sharding-jdbc 按月份分表
<!--sharding-jdbc -->
<dependency>
<groupId>io.shardingsphere</groupId>
<artifactId>sharding-jdbc-spring-boot-starter</artifactId>
<version>3.1.0</version>
</dependency>
<!--sharding-jdbc结束-->
sharding-jdbc 按月份分表须要本身实现。须要实现两个接口PreciseShardingAlgorithm，RangeShardingAlgorithm（还没实现）。并在配置文件里添加实现路径
以下：com.simianBook.conf.TimeShardingTableAlgorithm
那么yml 里的配置路径以下java
sharding:
jdbc:
datasource:
names: user-0,user-1
user-0: #springboot 在yml 配置里key不支持 '_' 推荐使用'-'
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/t_user_0?characterEncoding=UTF-8&serverTimezone=GMT
username: root
password: hou1147646079
user-1:
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/t_user_1?characterEncoding=UTF-8&serverTimezone=GMT
username: root
password: hou1147646079
config:
sharding: #分片
default-database-strategy:
inline:
sharding-column: user_id
algorithm-expression: user ->${user_id % 2}
props:
sql.show: true
tables:
user:
key-generator-column-name: user_id #user 表的主键
database-strategy:
inline:
shardingColumn: user_id #数据库分片测略
algorithm-expression: user-${user_id % 2} #
# actual-data-nodes: user-${0..1}.user_${0..1} #设置的datasource 的名字 如user-0,user-1,user_${0..1} 数据库中的
table-strategy:
standard: # 单列sharidng算法,须要配合对应的preciseShardingAlgorithm,rangeShardingAlgorithm接口的实现使用,目前无生产可用实现
shardingColumn: user_id # 列名,容许单列
precise-algorithm-class-name: com.simianBook.config.TimeShardingTableAlgorithm # preciseShardingAlgorithm接口的实现类
# rangeShardingAlgorithm: # rangeShardingAlgorithm接口的实现类
# inline:
# sharding-column: user_id
# algorithm-expression: user_${user_id % 2}
defaultTableStrategy:
none:
defaultKeyGenerator:
type: SNOWFLAKE
下面须要来编写按月分表的方法node
package com.simianBook.config;
import io.shardingsphere.api.algorithm.sharding.PreciseShardingValue;
import io.shardingsphere.api.algorithm.sharding.standard.PreciseShardingAlgorithm;
import io.shardingsphere.core.keygen.DefaultKeyGenerator;
import java.text.SimpleDateFormat;
import java.util.Collection;
public class TimeShardingTableAlgorithm implements PreciseShardingAlgorithm<Long> {
private SimpleDateFormat dateformat = new SimpleDateFormat("yyyyMM");
@Override
public String doSharding(Collection<String> availableTargetNames, PreciseShardingValue<Long> shardingValue) {
StringBuffer tableName = new StringBuffer();
tableName.append(shardingValue.getLogicTableName())
.append("_").append(getTime(shardingValue.getValue()));
return tableName.toString();
}
public String getTime(long shardingKey){
return dateformat.format(DefaultKeyGenerator.EPOCH+(Long.valueOf(shardingKey+"")>>22));
}
}
我是使用sharding-jdbc 自带的雪花算法 来生成主键的，雪花算法的实现逻辑
所以我在获得分片键时对分片键进行逆推能够推出分片键的时间戳。再根据时间戳获得建立此条数据建立的年月进而定位到那个表位置（或者说表名）
DefaultKeyGenerator.EPOCH+(Long.valueOf(shardingKey+"")>>22)
DefaultKeyGenerator.EPOCH 表示起始时间。在雪花算法当中生成的时间戳须要减去起始时间在进行左移22位在进行或运算
sharding-jdbc 的雪花实现方法以下 版本3.0 该版本有bug 并发量低的时候生成的分片键始终为偶数mysql
public synchronized Number generateKey() {
long currentMillis = timeService.getCurrentMillis();
Preconditions.checkState(this.lastTime <= currentMillis, "Clock is moving backwards, last time is %d milliseconds, current time is %d milliseconds", new Object[]{this.lastTime, currentMillis});
if (this.lastTime == currentMillis) { //最新时间与当前时间相同（发生并发）
// //sequence+1 若是suquence&4095L==0时条件成立时
if (0L == (this.sequence = this.sequence + 1L & 4095L)) {
currentMillis = this.waitUntilNextTime(currentMillis);//获取最新时间
}
} else {
this.sequence = 0L; //此处有bug 并发量低的时候this.sequence始终为0L的
}
this.lastTime = currentMillis;
return currentMillis - EPOCH << 22 | workerId << 12 | this.sequence;
}
3.1.0 版本解决了 本身能够看一下有什么不一样web
public synchronized Number generateKey() {
long currentMilliseconds = timeService.getCurrentMillis();
if (this.waitTolerateTimeDifferenceIfNeed(currentMilliseconds)) {
currentMilliseconds = timeService.getCurrentMillis();
}
if (this.lastMilliseconds == currentMilliseconds) {
if (0L == (this.sequence = this.sequence + 1L & 4095L)) {
currentMilliseconds = this.waitUntilNextTime(currentMilliseconds);
}
} else {
this.vibrateSequenceOffset();
this.sequence = (long)this.sequenceOffset;
}
this.lastMilliseconds = currentMilliseconds;
return currentMilliseconds - EPOCH << 22 | workerId << 12 | this.sequence;
}
更新RangeShardingAlgorithm 的实现算法
package com.simianBook.config;
import com.google.common.collect.Range;
import com.simianBook.tool.ParaseShardingKeyTool;
import io.shardingsphere.api.algorithm.sharding.RangeShardingValue;
import io.shardingsphere.api.algorithm.sharding.standard.RangeShardingAlgorithm;
import io.shardingsphere.core.keygen.DefaultKeyGenerator;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.LinkedHashSet;
import java.util.stream.Stream;
/**
* 搜查多表
* 范围搜索时（跨表）应传递时间戳并左移22位
*/
public class TimeRangeShardingAlgorithm implements RangeShardingAlgorithm<Long> {
private SimpleDateFormat dateformat = new SimpleDateFormat("yyyyMM");
@Override
public Collection<String> doSharding(Collection<String> availableTargetNames, RangeShardingValue<Long> shardingValue) {
Collection<String> result = new LinkedHashSet<String>();
Range<Long> shardingKey = shardingValue.getValueRange();
long startShardingKey = shardingKey.lowerEndpoint();
long endShardingKey = shardingKey.upperEndpoint();
String startTimeString = ParaseShardingKeyTool.getYearAndMonth(startShardingKey);//获取到开始时间戳
String endTimeString = ParaseShardingKeyTool.getYearAndMonth(endShardingKey);//获取结束时间戳
Calendar cal = Calendar.getInstance();
Date startTime = new Date(dateformat.format(startTimeString));//获取开始的年月
Date endTime = new Date(dateformat.format(endTimeString));//获取结束的年月
while(startTime.getTime() < endTime.getTime()){ //进行判断 获取跨月份的表 如201901,201902,201903 三个月的表
StringBuffer tableName = new StringBuffer();
tableName.append(shardingValue.getLogicTableName())
.append("_").append(dateformat.format(startTime));
result.add(tableName.toString());
}
return result;
}
}
ParaseShardingKeyToolspring
package com.simianBook.tool;
import io.shardingsphere.core.keygen.DefaultKeyGenerator;
import java.text.SimpleDateFormat;
public class ParaseShardingKeyTool {
private static SimpleDateFormat yearAndMonth = new SimpleDateFormat("yyyyMM");
private static SimpleDateFormat year = new SimpleDateFormat("yyyy");
public static String getYearAndMonth(long shardingKey){
return yearAndMonth.format(DefaultKeyGenerator.EPOCH+(Long.valueOf(shardingKey+"")>>22));
}
public static String getYear(long shardingKey){
return year.format(DefaultKeyGenerator.EPOCH+(Long.valueOf(shardingKey+"")>>22));
}
}