Create js_udaf_demo.sql

examples/udf/js_udaf_demo.sql

@@ -0,0 +1,70 @@
+CREATE AGGREGATE FUNCTION udf(col1 float32,col2 float32,col3 float32,col4 float32)
+RETURNS string
+LANGUAGE JAVASCRIPT AS $${
+  //A UDF to get recent 100 events and get their sum/count/min/max
+
+  initialize: function () {
+    this.last100 = [[], [], [], []];
+    this.reset();
+  },
+
+  reset: function () {
+    this.sum = 0;
+    this.count = 0;
+    this.min = Number.MAX_VALUE;
+    this.max = Number.MIN_VALUE;
+    this.result = {};
+  },
+
+  process: function (col1, col2, col3, col4) {
+    let inputs = [col1, col2, col3, col4];
+    for (let i = inputs[0].length - 1; i >= 0; i--) {
+      //add data to the beginning of the arrays
+      for (let j = 0; j < 4; j++) {
+        this.last100[j].unshift(inputs[j][i]);
+      }
+    }
+    this.reset();
+    for (let i = 0; i < 4; i++) {
+      //get the recent 100 values
+      this.last100[i].length = Math.min(this.last100[i].length, 100);
+      //calc sum/count/min/max
+      for (let j = this.last100[i].length - 1; j >= 0; j--) {
+        this.sum += this.last100[i][j];
+        this.count++;
+        if (this.last100[i][j] > this.max) {
+          this.max = this.last100[i][j];
+        }
+        if (this.last100[i][j] < this.min) {
+          this.min = this.last100[i][j];
+        }
+      }
+    }
+    //return result as a json
+    this.result = {
+      sum: this.sum,
+      count: this.count,
+      min: this.min,
+      max: this.max,
+    };
+  },
+
+  finalize: function () {
+    let old_results = this.result;
+    this.result = {};
+    return JSON.stringify(old_results);
+  },
+}
+$$
+;
+
+CREATE RANDOM STREAM test500k(
+  a float32 default rand(),
+  b float32 default rand()%1000/10,
+  c float32 default rand()%1000/100,
+  d float32 default rand()%10000/5
+  )
+  SETTINGS eps=500000
+;
+
+select udf(a,b,c,d) from test500k EMIT PERIODIC 1s;