / BLOB and JSON to illustrate. 1, TEXT / BLOB type The difference between TEXT and BLOB is very simple. TEXT is stored in plaintext, with cor ...

Posted on Wed, 15 Apr 2020 01:52:58 -0700 by Daen