Custom function

Kuiper can customize functions. For the development, compilation and use of functions, please see here.

echo plugin

Function	Example	Description
echo	echo(avg)	Output parameter value as it is

echo(avg) example

Assuming the type of avg is int and the value is 30, the result is: [{"r1":30}]

  SELECT echo(avg) as r1 FROM test;

Function	Example	Description
countPlusOne	countPlusOne(avg)	Output the value of the parameter length plus one

countPlusOne(avg) example

Assuming the type of avg is []int and the value is [1,2,3], the result is: [{"r1":4}]

  SELECT countPlusOne(avg) as r1 FROM test;

Function	Example	Description
accumulateWordCount	accumulateWordCount(avg,sep)	The function counts how many words there are

accumulateWordCount(avg,sep) example

Assuming that the avg type is string and the value is My name is Bob, the sep type is string and the value is a space, the result is: [{"r1":4}]

  SELECT accumulateWordCount(avg,sep) as r1 FROM test;

Image processing currently only supports the formats of png and jpeg

Function	Example	Description
resize	resize(avg,width, height)	Create a scaled image with new dimensions (width, height). If width or height is set to 0, it is set to the reserved value of aspect ratio
thumbnail	thumbnail(avg,maxWidth, maxHeight)	Reduce the image that retains the aspect ratio to the maximum size (maxWidth, maxHeight).

resize(avg,width, height) example

  SELECT resize(avg,width,height) as r1 FROM test;

thumbnail(avg,maxWidth, maxHeight) example

  SELECT countPlusOne(avg,maxWidth, maxHeight) as r1 FROM test;