This interface is used to execute the SQL statement of the specified object in the bucket, and select and return the specified content. The requester must have the read permission of the selected object. Before SelectObject, you need to ensure that the corresponding bucket and object already exist. For more information, see SelectObject Developer Documentation.
Detailed description of the message format:
There are 8 bytes in the prelude section. The first 4 bytes represent the total length of messages. The last 4 bytes represent the total length of headers, Total chunk length (prelude the value stored in the first 4bytes) - total header length - 8 bytes of prelude part - 4 bytes of crc32 = Total data length of the payload part. CRC32 represents the erasure code of the whole message.
Headers contain the following custom <key,value>: “message-type”: {"Records", "Cont", "End"}, "error-code": specific error code and "error-message": "detailed error information".
Payload represents the real data returned, which can be in any format. The payload of the Continuation message contains the Select progress information represented by BytesScanned and BytesReturned fields.
Request URI
POST /v1/{bucketName}/{objectKey}?select
Parameter Name
Parameter Type
Required
Description
Example Value
Parameter Position
bucketName
String
Yes
Bucket name
"bucketName_example"
Path
objectKey
String
Yes
Object name
"objectKey_example"
Path
type
String
Yes
Destination object type selected, which can be JSON/CSV currently.
"type_example"
Query
Request Body Parameters
Description of Data Structure for Request Body Field
Parameter Name
Parameter Type
Required
Description
Example Value
selectRequest
SelectRequest
Yes
JSON body root node
Description of Data Structure for SelectRequest Field
Query statement syntax type, which can be SQL only.
SQL
inputSerialization
InputSerialization
Yes
Input stream node, whose child node describes the queried object format information.
outputSerialization
OutputSerialization
Yes
Output stream node, whose child node describes the return format information of query result.
requestProgress
RequestProgress
No
+ requestProgress No - Select the progress information node, whose child node describes the execution progress of Select operation and returns it to the user within 3s regularly.
Data Structure Description of InputSerialization Field
Parameter Name
Parameter Type
Required
Description
Example Value
compressionType
String
No
Specify whether the queried object is compressed, whose optional value is "NONE" or "GZIP".
NONE
csv
Csv
No
CSV node, whose child node describes the CSV file related information.
Description of Data Structure for Csv Field
Parameter Name
Parameter Type
Required
Description
Example Value
fileHeaderInfo
String
No
The optional value is NONE/IGNORE/USE, which specifies the first-line header information of the CSV file. The default NONE represents that there is no header information, and IGNORE represents that there is the header information, but it is ignored. NONE and IGNORE mean that a column can be taken out with the column serial number only. USE represents that the header information is used, and a column can be taken out with the header name only.
NONE
recordDelimiter
String
No
Specify the newline character of the CSV file. which is Base64 encoded. The default value is \n (optional). It includes up to 2 characters, e.g., \r\n.
\r\n
fieldDelimiter
String
No
Specify the column separator of the CSV file, which is Base64 encoded. The default value is “,” (optional). It includes up to 1 character, e.g., “;”.
;
quoteCharacter
String
No
Specify the quotation marks character of the CSV file, which is Base64 encoded. The newline character and column separator in quotation marks in CSV are regarded as the ordinary character. The default value is double quotation marks (") (optional). It includes up to 1 character, such as single quotation marks (').
'
commentCharacter
String
No
Specify the comment character of the CSV file, which is Base64 encoded. If a line starts with the comment character, it indicates that this line can be ignored. The default value is # (optional). It includes up to 2 characters, e.g., //.
//
Description of Data Structure for OutputSerialization Field
Parameter Name
Parameter Type
Required?
Description
Example Value
outputHeader
Boolean
No
Output the CSV header information at the beginning of return results, which is false by default. The fileHeaderInfo field value must be “USE”. If this value is true, the corresponding CSV header name is added to the first line of each Records message in return results. The optional value is false/true.
false
csv
Csv
No
CSV node, whose child node describes the returned CSV data related information.
Data Structure Description of RequestProgress Field
Parameter Name
Parameter Type
Required?
Description
Example Value
enabled
Boolean
No
Describe whether the progress information needs to be returned regularly, whose optional value is false/true. If the data filtration takes a long time, it may cause the timeout error 504. You can set it to “True” to maintain the HTTP connection.
false
Response Body Parameters
Description of Data Structure for Response Body Field
Request Example
POST /v1/bucketName_example/objectKey_example?select&type=type_example
Common Request Header
{"selectRequest":{"outputSerialization":{"outputHeader":false,"csv":{"quoteFields":"ALWAYS","recordDelimiter":"Cg==","quoteCharacter":"Ig==","fieldDelimiter":"LA=="}},"expression":"c2VsZWN0IGNvdW50KCopIGZyb20gbxkl2JqZWN0IHdoZXJlIF80ID4gNDU=","expressionType":"SQL","requestProgress":{"enabled":false},"inputSerialization":{"csv":{"fileHeaderInfo":"NONE","recordDelimiter":"\\r\\n","quoteCharacter":"'","fieldDelimiter":";","commentCharacter":"//"},"compressionType":"NONE"}}}
