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mattlord merged 1 commit into from
Oct 4, 2021
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Document SHOW vitess_replication_status #839

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75 changes: 0 additions & 75 deletions content/en/docs/reference/compatibility/mysql-compatibility.md
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Original file line number Diff line number Diff line change
Expand Up @@ -129,81 +129,6 @@ Vitess supports all of the data types available in MySQL. Using the `FLOAT` data

Tables in sharded keyspaces do not support the `auto_increment` column attribute, as the values generated would be local only to each shard. [Vitess Sequences](../../features/vitess-sequences) are provided as an alternative, which have very close semantics to `auto_increment`.

## Extensions to MySQL Syntax

### SHOW Statements

Vitess supports a few additional options with the SHOW statement.

* `SHOW keyspaces` -- A list of keyspaces available.
```shell
Example Output:
+----------+
| Database |
+----------+
| commerce |
| customer |
+----------+
```
* `SHOW vitess_tablets` -- Information about the current Vitess tablets such as the keyspace, key ranges, tablet type, hostname, and status.
```shell
Example Output:
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
| Cell | Keyspace | Shard | TabletType | State | Alias | Hostname | PrimaryTermStartTime |
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
| zone1 | commerce | 0 | PRIMARY | SERVING | zone1-0000000100 | <redacted> | 2021-04-22T04:10:29Z |
| zone1 | commerce | 0 | REPLICA | SERVING | zone1-0000000101 | <redacted> | |
| zone1 | commerce | 0 | RDONLY | SERVING | zone1-0000000102 | <redacted> | |
| zone1 | customer | -80 | PRIMARY | SERVING | zone1-0000000300 | <redacted> | 2021-04-22T04:12:23Z |
| zone1 | customer | -80 | REPLICA | SERVING | zone1-0000000301 | <redacted> | |
| zone1 | customer | -80 | RDONLY | SERVING | zone1-0000000302 | <redacted> | |
| zone1 | customer | 80- | PRIMARY | SERVING | zone1-0000000400 | <redacted> | 2021-04-22T04:12:23Z |
| zone1 | customer | 80- | REPLICA | SERVING | zone1-0000000401 | <redacted> | |
| zone1 | customer | 80- | RDONLY | SERVING | zone1-0000000402 | <redacted> | |
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
```
* `SHOW vitess_shards` -- A list of shards that are available.
```shell
Example Output:
+--------------+
| Shards |
+--------------+
| commerce/0 |
| customer/-80 |
| customer/80- |
+--------------+
```
* `SHOW vschema tables` -- A list of tables available in the current keyspace's vschema.
```shell
Example Output for customer keyspace:
+----------+
| Tables |
+----------+
| corder |
| customer |
| dual |
+----------+
```
* `SHOW vschema vindexes` -- Information about the current keyspace's vindexes such as the keyspace, name, type, params, and owner. Optionally supports an "ON" clause with a table name.
```shell
Example Output:
+----------+------+------+--------+-------+
| Keyspace | Name | Type | Params | Owner |
+----------+------+------+--------+-------+
| customer | hash | hash | | |
+----------+------+------+--------+-------+
```
* `show global gtid_executed [FROM <keyspace>]` -- retrieves the global gtid_executed from each shard in the keyspace either selected or provided in the query.
```shell
Example Output for customer keyspace:
+----------+-------------------------------------------+-------+
| db_name | gtid_executed | shard |
+----------+-------------------------------------------+-------+
| customer | e9148eb0-a320-11eb-8026-98af65a6dc4a:1-43 | 80- |
| customer | e0f64aca-a320-11eb-9be4-98af65a6dc4a:1-43 | -80 |
+----------+-------------------------------------------+-------+
```

### USE Statements

Vitess allows you to select a keyspace using the MySQL `USE` statement, and corresponding binary API used by client libraries. SQL statements can refer to a table in another keyspace by using the standard _dot_ notation:
Expand Down
98 changes: 98 additions & 0 deletions content/en/docs/reference/features/mysql-query-extensions.md
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@@ -0,0 +1,98 @@
---
title: MySQL Query Language Extensions
weight: 9
aliases: []
---

Vitess uses the MySQL [client server protocol](https://dev.mysql.com/doc/internals/en/client-server-protocol.html) and [query language](https://dev.mysql.com/doc/refman/en/language-structure.html). While there are some [limitations and compatibility mismatches](../../compatibility/mysql-compatibility/), Vitess also expands on the MySQL query language for Vitess specific usage.

## Extensions to the MySQL Query Language

### SHOW Statements

Vitess supports the following additional SHOW statements:

* `SHOW global gtid_executed [FROM <keyspace>]` -- retrieves the global gtid_executed status variable from each shard in the keyspace either selected or provided in the query.
```shell
Example Output for customer keyspace:
+----------+-------------------------------------------+-------+
| db_name | gtid_executed | shard |
+----------+-------------------------------------------+-------+
| customer | e9148eb0-a320-11eb-8026-98af65a6dc4a:1-43 | 80- |
| customer | e0f64aca-a320-11eb-9be4-98af65a6dc4a:1-43 | -80 |
+----------+-------------------------------------------+-------+
```

* `SHOW keyspaces` -- A list of keyspaces available.
```shell
Example Output:
+----------+
| Database |
+----------+
| commerce |
| customer |
+----------+
```

* `SHOW vitess_replication_status [LIKE "<Keyspace/<Shard>"]` (**Experimental; 12.0+**) -- Shows the Replication (_not_ [VReplication](../../vreplication/vreplication/)) health for the Vitess deployment. It returns a row for each `REPLICA` and `RDONLY` tablet in the topology -- with support for filtering by Keyspace/Shard using a `LIKE` clause -- providing relevant health and status information, including the current [tablet throttler](../tablet-throttler/) status.
```shell
Example Output:
+----------+-------+------------+------------------+--------------+--------------------+-------------------------------------------------------------------------+----------------+-----------------------------------------+
| Keyspace | Shard | TabletType | Alias | Hostname | ReplicationSource | ReplicationHealth | ReplicationLag | ThrottlerStatus |
+----------+-------+------------+------------------+--------------+--------------------+-------------------------------------------------------------------------+----------------+-----------------------------------------+
| commerce | 0 | REPLICA | zone1-0000000101 | 52030e360852 | 52030e360852:17100 | {"EventStreamRunning":"Yes","EventApplierRunning":"Yes","LastError":""} | 0 | {"state":"OK","load":0.00,"message":""} |
| commerce | 0 | RDONLY | zone1-0000000102 | 52030e360852 | 52030e360852:17100 | {"EventStreamRunning":"Yes","EventApplierRunning":"Yes","LastError":""} | 0 | {"state":"OK","load":0.00,"message":""} |
+----------+-------+------------+------------------+--------------+--------------------+-------------------------------------------------------------------------+----------------+-----------------------------------------+
```

* `SHOW vitess_shards` -- A list of shards that are available.
```shell
Example Output:
+--------------+
| Shards |
+--------------+
| commerce/0 |
| customer/-80 |
| customer/80- |
+--------------+
```

* `SHOW vitess_tablets` -- Information about the current Vitess tablets such as the keyspace, key ranges, tablet type, hostname, and status.
```shell
Example Output:
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
| Cell | Keyspace | Shard | TabletType | State | Alias | Hostname | PrimaryTermStartTime |
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
| zone1 | commerce | 0 | PRIMARY | SERVING | zone1-0000000100 | <redacted> | 2021-04-22T04:10:29Z |
| zone1 | commerce | 0 | REPLICA | SERVING | zone1-0000000101 | <redacted> | |
| zone1 | commerce | 0 | RDONLY | SERVING | zone1-0000000102 | <redacted> | |
| zone1 | customer | -80 | PRIMARY | SERVING | zone1-0000000300 | <redacted> | 2021-04-22T04:12:23Z |
| zone1 | customer | -80 | REPLICA | SERVING | zone1-0000000301 | <redacted> | |
| zone1 | customer | -80 | RDONLY | SERVING | zone1-0000000302 | <redacted> | |
| zone1 | customer | 80- | PRIMARY | SERVING | zone1-0000000400 | <redacted> | 2021-04-22T04:12:23Z |
| zone1 | customer | 80- | REPLICA | SERVING | zone1-0000000401 | <redacted> | |
| zone1 | customer | 80- | RDONLY | SERVING | zone1-0000000402 | <redacted> | |
+-------+----------+-------+------------+---------+------------------+------------+----------------------+
```

* `SHOW vschema tables` -- A list of tables available in the current keyspace's vschema.
```shell
Example Output for customer keyspace:
+----------+
| Tables |
+----------+
| corder |
| customer |
| dual |
+----------+
```

* `SHOW vschema vindexes` -- Information about the current keyspace's vindexes such as the keyspace, name, type, params, and owner. Optionally supports an "ON" clause with a table name.
```shell
Example Output:
+----------+------+------+--------+-------+
| Keyspace | Name | Type | Params | Owner |
+----------+------+------+--------+-------+
| customer | hash | hash | | |
+----------+------+------+--------+-------+
```