Aerospike Go client example for Aggregate Query

udfFilter.go

package main

import (
  "fmt"
  . "github.com/aerospike/aerospike-client-go"
)

func panicOnError(err error) {
  if err != nil {
    panic(err)
  }
}

func setup(client *Client, ns string, set string, module string) {
  SetLuaPath("./")
  file := module + ".lua"
  t, err := client.RegisterUDFFromFile(nil, file, file, LUA)
  panicOnError(err)
  <- t.OnComplete()

  key1, _ := NewKey(ns, set, 1)
  client.PutBins(nil, key1, NewBin("filename", "file1"), NewBin("version", 3))
  key2, _ := NewKey(ns, set, 2)
  client.PutBins(nil, key2, NewBin("filename", "file2"), NewBin("version", 7))
  key3, _ := NewKey(ns, set, 3)
  client.PutBins(nil, key3, NewBin("filename", "file3"), NewBin("version", 2))
}

func main() {
  client, err := NewClient("192.168.33.10", 3000)
  panicOnError(err)

  ns := "test"
  set := "udf-go"
  module := "udfFilter"

  setup(client, ns, set, module)

  stmt := NewStatement(ns, set)
  recordset, err := client.QueryAggregate(nil, stmt, module, "maxVersion")
  panicOnError(err)
  for rec := range recordset.Results() {
    res := rec.Record.Bins["SUCCESS"].(map[interface{}]interface{})
    fmt.Printf("filename with max. version: %s (ver. %d)\n", res["filename"], res["version"])
  }
}

udfFilter.lua

function maxVersion(stream, bin)
  -- The stream function cannot return record objects directly,
  -- so we have to map to a Map data type first.
  local function toArray(rec)
    local result = map()
    result['filename'] = rec['filename']
    result['version'] = rec['version']
    return result
  end
  local function findMax(a, b)
    if a.version > b.version then
      return a
    else
      return b
    end
  end
  return stream : map(toArray) : reduce(findMax)
end