Search performance tuning in Elasticsearch - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to limit the number of search results returned to 10.

Elasticsearch

{
  "query": { "match_all": {} },
  "size": [1]
}

Drag options to blanks, or click blank then click option'

A100

B10

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or negative numbers disables results or causes errors.

Setting size to 10 limits the search results to 10 documents, improving performance by reducing data returned.

2fill in blank

medium

Complete the code to use a term query for exact match on the field status with value active.

Elasticsearch

{
  "query": {
    "[1]": {
      "status": "active"
    }
  }
}

Drag options to blanks, or click blank then click option'

Amatch

Brange

Cterm

Dexists

Attempts:

3 left

💡 Hint

Common Mistakes

Using match causes full-text search, which is slower and less precise.

The term query is used for exact matches, which is faster for keyword fields like status.

3fill in blank

hard

Fix the error in the aggregation to calculate average price.

Elasticsearch

{
  "aggs": {
    "avg_price": {
      "avg": {
        "field": "[1]"
      }
    }
  }
}

Drag options to blanks, or click blank then click option'

Aprice.raw

Bprice.keyword

Cprice.text

Dprice

Attempts:

3 left

💡 Hint

Common Mistakes

Using price.keyword or text fields causes aggregation errors.

The avg aggregation requires a numeric field like price, not keyword or text fields.

4fill in blank

hard

Fill both blanks to filter documents where age is greater than 30 and sort by join_date descending.

Elasticsearch

{
  "query": {
    "range": {
      "age": {
        "[1]": 30
      }
    }
  },
  "sort": [
    { "join_date": { "order": "[2]" } }
  ]
}

Drag options to blanks, or click blank then click option'

Agt

Bgte

Cdesc

Dasc

Attempts:

3 left

💡 Hint

Common Mistakes

Using gte includes 30, which is not requested.

Using asc sorts oldest first.

Use gt for greater than 30 and desc to sort newest first.

5fill in blank

hard

Fill all three blanks to create a filtered aggregation that counts documents with status 'active' and average score above 50.

Elasticsearch

{
  "query": {
    "term": { "status": "[1]" }
  },
  "aggs": {
    "high_score": {
      "filter": {
        "range": {
          "score": { "[2]": [3] }
        }
      },
      "aggs": {
        "avg_score": { "avg": { "field": "score" } }
      }
    }
  }
}

Drag options to blanks, or click blank then click option'

Aactive

Bgt

C50

Dgte

Attempts:

3 left

💡 Hint

Common Mistakes

Using gte includes 50, which is not requested.

Using wrong status value causes no results.

The query filters for status 'active', then the aggregation filters scores greater than 50 before averaging.

Practice

1. Which of the following is a common way to improve search performance in Elasticsearch?

easy

A. Limit the number of results returned using size parameter

B. Increase the number of shards without limit

C. Disable caching completely

D. Use wildcard queries on all fields

Solution

1. Step 1: Understand result limiting

   Limiting results with size reduces data processed and returned, speeding up queries.

2. Step 2: Evaluate other options

   Increasing shards without limit can hurt performance, disabling cache reduces speed, and wildcard queries are slow.

3. Final Answer:

   Limit the number of results returned using size parameter -> Option A

4. Quick Check:

   Limiting results = faster search [OK]

Hint: Use size to limit results for faster queries [OK]

Common Mistakes:

• Thinking more shards always improve speed
• Ignoring caching benefits
• Using wildcard queries on all fields

2. Which Elasticsearch query syntax correctly limits the returned fields to only title and author?

easy

A. {"return_fields": ["title", "author"], "query": {"match_all": {}}}

B. {"fields": ["title", "author"], "query": {"match_all": {}}}

C. {"select": ["title", "author"], "query": {"match_all": {}}}

D. {"_source": ["title", "author"], "query": {"match_all": {}}}

Solution

1. Step 1: Identify correct field limiting syntax

   Elasticsearch uses _source to specify which fields to return.

2. Step 2: Check other options

   fields, select, and return_fields are not valid for limiting returned fields in this context.

3. Final Answer:

   {"_source": ["title", "author"], "query": {"match_all": {}}} -> Option D

4. Quick Check:

   Use _source to limit fields [OK]

Hint: Use _source to specify returned fields [OK]

Common Mistakes:

• Using fields instead of _source
• Trying SQL-like select syntax
• Using unsupported keys like return_fields

3. Given this Elasticsearch query, what will be the effect of adding "timeout": "2s"?

{
  "query": {"match": {"content": "fast search"}},
  "timeout": "2s"
}

medium

A. The query will fail if it takes longer than 2 seconds

B. The query will cache results for 2 seconds

C. The query will return partial results after 2 seconds

D. The query will wait 2 seconds before starting

Solution

1. Step 1: Understand timeout behavior

   Elasticsearch's timeout stops the query after the specified time and returns partial results if available.

2. Step 2: Evaluate other options

   It does not fail immediately, does not delay start, and does not control caching.

3. Final Answer:

   The query will return partial results after 2 seconds -> Option C

4. Quick Check:

   timeout returns partial results [OK]

Hint: Timeout returns partial results if query is slow [OK]

Common Mistakes:

• Assuming timeout causes query failure
• Thinking timeout delays query start
• Confusing timeout with caching duration

4. You have this query to limit results and fields:

{
  "size": 10,
  "query": {
    "_source": ["title", "date"],
    "match_all": {}
  }
}

But the query returns all fields. What is the likely mistake?

medium

A. Using size instead of limit

B. Using _source inside the query body instead of top-level

C. Missing fields parameter to limit fields

D. The match_all query ignores field limits

Solution

1. Step 1: Check placement of _source

   _source must be at the top level of the query JSON, not inside query.

2. Step 2: Review other options

   fields is deprecated for this purpose, size is correct, and match_all does not ignore field limits.

3. Final Answer:

   Using _source inside the query body instead of top-level -> Option B

4. Quick Check:

   _source must be top-level [OK]

Hint: Place _source at top level, not inside query [OK]

Common Mistakes:

• Putting _source inside query
• Confusing size with limit
• Assuming match_all ignores field filtering

5. You want to optimize a search that returns many documents but only needs the id and summary fields, and must respond within 1 second. Which combination of settings best improves performance?

hard

A. Set size to a low number, use _source to limit fields, and add timeout of 1s

B. Set size high, disable _source, and remove timeout

C. Use wildcard queries on all fields and set timeout to 5s

D. Increase shards count and use fields to limit fields

Solution

1. Step 1: Limit results and fields

   Setting size low reduces returned documents; _source limits fields to needed ones.

2. Step 2: Use timeout to keep response fast

   Adding timeout of 1 second ensures query won't hang and keeps system responsive.

3. Step 3: Evaluate other options

   High size and disabling _source increase load; wildcard queries are slow; increasing shards without need can hurt performance.

4. Final Answer:

   Set size to a low number, use _source to limit fields, and add timeout of 1s -> Option A

5. Quick Check:

   Limit size + fields + timeout = best performance [OK]

Hint: Limit size, fields, and add timeout for fast, efficient search [OK]

Common Mistakes:

• Setting size too high
• Disabling field filtering
• Ignoring timeout setting
• Increasing shards unnecessarily