When to multi_field


(gek8365) #1

Greetings,

I am somewhat new to elasticsearch and I am trying to understand the
implications of multi_fields in terms of performance/memory consumption. I
see from the documents that multi_fields are useful when you want to
analyze field data in different ways. What I do not see is any discussion
on how expensive it is to have these additional "fields." I realize that
this is a very glib question, which is due in large to my ignorance, so any
advice or links to documents that might have some information on this would
be very useful and I would be grateful. Thanks in advance.

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(Ivan Brusic) #2

The standard use case for a multi-field is when a field needs to be both
analyzed (for searching) and not analyzed (for aggregating/sorting). In
this case, there really is no workaround, so a multi-field is essential.

In the different analyzer case, it gets more complicated. How much can you
get away with with just one field? How important is query precision
compared to storage? In general, more fields are needed because they are
truly needed.

The upcoming Elasticsearch book has a good chapter on languages, which is
one use case in which multi fields are used. The pitfalls of mixing
languages section is what you might encounter when attempting to use fewer
fields.

http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/languages.html

Cheers,

Ivan

On Wed, Aug 27, 2014 at 11:02 AM, gek8365 glenn.kidd@gmail.com wrote:

Greetings,

I am somewhat new to elasticsearch and I am trying to understand the
implications of multi_fields in terms of performance/memory consumption. I
see from the documents that multi_fields are useful when you want to
analyze field data in different ways. What I do not see is any discussion
on how expensive it is to have these additional "fields." I realize that
this is a very glib question, which is due in large to my ignorance, so any
advice or links to documents that might have some information on this would
be very useful and I would be grateful. Thanks in advance.

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(system) #3