Version: latest

Quick start

CnosDB SQL is inspired by DataFusion, We support most of the SQL syntax of DataFusion.

Note: In order to query more efficiently, the order of each row may not be the same for queries without specified sorting

Sample Data

To learn more about CnosDB, this section provides sample data for you to download and teaches you how to import data into the database.The data sources cited in later chapters are taken from this example data.

Download Data

If in cnosdb-cli, type \q to exit

Executing the following command in the shell will generate a local data file named oceanic_station in Line Protocol format.

curl -o oceanic_station.txt https://dl.cnosdb.com/sample/oceanic_station.txt

Import Data

Start the CLI
```
cnosdb-cli
```
Create the database
```
create database oceanic_station;
```
Switch to the specified database
```
\c oceanic_station
```
Import data
Execute the \w command, followed by the absolute path of the data file or the working path relative to cnosdb-cli.
```
\w oceanic_station.txt
```

Syntax

[ WITH with_query [, ...] ]
SELECT [ ALL | DISTINCT ] select_expression [, ...]
    [ FROM from_item [, ...] ]
    [ WHERE condition ]
    [ GROUP BY [ ALL | DISTINCT ] grouping_element [, ...] ]
    [ HAVING condition ]
    [ { UNION | INTERSECT | EXCEPT } [ ALL | DISTINCT ] select ]
    [ ORDER BY expression [ ASC | DESC ] [, ...] ]
    [ OFFSET count ]
    [ LIMIT { count | ALL } ];

-- from_item
-- 1.
    tb_name [ [ AS ] alias [ ( column_alias [, ...] ) ] ]
-- 2.
    from_item join_type from_item
    { ON join_condition | USING ( join_column [, ...] ) }

-- join_type
    [ INNER ] JOIN
    LEFT [ OUTER ] JOIN
    RIGHT [ OUTER ] JOIN
    FULL [ OUTER ] JOIN
    CROSS JOIN

-- grouping_element
    ()

SELECT Clause

SELECT *

The wildcard * can be used to refer to all columns.

Example

SELECT * FROM air;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:21:00 | XiaoMaiDao  | 56         | 69          | 77       |
| 2022-01-28 13:24:00 | XiaoMaiDao  | 50         | 78          | 66       |
| 2022-01-28 13:27:00 | XiaoMaiDao  | 67         | 62          | 59       |
| 2022-01-28 13:30:00 | XiaoMaiDao  | 65         | 79          | 77       |
| 2022-01-28 13:33:00 | XiaoMaiDao  | 53         | 53          | 68       |
| 2022-01-28 13:36:00 | XiaoMaiDao  | 74         | 72          | 68       |
| 2022-01-28 13:39:00 | XiaoMaiDao  | 71         | 71          | 80       |
| 2022-01-28 13:21:00 | LianYunGang | 78         | 69          | 71       |
| 2022-01-28 13:24:00 | LianYunGang | 79         | 80          | 51       |
| 2022-01-28 13:27:00 | LianYunGang | 59         | 74          | 59       |
| 2022-01-28 13:30:00 | LianYunGang | 67         | 70          | 72       |
| 2022-01-28 13:33:00 | LianYunGang | 80         | 70          | 68       |
| 2022-01-28 13:36:00 | LianYunGang | 59         | 70          | 54       |
+---------------------+-------------+------------+-------------+----------+

ALL/DISTINCT

Syntax

SELECT [ ALL | DISTINCT ] select_expression [, ...];

You can use DISTINCT after the SELECT keyword to remove duplicate fields and return only the de-duplicated values. Using ALL returns all duplicate values in the field.When this option is not specified, the default value is ALL.

Example

SELECT DISTINCT station, visibility FROM air;

+-------------+------------+
| station     | visibility |
+-------------+------------+
| XiaoMaiDao  | 56         |
| XiaoMaiDao  | 50         |
| XiaoMaiDao  | 67         |
| XiaoMaiDao  | 65         |
| XiaoMaiDao  | 53         |
| XiaoMaiDao  | 74         |
| XiaoMaiDao  | 71         |
| LianYunGang | 78         |
| LianYunGang | 79         |
| LianYunGang | 59         |
| LianYunGang | 67         |
| LianYunGang | 80         |
+-------------+------------+

SELECT station, visibility FROM air;

+-------------+------------+
| station     | visibility |
+-------------+------------+
| XiaoMaiDao  | 56         |
| XiaoMaiDao  | 50         |
| XiaoMaiDao  | 67         |
| XiaoMaiDao  | 65         |
| XiaoMaiDao  | 53         |
| XiaoMaiDao  | 74         |
| XiaoMaiDao  | 71         |
| LianYunGang | 78         |
| LianYunGang | 79         |
| LianYunGang | 59         |
| LianYunGang | 67         |
| LianYunGang | 80         |
| LianYunGang | 59         |
+-------------+------------+

Alias

You can use the keyword AS to alias a column expression or table.

Alias for column expression

Syntax

expression [ [ AS ] column_alias ]

Example

SELECT station s, visibility AS v FROM air;

+-------------+----+
| s           | v  |
+-------------+----+
| XiaoMaiDao  | 56 |
| XiaoMaiDao  | 50 |
| XiaoMaiDao  | 67 |
| XiaoMaiDao  | 65 |
| XiaoMaiDao  | 53 |
| XiaoMaiDao  | 74 |
| XiaoMaiDao  | 71 |
| LianYunGang | 78 |
| LianYunGang | 79 |
| LianYunGang | 59 |
| LianYunGang | 67 |
| LianYunGang | 80 |
| LianYunGang | 59 |
+-------------+----+

Alias for table

You can also use the keyword AS to alias the table.

Syntax

FROM tb_name [AS] alias_name

Example

SELECT a.visibility, s.temperature
FROM air AS a JOIN sea s ON a.temperature = s.temperature limit 10;

+------------+-------------+
| visibility | temperature |
+------------+-------------+
| 80.0       | 56.0        |
| 57.0       | 56.0        |
| 70.0       | 56.0        |
| 78.0       | 56.0        |
| 56.0       | 56.0        |
| 63.0       | 56.0        |
| 69.0       | 56.0        |
| 59.0       | 56.0        |
| 60.0       | 56.0        |
| 51.0       | 56.0        |
+------------+-------------+

SELECT Limitation

If the SELECT clause contains only the Tag column, it is equivalent to the SELECT DISTINCT Tag column.

Example

-- station是Tag列，temperature是Field列
SELECT station, temperature FROM air;

+-------------+-------------+
| station     | temperature |
+-------------+-------------+
| XiaoMaiDao  | 69          |
| XiaoMaiDao  | 78          |
| XiaoMaiDao  | 62          |
| XiaoMaiDao  | 79          |
| XiaoMaiDao  | 53          |
| XiaoMaiDao  | 72          |
| XiaoMaiDao  | 71          |
| LianYunGang | 69          |
| LianYunGang | 80          |
| LianYunGang | 74          |
| LianYunGang | 70          |
| LianYunGang | 70          |
| LianYunGang | 70          |
+-------------+-------------+

-- station is a Tag column
SELECT station FROM air;

+-------------+
| station     |
+-------------+
| XiaoMaiDao  |
| LianYunGang |
+-------------+ 

LIMIT Clause

Syntax

LIMIT n

Limit the number of rows returned from the result set to n, and n must be non-negative.

Example

SELECT *
FROM air LIMIT 10;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:21:00 | XiaoMaiDao  | 56         | 69          | 77       |
| 2022-01-28 13:24:00 | XiaoMaiDao  | 50         | 78          | 66       |
| 2022-01-28 13:27:00 | XiaoMaiDao  | 67         | 62          | 59       |
| 2022-01-28 13:30:00 | XiaoMaiDao  | 65         | 79          | 77       |
| 2022-01-28 13:33:00 | XiaoMaiDao  | 53         | 53          | 68       |
| 2022-01-28 13:36:00 | XiaoMaiDao  | 74         | 72          | 68       |
| 2022-01-28 13:39:00 | XiaoMaiDao  | 71         | 71          | 80       |
| 2022-01-28 13:21:00 | LianYunGang | 78         | 69          | 71       |
| 2022-01-28 13:24:00 | LianYunGang | 79         | 80          | 51       |
| 2022-01-28 13:27:00 | LianYunGang | 59         | 74          | 59       |
+---------------------+-------------+------------+-------------+----------+

OFFSET Clause

Syntax

OFFSET m

The returned result set skips m records. default m=0. Example

SELECT *
FROM air OFFSET 10;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:30:00 | LianYunGang | 67         | 70          | 72       |
| 2022-01-28 13:33:00 | LianYunGang | 80         | 70          | 68       |
| 2022-01-28 13:36:00 | LianYunGang | 59         | 70          | 54       |
+---------------------+-------------+------------+-------------+----------+

OFFSET can be used with the LIMIT statement to specify the number of lines to skip. The format is LIMIT n OFFSET m, or it can be abbreviated as LIMIT n, m. LIMIT n controls the output of n rows of data, and OFFSET m indicates the number of rows skipped before starting to return data. OFFSET 0 has the same effect as omitting the OFFSET clause. Among them: LIMIT n controls the output of n rows of data, OFFSET m indicates the number of rows to skip before starting to return data. OFFSET 0 is equivalent to omitting the OFFSET clause.

Example

SELECT *
FROM air LIMIT 3 OFFSET 3;

+---------------------+------------+------------+-------------+----------+
| time                | station    | visibility | temperature | pressure |
+---------------------+------------+------------+-------------+----------+
| 2022-01-28 13:30:00 | XiaoMaiDao | 65         | 79          | 77       |
| 2022-01-28 13:33:00 | XiaoMaiDao | 53         | 53          | 68       |
| 2022-01-28 13:36:00 | XiaoMaiDao | 74         | 72          | 68       |
+---------------------+------------+------------+-------------+----------+

WITH Clause

Syntax

WITH cte AS cte_query_definiton [, ...] query

Optional.The WITH clause contains one or more common expressions CTE (Common Table Expression). The CTE acts as a temporary table in the current runtime environment that you can refer to in subsequent queries.The following rules for use by CTE are:

CTE in the same WITH clause must have a unique name.
A CTE defined in a WITH clause is available only to other CTEs defined thereafter in the same WITH clause. Assume A is the first CTE, B is the second CTE:

Example

SELECT station, avg 
FROM (  SELECT station, AVG(visibility) AS avg 
        FROM air 
        GROUP BY station) AS x;

+-------------+--------------------+
| station     | avg                |
+-------------+--------------------+
| XiaoMaiDao  | 62.285714285714285 |
| LianYunGang | 70.33333333333333  |
+-------------+--------------------+

WITH x AS 
    (SELECT station, AVG(visibility) AS avg FROM air GROUP BY station)
SELECT station, avg
FROM x;

+-------------+--------------------+
| station     | avg                |
+-------------+--------------------+
| XiaoMaiDao  | 62.285714285714285 |
| LianYunGang | 70.33333333333333  |
+-------------+--------------------+

UNION Clause

The UNION clause is used to combine the analysis results of multiple SELECT statements.

Syntax

select_clause_set_left
[ UNION | UNION ALL| EXCEPT | INTERSECT]
select_clause_set_right
[sort_list_columns] [limit_clause]

UNION will de-duplicate the merged result set. UNION ALL will retain the same data in the merged result set. EXCEPT will make the difference between the two result sets, return all non-duplicate values not found in the right query from the left query. INTERSECT returns the intersection of the two result sets (that means, all non-duplicate values are returned by both queries).

Note

Each SELECT clause in the UNION must have the same number of columns, and the corresponding columns have the same data type.

Example

UNION ALL

SELECT visibility FROM air WHERE temperature < 60
UNION ALL
SELECT visibility FROM air WHERE temperature > 50 LIMIT 10;

+------------+
| visibility |
+------------+
| 53         |
| 56         |
| 50         |
| 67         |
| 65         |
| 53         |
| 74         |
| 71         |
| 78         |
| 79         |
+------------+

UNION

SELECT visibility FROM air WHERE temperature < 60
UNION
SELECT visibility FROM air WHERE temperature > 50 LIMIT 10;

+------------+
| visibility |
+------------+
| 53         |
| 56         |
| 50         |
| 67         |
| 65         |
| 74         |
| 71         |
| 78         |
| 79         |
| 59         |
+------------+

EXCEPT

SELECT visibility FROM air
EXCEPT
SELECT visibility FROM air WHERE temperature < 50 LIMIT 10;

+------------+
| visibility |
+------------+
| 56         |
| 50         |
| 67         |
| 65         |
| 53         |
| 74         |
| 71         |
| 78         |
| 79         |
| 59         |
+------------+

INTERSECT

SELECT visibility FROM air
INTERSECT
SELECT visibility FROM air WHERE temperature > 50 LIMIT 10;

+------------+
| visibility |
+------------+
| 56         |
| 50         |
| 67         |
| 65         |
| 53         |
| 74         |
| 71         |
| 78         |
| 79         |
| 59         |
+------------+

ORDER BY Clause

Sort the results by the quoted expression.Default usage ascending (ASC).Sort the results by the referenced expression. Ascending (ASC) is used by default. Sort in descending order by adding DESC after the expression of ORDER BY.

Example

SELECT * FROM air ORDER BY temperature;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:33:00 | XiaoMaiDao  | 53         | 53          | 68       |
| 2022-01-28 13:27:00 | XiaoMaiDao  | 67         | 62          | 59       |
| 2022-01-28 13:21:00 | XiaoMaiDao  | 56         | 69          | 77       |
| 2022-01-28 13:21:00 | LianYunGang | 78         | 69          | 71       |
| 2022-01-28 13:30:00 | LianYunGang | 67         | 70          | 72       |
| 2022-01-28 13:33:00 | LianYunGang | 80         | 70          | 68       |
| 2022-01-28 13:36:00 | LianYunGang | 59         | 70          | 54       |
| 2022-01-28 13:39:00 | XiaoMaiDao  | 71         | 71          | 80       |
| 2022-01-28 13:36:00 | XiaoMaiDao  | 74         | 72          | 68       |
| 2022-01-28 13:27:00 | LianYunGang | 59         | 74          | 59       |
| 2022-01-28 13:24:00 | XiaoMaiDao  | 50         | 78          | 66       |
| 2022-01-28 13:30:00 | XiaoMaiDao  | 65         | 79          | 77       |
| 2022-01-28 13:24:00 | LianYunGang | 79         | 80          | 51       |
+---------------------+-------------+------------+-------------+----------+

SELECT * FROM air ORDER BY temperature DESC;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:24:00 | LianYunGang | 79         | 80          | 51       |
| 2022-01-28 13:30:00 | XiaoMaiDao  | 65         | 79          | 77       |
| 2022-01-28 13:24:00 | XiaoMaiDao  | 50         | 78          | 66       |
| 2022-01-28 13:27:00 | LianYunGang | 59         | 74          | 59       |
| 2022-01-28 13:36:00 | XiaoMaiDao  | 74         | 72          | 68       |
| 2022-01-28 13:39:00 | XiaoMaiDao  | 71         | 71          | 80       |
| 2022-01-28 13:30:00 | LianYunGang | 67         | 70          | 72       |
| 2022-01-28 13:33:00 | LianYunGang | 80         | 70          | 68       |
| 2022-01-28 13:36:00 | LianYunGang | 59         | 70          | 54       |
| 2022-01-28 13:21:00 | XiaoMaiDao  | 56         | 69          | 77       |
| 2022-01-28 13:21:00 | LianYunGang | 78         | 69          | 71       |
| 2022-01-28 13:27:00 | XiaoMaiDao  | 67         | 62          | 59       |
| 2022-01-28 13:33:00 | XiaoMaiDao  | 53         | 53          | 68       |
+---------------------+-------------+------------+-------------+----------+

SELECT * FROM air ORDER BY station, temperature;

+---------------------+-------------+------------+-------------+----------+
| time                | station     | visibility | temperature | pressure |
+---------------------+-------------+------------+-------------+----------+
| 2022-01-28 13:21:00 | LianYunGang | 78         | 69          | 71       |
| 2022-01-28 13:30:00 | LianYunGang | 67         | 70          | 72       |
| 2022-01-28 13:33:00 | LianYunGang | 80         | 70          | 68       |
| 2022-01-28 13:36:00 | LianYunGang | 59         | 70          | 54       |
| 2022-01-28 13:27:00 | LianYunGang | 59         | 74          | 59       |
| 2022-01-28 13:24:00 | LianYunGang | 79         | 80          | 51       |
| 2022-01-28 13:33:00 | XiaoMaiDao  | 53         | 53          | 68       |
| 2022-01-28 13:27:00 | XiaoMaiDao  | 67         | 62          | 59       |
| 2022-01-28 13:21:00 | XiaoMaiDao  | 56         | 69          | 77       |
| 2022-01-28 13:39:00 | XiaoMaiDao  | 71         | 71          | 80       |
| 2022-01-28 13:36:00 | XiaoMaiDao  | 74         | 72          | 68       |
| 2022-01-28 13:24:00 | XiaoMaiDao  | 50         | 78          | 66       |
| 2022-01-28 13:30:00 | XiaoMaiDao  | 65         | 79          | 77       |
+---------------------+-------------+------------+-------------+----------+

IN

The IN operator allows you to specify multiple values in the WHERE clause.

Example

SELECT station, temperature, visibility FROM air WHERE temperature  IN (68, 69);

+-------------+-------------+------------+
| station     | temperature | visibility |
+-------------+-------------+------------+
| XiaoMaiDao  | 69          | 56         |
| LianYunGang | 69          | 78         |
+-------------+-------------+------------+

Note

The IN list does not support expressions currently, but only constants.

SHOW

Syntax

SHOW {DATABASES | TABLES | QUERIES}

Show all databases or all tables.

Example

SHOW DATABASES;

+----------+
| Database |
+----------+
| public   |
+----------+

SHOW TABLES;

+-------+
| Table |
+-------+
| sea   |
| air   |
| wind  |
+-------+

SHOW QUERIES;

+----------+------------------------------------------------------------------+-----------------------------------------+-----------+----------------------------------------+-------------+------------+--------------+
| query_id | query_text                                                       | user_id                                 | user_name | tenant_id                              | tenant_name | state      | duration     |
+----------+------------------------------------------------------------------+-----------------------------------------+-----------+----------------------------------------+-------------+------------+--------------+
| 36       | select * FROM air join sea ON air.temperature = sea.temperature; | 108709109615072923019194003831375742761 | root      | 13215126763611749424716665303609634152 | cnosdb      | SCHEDULING | 12.693345666 |
+----------+------------------------------------------------------------------+-----------------------------------------+-----------+----------------------------------------+-------------+------------+--------------+

Detailed information on SHOW QUERIES statements can be found in System Table QUERIES

EXPLAIN

Syntax

EXPLAIN [ ANALYZE ] [ VERBOSE ] <statement>;

Explanation

EXPLAIN is only used to display the execution plan of a query, and does not execute the query.

EXPLAIN ANALYZE executes the query and displays the execution plan of the query.

EXPLAIN ANALYZE VERBOSE executes the query and displays a more detailed execution plan, including the number of rows read.

Example

EXPLAIN SELECT station, temperature, visibility FROM air;

+---------------+-----------------------------------------------------------------------------------------------------------------------------+
| plan_type     | plan                                                                                                                        |
+---------------+-----------------------------------------------------------------------------------------------------------------------------+
| logical_plan  | Projection: #air.station, #air.temperature, #air.visibility                                                                 |
|               |   TableScan: air projection=[station, visibility, temperature]                                                              |
| physical_plan | ProjectionExec: expr=[station@0 as station, temperature@2 as temperature, visibility@1 as visibility]                       |
|               |   TskvExec: limit=None, predicate=ColumnDomains { column_to_domain: Some({}) }, projection=[station,visibility,temperature] |
|               |                                                                                                                             |
+---------------+-----------------------------------------------------------------------------------------------------------------------------+

EXPLAIN ANALYZE SELECT station, temperature, visibility FROM air;

+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type         | plan                                                                                                                                                                                                                                                                                                                                    |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | ProjectionExec: expr=[station@0 as station, temperature@2 as temperature, visibility@1 as visibility], metrics=[output_rows=13, elapsed_compute=20.375µs, spill_count=0, spilled_bytes=0, mem_used=0]                                                                                                                                   |
|                   |   TskvExec: limit=None, predicate=ColumnDomains { column_to_domain: Some({}) }, projection=[station,visibility,temperature], metrics=[output_rows=13, elapsed_compute=15.929624ms, spill_count=0, spilled_bytes=0, mem_used=0, elapsed_series_scan=1.698791ms, elapsed_point_to_record_batch=4.572954ms, elapsed_field_scan=5.119076ms] |
|                   |                                                                                                                                                                                                                                                                                                                                         |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

EXPLAIN ANALYZE SELECT station, temperature, visibility FROM air;

+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type         | plan                                                                                                                                                                                                                                                                                                                                    |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics | ProjectionExec: expr=[station@0 as station, temperature@2 as temperature, visibility@1 as visibility], metrics=[output_rows=13, elapsed_compute=20.375µs, spill_count=0, spilled_bytes=0, mem_used=0]                                                                                                                                   |
|                   |   TskvExec: limit=None, predicate=ColumnDomains { column_to_domain: Some({}) }, projection=[station,visibility,temperature], metrics=[output_rows=13, elapsed_compute=15.929624ms, spill_count=0, spilled_bytes=0, mem_used=0, elapsed_series_scan=1.698791ms, elapsed_point_to_record_batch=4.572954ms, elapsed_field_scan=5.119076ms] |
|                   |                                                                                                                                                                                                                                                                                                                                         |
+-------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

EXPLAIN ANALYZE VERBOSE SELECT station, temperature, visibility FROM air;

+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| plan_type              | plan                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Plan with Metrics      | ProjectionExec: expr=[station@0 as station, temperature@2 as temperature, visibility@1 as visibility], metrics=[output_rows=13, elapsed_compute=26.75µs, spill_count=0, spilled_bytes=0, mem_used=0]                                                                                                                                                                                                                                                                                                                                                                    |
|                        |   TskvExec: limit=None, predicate=ColumnDomains { column_to_domain: Some({}) }, projection=[station,visibility,temperature], metrics=[output_rows=13, elapsed_compute=13.225875ms, spill_count=0, spilled_bytes=0, mem_used=0, elapsed_point_to_record_batch=3.918163ms, elapsed_field_scan=3.992161ms, elapsed_series_scan=1.657416ms]                                                                                                                                                                                                                                 |
|                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Plan with Full Metrics | ProjectionExec: expr=[station@0 as station, temperature@2 as temperature, visibility@1 as visibility], metrics=[start_timestamp{partition=0}=2022-10-25 03:00:14.865034 UTC, end_timestamp{partition=0}=2022-10-25 03:00:14.879596 UTC, elapsed_compute{partition=0}=26.75µs, spill_count{partition=0}=0, spilled_bytes{partition=0}=0, mem_used{partition=0}=0, output_rows{partition=0}=13]                                                                                                                                                                           |
|                        |   TskvExec: limit=None, predicate=ColumnDomains { column_to_domain: Some({}) }, projection=[station,visibility,temperature], metrics=[start_timestamp{partition=0}=2022-10-25 03:00:14.864225 UTC, end_timestamp{partition=0}=2022-10-25 03:00:14.879596 UTC, elapsed_compute{partition=0}=13.225875ms, spill_count{partition=0}=0, spilled_bytes{partition=0}=0, mem_used{partition=0}=0, output_rows{partition=0}=13, elapsed_point_to_record_batch{partition=0}=3.918163ms, elapsed_field_scan{partition=0}=3.992161ms, elapsed_series_scan{partition=0}=1.657416ms] |
|                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| Output Rows            | 13                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Duration               | 13.307708ms                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

DESCRIBE

Syntax

DESCRIBE {DATABASE db_name | TABLE tb_name};

Describe the parameters of the database and the pattern of the table.

Example

DESCRIBE TABLE air;

+-------------+-----------+-------+-------------+
| FIELDNAME   | TYPE      | ISTAG | COMPRESSION |
+-------------+-----------+-------+-------------+
| time        | TIMESTAMP | false | Default     |
| station     | STRING    | true  | Default     |
| visibility  | DOUBLE    | false | Default     |
| temperature | DOUBLE    | false | Default     |
| pressure    | DOUBLE    | false | Default     |
+-------------+-----------+-------+-------------+

DESCRIBE DATABASE public;

+----------+-------+----------------+---------+-----------+
| TTL      | SHARD | VNODE_DURATION | REPLICA | PRECISION |
+----------+-------+----------------+---------+-----------+
| 365 Days | 1     | 365 Days       | 1       | NS        |
+----------+-------+----------------+---------+-----------+

Quick start

Sample Data​

Download Data​

Import Data​

Syntax​

SELECT Clause​

SELECT *​

ALL/DISTINCT​

Alias​

Alias for column expression​

Alias for table​

SELECT Limitation​

LIMIT Clause​

OFFSET Clause​

WITH Clause​

UNION Clause​

ORDER BY Clause​

IN​

SHOW​

EXPLAIN​

DESCRIBE​

Sample Data

Download Data

Import Data

Syntax

SELECT Clause

SELECT *

ALL/DISTINCT

Alias

Alias for column expression

Alias for table

SELECT Limitation

LIMIT Clause

OFFSET Clause

WITH Clause

UNION Clause

ORDER BY Clause

IN

SHOW

EXPLAIN

DESCRIBE