isEmpty faster thanempty

#!/bin/bash

curl -s -XDELETE "http://localhost:9200/test?pretty" | tee /tmp/check_script_speed.log
curl -s -XPOST "http://localhost:9200/test?pretty" | tee -a /tmp/check_script_speed.log
curl -s -XPUT http://localhost:9200/test/test/_mapping?pretty -d'{
  "test" : {
    "properties": {
      "i" : {
        "type": "integer"
      }
    }
  }
}' | tee -a /tmp/check_script_speed.log

echo -n "Indexing" | tee -a /tmp/check_script_speed.log
for j in {1..1000}; do
  rm /tmp/check_script_speed_bulk.txt
  for i in {1..1000}; do
    echo '{ "index" : { "_index" : "test", "_type" : "test" } }' >> /tmp/check_script_speed_bulk.txt
    if [ "$j" -lt 5 ]; then
      echo '{"i": '$i'}' >> /tmp/check_script_speed_bulk.txt
    else
      echo '{"nothing": "some text"}' >> /tmp/check_script_speed_bulk.txt
    fi
  done
  curl -s -XPOST "http://localhost:9200/_bulk?pretty" --data-binary @/tmp/check_script_speed_bulk.txt >> \
    /tmp/check_script_speed.log
  echo -n '.'
done
echo 'Done'

curl -s -XPOST http://localhost:9200/test/_refresh?pretty | tee -a /tmp/check_script_speed.log

# Ignore first execution's time because it includes cache population and script compilation
curl -s http://localhost:9200/test/_search?pretty -d '{
  "size": 1,
  "query": {
    "function_score": {
      "functions": [
        {
          "script_score": {
            "script": '"\"log10((doc['i'].isEmpty() ? 0 : doc['i'].value) + 2)\""'
          }
        }
      ]
    }
  }
}' | tee -a /tmp/check_script_speed.log
curl -s http://localhost:9200/test/_search?pretty -d '{
  "size": 1,
  "query": {
    "function_score": {
      "functions": [
        {
          "script_score": {
            "script": '"\"log10((doc['i'].empty ? 0 : doc['i'].value) + 2)\""'
          }
        }
      ]
    }
  }
}' | tee -a /tmp/check_script_speed.log

time curl -s http://localhost:9200/test/_search?pretty -d '{
  "size": 1,
  "query": {
    "function_score": {
      "functions": [
        {
          "script_score": {
            "script": '"\"log10((doc['i'].isEmpty() ? 0 : doc['i'].value) + 2)\""'
          }
        }
      ]
    }
  }
}' 2>&1 | tee -a /tmp/check_script_speed.log

time curl -s http://localhost:9200/test/_search?pretty -d '{
  "size": 1,
  "query": {
    "function_score": {
      "functions": [
        {
          "script_score": {
            "script": '"\"log10((doc['i'].empty ? 0 : doc['i'].value) + 2)\""'
          }
        }
      ]
    }
  }
}' 2>&1 | tee -a /tmp/check_script_speed.log