Scripts and search speed
editScripts and search speed
editScripts can’t make use of Elasticsearch’s index structures or related optimizations. This can sometimes result in slower search speeds.
If you often use scripts to transform indexed data, you can speed up search by making these changes during ingest instead. However, that often means slower index speeds.
Example
An index, my_test_scores, contains two long fields:
-
math_score -
verbal_score
When running searches, users often use a script to sort results by the sum of these two field’s values.
GET /my_test_scores/_search
{
"query": {
"term": {
"grad_year": "2099"
}
},
"sort": [
{
"_script": {
"type": "number",
"script": {
"source": "doc['math_score'].value + doc['verbal_score'].value"
},
"order": "desc"
}
}
]
}
To speed up search, you can perform this calculation during ingest and index the sum to a field instead.
First, add a new field, total_score, to the index. The
total_score field will contain sum of the math_score and verbal_score
field values.
PUT /my_test_scores/_mapping
{
"properties": {
"total_score": {
"type": "long"
}
}
}
Next, use an ingest pipeline containing the
script processor to calculate the sum of math_score and
verbal_score and index it in the total_score field.
PUT _ingest/pipeline/my_test_scores_pipeline
{
"description": "Calculates the total test score",
"processors": [
{
"script": {
"source": "ctx.total_score = (ctx.math_score + ctx.verbal_score)"
}
}
]
}
To update existing data, use this pipeline to reindex any
documents from my_test_scores to a new index, my_test_scores_2.
POST /_reindex
{
"source": {
"index": "my_test_scores"
},
"dest": {
"index": "my_test_scores_2",
"pipeline": "my_test_scores_pipeline"
}
}
Continue using the pipeline to index any new documents to my_test_scores_2.
POST /my_test_scores_2/_doc/?pipeline=my_test_scores_pipeline
{
"student": "kimchy",
"grad_year": "2099",
"math_score": 800,
"verbal_score": 800
}
These changes may slow indexing but allow for faster searches. Users can now
sort searches made on my_test_scores_2 using the total_score field instead
of using a script.
GET /my_test_scores_2/_search
{
"query": {
"term": {
"grad_year": "2099"
}
},
"sort": [
{
"total_score": {
"order": "desc"
}
}
]
}
We recommend testing and benchmarking any indexing changes before deploying them in production.
Script errors
editElasticsearch returns error details when there is a compliation or runtime exception. The contents of this response are useful for tracking down the problem.
This functionality is in technical preview and may be changed or removed in a future release. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of official GA features.
The contents of position are experimental and subject to change.