Elasticsearch | Very slow search

Elastic Stack Elasticsearch
1

Hi,

I am benchmarking search speed using different parameters.
One specific parameter used is copy_to implementation.

Scenario 1.

  1. Number of Fields : 10000
  2. Documents indexed : 500
  3. Indices : 10
  4. Search on Indices : 10 at once
    Search Speed using copy_to field: 20ms -3s

Scenario 2.

  1. Number of Fields : 10000
  2. Documents indexed : 100000
  3. Indices : 10
  4. Search on Indices : 10 at once
    Search Speed using copy_to field: 6s - 18s

I suppose the number of documents stored in Elasticsearch will not affect the search speed.
Also, since the use of copy_to field, it will reduce the number of disk seeks during search to one field. Hence even this should not be something to worry about
Why is there a drastic increase in search speed when number of documents increased?
Am I missing something here? Because this is driving me crazy!

2

What kind of searches are you running?

3

Multiple should clauses

  1. Phrase match
  2. Phrase with slop
  3. Word based Fuzziness
  4. Word based match
4

Are you running these against the copy_to field you mentioned? Can you show some examples?

5

yes, I am running these against copy_to.
The query contains

  1. "query_string_query" for exact phrase match,
  2. "multi_match" for phrase with slop
  3. "multi_match" for word with fuzziness
  4. "multi_match" for word based match
6

@Christian_Dahlqvist any suggestions?

7

Can you show some full example queries and how long they take to run? Why do you have so many fields in your index?

8

Thanks Christian for quick response.
Like I mentioned earlier, this is a benchmarking process.
My query is something of this sort

{
	"query": {
  
          "bool": {
            "should": [
             1. Query String query of exact match
             2. Multi_match of type phrase with slop of 1
             3.  Multi_match with fuzziness 
             4. Multi_match without fuzziness 
            ],
            "minimum_should_match": 1
          }
        }
     
  }
9

That does not look like a valid query. Can you please show a full example?

10

These four are the clauses of bool should query.

11

I give up. As you are not answering my questions I will leave this for someone else.

1 Like
12

As @Christian_Dahlqvist asked, you need to give a real and complete example. Not pseudo-code. Otherwise, there is no way to help you I'm afraid.

13

If you are using query string queries without specifying a field name, be aware that the old _all field has been replaced by an all_fields mode, which can be slow if you have a lot of fields it need to iterate over. Combine this with slop and fuzziness and you could have a very expensive (and slow) query. You may also want to look into creating a custom copy_all field to use by default, much like the old _all field worked.

14

Thanks for your suggestion. I am using copy_to field.

15

Then please provide detailed information, mappings and actual queries. Without that it is impossible to help.

16

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