testrecord數據庫中存儲着玩家行為記錄，每三個月需要清理掉。
刪除數據前的准備
查看testrecord數據庫的大小：
MySQL [(none)]> USE information_schema;
Database changed
MySQL [information_schema]> SELECT CONCAT(ROUND(SUM(DATA_LENGTH/1024/1024/1024),2),'GB')
-> as DATA FROM TABLES WHERE
-> table_schema='testrecord';
+---------+
| DATA |
+---------+
| 56.70GB |
+---------+
1 row in set (0.00 sec)
查看testrecord數據庫各數據表大小：
MySQL [information_schema]> SELECT
-> table_schema as '數據庫',
-> table_name as '表名',
-> table_rows as '記錄數',
-> TRUNCATE(data_length/1024/1024/1024, 2) as '數據容量(GB)',
-> TRUNCATE(index_length/1024/1024/1024, 2) as '索引容量(GB)'
-> FROM information_schema.tables
-> WHERE table_schema='testrecord'
-> ORDER BY data_length DESC, index_length DESC;
+----------- +-------------------+-----------+----------------+----------------+
| 數據庫 | 表名 | 記錄數 | 數據容量(GB) | 索引容量(GB) |
+----------- +-------------------+----------------------------+----------------+
| testrecord | playeritem | 71206129 | 9.71 | 4.17 |
| testrecord | dropcord | 102342337 | 7.92 | 6.22 |
| testrecord | ipcord | 22256444 | 4.97 | 3.93 |
| testrecord | store | 16583137 | 2.58 | 1.20 |
| testrecord | teip | 6887136 | 2.43 | 1.28 |
以上得知：
需要清理數據的前三個數據表分別是：playeritem、dropcord、ipcord
查看創建數據表的SQL語句：
MySQL [(none)]> USE testrecord;
Database changed
MySQL [testrecord]> SHOW CREATE TABLE playeritem \G
*************************** 1. row ***************************
Table: playeritem
Create Table: CREATE TABLE `playeritem` (
#——————————————————字段結構略————————————————————————#
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT
/*!50100 PARTITION BY RANGE (`cordTime`)
(PARTITION `playeritem_2021-05` VALUES LESS THAN (1622476800) ENGINE = InnoDB,
PARTITION `playeritem_2021-06` VALUES LESS THAN (1625068800) ENGINE = InnoDB,
PARTITION `playeritem_2021-07` VALUES LESS THAN (1627747200) ENGINE = InnoDB,
PARTITION `playeritem_2021-08` VALUES LESS THAN (1630425600) ENGINE = InnoDB,
PARTITION `playeritem_2021-09` VALUES LESS THAN (1633017600) ENGINE = InnoDB,
PARTITION `playeritem_2021-10` VALUES LESS THAN (1635696000) ENGINE = InnoDB,
PARTITION `playeritem_2021-11` VALUES LESS THAN (1638288000) ENGINE = InnoDB,
PARTITION `playeritem_2021-12` VALUES LESS THAN (1640966400) ENGINE = InnoDB,
PARTITION playeritem_max VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */
1 row in set (0.00 sec)
MySQL [testrecord]> SHOW CREATE TABLE dropcord \G
*************************** 1. row ***************************
Table: dropcord
Create Table: CREATE TABLE `dropcord` (
#——————————————————字段結構略————————————————————————#
) ENGINE=InnoDB DEFAULT CHARSET=utf8
/*!50100 PARTITION BY RANGE (to_days(cordtime))
(PARTITION p202105 VALUES LESS THAN (738307) ENGINE = InnoDB,
PARTITION p202106 VALUES LESS THAN (738337) ENGINE = InnoDB,
PARTITION p202107 VALUES LESS THAN (738368) ENGINE = InnoDB,
PARTITION p202108 VALUES LESS THAN (738399) ENGINE = InnoDB,
PARTITION p202109 VALUES LESS THAN (738429) ENGINE = InnoDB,
PARTITION p202110 VALUES LESS THAN (738460) ENGINE = InnoDB,
PARTITION p202111 VALUES LESS THAN (738490) ENGINE = InnoDB,
PARTITION p202112 VALUES LESS THAN (738521) ENGINE = InnoDB,
PARTITION pmax VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */
1 row in set (0.00 sec)
MySQL [testrecord]> SHOW CREATE TABLE ipcord \G
*************************** 1. row ***************************
Table: ipcord
Create Table: CREATE TABLE `ipcord` (
#——————————————————字段結構略————————————————————————#
) ENGINE=InnoDB DEFAULT CHARSET=utf8
/*!50100 PARTITION BY RANGE (to_days(cordtime))
(PARTITION p202105 VALUES LESS THAN (738307) ENGINE = InnoDB,
PARTITION p202106 VALUES LESS THAN (738337) ENGINE = InnoDB,
PARTITION p202107 VALUES LESS THAN (738368) ENGINE = InnoDB,
PARTITION p202108 VALUES LESS THAN (738399) ENGINE = InnoDB,
PARTITION p202109 VALUES LESS THAN (738429) ENGINE = InnoDB,
PARTITION p202110 VALUES LESS THAN (738460) ENGINE = InnoDB,
PARTITION p202111 VALUES LESS THAN (738490) ENGINE = InnoDB,
PARTITION p202112 VALUES LESS THAN (738521) ENGINE = InnoDB,
PARTITION pmax VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */
1 row in set (0.00 sec)
以上得知：
數據表采用了RNAGE分區，分別以月份天數創建了分區
查看數據表分區情況
MySQL [testrecord]> SELECT PARTITION_NAME part,
-> PARTITION_EXPRESSION expr,
-> PARTITION_DESCRIPTION descr,
-> TABLE_ROWS
-> FROM information_schema.PARTITIONS
-> WHERE TABLE_SCHEMA = schema() AND TABLE_NAME = 'playeritem';
+--------------------+------------+------------+------------+
| part | expr | descr | TABLE_ROWS |
+--------------------+------------+------------+------------+
| playeritem_2021-05 | `cordTime` | 1622476800 | 96549342 |
| playeritem_2021-06 | `cordTime` | 1625068800 | 26259322 |
| playeritem_2021-07 | `cordTime` | 1627747200 | 44541353 |
| playeritem_2021-08 | `cordTime` | 1630425600 | 27246100 |
| playeritem_2021-09 | `cordTime` | 1633017600 | 29226451 |
| playeritem_2021-10 | `cordTime` | 1635696000 | 6806093 |
| playeritem_2021-11 | `cordTime` | 1638288000 | 0 |
| playeritem_2021-12 | `cordTime` | 1640966400 | 0 |
| playeritem_max | `cordTime` | MAXVALUE | 0 |
+------------------------+-------------------+------------+------------+
9 rows in set (0.00 sec)
MySQL [testrecord]> SELECT PARTITION_NAME part,
-> PARTITION_EXPRESSION expr,
-> PARTITION_DESCRIPTION descr,
-> TABLE_ROWS
-> FROM information_schema.PARTITIONS
-> WHERE TABLE_SCHEMA = schema() AND TABLE_NAME = 'dropcord';
+---------+-------------------+----------+------------+
| part | expr | descr | TABLE_ROWS |
+---------+-------------------+----------+------------+
| p202105 | to_days(cordtime) | 738307 | 60519201 |
| p202106 | to_days(cordtime) | 738337 | 30759304 |
| p202107 | to_days(cordtime) | 738368 | 55525655 |
| p202108 | to_days(cordtime) | 738399 | 51800453 |
| p202109 | to_days(cordtime) | 738429 | 58897747 |
| p202110 | to_days(cordtime) | 738460 | 14470693 |
| p202111 | to_days(cordtime) | 738490 | 0 |
| p202112 | to_days(cordtime) | 738521 | 0 |
| pmax | to_days(cordtime) | MAXVALUE | 0 |
+---------+---------------------+----------+------------+
9 rows in set (0.00 sec)
MySQL [testrecord]> SELECT PARTITION_NAME part,
-> PARTITION_EXPRESSION expr,
-> PARTITION_DESCRIPTION descr,
-> TABLE_ROWS
-> FROM information_schema.PARTITIONS
-> WHERE TABLE_SCHEMA = schema() AND TABLE_NAME = 'ipcord';
+---------+---------------------+----------+------------+
| part | expr | descr | TABLE_ROWS |
+---------+---------------------+----------+------------+
| p202105 | to_days(cordtime) | 738307 | 70512202 |
| p202106 | to_days(cordtime) | 738337 | 50759503 |
| p202107 | to_days(cordtime) | 738368 | 65529654 |
| p202108 | to_days(cordtime) | 738399 | 11692729 |
| p202109 | to_days(cordtime) | 738429 | 17989204 |
| p202110 | to_days(cordtime) | 738460 | 5010364 |
| p202111 | to_days(cordtime) | 738490 | 0 |
| p202112 | to_days(cordtime) | 738521 | 0 |
| pmax | to_days(cordtime) | MAXVALUE | 0 |
+---------+---------------------+----------+------------+
9 rows in set (0.00 sec)
刪除數據
依次刪除5、6、7月的數據
ALTER TABLE playeritem DROP PARTITION playeritem_2021-05;
ALTER TABLE dropcord DROP PARTITION p202105;
ALTER TABLE ipcord DROP PARTITION p202105;
刪除數據后的檢查
依次檢查分區表情況
MySQL [testrecord]> SELECT PARTITION_NAME part,
-> PARTITION_EXPRESSION expr,
-> PARTITION_DESCRIPTION descr,
-> TABLE_ROWS
-> FROM information_schema.PARTITIONS
-> WHERE TABLE_SCHEMA = schema() AND TABLE_NAME = 'dropcord';
+---------+---------------------+----------+------------+
| part | expr | descr | TABLE_ROWS |
+---------+---------------------+----------+------------+
| p202108 | to_days(recordtime) | 738399 | 51800453 |
| p202109 | to_days(recordtime) | 738429 | 58897747 |
| p202110 | to_days(recordtime) | 738460 | 14496732 |
| p202111 | to_days(recordtime) | 738490 | 0 |
| p202112 | to_days(recordtime) | 738521 | 0 |
| pmax | to_days(recordtime) | MAXVALUE | 0 |
+---------+---------------------+----------+------------+
6 rows in set (0.00 sec)
並再次檢查數據表大小確認存儲空間是否已釋放。
將以上操作寫入腳本
clear_table_partition.sh
#!/bin/sh
source /root/.bash_profile
for db in $(mysql_cmd -Ne "SHOW DATABASES;" | grep testrecord)
do
# look the table partitions
l_t_cmd="SELECT PARTITION_NAME part, \
PARTITION_EXPRESSION expr, \
PARTITION_DESCRIPTION descr, \
TABLE_ROWS \
FROM information_schema.PARTITIONS \
WHERE \
TABLE_SCHEMA = schema() \
AND TABLE_NAME = 'ipcord';"
echo $l_t_cmd
echo $db
mysql_cmd -e "USE $db; $l_t_cmd;"
# drop the table partitions
d_t_cmd="ALTER TABLE playeritem DROP PARTITION playeritem_2021-05;
ALTER TABLE playeritem DROP PARTITION playeritem_2021-06;
ALTER TABLE playeritem DROP PARTITION playeritem_2021-07;
ALTER TABLE dropcord DROP PARTITION p202105;
ALTER TABLE dropcord DROP PARTITION p202106;
ALTER TABLE dropcord DROP PARTITION p202107;
ALTER TABLE ipcord DROP PARTITION p202105;
ALTER TABLE ipcord DROP PARTITION p202106;
ALTER TABLE ipcord DROP PARTITION p202107;"
echo $d_t_cmd
echo $db
mysql_cmd -e "USE $db; $d_t_cmd;"
done
總結
1、source命令可在當前shell環境中讀取並執行來自文件里的命令
2、環境變量文件.bash_profile對當前登錄用戶有效，在文件內設置登錄MySQL別名，簡化代碼：
3、mysql命令行工具選項 -Ne 的解釋：
-e, --execute=name 表示執行MySQL語句並退出
-N, --skip-column-names 選項表示不要在結果中寫入列名
有無 -N選項的區別如下：
[root@mysql ~]# mysql -uroot -p -e "SHOW DATABASES;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
[root@mysql ~]# mysql -uroot -p -Ne "SHOW DATABASES;"
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4、$()是shell的命令替換字符，shell會先執行括號里面的命令，並返回命令執行的標准輸出結果
5、變量名l_t_cmd 定義的是查看表分區的語句，由此得知數據表采用了表分區
6、echo ${l_t_cmd}、echo ${db}，使用echo將變量值輸出，使腳本在執行過程中具有可讀性
7、變量名d_t_cmd定義了刪除表分區的語句，即使用ALTER TABLE table_name DROP PARTITION part_name語句刪除表分區
8、INFORMATION_SCHEMA是每個 MySQL 實例中的數據庫，存儲有關 MySQL 服務器維護的所有其他數據庫的詳細信息
9、前面查看見建表語句時，descr列的數字代表的是時間戳，時間戳的值如何得來？
通過以下語句獲得，
TO_DAY(date)函數返回日期date距離0000年1月1日的天數。
UNIX_TIMESTAMP(date)函數返回UNIX時間戳，自'1970-01-01 00:00:00'的到當前時間的秒數差
MariaDB [(none)]> SELECT TO_DAYS('2021-07-01 00:00:00');
+--------------------------------+
| TO_DAYS('2021-07-01 00:00:00') |
+--------------------------------+
| 738337 |
+--------------------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT UNIX_TIMESTAMP('2021-07-01 00:00:00');
+---------------------------------------+
| UNIX_TIMESTAMP('2021-07-01 00:00:00') |
+---------------------------------------+
| 1625068800 |
+---------------------------------------+
1 row in set (0.00 sec)