Cache range filter on date field by default

[dadoonet]

A range filter on a date field with a numeric from/to value is not cached by default:

DELETE /test

PUT /test/t/1
{
  "date": "2014-01-01"
}

GET /_validate/query?explain
{
  "query": {
    "filtered": {
      "filter": {
        "range": {
          "date": {
            "from": 0
          }
        }
      }
    }
  }
}

Returns:

"explanation": "ConstantScore(no_cache(date:[0 TO *]))"

This patch fixes as well not caching from/to when using now value not rounded.
Previously, a query like:

GET /_validate/query?explain
{
  "query": {
    "filtered": {
      "filter": {
        "range": {
          "date": {
            "from": "now"
            "to": "now/d+1"
          }
        }
      }
    }
  }
}

was cached.

Also, this patch does not cache anymore now even if the user asked for caching it.
As it won't be cached at all by definition.

Added as well tests for all possible combinations.

Closes #7114.

[dadoonet]

@martijnvg Could you review my PR? Thanks! :)

[dadoonet]

@martijnvg The more I look at this, the more I think there something wrong here.
I tried to fix an issue when you explicitly set _cache:false. But in that case, even if you don't want to cache the filter, as soon as you don't use now, it will be cached because of || !hasNowExpressionWithNoRounding(value).

That's what we have in the past, so it's not a regression here.

Though, I think I need to update the PR with that finding.

Will rebase on master as recent changes - support timezone - created a git conflict.

[martijnvg]

sorry, I missed this comment. You're right. If explicit caching is configured and set to true, we override it to false if now without rounding is used. If no explicit caching is defined we should set cache to true if now with no rounding is specified.

It should look something like this:

if (explicitCaching != null) {
  if (explicitCaching) {
     cache = hasNowExpressionWithNoRounding(value) == false;
  } else {
     cache = false;
  }
} else {
   cache = hasNowExpressionWithNoRounding(value) == false;
}

[martijnvg]

this method looks unused?

[dadoonet]

Argh! I forgot to remove it! :)

[martijnvg]

Left two comments, also the SimpleQueryTests#testRangeFilterNoCacheWithNow fails, because it assumes that a filter with now is being cached and that is no longer the case. Can you change that assertion as well?

[dadoonet]

I don't understand. When I run test locally, I don't get any error for test org.elasticsearch.search.query.SimpleQueryTests#testRangeFilterNoCacheWithNow. Could you paste your seed?

[martijnvg]

LGTM, I find the code much more understandable than was before!