### TiUP Command Examples

Source: https://docs.pingcap.com/tidb/stable/tiup-overview

Illustrates common usage patterns for TiUP commands, including starting a playground, installing components, updating, listing, and cleaning instances.

```bash
tiup playground

```

```bash
tiup playground nightly

```

```bash
tiup install <component>[:version]

```

```bash
tiup update --all

```

```bash
tiup update --nightly

```

```bash
tiup update --self

```

```bash
tiup list

```

```bash
tiup status

```

```bash
tiup clean <name>

```

```bash
tiup clean --all

```

--------------------------------

### Setup and Data Insertion for Binding Examples

Source: https://docs.pingcap.com/tidb/stable/sql-statement-create-binding

Sets up tables and inserts data, demonstrating operations that might be used to generate historical execution plans for binding creation.

```sql
USE test;
CREATE TABLE t1(a INT, b INT, c INT, INDEX ia(a));
CREATE TABLE t2(a INT, b INT, c INT, INDEX ia(a));
INSERT INTO t1 SELECT * FROM t2 WHERE a = 1;
SELECT @@LAST_PLAN_FROM_BINDING;
UPDATE /*+ INL_JOIN(t2) */ t1, t2 SET t1.a = 1 WHERE t1.b = t2.a;
SELECT @@LAST_PLAN_FROM_BINDING;
DELETE /*+ HASH_JOIN(t1) */ t1 FROM t1 JOIN t2 WHERE t1.b = t2.a;
SELECT @@LAST_PLAN_FROM_BINDING;
SELECT * FROM t1 WHERE t1.a IN (SELECT a FROM t2);
SELECT @@LAST_PLAN_FROM_BINDING;
```

--------------------------------

### Start a task with a specified source

Source: https://docs.pingcap.com/tidb/stable/dm-create-task

Example of starting a data migration task using `start-task` with a specific source and configuration file. The `-s` flag is optional and specifies the MySQL source.

```bash
start-task [ -s "mysql-replica-01"] ./task.yaml
```

--------------------------------

### Create a List Partitioned Table with a Default Partition

Source: https://docs.pingcap.com/tidb/stable/partitioned-table

Example of creating a new List partitioned table that includes a default partition from the start.

```sql
CREATE TABLE employees (
    id INT NOT NULL,
    hired DATE NOT NULL DEFAULT '1970-01-01',
    store_id INT
)
PARTITION BY LIST (store_id) (
    PARTITION pNorth VALUES IN (1, 2, 3, 4, 5),
    PARTITION pEast VALUES IN (6, 7, 8, 9, 10),
    PARTITION pWest VALUES IN (11, 12, 13, 14, 15),
    PARTITION pCentral VALUES IN (16, 17, 18, 19, 20),
    PARTITION pDefault DEFAULT
);
```

--------------------------------

### Create a Database, Select It, and Show Tables

Source: https://docs.pingcap.com/tidb/stable/sql-statement-use

Illustrates the process of creating a new database, selecting it as the current database using USE, and then verifying that it is empty by showing tables. This is a common workflow for setting up new schemas.

```sql
mysql> CREATE DATABASE newtest;
Query OK, 0 rows affected (0.10 sec)

mysql> USE newtest;
Database changed
mysql> SHOW TABLES;
Empty set (0.00 sec)
```

--------------------------------

### Display Help for a Specific TiUP Command

Source: https://docs.pingcap.com/tidb/stable/tiup-command-help

To view help for a specific TiUP command, append the command name after `tiup help`. For example, to get help for the `install` command, use `tiup help install`.

```shell
tiup help [command]
```

--------------------------------

### tiup install Command Syntax

Source: https://docs.pingcap.com/tidb/stable/tiup-command-install

Use this syntax to install one or more components, optionally specifying versions. If no version is provided, the latest stable version is installed.

```shell
tiup install <component1>[:version] [component2...N] [flags]
```

--------------------------------

### Create Sample Database and Table (SQL)

Source: https://docs.pingcap.com/tidb/stable/quick-start-with-dm

Create a sample database named 'hello' with a table 'hello_tidb' and insert a record. This is used to verify the source database setup.

```sql
CREATE DATABASE hello;
USE hello;

CREATE TABLE hello_tidb (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50)
);

INSERT INTO hello_tidb (name) VALUES ('Hello World');

SELECT * FROM hello_tidb;
```

--------------------------------

### Example: Get Schema for 'db' Table in 'mysql' Database

Source: https://docs.pingcap.com/tidb/stable/tidb-control

This example shows how to get the schema for the 'db' table in the 'mysql' database. The output is truncated.

```json
{
    "id": 9,
    "name": {
        "O": "db",
        "L": "db"
    },
    ...
    "Partition": null
}
```

--------------------------------

### Setup Sample Data and Enable MPP Mode

Source: https://docs.pingcap.com/tidb/stable/explain-mpp

Prepare sample data and enable MPP mode for testing EXPLAIN statements. Ensure the table has a TiFlash replica.

```sql
CREATE TABLE t1 (id int, value int);
INSERT INTO t1 values(1,2),(2,3),(1,3);
ALTER TABLE t1 set tiflash replica 1;
ANALYZE TABLE t1;
SET tidb_allow_mpp = 1;
```

--------------------------------

### Install and Enable NTP Service on CentOS 7

Source: https://docs.pingcap.com/tidb/stable/check-before-deployment

These commands install the `ntp` and `ntpdate` packages, start the `ntpd` service, and enable it to start automatically on boot for CentOS 7 systems.

```bash
sudo yum install ntp ntpdate && \
sudo systemctl start ntpd.service && \
sudo systemctl enable ntpd.service
```

--------------------------------

### Start Log Backup Task Help

Source: https://docs.pingcap.com/tidb/stable/br-pitr-manual

Shows detailed help for the `start` subcommand, including available flags and their descriptions. Useful for understanding how to configure a new log backup task.

```shell
tiup br log start --help
```

--------------------------------

### Start Log Backup Task Example

Source: https://docs.pingcap.com/tidb/stable/br-pitr-manual

An example of how to start a log backup task named 'pitr'. It specifies the PD address and the S3 storage location, including authentication details.

```shell
tiup br log start \
  --task-name=pitr \
  --pd="${PD_IP}:2379" \
  --storage='s3://backup-101/logbackup?access-key=${access-key}&secret-access-key=${secret-access-key}'
```

--------------------------------

### Replace substrings with a starting position constraint

Source: https://docs.pingcap.com/tidb/stable/string-functions

The REGEXP_REPLACE function allows specifying a starting position for the match. This example starts searching from the third character, preventing a match.

```sql
SELECT REGEXP_REPLACE('TooDB', 'o{2}', 'i',3);
```

--------------------------------

### Show Create Table Output Example

Source: https://docs.pingcap.com/tidb/stable/partitioned-table

This is an example output of the 'SHOW CREATE TABLE' command for a partitioned table, illustrating the partition definitions and comments.

```sql
*************************** 1. row ***************************
       Table: example
Create Table: CREATE TABLE `example` (
  `id` int NOT NULL,
  `data` varchar(1024) DEFAULT NULL,
  PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
PARTITION BY HASH (`id`)
(
PARTITION `p0`,
 PARTITION `p1`,
 PARTITION `p2`,
 PARTITION `pExample4` COMMENT 'not p3, but pExample4 instead')
1 row in set (0.01 sec)
```

--------------------------------

### Example: Get Schema for 'mysql' Database

Source: https://docs.pingcap.com/tidb/stable/tidb-control

This example demonstrates retrieving the schema for all tables in the 'mysql' database. The output is truncated.

```json
[
    {
        "id": 13,
        "name": {
            "O": "columns_priv",
            "L": "columns_priv"
        },
              ...
        "update_timestamp": 399494726837600268,
        "ShardRowIDBits": 0,
        "Partition": null
    }
]
```

--------------------------------

### Example Workflow: Create Database, Use, and Create Table

Source: https://docs.pingcap.com/tidb/stable/sql-statement-create-database

This example demonstrates a common workflow: creating a database, switching to it using the USE statement, and then creating a table within that database.

```sql
mysql> CREATE DATABASE mynewdatabase;
Query OK, 0 rows affected (0.09 sec)

mysql> USE mynewdatabase;
Database changed
mysql> CREATE TABLE t1 (a int);
Query OK, 0 rows affected (0.11 sec)

mysql> SHOW TABLES;
+-------------------------+
| Tables_in_mynewdatabase |
+-------------------------+
| t1                      |
+-------------------------+
1 row in set (0.00 sec)
```

--------------------------------

### Install TiUP

Source: https://docs.pingcap.com/tidb/stable/deploy-tidb-lightning

Installs TiUP, a package manager for TiDB components. After installation, start a new terminal session or run `source ~/.bashrc` (or `source ~/.profile`) to add TiUP to your PATH.

```shell
curl --proto '=https' --tlsv1.2 -sSf https://tiup-mirrors.pingcap.com/install.sh | sh
```

--------------------------------

### Example: Get Schema for Table ID 21

Source: https://docs.pingcap.com/tidb/stable/tidb-control

This example demonstrates retrieving the schema for a table with ID 21, which corresponds to 'mysql.stats_meta'.

```json
{
 "id": 21,
 "name": {
  "O": "stats_meta",
  "L": "stats_meta"
 },
 "charset": "utf8mb4",
 "collate": "utf8mb4_bin",
  ...
}
```

--------------------------------

### Prepare Data for MySQL Instance 1

Source: https://docs.pingcap.com/tidb/stable/quick-start-create-task

Write example data into the `sharding1` database on the first MySQL instance. This includes creating tables and inserting sample records.

```sql
drop database if exists `sharding1`;
create database `sharding1`;
use `sharding1`;
create table t1 (id bigint, uid int, name varchar(80), info varchar(100), primary key (`id`), unique key(`uid`)) DEFAULT CHARSET=utf8mb4;
create table t2 (id bigint, uid int, name varchar(80), info varchar(100), primary key (`id`), unique key(`uid`)) DEFAULT CHARSET=utf8mb4;
insert into t1 (id, uid, name) values (1, 10001, 'Gabriel García Márquez'), (2 ,10002, 'Cien años de soledad');
insert into t2 (id, uid, name) values (3,20001, 'José Arcadio Buendía'), (4,20002, 'Úrsula Iguarán'), (5,20003, 'José Arcadio');
```

--------------------------------

### Create Table and Analyze

Source: https://docs.pingcap.com/tidb/stable/statistics

This snippet demonstrates the initial setup of a partitioned table and the execution of an `ANALYZE TABLE` command. It highlights potential warnings related to missing global stats and auto-adjusted sample rates.

```sql
mysql> CREATE TABLE t(a INT, b INT) PARTITION BY RANGE (a) (PARTITION p0 VALUES LESS THAN (10), PARTITION p1 VALUES LESS THAN (20), PARTITION p2 VALUES LESS THAN (30));
Query OK, 0 rows affected (0.03 sec)

mysql> INSERT INTO t VALUES (1,2), (3,4), (5,6), (7,8);
Query OK, 4 rows affected (0.00 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> ANALYZE TABLE t;
Query OK, 0 rows affected, 6 warnings (0.02 sec)

mysql> SHOW WARNINGS;
+---------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 
| Level   | Code | Message                                                                                                                                                                                                                              | 
+---------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 
| Warning | 1105 | disable dynamic pruning due to t has no global stats                                                                                                                                                                                 | 
| Note    | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t's partition p0, reason to use this rate is "Row count in stats_meta is much smaller compared with the row count got by PD, use min(1, 15000/4) as the sample-rate=1" | 
| Warning | 1105 | disable dynamic pruning due to t has no global stats                                                                                                                                                                                 | 
| Note    | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t's partition p1, reason to use this rate is "TiDB assumes that the table is empty, use sample-rate=1"                                                                 | 
| Warning | 1105 | disable dynamic pruning due to t has no global stats                                                                                                                                                                                 | 
| Note    | 1105 | Analyze use auto adjusted sample rate 1.000000 for table test.t's partition p2, reason to use this rate is "TiDB assumes that the table is empty, use sample-rate=1"                                                                 | 
+---------+------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 
6 rows in set (0.01 sec)
```

--------------------------------

### List All Installable Versions of a Component with TiUP

Source: https://docs.pingcap.com/tidb/stable/tiup-component-management

Get a list of all installable versions for a specific component, such as TiKV, from the server using `tiup list <component>`.

```shell
tiup list tikv
```

--------------------------------

### Start Cluster with System SSH

Source: https://docs.pingcap.com/tidb/stable/tiup-cluster

Example of starting a TiDB cluster using the system's native SSH client by specifying the `--ssh=system` flag.

```bash
tiup cluster start <cluster-name> --ssh=system
```

--------------------------------

### Create Table for INTO OUTFILE Examples

Source: https://docs.pingcap.com/tidb/stable/sql-statement-select

Sets up a sample table with integer, varchar, and decimal columns for demonstrating the SELECT ... INTO OUTFILE statement.

```sql
mysql> CREATE TABLE t (a INT, b VARCHAR(10), c DECIMAL(10,2));
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO t VALUES (1, 'a', 1.1), (2, 'b', 2.2), (3, 'c', 3.3);
Query OK, 3 rows affected (0.01 sec)
```

--------------------------------

### Example: Starting a Transaction

Source: https://docs.pingcap.com/tidb/stable/sql-statement-savepoint

Begins a transaction block to demonstrate savepoint functionality.

```sql
BEGIN;
```

--------------------------------

### Example Table Schema

Source: https://docs.pingcap.com/tidb/stable/handle-failed-ddl-statements

This is an example output of the `SHOW CREATE TABLE` command, illustrating a basic table structure.

```sql
+-------+-----------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                              |
+-------+-----------------------------------------------------------------------------------------------------------+
| tb    | CREATE TABLE `shard_table` (
  `id` int DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_bin |
+-------+-----------------------------------------------------------------------------------------------------------+
```

--------------------------------

### Create Table, Insert Data, and Explain Query

Source: https://docs.pingcap.com/tidb/stable/explain-overview

This snippet demonstrates creating a table, inserting sample data, and then using the `EXPLAIN` statement to view the execution plan for a simple select query.

```sql
CREATE TABLE t (id INT NOT NULL PRIMARY KEY auto_increment, a INT NOT NULL, pad1 VARCHAR(255), INDEX(a));
INSERT INTO t VALUES (1, 1, 'aaa'),(2,2, 'bbb');
EXPLAIN SELECT * FROM t WHERE a = 1;
```

--------------------------------

### TiDB Safe Start Success Output

Source: https://docs.pingcap.com/tidb/stable/production-deployment-using-tiup

Example output indicating a successful safe start of a TiDB cluster. It confirms the cluster has started and provides the newly generated root password for the TiDB database, emphasizing that this password is only displayed once.

```shell
Started cluster `tidb-test` successfully.
The root password of TiDB database has been changed.
The new password is: 'y_+3Hwp=*AWz8971s6'.
Copy and record it to somewhere safe, it is only displayed once, and will not be stored.
The generated password can NOT be got again in future.
```

--------------------------------

### Start a replication task

Source: https://docs.pingcap.com/tidb/stable/dm-open-api

Starts a specified replication task. This is an asynchronous operation. Use the 'get the information of a replication task' endpoint to check the task's status.

```APIDOC
## PUT /api/v1/tasks/task-1

### Description
This endpoint is used to create or update a replication task with specified configurations. It allows for detailed setup of migration rules, source and target configurations, and filtering.

### Method
PUT

### Endpoint
`/api/v1/tasks/{task-name}`

### Request Body
- **task** (object) - Required - The configuration object for the replication task.
  - **name** (string) - Required - The name of the task.
  - **task_mode** (string) - Required - The mode of the task (e.g., "all").
  - **shard_mode** (string) - Required - The sharding mode (e.g., "pessimistic").
  - **meta_schema** (string) - Required - The schema for metadata storage.
  - **enhance_online_schema_change** (boolean) - Required - Whether to enhance online schema change.
  - **on_duplicate** (string) - Required - Action to take on duplicate data (e.g., "overwrite").
  - **target_config** (object) - Required - Configuration for the target database.
    - **host** (string) - Required - Target database host.
    - **port** (integer) - Required - Target database port.
    - **user** (string) - Required - Target database user.
    - **password** (string) - Required - Target database password.
    - **security** (object) - Optional - Security settings for the target connection.
      - **ssl_ca_content** (string) - Optional - SSL CA certificate content.
      - **ssl_cert_content** (string) - Optional - SSL certificate content.
      - **ssl_key_content** (string) - Optional - SSL key content.
      - **cert_allowed_cn** (array of strings) - Optional - Allowed common names for the certificate.
  - **binlog_filter_rule** (object) - Optional - Rules for filtering binlog events.
    - **rule-name** (object) - Key-value pairs where keys are rule names and values are rule definitions.
      - **ignore_event** (array of strings) - Optional - Events to ignore.
      - **ignore_sql** (array of strings) - Optional - SQL statements to ignore.
  - **table_migrate_rule** (array of objects) - Optional - Rules for migrating specific tables.
    - **source** (object) - Required - Source table definition.
      - **source_name** (string) - Optional - Name of the source.
      - **schema** (string) - Required - Source schema pattern.
      - **table** (string) - Required - Source table pattern.
    - **target** (object) - Required - Target table definition.
      - **schema** (string) - Required - Target schema name.
      - **table** (string) - Required - Target table name.
    - **binlog_filter_rule** (array of strings) - Optional - References to binlog filter rules.
  - **source_config** (object) - Required - Configuration for the data source.
    - **full_migrate_conf** (object) - Optional - Configuration for full data migration.
      - **export_threads** (integer) - Optional - Number of export threads.
      - **import_threads** (integer) - Optional - Number of import threads.
      - **data_dir** (string) - Optional - Directory for exported data.
      - **consistency** (string) - Optional - Consistency level (e.g., "auto").
      - **import_mode** (string) - Optional - Import mode (e.g., "physical").
      - **sorting_dir** (string) - Optional - Directory for sorting data.
      - **disk_quota** (string) - Optional - Disk quota for data export.
      - **checksum** (string) - Optional - Checksum requirement (e.g., "required").
      - **analyze** (string) - Optional - Whether to analyze tables (e.g., "optional").
      - **range_concurrency** (integer) - Optional - Concurrency for range operations.
      - **compress_kv_pairs** (string) - Optional - Compression settings for KV pairs.
      - **pd_addr** (string) - Optional - PD server address.
      - **on_duplicate_logical** (string) - Optional - Action on duplicate logical data.
      - **on_duplicate_physical** (string) - Optional - Action on duplicate physical data.
    - **incr_migrate_conf** (object) - Optional - Configuration for incremental data migration.
      - **repl_threads** (integer) - Optional - Number of replication threads.
      - **repl_batch** (integer) - Optional - Batch size for replication.
    - **source_conf** (array of objects) - Required - Configuration for each source instance.
      - **source_name** (string) - Required - Name of the source instance.
      - **binlog_name** (string) - Optional - Binlog file name.
      - **binlog_pos** (integer) - Optional - Binlog position.
      - **binlog_gtid** (string) - Optional - Binlog GTID.

### Request Example
```json
{
  "task": {
    "name": "task-1",
    "task_mode": "all",
    "shard_mode": "pessimistic",
    "meta_schema": "dm-meta",
    "enhance_online_schema_change": true,
    "on_duplicate": "overwrite",
    "target_config": {
      "host": "127.0.0.1",
      "port": 3306,
      "user": "root",
      "password": "123456",
      "security": {
        "ssl_ca_content": "",
        "ssl_cert_content": "",
        "ssl_key_content": "",
        "cert_allowed_cn": [
          "string"
        ]
      }
    },
    "binlog_filter_rule": {
      "rule-1": {
        "ignore_event": [
          "all dml"
        ],
        "ignore_sql": [
          "^Drop"
        ]
      },
      "rule-2": {
        "ignore_event": [
          "all dml"
        ],
        "ignore_sql": [
          "^Drop"
        ]
      },
      "rule-3": {
        "ignore_event": [
          "all dml"
        ],
        "ignore_sql": [
          "^Drop"
        ]
      }
    },
    "table_migrate_rule": [
      {
        "source": {
          "source_name": "source-name",
          "schema": "db-*",
          "table": "tb-*"
        },
        "target": {
          "schema": "db1",
          "table": "tb1"
        },
        "binlog_filter_rule": [
          "rule-1",
          "rule-2",
          "rule-3"
        ]
      }
    ],
    "source_config": {
      "full_migrate_conf": {
        "export_threads": 4,
        "import_threads": 16,
        "data_dir": "./exported_data",
        "consistency": "auto",
        "import_mode": "physical",
        "sorting_dir": "./sort_dir",
        "disk_quota": "80G",
        "checksum": "required",
        "analyze": "optional",
        "range_concurrency": 0,
        "compress-kv-pairs": "",
        "pd_addr": "",
        "on_duplicate_logical": "error",
        "on_duplicate_physical": "none"
      },
      "incr_migrate_conf": {
        "repl_threads": 16,
        "repl_batch": 100
      },
      "source_conf": [
        {
          "source_name": "mysql-replica-01",
          "binlog_name": "binlog.000001",
          "binlog_pos": 4,
          "binlog_gtid": "03fc0263-28c7-11e7-a653-6c0b84d59f30:1-7041423,05474d3c-28c7-11e7-8352-203db246dd3d:1-170"
        }
      ]
    }
  }
}
```

### Response
#### Success Response (204)
No content is returned on success.

#### Error Response
- **400 Bad Request**: Invalid request payload or parameters.
- **404 Not Found**: Task not found.
- **500 Internal Server Error**: Server encountered an error.
```

```APIDOC
## POST /api/v1/tasks/{task-name}/start

### Description
Starts a specified replication task. This is an asynchronous operation. Use the 'get the information of a replication task' endpoint to check the task's status.

### Method
POST

### Endpoint
`/api/v1/tasks/{task-name}/start`

### Parameters
#### Path Parameters
- **task-name** (string) - Required - The name of the task to start.

### Request Example
```shell
curl -X 'POST' \
  'http://127.0.0.1:8261/api/v1/tasks/task-1/start' \
  -H 'accept: */*'
```

### Response
#### Success Response (204)
No content is returned on success.

#### Error Response
- **404 Not Found**: Task not found.
- **500 Internal Server Error**: Server encountered an error.
```

--------------------------------

### Prepare Data for MySQL Instance 2

Source: https://docs.pingcap.com/tidb/stable/quick-start-create-task

Write example data into the `sharding2` database on the second MySQL instance. This includes creating tables and inserting sample records.

```sql
drop database if exists `sharding2`;
create database `sharding2`;
use `sharding2`;
create table t2 (id bigint, uid int, name varchar(80), info varchar(100), primary key (`id`), unique key(`uid`)) DEFAULT CHARSET=utf8mb4;
create table t3 (id bigint, uid int, name varchar(80), info varchar(100), primary key (`id`), unique key(`uid`)) DEFAULT CHARSET=utf8mb4;
insert into t2 (id, uid, name, info) values (6, 40000, 'Remedios Moscote', '{}');
insert into t3 (id, uid, name, info) values (7, 30001, 'Aureliano José', '{}'), (8, 30002, 'Santa Sofía de la Piedad', '{}'), (9, 30003, '17 Aurelianos', NULL);
```

--------------------------------

### Prepare Database and Table Schema

Source: https://docs.pingcap.com/tidb/stable/tidb-lightning-error-resolution

Creates the schema and table for the example data import. Ensure you are in the 'example' directory before running.

```shell
mkdir example && cd example

echo 'CREATE SCHEMA;' > example-schema-create.sql
echo 'CREATE TABLE t(a TINYINT PRIMARY KEY, b VARCHAR(12) NOT NULL UNIQUE);' > example.t-schema.sql
```

--------------------------------

### Get First Sequence Value with Custom Start

Source: https://docs.pingcap.com/tidb/stable/sql-statement-create-sequence

Shows that the first value returned by NEXTVAL() for a custom sequence is its defined START parameter. This confirms the sequence begins as configured.

```sql
SELECT NEXTVAL(seq2);
```

```sql
+---------------+
| NEXTVAL(seq2) |
+---------------+
|             3 |
+---------------+
1 row in set (0.00 sec)
```

--------------------------------

### TiKV Configuration Example with JSON Output

Source: https://docs.pingcap.com/tidb/stable/command-line-flags-for-tikv-configuration

This example shows how to use the `--config-info` flag to list available configuration parameters in JSON format. It includes parameters from a configuration file and default values.

```json
{
"Component": "TiKV Server",
"Version": "6.2.0",
"Parameters": [
    {
    "Name": "log-level",
    "DefaultValue": "info",
    "ValueInFile": "warn"
    },
    {
    "Name": "log-file",
    "DefaultValue": ""
    },
    ...
]
}
```

--------------------------------

### Find first occurrence starting from a specific position

Source: https://docs.pingcap.com/tidb/stable/string-functions

This example demonstrates using the third argument of REGEXP_INSTR() to specify a different starting position for the search. Here, the search for 'a' begins from the second character of the string 'abcabc'.

```sql
SELECT REGEXP_INSTR('abcabc','a',2);
```

--------------------------------

### Example: Initial Cluster Configuration

Source: https://docs.pingcap.com/tidb/stable/command-line-flags-for-pd-configuration

Defines the initial cluster for bootstrapping PD. It maps member names to their peer URLs.

```bash
--initial-cluster "pd=http://192.168.100.113:2380"
```

--------------------------------

### Start Flink SQL Client

Source: https://docs.pingcap.com/tidb/stable/replicate-data-to-kafka

Command to launch the Flink SQL client from the Flink installation directory.

```shell
[root@flink flink-1.15.0]# ./bin/sql-client.sh
```

--------------------------------

### Example: Enabling TLS with Client Certificate and Key

Source: https://docs.pingcap.com/tidb/stable/command-line-flags-for-pd-configuration

Configures TLS by providing the paths to the X509 certificate and its corresponding private key in PEM format.

```bash
--cert "/path/to/pd-cert.pem" --key "/path/to/pd-key.pem"
```

--------------------------------

### Create Table Example

Source: https://docs.pingcap.com/tidb/stable/sql-statement-insert

Demonstrates the creation of a simple integer table.

```sql
CREATE TABLE t1 (a INT);

```

```sql
CREATE TABLE t2 LIKE t1;

```

--------------------------------

### Get Data Source Response

Source: https://docs.pingcap.com/tidb/stable/dm-open-api

Example JSON response when retrieving a data source with its status information.

```json
{
  "source_name": "mysql-01",
  "host": "127.0.0.1",
  "port": 3306,
  "user": "root",
  "password": "123456",
  "enable_gtid": false,
  "enable": false,
  "flavor": "mysql",
  "task_name_list": [
    "task1"
  ],
  "security": {
    "ssl_ca_content": "",
    "ssl_cert_content": "",
    "ssl_key_content": "",
    "cert_allowed_cn": [
      "string"
    ]
  },
  "purge": {
    "interval": 3600,
    "expires": 0,
    "remain_space": 15
  },
  "status_list": [
    {
      "source_name": "mysql-replica-01",
      "worker_name": "worker-1",
      "relay_status": {
        "master_binlog": "(mysql-bin.000001, 1979)",
        "master_binlog_gtid": "e9a1fc22-ec08-11e9-b2ac-0242ac110003:1-7849",
        "relay_dir": "./sub_dir",
        "relay_binlog_gtid": "e9a1fc22-ec08-11e9-b2ac-0242ac110003:1-7849",
        "relay_catch_up_master": true,
        "stage": "Running"
      },
      "error_msg": "string"
    }
  ],
  "relay_config": {
    "enable_relay": true,
    "relay_binlog_name": "mysql-bin.000002",
    "relay_binlog_gtid": "e9a1fc22-ec08-11e9-b2ac-0242ac110003:1-7849",
    "relay_dir": "./relay_log"
  }
}
```

--------------------------------

### TiDB Write Conflict Log Example

Source: https://docs.pingcap.com/tidb/stable/troubleshoot-write-conflicts

Example of a TiDB log entry indicating a write conflict. This log provides transaction start and conflict timestamps, as well as the conflicting key and primary key information.

```log
[2020/05/12 15:17:01.568 +08:00] [WARN] [session.go:446] ["commit failed"] [conn=3] ["finished txn"="Txn{state=invalid}"] [error="[kv:9007]Write conflict, txnStartTS=416617006551793665, conflictStartTS=416617018650001409, conflictCommitTS=416617023093080065, key={tableID=47, indexID=1, indexValues={string, }} primary={tableID=47, indexID=1, indexValues={string, }} [try again later]"]
```

--------------------------------

### Create Table, Policy, and Show Placement

Source: https://docs.pingcap.com/tidb/stable/information-schema-placement-policies

Demonstrates creating a table, a placement policy, assigning the policy to the table, and then viewing all placement information using `SHOW PLACEMENT` and querying `information_schema.placement_policies`.

```sql
CREATE TABLE t1 (a INT);
CREATE PLACEMENT POLICY p1 primary_region="us-east-1" regions="us-east-1";
CREATE TABLE t3 (a INT) PLACEMENT POLICY=p1;
SHOW PLACEMENT; -- Shows all information, including table t3.
SELECT * FROM information_schema.placement_policies; -- Only shows placement policies, excluding t3.
```

```text
Query OK, 0 rows affected (0.09 sec)

Query OK, 0 rows affected (0.11 sec)

Query OK, 0 rows affected (0.08 sec)

+---------------+------------------------------------------------+
| Target        | Placement                                      |
+---------------+------------------------------------------------+
| POLICY p1     | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" |
| TABLE test.t3 | PRIMARY_REGION="us-east-1" REGIONS="us-east-1" |
+---------------+------------------------------------------------+
2 rows in set (0.00 sec)

+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
| POLICY_ID | CATALOG_NAME | POLICY_NAME | PRIMARY_REGION | REGIONS   | CONSTRAINTS | LEADER_CONSTRAINTS | FOLLOWER_CONSTRAINTS | LEARNER_CONSTRAINTS | SCHEDULE | FOLLOWERS | LEARNERS |
+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
| 1         | def          | p1          | us-east-1      | us-east-1 |             |                    |                      |                     |          | 2         | 0        |
+-----------+--------------+-------------+----------------+-----------+-------------+--------------------+----------------------+---------------------+----------+-----------+----------+
1 rows in set (0.00 sec)
```

--------------------------------

### Return position after the match

Source: https://docs.pingcap.com/tidb/stable/string-functions

This example shows how to use the fifth argument of REGEXP_INSTR() to return the position immediately following the matched substring, instead of the starting position of the match. The search is for the first 'a' starting from position 1.

```sql
SELECT REGEXP_INSTR('abcabc','a',1,1,1);
```

--------------------------------

### Sysbench Configuration Example

Source: https://docs.pingcap.com/tidb/stable/benchmark-tidb-using-sysbench

This is an example Sysbench configuration file. Adjust parameters like `TIDB_HOST` and `threads` based on your specific testing environment and needs. It's recommended to set `threads` to 8 or 16 when importing data.

```text
mysql-host={TIDB_HOST}
mysql-port=4000
mysql-user=root
mysql-password=password
mysql-db=sbtest
time=600
threads={8, 16, 32, 64, 128, 256}
report-interval=10
db-driver=mysql
```

--------------------------------

### Example ntpd Service Status Output

Source: https://docs.pingcap.com/tidb/stable/check-before-deployment

This output indicates that the `ntpd` service is loaded, enabled to start, and currently active.

```text
ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; disabled; vendor preset: disabled)
Active: active (running) since 一 2017-12-18 13:13:19 CST; 3s ago
```

--------------------------------

### Create a table

Source: https://docs.pingcap.com/tidb/stable/sql-statement-add-column

This snippet demonstrates the creation of a sample table used in subsequent examples.

```sql
mysql> CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT);
Query OK, 0 rows affected (0.11 sec)
```

--------------------------------

### INSERT Statement with Index Hint

Source: https://docs.pingcap.com/tidb/stable/sql-statement-create-binding

Example of an INSERT statement using `use_index` and `no_order_index` hints to guide the query optimizer.

```sql
INSERT INTO `test`.`t1` SELECT /*+ use_index(@`sel_1` `test`.`t2` `ia`) no_order_index(@`sel_1` `test`.`t2` `ia`)*/ * FROM `test`.`t2` WHERE `a` = 1
```

--------------------------------

### Example: Multi-Node Initial Cluster Configuration

Source: https://docs.pingcap.com/tidb/stable/command-line-flags-for-pd-configuration

Specifies the initial cluster configuration for bootstrapping a multi-node PD cluster, listing each member's name and its advertise peer URL.

```bash
pd1=http://192.168.100.113:2380, pd2=http://192.168.100.114:2380, pd3=192.168.100.115:2380
```

--------------------------------

### Create Partitioned Table and Explain Query in Static Mode

Source: https://docs.pingcap.com/tidb/stable/partitioned-table

Demonstrates creating a partitioned table and then using 'EXPLAIN' to show how TiDB would process a query in 'static' mode, typically involving multiple operators and a 'Union' for merging results from different partitions.

```sql
mysql> create table t1(id int, age int, key(id)) partition by range(id) (
        partition p0 values less than (100),
        partition p1 values less than (200),
        partition p2 values less than (300),
        partition p3 values less than (400));
Query OK, 0 rows affected (0.01 sec)

mysql> explain select * from t1 where id < 150;
```

--------------------------------

### Get Password Strength with Numbers

Source: https://docs.pingcap.com/tidb/stable/encryption-and-compression-functions

Assesses the strength of 'Abcdefghi123'. This example illustrates the impact of including numbers on the password strength score.

```sql
SELECT VALIDATE_PASSWORD_STRENGTH('Abcdefghi123');
```

--------------------------------

### Create Databases and Tables for Cross-Database Binding Example

Source: https://docs.pingcap.com/tidb/stable/sql-plan-management

Sets up the necessary database and table structures required for demonstrating cross-database binding functionality.

```sql
CREATE DATABASE db1;
CREATE TABLE db1.t1 (a INT, KEY(a));
CREATE TABLE db1.t2 (a INT, KEY(a));
CREATE DATABASE db2;
CREATE TABLE db2.t1 (a INT, KEY(a));
CREATE TABLE db2.t2 (a INT, KEY(a));
```

--------------------------------

### Basic TiUP Playground Usage

Source: https://docs.pingcap.com/tidb/stable/tiup-playground

Starts a local TiDB cluster with default settings. TiUP installs the latest stable components if not present.

```bash
tiup playground ${version} [flags]
```

--------------------------------

### Create Sample Table and Insert Data

Source: https://docs.pingcap.com/tidb/stable/explain-indexes

Sets up a sample table 't1' with an auto-incrementing primary key, an integer column with an index, and a large binary column. It then populates the table with a significant amount of random data to facilitate index usage examples.

```sql
CREATE TABLE t1 (
 id INT NOT NULL PRIMARY KEY auto_increment,
 intkey INT NOT NULL,
 pad1 VARBINARY(1024),
 INDEX (intkey)
);

INSERT INTO t1 SELECT NULL, FLOOR(RAND()*1024), RANDOM_BYTES(1024) FROM dual;
INSERT INTO t1 SELECT NULL, FLOOR(RAND()*1024), RANDOM_BYTES(1024) FROM t1 a JOIN t1 b JOIN t1 c LIMIT 10000;
INSERT INTO t1 SELECT NULL, FLOOR(RAND()*1024), RANDOM_BYTES(1024) FROM t1 a JOIN t1 b JOIN t1 c LIMIT 10000;
INSERT INTO t1 SELECT NULL, FLOOR(RAND()*1024), RANDOM_BYTES(1024) FROM t1 a JOIN t1 b JOIN t1 c LIMIT 10000;
```

--------------------------------

### Get default kernel version

Source: https://docs.pingcap.com/tidb/stable/check-before-deployment

Use the 'grubby' command to retrieve the default kernel version. Ensure the 'grubby' package is installed before execution.

```bash
grubby --default-kernel
```

--------------------------------

### Create Global Bindings

Source: https://docs.pingcap.com/tidb/stable/sql-statement-drop-binding

Sets up sample tables and creates global SQL bindings for different query patterns.

```sql
CREATE TABLE t1(a INT, b INT, c INT, INDEX ia(a));
CREATE TABLE t2(a INT, b INT, c INT, INDEX ia(a));
CREATE GLOBAL BINDING FOR SELECT * FROM t1 WHERE a > 1 USING SELECT * FROM t1 USE INDEX (ia) WHERE a > 1;
CREATE GLOBAL BINDING FOR SELECT * FROM t2 WHERE a < 1 USING SELECT * FROM t2 USE INDEX (ia) WHERE a < 1;
CREATE GLOBAL BINDING FOR SELECT * FROM t1 JOIN t2 ON t1.b = t2.a USING SELECT /*+ HASH_JOIN(t1) */ * FROM t1 JOIN t2 ON t1.b = t2.a;
SHOW GLOBAL BINDINGS;
```

--------------------------------

### Create Table and Insert Data

Source: https://docs.pingcap.com/tidb/stable/explain-aggregation

Sets up a table and populates it with sample data for aggregation examples.

```sql
CREATE TABLE t2 (id INT NOT NULL PRIMARY KEY, col1 INT NOT NULL);
INSERT INTO t2 VALUES (1, 9),(2, 3),(3,1),(4,8),(6,3);
```

--------------------------------

### List Available TiUP Components

Source: https://docs.pingcap.com/tidb/stable/migration-tools

Lists all available components that can be installed using TiUP. This helps in identifying the tools needed for your TiDB setup.

```bash
tiup list
```

--------------------------------

### Find first occurrence of a character

Source: https://docs.pingcap.com/tidb/stable/string-functions

This example shows how to find the first occurrence of the character 'a' in the string 'abcabc'. By default, the search starts from the beginning of the string.

```sql
SELECT REGEXP_INSTR('abcabc','a');
```

--------------------------------

### Create Placement Policy and Table, then Show Placement

Source: https://docs.pingcap.com/tidb/stable/sql-statement-show-placement

Demonstrates the creation of a placement policy and a table using that policy, followed by a SHOW PLACEMENT query to view the configurations.

```sql
CREATE PLACEMENT POLICY p1 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-west-1" FOLLOWERS=4;
CREATE TABLE t1 (a INT) PLACEMENT POLICY=p1;
SHOW PLACEMENT;
```

--------------------------------

### LIKE for Numeric String Mismatch

Source: https://docs.pingcap.com/tidb/stable/string-functions

Shows a failed numeric string match using LIKE. This example returns 0 as '10000' does not start with '12'.

```sql
SELECT 10000 LIKE '12%' AS result;
```

--------------------------------

### Create and Show Global Bindings (Execution)

Source: https://docs.pingcap.com/tidb/stable/sql-statement-drop-binding

Demonstrates the execution of creating global bindings and then showing them.

```sql
> CREATE TABLE t1(a INT, b INT, c INT, INDEX ia(a));
Query OK, 0 rows affected (0.044 sec)

> CREATE TABLE t2(a INT, b INT, c INT, INDEX ia(a));
Query OK, 0 rows affected (0.035 sec)

> CREATE GLOBAL BINDING FOR SELECT * FROM t1 WHERE a > 1 USING SELECT * FROM t1 USE INDEX (ia) WHERE a > 1;
Query OK, 0 rows affected (0.011 sec)

> CREATE GLOBAL BINDING FOR SELECT * FROM t2 WHERE a < 1 USING SELECT * FROM t2 USE INDEX (ia) WHERE a < 1;
Query OK, 0 rows affected (0.013 sec)

> CREATE GLOBAL BINDING FOR SELECT * FROM t1 JOIN t2 ON t1.b = t2.a USING SELECT /*+ HASH_JOIN(t1) */ * FROM t1 JOIN t2 ON t1.b = t2.a;
Query OK, 0 rows affected (0.012 sec)

> SHOW GLOBAL BINDINGS;
```

--------------------------------

### Create Table with Prefix Index

Source: https://docs.pingcap.com/tidb/stable/system-variables

Example of creating a table with a prefix index on columns 'a' and 'b'. This setup is used to demonstrate the behavior of the tidb_opt_prefix_index_single_scan variable.

```sql
CREATE TABLE t (a INT, b VARCHAR(10), c INT, INDEX idx_a_b(a, b(5)));
```

--------------------------------

### TiProxy Servers Configuration Example

Source: https://docs.pingcap.com/tidb/stable/tiup-cluster-topology-reference

This example demonstrates how to configure multiple TiProxy servers, specifying their hosts, ports, status ports, and label configurations for different zones.

```yaml
tiproxy_servers:
  - host: 10.0.1.21
    port: 6000
    status_port: 3080
    config:
      labels: { zone: "zone1" }
  - host: 10.0.1.22
    port: 6000
    status_port: 3080
    config:
      labels: { zone: "zone2" }
```

--------------------------------

### Create a RANGE Partitioned Table

Source: https://docs.pingcap.com/tidb/stable/partitioned-table

Example of creating a table with RANGE partitioning based on a region code. This setup is used to illustrate partition pruning.

```sql
CREATE TABLE t1 (
    fname VARCHAR(50) NOT NULL,
    lname VARCHAR(50) NOT NULL,
    region_code TINYINT UNSIGNED NOT NULL,
    dob DATE NOT NULL
)

PARTITION BY RANGE( region_code ) (
    PARTITION p0 VALUES LESS THAN (64),
    PARTITION p1 VALUES LESS THAN (128),
    PARTITION p2 VALUES LESS THAN (192),
    PARTITION p3 VALUES LESS THAN MAXVALUE
);
```

--------------------------------

### Monitoring Servers Configuration Example

Source: https://docs.pingcap.com/tidb/stable/tiup-dm-topology-reference

An example demonstrating how to configure monitoring servers, including remote write/read endpoints and external alert managers.

```yaml
monitoring_servers:
  - host: 10.0.1.11
    rule_dir: /local/rule/dir
    remote_config:
      remote_write:
      - queue_config:
          batch_send_deadline: 5m
          capacity: 100000
          max_samples_per_send: 10000
          max_shards: 300
        url: http://127.0.0.1:8003/write
      remote_read:
      - url: http://127.0.0.1:8003/read\
      external_alertmanagers:
      - host: 10.1.1.1
      web_port: 9093
      - host: 10.1.1.2
      web_port: 9094
```

--------------------------------

### Switch database and show tables

Source: https://docs.pingcap.com/tidb/stable/sql-statement-rename-table

These snippets demonstrate switching the current database context and then listing tables within that database.

```sql
USE db1; SHOW TABLES;
```

```sql
USE db2; SHOW TABLES;
```

```sql
USE db3; SHOW TABLES;
```

```sql
USE db4; SHOW TABLES;
```

--------------------------------

### Example Output of Blocking Transaction Query

Source: https://docs.pingcap.com/tidb/stable/troubleshoot-lock-conflicts

This is an example output from the query to identify blocking transactions. It shows details of the blocking transaction, including its ID, start time, current SQL, state, and associated SQL digests which can be decoded into normalized SQL statements using `TIDB_DECODE_SQL_DIGESTS`.

```sql
*************************** 1. row ***************************
                    key: 74800000000000004D5F728000000000000001
               INSTANCE: 127.0.0.1:10080
                     ID: 426832040186609668
             START_TIME: 2021-08-06 07:30:16.581000
     CURRENT_SQL_DIGEST: 06da614b93e62713bd282d4685fc5b88d688337f36e88fe55871726ce0eb80d7
CURRENT_SQL_DIGEST_TEXT: update `t` set `v` = `v` + ? where `id` = ? ;
                  STATE: LockWaiting
     WAITING_START_TIME: 2021-08-06 07:30:16.592763
        MEM_BUFFER_KEYS: 1
       MEM_BUFFER_BYTES: 19
             SESSION_ID: 113
                   USER: root
                     DB: test
        ALL_SQL_DIGESTS: ["0fdc781f19da1c6078c9de7eadef8a307889c001e05f107847bee4cfc8f3cdf3","a4e28cc182bdd18288e2a34180499b9404cd0ba07e3cc34b6b3be7b7c2de7fe9","06da614b93e62713bd282d4685fc5b88d688337f36e88fe55871726ce0eb80d7"]
                   sqls: ["begin ;","select * from `t` where `id` = ? for update ;","update `t` set `v` = `v` + ? where `id` = ? ;"]
1 row in set (0.01 sec)
```