REST API

The QuestDB REST API is based on standard HTTP features and is understood by off-the-shelf HTTP clients. It provides a simple way to interact with QuestDB and is compatible with most programming languages. API functions are fully keyed on the URL and they use query parameters as their arguments.

The Web Console is the official Web client relying on the REST API. Find out more in the section using the Web Console.

Available methods

/imp for importing data from .CSV files
/exec to execute a SQL statement
/exp to export data

Examples#

We provide examples in a number of programming languages. See our "develop" docs for:

/imp - Import data#

/imp streams tabular text data directly into a table. It supports CSV, TAB and pipe (|) delimited inputs with optional headers. There are no restrictions on data size. Data types and structures are detected automatically, without additional configuration. In some cases, additional configuration can be provided to improve the automatic detection as described in user-defined schema.

note

The structure detection algorithm analyses the chunk in the beginning of the file and relies on relative uniformity of data. When the first chunk is non-representative of the rest of the data, automatic imports can yield errors.

If the data follows a uniform pattern, the number of lines which are analyzed for schema detection can be reduced to improve performance during uploads using the http.text.analysis.max.lines key. Usage of this setting is described in the HTTP server configuration documentation.

URL parameters#

/imp is expecting an HTTP POST request using the multipart/form-data Content-Type with following optional URL parameters which must be URL encoded:

Parameter	Required	Default	Description
`atomicity`	No	`2`	`0`, `1` or `2`. Behaviour when an error is detected in the data. `0`: the entire file will be skipped. `1`: the row is skipped. `2`: the column is skipped.
`commitLag`	No	`0`	commit lag of the import in microsecond precision (e.g. 2 minutes is expressed as 120000000, 120 followed by 6 zeros). For context, see the commit lag guide.
`delimiter`	No		URL encoded delimiter character. When set, import will try to detect the delimiter automatically. Since automatic delimiter detection requires at least two lines (rows) to be present in the file, this parameter may be used to allow single line file import.
`durable`	No	`false`	`true` or `false`. When set to `true`, import will be resilient against OS errors or power losses by forcing the data to be fully persisted before sending a response back to the user.
`fmt`	No	`tabular`	Can be set to `json` to get the response formatted as such.
`forceHeader`	No	`false`	`true` or `false`. When `false`, QuestDB will try to infer if the first line of the file is the header line. When set to `true`, QuestDB will expect that line to be the header line.
`maxUncommittedRows`	No	0	The maximum number of uncommitted rows to keep in memory before triggering a sort and commit operation. For context, see the commit lag guide.
`name`	No	Name of the file	Name of the table to create, see below.
`overwrite`	No	`false`	`true` or `false`. When set to true, any existing data or structure will be overwritten.
`partitionBy`	No	`NONE`	See partitions.
`skipLev`	No	`false`	`true` or `false`. Skip “Line Extra Values”, when set to true, the parser will ignore those extra values rather than ignoring entire line. An extra value is something in addition to what is defined by the header.
`timestamp`	No		Name of the column that will be used as a designated timestamp.

Example usage

curl -F data=@weather.csv \
'http://localhost:9000/imp?overwrite=true&name=new_table&timestamp=ts&partitionBy=MONTH'

Further example queries with context on the source CSV file contents relative and the generated tables are provided in the examples section below.

Names#

Table and column names are subject to restrictions, the following list of characters are automatically removed:

[whitespace]
.
?
,
:
\
/
\\
\0
)
(
_
+
-
*
~
%

When the header row is missing, column names are generated automatically.

Consistency guarantees#

/imp benefits from the properties of the QuestDB storage model, although Atomicity and Durability can be relaxed to meet convenience and performance demands.

Atomicity#

QuestDB is fully insured against any connection problems. If the server detects closed socket(s), the entire request is rolled back instantly and transparently for any existing readers. The only time data can be partially imported is when atomicity is in relaxed mode and data cannot be converted to column type. In this scenario, any "defective" row of data is discarded and /imp continues to stream request data into table.

Consistency#

This property is guaranteed by consistency of append transactions against QuestDB storage engine.

Isolation#

Data is committed to QuestDB storage engine at end of request. Uncommitted transactions are not visible to readers.

Durability#

/imp streams data from network socket buffer directly into memory mapped files. At this point data is handed over to the OS and is resilient against QuestDB internal errors and unlikely but hypothetically possible crashes. This is default method of appending data and it is chosen for its performance characteristics.

Examples#

Automatic schema detection#

The following example uploads a file ratings.csv which has the following contents:

ts	visMiles	tempF	dewpF
2010-01-01T00:00:00.000000Z	8.8	34	30
2010-01-01T00:51:00.000000Z	9.100000000000	34	30
2010-01-01T01:36:00.000000Z	8.0	34	30
...	...	...	...

An import can be performed with automatic schema detection with the following request:

curl -F data=@weather.csv 'http://localhost:9000/imp'

A HTTP status code of 200 will be returned and the response will be:

+-------------------------------------------------------------------------------+
|      Location:  |     weather.csv  |        Pattern  | Locale  |      Errors  |
|   Partition by  |            NONE  |                 |         |              |
|      Timestamp  |            NONE  |                 |         |              |
+-------------------------------------------------------------------------------+
|   Rows handled  |           49976  |                 |         |              |
|  Rows imported  |           49976  |                 |         |              |
+-------------------------------------------------------------------------------+
|              0  |              ts  |                TIMESTAMP  |           0  |
|              1  |        visMiles  |                   DOUBLE  |           0  |
|              2  |           tempF  |                      INT  |           0  |
|              3  |           dewpF  |                      INT  |           0  |
+-------------------------------------------------------------------------------+

User-defined schema#

To specify the schema of a table, a schema object can be provided:

curl \
-F schema='[{"name":"dewpF", "type": "STRING"}]' \
-F data=@weather.csv 'http://localhost:9000/imp'

Response

+------------------------------------------------------------------------------+
|      Location:  |    weather.csv  |        Pattern  | Locale  |      Errors  |
|   Partition by  |           NONE  |                 |         |              |
|      Timestamp  |           NONE  |                 |         |              |
+------------------------------------------------------------------------------+
|   Rows handled  |          49976  |                 |         |              |
|  Rows imported  |          49976  |                 |         |              |
+------------------------------------------------------------------------------+
|              0  |             ts  |                TIMESTAMP  |           0  |
|              1  |       visMiles  |                   DOUBLE  |           0  |
|              2  |          tempF  |                      INT  |           0  |
|              3  |          dewpF  |                   STRING  |           0  |
+------------------------------------------------------------------------------+

Non-standard timestamp formats

Given a file weather.csv with the following contents which contains a timestamp with a non-standard format:

ts	visMiles	tempF	dewpF
2010-01-01 - 00:00:00	8.8	34	30
2010-01-01 - 00:51:00	9.100000000000	34	30
2010-01-01 - 01:36:00	8.0	34	30
...	...	...	...

The file can be imported as usual with the following request:

Importing CSV with non-standard timestamp

curl -F data=@weather.csv 'http://localhost:9000/imp'

A HTTP status code of 200 will be returned and the import will be successful, but the timestamp column is detected as a STRING type:

Response with timestamp as STRING type

+-------------------------------------------------------------------------------+
|      Location:  |     weather.csv  |        Pattern  | Locale  |      Errors  |
|   Partition by  |            NONE  |                 |         |              |
|      Timestamp  |            NONE  |                 |         |              |
+-------------------------------------------------------------------------------+
|   Rows handled  |           49976  |                 |         |              |
|  Rows imported  |           49976  |                 |         |              |
+-------------------------------------------------------------------------------+
|              0  |              ts  |                   STRING  |           0  |
|              1  |        visMiles  |                   DOUBLE  |           0  |
|              2  |           tempF  |                      INT  |           0  |
|              3  |           dewpF  |                      INT  |           0  |
+-------------------------------------------------------------------------------+

To amend the timestamp column type, this example curl can be used which has a schema JSON object to specify that the ts column is of TIMESTAMP type with the pattern yyyy-MM-dd - HH:mm:ss

Additionally, URL parameters are provided:

overwrite=true to overwrite the existing table
timestamp=ts to specify that the ts column is the designated timestamp column for this table
partitionBy=MONTH to set a partitioning strategy on the table by MONTH

Providing a user-defined schema

curl \
-F schema='[{"name":"ts", "type": "TIMESTAMP", "pattern": "yyyy-MM-dd - HH:mm:ss"}]' \
-F data=@weather.csv \
'http://localhost:9000/imp?overwrite=true&timestamp=ts&partitionBy=MONTH'

The HTTP status code will be set to 200 and the response will show 0 errors parsing the timestamp column:

+------------------------------------------------------------------------------+
|      Location:  |    weather.csv  |        Pattern  | Locale  |      Errors  |
|   Partition by  |          MONTH  |                 |         |              |
|      Timestamp  |             ts  |                 |         |              |
+------------------------------------------------------------------------------+
|   Rows handled  |          49976  |                 |         |              |
|  Rows imported  |          49976  |                 |         |              |
+------------------------------------------------------------------------------+
|              0  |             ts  |                TIMESTAMP  |           0  |
|              1  |       visMiles  |                   DOUBLE  |           0  |
|              2  |          tempF  |                      INT  |           0  |
|              3  |          dewpF  |                      INT  |           0  |
+------------------------------------------------------------------------------+

JSON response#

If you intend to upload CSV programmatically, it's easier parse the reponse as JSON. Set fmt=json query argument on the request.

Here's an example of a successful response:

{
  "status": "OK",
  "location": "example_table",
  "rowsRejected": 0,
  "rowsImported": 3,
  "header": false,
  "columns": [
    {"name": "col1", "type": "SYMBOL", "size": 4, "errors": 0},
    {"name": "col2", "type": "DOUBLE", "size": 8, "errors": 0},
    {"name": "col3", "type": "BOOLEAN", "size": 1, "errors": 0}]
}

Here is an example with request-level errors:

{
  "status": "not enough lines [table=example_table]"
}

Here is an example with column-level errors due to unsuccessful casts:

{
  "status": "OK",
  "location": "example_table2",
  "rowsRejected": 0,
  "rowsImported": 3,
  "header": false,
  "columns": [
    {"name": "col1", "type": "DOUBLE", "size": 8, "errors": 3},
    {"name": "col2", "type": "SYMBOL", "size": 4, "errors": 0},
    {"name": "col3", "type": "BOOLEAN", "size": 1, "errors": 0}]}

Out-of-order import#

The following example imports a file which contains out-of-order records. The timestamp and partitionBy parameters must be provided for commit lag and max uncommitted rows to have any effect. For more information on these parameters, see the commit lag guide.

curl -F data=@weather.csv \
'http://localhost:9000/imp?&timestamp=ts&partitionBy=DAY&commitLag=120000000&maxUncommittedRows=10000'

/exec - Execute queries#

/exec compiles and executes the SQL query supplied as a parameter and returns a JSON response.

note

The query execution terminates automatically when the socket connection is closed.

Overview#

Parameters#

/exec is expecting an HTTP GET request with following query parameters:

Parameter	Required	Default	Description
`count`	No	`false`	`true` or `false`. Counts the number of rows and returns this value.
`limit`	No		Allows limiting the number of rows to return. `limit=10` will return the first 10 rows (equivalent to `limit=1,10`), `limit=10,20` will return row numbers 10 through to 20 inclusive.
`nm`	No	`false`	`true` or `false`. Skips the metadata section of the response when set to `true`.
`query`	Yes		URL encoded query text. It can be multi-line.
`timings`	No	`false`	`true` or `false`. When set to `true`, QuestDB will also include a `timings` property in the response which gives details about the execution times.
`explain`	No	`false`	`true` or `false`. When set to `true`, QuestDB will also include an `explain` property in the response which gives details about the execution plan.
`quoteLargeNum`	No	`false`	`true` or `false`. When set to `true`, QuestDB will surround `LONG` type numbers with double quotation marks that will make them parsed as strings.

The parameters must be URL encoded.

Headers#

Supported HTTP headers:

Header	Required	Description
`Statement-Timeout`	No	Query timeout in milliseconds, overrides default timeout from server.conf

Examples#

SELECT query example:#

curl -G \
  --data-urlencode "query=SELECT timestamp, tempF FROM weather LIMIT 2;" \
  --data-urlencode "count=true" \
  http://localhost:9000/exec

A HTTP status code of 200 is returned with the following response body:

{
  "query": "SELECT timestamp, tempF FROM weather LIMIT 2;",
  "columns": [
    {
      "name": "timestamp",
      "type": "TIMESTAMP"
    },
    {
      "name": "tempF",
      "type": "INT"
    }
  ],
  "dataset": [
    ["2010-01-01T00:00:00.000000Z", 34],
    ["2010-01-01T00:51:00.000000Z", 34]
  ],
  "count": 2
}

SELECT query returns response in the following format:

{
  "query": string,
  "columns": Array<{ "name": string, "type": string }>
  "dataset": Array<Array<Value for Column1, Value for Column2>>,
  "count": Optional<number>,
  "timings": Optional<{ compiler: number, count: number, execute: number }>,
  "explain": Optional<{ jitCompiled: boolean }>
}

You can find the exact list of types in the dedicated page.

UPDATE query example:#

This request executes an update of table weather setting 2 minutes query timeout

curl -G \
  -H "Statement-Timeout: 120000" \
  --data-urlencode "query=UPDATE weather SET tempF = tempF + 0.12 WHERE tempF > 60" \
  http://localhost:9000/exec

A HTTP status code of 200 is returned with the following response body:

{
  "ddl": "OK",
  "updated": 34
}

/exp - Export data#

This endpoint allows you to pass url-encoded queries but the request body is returned in a tabular form to be saved and reused as opposed to JSON.

Overview#

/exp is expecting an HTTP GET request with following parameters:

Parameter	Required	Description
`limit`	No	Paging opp parameter. For example, `limit=10,20` will return row numbers 10 through to 20 inclusive and `limit=20` will return first 20 rows, which is equivalent to `limit=0,20`. `limit=-20` will return the last 20 rows.
`query`	Yes	URL encoded query text. It can be multi-line.

The parameters must be URL encoded.

Examples#

Considering the query:

curl -G \
  --data-urlencode "query=SELECT AccidentIndex2, Date, Time FROM 'Accidents0514.csv'" \
  --data-urlencode "limit=5" \
  http://localhost:9000/exp

A HTTP status code of 200 is returned with the following response body:

"AccidentIndex","Date","Time"
200501BS00001,"2005-01-04T00:00:00.000Z",17:42
200501BS00002,"2005-01-05T00:00:00.000Z",17:36
200501BS00003,"2005-01-06T00:00:00.000Z",00:15
200501BS00004,"2005-01-07T00:00:00.000Z",10:35
200501BS00005,"2005-01-10T00:00:00.000Z",21:13

Error responses#

Malformed queries#

A successful call to /exec or /exp which also contains a malformed query will return response bodies with the following format:

{
  "query": string,
  "error": string,
  "position": number
}

The position field is the character number from the beginning of the string where the error was found.

Considering the query:

curl -G \
  --data-urlencode "query=SELECT * FROM table;" \
  http://localhost:9000/exp

A HTTP status code of 400 is returned with the following response body:

{
  "query": "SELECT * FROM table;",
  "error": "function, literal or constant is expected",
  "position": 8
}