MySQL大表基于主键ID删除逻辑

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• 测试环境准备
  • 创建测试表
  • 灌测试数据
  • 创建日志表
• 运行删除数据操作
• 删除后的收尾操作
• MySQL 列转行

测试环境准备

创建测试表

-- 表结构示例
CREATE TABLE `g_device_action_base` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `uid` char(32)  DEFAULT '',
  `domain_id` char(16)  DEFAULT '',
  `machine` char(200)  NOT NULL DEFAULT '',
  `app_type` char(32)  NOT NULL DEFAULT '' ,
  `app_id` char(32)  NOT NULL DEFAULT '' ,
  `action_time` int(11) NOT NULL DEFAULT '0',
  `action_status` int(11) NOT NULL DEFAULT '0',
  `source` char(32)  NOT NULL DEFAULT '',
  `url` varchar(512)  NOT NULL DEFAULT '' COMMENT 'url',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB;

-- 记录示例
mysql> select * from g_device_action_base limit 1\G
           id: 24244024
          uid: 779085e3ac9
    domain_id: LhziEhqb8W
      machine: DBA
     app_type: wechat
       app_id: 3e261dcf5485fb0f1c00
  action_time: 1595222484
action_status: 1
       source: jw_app_hard
          url: https://www.cnblogs.com/zhenxing/

-- 造数据
-- 插入一条基础数据
set session sql_log_bin=off;
insert into g_device_action_base(uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url)
	values('779085e3ac9a32e8927099c2be506228','LhziEhqb8WgS','IOS','jw_app_thirdapp','3e261dcf5485fb0f1c0052f838ae6779',1595222484,1,'zhenxing','https://www.cnblogs.com/zhenxing/');

-- 反复执行,成倍增加
insert into g_device_action_base(id,uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url) select null,uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url from g_device_action_base;

-- 直到生成100W测试数据
select count(*) from g_device_action_base;

-- 基于数据基础表创建测试表
create table g_device_action like g_device_action_base;

灌测试数据

假设g_device_action_base表注入了100万测试数据,现在要模拟5000万的数据删除操作,循环50次,每次重复插入100万数据到g_device_action表中,以下是基本的插入数据的脚本逻辑

#!/bin/bash
for ((i=1;i<=50;i++))
do
echo "load batch $i"
mysql <<EOF
set session sql_log_bin=off;
use demo
insert into g_device_action(uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url)
        select uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url from g_device_action_base;
select sleep(2);
EOF
done

创建日志表

日志表用来分批次删除数据的状态和执行时间等情况,便于追溯删除操作

CREATE TABLE `delete_batch_log` (
  `ID` bigint(20) PRIMARY key AUTO_INCREMENT,
  `BATCH_ID` bigint(20) NOT NULL comment "批次号",
  `SCHEMA_NAME` varchar(64) NOT NULL comment "数据库名称",
  `TABLE_NAME` varchar(64) NOT NULL comment "表名称",
  `BATCH_COUNT` bigint(20) NOT NULL comment "涉及的记录数",
  `BEGIN_RECORD` varchar(100) DEFAULT NULL comment "ID最小值",
  `END_RECORD` varchar(100)DEFAULT NULL comment "ID最大值",
  `BEGIN_TIME` datetime(6) DEFAULT NULL comment "开始时间",
  `END_TIME` datetime(6) DEFAULT NULL comment "结束时间",
  `ERROR_NO` bigint(20) DEFAULT NULL comment "错误码",
  `crc32_values` varchar(64) DEFAULT NULL comment "校验码"
);

-- 创建相关查询需要的索引
CREATE INDEX IDX_DELETE_BATCH_LOG_M1 ON delete_batch_log(BEGIN_RECORD,END_RECORD);
CREATE INDEX IDX_DELETE_BATCH_LOG_M2 ON delete_batch_log(BEGIN_TIME,END_TIME);
CREATE INDEX IDX_DELETE_BATCH_LOG_M3 ON delete_batch_log(TABLE_NAME,SCHEMA_NAME);

运行删除数据操作

脚本batch_delete_table.sh完成了以下任务

1. 设置批量删除的并发度
2. 连接MySQL查询出该表的最小主键ID和最大主键ID
3. 基于最小主键ID和最大主键ID计算以每批次1万条记录的区间,需要执行多少次循环
4. 将删除操作的会话级别设置为RR且binlog格式设置为statement减少binlog的写入量(减少IO压力及从库回放压力)
5. 将每个批次的删除操作基本信息写入到日志表中,包含以下信息

• 数据库名称
• 数据表名称
• 批次号
• 该批次删除的记录数
• 该批次的起始ID
• 该批次的结束ID
• 该批次删除的开始时间
• 该批次删除的结束时间
• 该批次删除是否存在错误(记录错误码)

#!/bin/bash

## SET MySQL CONN INFO
MYSQL_HOST=10.186.61.162
MYSQL_USER=zhenxing
MYSQL_PASS=zhenxing
MYSQL_PORT=3306
MYSQL_DB=demo
BATCH_ROWS=10000
MYSQL_TABLE=g_device_action
PARALLEL_WORKERS=5

## Create Named pipe And File descriptor
[ -e /tmp/fd1 ] || mkfifo /tmp/fd1
exec 3<>/tmp/fd1
rm -rf /tmp/fd1

## Set the parallel
for ((i=1;i<= $PARALLEL_WORKERS;i++))
do
    echo >&3
done

MINID=`mysql -sse "select min(id) from ${MYSQL_DB}.${MYSQL_TABLE};"`
BATCH_TOTAL=`mysql -sse "select ceil((max(id)-min(id))/${BATCH_ROWS}) from ${MYSQL_DB}.${MYSQL_TABLE};"`

## PARALLEL LOAD DATA
for ((i=1;i<=$BATCH_TOTAL;i++))
do
read -u3
{
    BEGIN_RECORD=$[($i-1)*${BATCH_ROWS}+${MINID}]
    END_RECORD=$[($i-0)*${BATCH_ROWS}+${MINID}]
    mysql -h$MYSQL_HOST -u$MYSQL_USER -p$MYSQL_PASS -P$MYSQL_PORT << EOF
    set session transaction_isolation='REPEATABLE-READ';
    set session binlog_format='statement';
    -- set session sql_log_bin=off;
    set @BEGIN_TIME=now(6);
    select count(*),CONV(bit_xor(crc32(concat_ws('',id,uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url))),10,16) into @row_count,@crc32_values from ${MYSQL_DB}.${MYSQL_TA
BLE} where id>=${BEGIN_RECORD} and id<${END_RECORD} and action_time<1595222485;
    delete from ${MYSQL_DB}.${MYSQL_TABLE} where id>=${BEGIN_RECORD} and id<${END_RECORD} and action_time<1595222485;
    set @END_TIME=now(6);

    GET DIAGNOSTICS @p1=NUMBER,@p2=ROW_COUNT;
    insert into ${MYSQL_DB}.delete_batch_log(BATCH_ID,SCHEMA_NAME,TABLE_NAME,BATCH_COUNT,BEGIN_RECORD,END_RECORD,BEGIN_TIME,END_TIME,ERROR_NO,crc32_values) values (${i},'${MYSQL_DB}','${MYSQL
_TABLE}',@row_count,${BEGIN_RECORD},${END_RECORD},@BEGIN_TIME,@END_TIME,@p1,@crc32_values);
EOF
    echo >&3
} &
done
wait

exec 3<&-
exec 3>&-

删除后的收尾操作

删除完成后可用以下SQL查看删除的汇总情况

select SCHEMA_NAME,TABLE_NAME,min(BATCH_ID) as "最小批次",max(BATCH_ID) as "最大批次",sum(BATCH_COUNT) as "删除记录总数",min(BEGIN_TIME) as "开始时间",max(END_TIME) as "结束时间",TIMESTAMPDIFF(SECOND,min(BEGIN_TIME),max(END_TIME)) as "时间消耗(秒)" from delete_batch_log group by SCHEMA_NAME,TABLE_NAME;
*************************** 1. row ***************************
       SCHEMA_NAME: demo
        TABLE_NAME: g_device_action
      最小批次: 1
      最大批次: 5415
删除记录总数: 51534336
      开始时间: 2020-07-16 10:56:46.347799
      结束时间: 2020-07-16 11:00:29.617498
 时间消耗(秒): 223
1 row in set (0.01 sec)

大表通过以上方式删除大量数据后,磁盘表空间并不会释放,需要将表进行收缩,该操作根据表空间的大小执行时间不同,以当前测试环境为例,表空间大小为32G,删除了5000万数据,耗时约1分钟

alter table g_device_action engine=innodb;

删除5000万条记录,基于statement模式产生的binlog约20M

校验命令

select count(*),CONV(bit_xor(crc32(concat(id,uid,domain_id,machine,app_type,app_id,action_time,action_status,source,url))),10,16) as crc32_values  from g_device_action where id>=12520001 and id<12530001;

MySQL 列转行

set global group_concat_max_len=102400;
set group_concat_max_len=102400;
SELECT @@global.group_concat_max_len;
SELECT @@group_concat_max_len;
select table_name,concat(group_concat(COLUMN_NAME order by ORDINAL_POSITION separator ',')) as all_columns
from information_schema.COLUMNS tb1
where table_schema='demo'
and table_name='g_device_action'
group by table_name;

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