# 实验 6：使用 TiDB Lightning 将数据导入 TiDB ## 概述 在本实验中，你将使用 `TiDB Lightning` 将数据导入 TiDB。以下展示了 TiDB 集群的部署拓扑图。 ![60%](https://lab-static.pingcap.com/quick-demo/TiDBClusterDeploymentTopologyExercisewithLighting_aa_003_20230301.png) > [!TIP] > 点击 **开始** 启动实验环境。 > 环境准备就绪后，点击底部工具栏中的 **前进** 进入 **模块 1**。 > 然后，按照实验指南的步骤连接到实践环境并开始你的任务。 ## 模块 1：将 CSV 文件导入 TiDB ### 步骤 1：登录远程 Linux + 点击这里 - [终端 1](ssh://monitor1-ssh#1) 打开一个新的终端，连接到为你的实践实验分配的虚拟机。 + 登录后显示的横幅： ```output , #_ ~\_ ####_ Amazon Linux 2 ~~ \_#####\ ~~ \###| ~~ \#/ ___ ~~ V~' '-> ~~~ / A newer version of Amazon Linux is available! ~~._. _/ _/ _/ Amazon Linux 2023, GA and supported until 2028-03-15. _/m/' https://aws.amazon.com/linux/amazon-linux-2023/ ``` ### 步骤 2. 为 Lightning 任务创建一个用户 ```bash source hosts-env.sh ``` ```bash mysql -h ${HOST_DB1_PRIVATE_IP} -uroot -P4000 ``` ```sql CREATE USER ltask@'%' IDENTIFIED BY 'q1w2e3R4_'; ``` ```output mysql> CREATE USER ltask@'%' IDENTIFIED BY 'q1w2e3R4_'; Query OK, 0 rows affected (0.05 sec) ``` ```sql GRANT ALL PRIVILEGES ON *.* TO ltask@'%'; ``` ```output mysql> GRANT ALL PRIVILEGES ON *.* TO ltask@'%'; Query OK, 0 rows affected (0.05 sec) ``` ```sql EXIT; ``` ```output mysql> EXIT; ``` ### 步骤 3. 在 `monitor1` 上安装 `TiDB Lightning` ```bash tiup install tidb-lightning ``` ### 步骤 4. 解压数据 ```bash unzip -u stage/tidb-admin-dataset-v2.zip -d stage/ ``` ```output Archive: tidb-admin-dataset-v2.zip creating: TiDB-Administration-exercise-data-v2/ ... ``` ### 步骤 5. 列出 CSV 数据目录中的文件 ```bash ls ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-CSV-File ``` ```output emp.sal.000000000.csv emp.sal.000000002.csv emp.sal.000000004.csv emp.sal.000000006.csv emp.sal.000000008.csv emp.sal.000000010.csv emp.sal.000000001.csv emp.sal.000000003.csv emp.sal.000000005.csv emp.sal.000000007.csv emp.sal.000000009.csv metadata ``` ### 步骤 6. 查看 `emp.sal.000000000.csv` 文件 ```bash head -n 10 ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-CSV-File/emp.sal.000000000.csv ``` ```output "emp_no","salary","from_date","to_date" 10001,60117,"1986-06-26","1987-06-26" 10001,62102,"1987-06-26","1988-06-25" 10001,66074,"1988-06-25","1989-06-25" 10001,66596,"1989-06-25","1990-06-25" 10001,66961,"1990-06-25","1991-06-25" 10001,71046,"1991-06-25","1992-06-24" 10001,74333,"1992-06-24","1993-06-24" 10001,75286,"1993-06-24","1994-06-24" 10001,75994,"1994-06-24","1995-06-24" ``` ```bash wc -l ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-CSV-File/emp.sal.000000000.csv ``` ```output 275696 /home/ec2-user/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-CSV-File/emp.sal.000000000.csv ``` ### 步骤 7. 查看 lightning 的配置文件 + 查看 `solution-lightning-csv.toml`。下面显示的 IP 地址可能会与你的不同。 ```bash cd ``` ```bash cat solution-lightning-csv.toml ``` ```output [lightning] # The concurrency number of data. It is set to the number of logical CPU # cores by default. When deploying together with other components, you can # set it to 75% of the size of logical CPU cores to limit the CPU usage. # region-concurrency = 1 # Logging level = "info" file = "tidb-lightning-csv.log" [tikv-importer] # Sets the backend to the "local" mode. backend = "local" # Sets the directory of temporary local storage. sorted-kv-dir = "/tmp/sorted-kv-dir" [mydumper] # Local source data directory data-source-dir = "/home/ec2-user/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-CSV-File" # Configures the wildcard rule. By default, all tables in the mysql, sys, INFORMATION_SCHEMA, PERFORMANCE_SCHEMA, METRICS_SCHEMA, and INSPECTION_SCHEMA system databases are filtered. # If this item is not configured, the "cannot find schema" error occurs when system tables are imported. filter = ['*.*', '!mysql.*', '!sys.*', '!INFORMATION_SCHEMA.*', '!PERFORMANCE_SCHEMA.*', '!METRICS_SCHEMA.*', '!INSPECTION_SCHEMA.*'] [[mydumper.files]] # Import only 00001~05000 data files and ignore other files pattern = '(?i)(?:[/]*/)*emp\.sal\.(00000000[0-1]|000000001)\.csv' schema = "emp" table = "sal" type = "csv" [mydumper.csv] # Separator between fields. Must not be empty. separator = ',' # Quoting delimiter. Empty value means no quoting. delimiter = '"' # Line terminator. Empty value means both "\n" (LF) and "\r\n" (CRLF) are line terminators. terminator = "" # Whether the CSV files contain a header. # If `header` is true, the first line will be skipped. header = true # Whether the CSV contains any NULL value. # If `not-null` is true, all columns from CSV cannot be NULL. not-null = false # When `not-null` is false (that is, CSV can contain NULL), # fields equal to this value will be treated as NULL. null = '\N' # Whether to interpret backslash escapes inside fields. backslash-escape = true # If a line ends with a separator, remove it. trim-last-separator = false [tidb] # Configuration of any TiDB server from the cluster. host = "" port = 4000 user = "ltask" password = "q1w2e3R4_" # Table schema information is fetched from TiDB via this status-port. status-port = 10080 # Address of any PD server from the cluster. pd-addr = "10.90.2.84:2379" ``` ### 步骤 8. 连接到 TiDB ```bash mysql -h ${HOST_DB1_PRIVATE_IP} --port 4000 -u root ``` ### 步骤 9. 准备 schema ```sql DROP DATABASE IF EXISTS emp; ``` ```output mysql> DROP DATABASE IF EXISTS emp; Query OK, 0 rows affected (0.21 sec) ``` ```sql CREATE DATABASE emp; ``` ```output mysql> CREATE DATABASE emp; Query OK, 0 rows affected (0.07 sec) ``` ```sql USE emp; ``` ```output mysql> USE emp; Database changed ``` ```sql CREATE TABLE `sal` ( `emp_no` INT(11) NOT NULL, `salary` INT(11) NOT NULL, `from_date` DATE NOT NULL, `to_date` DATE NOT NULL, PRIMARY KEY (`emp_no`,`from_date`)); ``` ```output mysql> CREATE TABLE `sal` ( `emp_no` INT(11) NOT NULL, `salary` INT(11) NOT NULL, `from_date` DATE NOT NULL, `to_date` DATE NOT NULL, PRIMARY KEY (`emp_no`,`from_date`)); Query OK, 0 rows affected (0.08 sec) ``` ```sql SELECT COUNT(*) FROM emp.sal; ``` ```output mysql> SELECT COUNT(*) FROM emp.sal; +----------+ | COUNT(*) | +----------+ | 0 | +----------+ 1 row in set (0.00 sec) ``` ```sql EXIT; ``` ```output mysql> EXIT; ``` ### 步骤 10. 使用 Lightning 导入数据 + 使用 `nohup` 命令启动 `tidb-lightning` 进程。（你可以按 Enter `tidb-lighting` 在后台运行）： ```bash nohup tiup tidb-lightning -config solution-lightning-csv.toml > nohup.out & ``` ```output [1] 17481 nohup: ignoring input and redirecting stderr to stdout ... [1]+ Done nohup tiup tidb-lightning -config solution-tidb-lightning-csv.toml > nohup.out ``` ### 步骤 11. 查看 Lightning 的输出 + 查看 `nohup.out` 文件的内容，以验证 `TiDB Lightning` 已退出： ```bash cat nohup.out ``` ```output Verbose debug logs will be written to tidb-lightning-csv.log +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | # | CHECK ITEM | TYPE | PASSED | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 1 | Source csv files size is proper | performance | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 2 | checkpoints are valid | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 3 | table schemas are valid | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 4 | Cluster is available | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 5 | Lightning has the correct storage permission | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 6 | sorted-kv-dir:/tmp/sorted-kv-dir and data-source-dir:/home/ec2-user/sample/csv are in the same disk, may slow down performance | performance | false | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 7 | local disk resources are rich, estimate sorted data size 20.53MiB, local available is 5.15GiB | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 8 | Cluster available is rich, available is 54.48GiB, we need 61.58MiB | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 9 | Cluster doesn't have too many empty regions | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 10 | Cluster region distribution is balanced | critical | true | +----+-----------------------------------------------------------------------------------------------------------------------+-------------+--------+ tidb lightning exit successfully ``` + 如果发生任何错误，查看 `tidb-lightning-csv.log` 文件的内容，以确定错误原因： ```bash less tidb-lightning-csv.log ``` + 你可能需要在再次导入数据之前删除 lightning checkpoint 检查点。以下命令假设检查点存储在 `/tmp/` 中。 ```bash rm /tmp/tidb_lightning_checkpoint.pb ``` ### 步骤 12. 在 TiDB 中查看数据 ```bash mysql -h ${HOST_DB1_PRIVATE_IP} --port 4000 -u root ``` ```sql SELECT COUNT(*) FROM emp.sal; ``` ```output mysql> SELECT COUNT(*) FROM emp.sal; +----------+ | COUNT(*) | +----------+ | 551395 | +----------+ 1 row in set (0.20 sec) ``` ```sql EXIT ``` ```output mysql> EXIT; Bye ``` ## 模块 2：并行将数据导入 TiDB + 在本练习中，你将使用 `TiDB Lightning` 并行地将多个表导入 TiDB。下图展示了如何使用 `TiDB Lightning` 并行地将分片数据库和表导入 TiDB。在我们的示例中，`my_table_1` 包含所有 ID 为奇数的记录，而 `my_table_2` 包含所有 ID 为偶数的记录 ![60%](https://lab-static.pingcap.com/quick-demo/TiDBLightningLabToplogy_aa_003_20220725.png) ### 步骤 1. 列出数据文件目录的文件 ```bash ls ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_1 ``` ```output metadata my_db.my_table_1.000000000.sql my_db.my_table_1-schema.sql my_db-schema-create.sql ``` ### 步骤 2. 检查数据源文件 + 查看 `my_db-schema-create.sql`, `my_db.my_table_1-schema.sql` 和 `my_db.my_table_1.000000000.sql` 文件，了解它们的结构。 ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_1/my_db-schema-create.sql ``` ```output /*!40101 SET NAMES binary*/; CREATE DATABASE `my_db` /*!40100 DEFAULT CHARACTER SET latin1 */; ``` ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_1/my_db.my_table_1-schema.sql ``` ```output /*!40101 SET NAMES binary*/; CREATE TABLE `my_table_1` ( `id` int(11) NOT NULL, `name` varchar(32) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; ``` ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_1/my_db.my_table_1.000000000.sql ``` ```output /*!40101 SET NAMES binary*/; > INSERT INTO `my_table_1` VALUES (1,'tom'), (3,'frank'); ... ``` ### 步骤 3. 打开一个新终端（终端 2） + 点击这里 - [终端 2](ssh://monitor1-ssh#2) 打开一个新的终端，连接到为你的实践实验分配的虚拟机。 + 登录后显示的横幅： ```output , #_ ~\_ ####_ Amazon Linux 2 ~~ \_#####\ ~~ \###| ~~ \#/ ___ ~~ V~' '-> ~~~ / A newer version of Amazon Linux is available! ~~._. _/ _/ _/ Amazon Linux 2023, GA and supported until 2028-03-15. _/m/' https://aws.amazon.com/linux/amazon-linux-2023/ ``` ### 步骤 4. 在终端 2 中，登录到 `PD1` ```bash ./ssh-to-pd1.sh ``` ```output ... , #_ ~\_ ####_ Amazon Linux 2 ~~ \_#####\ ~~ \###| ~~ \#/ ___ ~~ V~' '-> ~~~ / A newer version of Amazon Linux is available! ~~._. _/ _/ _/ Amazon Linux 2023, GA and supported until 2028-03-15. _/m/' https://aws.amazon.com/linux/amazon-linux-2023/ ... ``` ### 步骤 5. 在终端 2 中，解压数据 ```bash unzip -u stage/tidb-admin-dataset-v2.zip -d stage/ ``` ```bash ls ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_2 ``` ```output metadata my_db.my_table_2.000000000.sql my_db.my_table_2-schema.sql my_db-schema-create.sql ``` ### 步骤 6. 在终端 2 中，检查数据文件 ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_2/my_db-schema-create.sql ``` ```output /*!40101 SET NAMES binary*/; CREATE DATABASE `my_db` /*!40100 DEFAULT CHARACTER SET latin1 */; ``` ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_2/my_db.my_table_2-schema.sql ``` ```output /*!40101 SET NAMES binary*/; CREATE TABLE `my_table_2` ( `id` int(11) NOT NULL, `name` varchar(32) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; ``` ```bash cat ~/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_2/my_db.my_table_2.000000000.sql ``` ```output /*!40101 SET NAMES binary*/; INSERT INTO `my_table_2` VALUES (2,'jack'), (4,'tony'); ... ``` ### 步骤 7. 在终端 1 中，查看 `solution-lightning-p1.toml`. + 下面显示的 IP 地址可能会与你的不同。 ```bash cat solution-lightning-p1.toml ``` ```output [lightning] # The concurrency number of data. It is set to the number of logical CPU # cores by default. When deploying together with other components, you can # set it to 75% of the size of logical CPU cores to limit the CPU usage. # region-concurrency = 1 # Logging level = "info" file = "tidb-lightning-p1.log" [tikv-importer] # Whether to allow importing data to tables with data. The default value is `false`. # When you use parallel import mode, you must set it to `true`, because multiple TiDB Lightning instances are importing the same table at the same time. incremental-import = true # Sets the backend to the "local" mode. backend = "local" # Sets the directory of temporary local storage. sorted-kv-dir = "/tmp/sorted-kv-dir" [mydumper] # Local source data directory data-source-dir = "/home/ec2-user/stage/TiDB-Administration-exercise-data-v2/exercise-lightning/Importing-Data-into-TiDB-in-Parallel/my_table_1" # Only import tables if these wildcard rules are matched. See the corresponding section for details. filter = ['*.*', '!mysql.*', '!sys.*', '!INFORMATION_SCHEMA.*', '!PERFORMANCE_SCHEMA.*', '!METRICS_SCHEMA.*', '!INSPECTION_SCHEMA.*'] [[routes]] schema-pattern = "my_db" table-pattern = "my_table_*" target-schema = "my_db" target-table = "my_table" [tidb] # Configuration of any TiDB server from the cluster. host = "" port = 4000 user = "ltask" password = "q1w2e3R4_" # Table schema information is fetched from TiDB via this status-port. status-port = 10080 # Address of any PD server from the cluster. pd-addr = "10.90.2.84:2379" ``` ### 步骤 8. 在终端 2 中，安装 `TiUP` 和 `Lightning` ```bash ./01-install-tiup.sh ``` ```bash source .bash_profile ``` ```bash tiup mirror set tidb-community-server-7.5.1-linux-amd64 tiup install tidb-lightning ``` ### 步骤 9. 在终端 1 中，将 `solution-lightning-p2.toml` 文件复制到 `pd1` ```bash scp -i ~/.ssh/pe-class-key-oregon.pem solution-lightning-p2.toml ec2-user@${HOST_PD1_PRIVATE_IP}:/home/ec2-user/ ``` ```output solution-lightning-p2.toml 100% 720 678.5KB/s 00:00 ``` ### 步骤 10. 在终端 1 中，连接到 TiDB 并删除 `my_db` 数据库 ```bash mysql -h ${HOST_DB1_PRIVATE_IP} --port 4000 -u root ``` ```bash DROP DATABASE IF EXISTS my_db; ``` ```output mysql> DROP DATABASE IF EXISTS my_db; ``` ```bash EXIT ``` ```output mysql> EXIT; Bye ``` ### 步骤 11. 在终端 1 中，使用 Lightning 导入数据 + 使用 `nohup` 命令启动 `tidb-lightning` 进程（按 Enter 让 `tidb-lighting` 在后台运行）。 + 请同时执行步骤 11 和步骤 12。 ```bash nohup tiup tidb-lightning -config solution-lightning-p1.toml > nohup.out & ``` ```output [1] 4256 # nohup: ignoring input and redirecting stderr to stdout ... [1]+ Done nohup tidb-lightning -config solution-lightning-p1.toml > nohup ``` ### 步骤 12. 在终端 2 中，使用 Lightning 导入数据 ```bash nohup .tiup/bin/tiup tidb-lightning -config solution-lightning-p2.toml > nohup.out & ``` ```output [1] 4256 # nohup: ignoring input and redirecting stderr to stdout ... [1]+ Done nohup tidb-lightning -config solution-lightning-p2.toml > nohup ``` ### 步骤 13. 在两个终端中，查看 Lightning 的输出 + 在[终端 1](ssh://monitor1-ssh#1)中，查看 `nohup.out` 文件的内容，以验证 `TiDB Lightning` 已成功退出。 ，然后输入 `:q!` 退出终端： ```bash cat nohup.out ``` ```output +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | # | CHECK ITEM | TYPE | PASSED | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 1 | Source csv files size is proper | performance | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 2 | checkpoints are valid | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 3 | table schemas are valid | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 4 | Cluster is available | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 5 | Lightning has the correct storage permission | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 6 |sorted-kv-dir:/tmp/sorted-kv-dir and data-source-dir:/home/ec2-user/sample/sql/my_table_1 are in the same disk, may slow down performance | performance | false | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 7 | local disk resources are rich, estimate sorted data size 85B, local available is 5.149GiB | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 8 | Cluster available is rich, available is 54.46GiB, we need 255B | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 9 | Cluster doesn't have too many empty regions | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 10 | Cluster region distribution is balanced | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ tidb lightning exit successfully ``` + 如果发生任何错误，查看 `tidb-lightning-p1.log` 文件的内容，以确定错误原因。 ```bash cat tidb-lightning-p1.log ``` + 你可能需要在再次导入数据之前删除 lightning 检查点。以下命令假设检查点存储在 `/tmp/` 中。 ```bash rm /tmp/tidb_lightning_checkpoint.pb ``` + 在[终端 2](ssh://monitor1-ssh#2)中，查看 `nohup.out` 文件的内容，以验证 `TiDB Lightning` 已成功退出。 ```bash cat nohup.out ``` ```output Verbose debug logs will be written to tidb-lightning-p2.log +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | # | CHECK ITEM | TYPE | PASSED | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 1 | Source csv files size is proper | performance | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 2 | checkpoints are valid | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 3 | table schemas are valid | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 4 | Cluster is available | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 5 | Lightning has the correct storage permission | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 6 |sorted-kv-dir:/tmp/sorted-kv-dir and data-source-dir:/home/ec2-user/sample/sql/my_table_2 are in the same disk, may slow down performance | performance | false | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 7 | local disk resources are rich, estimate sorted data size 85B, local available is 7.173GiB | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 8 | Cluster available is rich, available is 54.46GiB, we need 255B | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 9 | Cluster doesn't have too many empty regions | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ | 10 | Cluster region distribution is balanced | critical | true | +----+----------------------------------------------------------------------------------------------------------------------------------+-------------+--------+ tidb lightning exit successfully ``` ### 步骤 14. 在终端 1 中，连接到 TiDB 并查询 `emp.sal` table ```bash mysql -h ${HOST_DB1_PRIVATE_IP} --port 4000 -u root ``` ```bash SELECT COUNT(*) FROM my_db.my_table; ``` ```output mysql> SELECT COUNT(*) FROM my_db.my_table; +----------+ | COUNT(*) | +----------+ | 40156 | +----------+ 1 row in set (0.01 sec) ``` ## 实验结束