I'm trying to get an nGram filter to work with a fuzzy search, but it won't. Specifically, I'm trying to get "rugh" to match on "rough".
I don't know whether it's just not possible, or it is possible but I've defined the mapping wrong, or the mapping is fine but my search isn't defined correctly.
Mapping:
{
settings = new
{
index = new
{
number_of_shards = 1,
number_of_replicas = 1,
analysis = new
{
filter = new
{
edge_ngram_filter = new
{
type = "nGram",
min_gram = 3,
max_gram = 8
}
}, // filter
analyzer = new
{
analyzer_ngram = new
{
type = "custom",
tokenizer = "standard",
filter = new string[]
{
"lowercase",
"edge_ngram_filter"
}
}
} // analyzer
} // analysis
} // index
}, // settings
mappings = new
{
j_cv = new
{
properties = new
{
Text = new
{
type = "text",
include_in_all = false,
analyzer = "analyzer_ngram",
search_analyzer = "standard"
}
}
} // j_cv
} // mappings
}
Document:
{
Id = Guid.NewGuid(),
Name = "Jimmy Riddle",
Keyword = new List<string>(new string[] { "Hunting", "High", "Hotel", "California" }),
Text = "Rough Justice was a program on BBC some years ago. It was quite interesting. Will this match?"
}
Search:
{
query = new
{
query_string = new
{
fields = new string[] { "Text" },
fuzziness = "3",
query = "rugh"
}
}
}
Incidentally, "ugh" does match which is what you'd expect.
The same analyzer should usually be applied at index and search time, so search_analyzer=standard is wrong, it should be working if you remove it.
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-analyzer.html
Edit: You forgot the fuzzy operator "~" in your query, if you add it to "rugh" it will work!