tuple_sketch_extract_avg.sqlx

config { hasOutput: true }
/*
 * Copyright 2024 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


CREATE OR REPLACE FUNCTION ${self()}(sketch BYTES)
RETURNS INT64
LANGUAGE js
OPTIONS (
  library=["${JS_BUCKET}/tuple_sketch.js"],
  description = '''Takes in a tuple sketch, combines the summary values of
the value_col (using sum) from the random sample of id_col stored within the 
Tuple sketch, calculates an estimate that applies to the entire dataset and returns the avg.
For more details: https://datasketches.apache.org/docs/Tuple/TupleOverview.html'''
) AS '''
var sketchBinary = intArrayFromBase64(sketch);
var ptr = Module._malloc(sketchBinary.length);
Module.HEAPU8.subarray(ptr, ptr + sketchBinary.length).set(sketchBinary);

var compact_sketch =
    Module._compact_sketch_deserialize(ptr, sketchBinary.length);
try {
  return Module._compact_sketch_get_estimate_avg(compact_sketch);
} finally {
  Module._compact_sketch_destroy(compact_sketch);
  Module._free(ptr);
}
''';