How to apply default post filter with ElasticSearch? - elasticsearch

Question

I would like to implement an engine of backtesting using elasticsearch. To be able to do that I would need to filter the hits by excluding the ones that are posterior to the testing date and I would like to do that by default because the algorithm (that I want to backtest) is not supposed to know about the backtesting.
In other words, is it possible to apply a default post filter to ElasticSearch queries?
For example, let's say that those documents are in ES:
{ name: 'Jean', weight: 70, date: 2012-01-01 }
{ name: 'Jules', weight: 70, date: 2010-01-01 }
{ name: 'David', weight: 80, date: 2010-01-01 }
I want to apply a default post filter to exclude documents posterior to 2011 in a way that if I do a query to get every persons with a weight of 70, the only result I have is Jules.

Answer 1

You can do that with Filtered Aliases. When you query through the alias, the filter is automatically applied to your query...which hides it from your application:
// Insert the data
curl -XPOST "http://localhost:9200/people/data/" -d'
{ "name": "Jean", "weight" : 70, "date": "2012-01-01" }'
curl -XPOST "http://localhost:9200/people/ata" -d'
{ "name": "Jules", "weight" : 70, "date": "2010-01-01" }'
curl -XPOST "http://localhost:9200/people/data/" -d'
{ "name": "David", "weight" : 80, "date": "2010-01-01" }'
// Add a filtered alias
curl -XPOST "http://localhost:9200/_aliases" -d'
{
"actions" : [
{
"add" : {
"index" : "people",
"alias" : "filtered_people",
"filter" : {
"range" : {
"date" : { "gte" : "2011-01-01"}
}
}
}
}
]
}'
Now you execute the search against filtered_people instead of the underlying people index:
curl -XGET "http://localhost:9200/filtered_people/_search" -d'
{
"query": {
"filtered": {
"filter": {
"term": {
"weight": 70
}
}
}
}
}'
Which will return just the doc you are interested in:
{
"took": 3,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 1,
"hits": [
{
"_index": "people",
"_type": "ata",
"_id": "AUudZPUfCSiheYJkTW-h",
"_score": 1,
"_source": {
"name": "Jules",
"weight": 70,
"date": "2010-01-01"
}
}
]
}
}