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mysql one or multiple data bases?


mysql one or multiple data bases?

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mysql one or multiple data bases?
Tag : mysql , By : stan
Date : January 12 2021, 08:33 AM

hop of those help? You should stick with one database and one database only unless you have specific reasons to violate that rule. Examples of valid reasons include:
You've got a multi-tenant application and the instances of this application do not share data, so you spread them out across multiple databases to eliminate a single point of failure. Even then, these instances are just clones of the same basic schema. You need to shard your data across multiple instances for performance reasons or because of storage constraints that can't be solved in a cost-effective manner any other way. These shards share a schema, but only a portion of the complete data set. You need to create a replica or derivative set of data for data-warehouse and/or reporting reasons. These instances may have a radically different schema because they're optimized around read activities, not writes.

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How to migrate data between MySQL bases on different servers?


Tag : mysql , By : dummyadresse
Date : March 29 2020, 07:55 AM
may help you . You can do it with a combination of UPDATE and SELECT query. However since TABLE 1 has the column title which is of type VARCHAR(255) and TABLE 2 has the column Name which is of type VARCHAR(100) might give a problem.
The following query can do this migration however any row with column title having length more than 100 will be SHORTENED to 100.
INSERT INTO T2 
(ID, Name, UserID) 
SELECT id, SUBSTR(title, 0, 100), uid 
FROM T1

Spring Framework connect to multiple data bases xml JAVA


Tag : java , By : Alex Bartzas
Date : March 29 2020, 07:55 AM
help you fix your problem I am trying to connect to two data bases in using my db config file. If i define second bean for data source i have an exception for a not writable property. Which is the correct way to define two data sources ? And do i need to do something in my java classes ? , I find the solution of my problem.
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans     
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="org.postgresql.Driver" />
        <property name="url" value="jdbc:postgresql://localhost:5432/test" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </bean>

    <bean id="dataSourceSecond"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="org.postgresql.Driver" />
        <property name="url" value="jdbc:postgresql://localhost:5432/test" />
        <property name="username" value="root" />
        <property name="password" value="root" />
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource" />
    </bean>

    <bean id="jdbcTemplateSecond" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSourceSecond" />
    </bean>

</beans> 

Executing raw sql against multiple data bases


Tag : ruby-on-rails , By : vasil
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further You may use ActiveRecord::Base.establish_connection to switch database connection. Code should be like this:
#database.yml
development:
  adapter: postgresql
  host: 127.0.0.1
  username: postgres
  password: postgres
  database: development_db

development_another_db:
  adapter: postgresql
  host: 127.0.0.1
  username: postgres
  password: postgres
  database: another_db


ActiveRecord::Base.establish_connection :development_another_db
sql = "Select * from ... your sql query here"
records_array = ActiveRecord::Base.connection.execute(sql)

ActiveRecord::Base.establish_connection :development
sql = "Another select"
records_array = ActiveRecord::Base.connection.execute(sql)

If I reinstall MySql Workbech will i lose my data bases and saved connections?


Tag : mysql , By : jamerson
Date : March 29 2020, 07:55 AM
wish help you to fix your issue Mysql workbench is a standalone software. It won't affect your MySQL databases. It's same as removing phpMyAdmin from your server won't affect your databases.

Connect to Multiple data bases using Zend Framework 2 and DoctrineORMModule


Tag : database , By : Simon Hogg
Date : March 29 2020, 07:55 AM
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