Range query in Elasticsearch - Step-by-Step Execution

Concept Flow - Range query

Start Range Query

↓

Specify Field

↓

Set Range Conditions

↓

gte

↓

Execute Query

↓

Return Matching Documents

↓

End

The range query starts by choosing a field, then sets conditions like greater than or less than, executes the query, and returns matching documents.

Execution Sample

Elasticsearch

{
  "query": {
    "range": {
      "age": { "gte": 30, "lt": 40 }
    }
  }
}

This query finds documents where the 'age' field is greater than or equal to 30 and less than 40.

Execution Table

Step	Action	Field	Condition	Evaluation	Result
1	Start query	-	-	-	Ready to build range query
2	Specify field	age	-	-	Field set to 'age'
3	Set condition gte	age	gte: 30	Check if age >= 30	Condition added
4	Set condition lt	age	lt: 40	Check if age < 40	Condition added
5	Execute query	age	gte:30 and lt:40	Filter documents by conditions	Documents filtered
6	Return results	-	-	-	Documents with 30 <= age < 40 returned
7	End	-	-	-	Query complete

💡 All conditions applied and matching documents returned

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
field	undefined	age	age	age	age
conditions	empty	empty	{"gte":30}	{"gte":30, "lt":40}	{"gte":30, "lt":40}
result	none	none	none	none	documents with age >=30 and <40

Key Moments - 2 Insights

Why do we specify both 'gte' and 'lt' instead of just one?

Using both 'gte' and 'lt' defines a range between two values. The execution_table rows 3 and 4 show adding each condition separately to narrow down the results.

What happens if we only use 'gte' without 'lt'?

The query will return all documents with the field value greater than or equal to the specified number, without an upper limit. This is shown by the condition in row 3 alone.

Visual Quiz - 3 Questions

Look at the execution_table, what is the field set to after step 2?

A gte

B age

C undefined

D lt

💡 Hint

Check the 'Field' column in row with Step 2

At which step are both range conditions applied together?

A Step 5

B Step 3

C Step 4

D Step 6

💡 Hint

Look at the 'Condition' and 'Evaluation' columns in the execution_table rows

If we remove the 'lt' condition, how does the 'conditions' variable change after step 4?

A {}

B {"lt":40}

C {"gte":30}

D {"gte":30, "lt":40}

💡 Hint

Refer to variable_tracker 'conditions' row after Step 4

Concept Snapshot

Range query syntax:
{
  "query": {
    "range": {
      "field": { "gte": value1, "lt": value2 }
    }
  }
}
Use 'gte' for greater or equal, 'lt' for less than.
Combines conditions to filter documents within a range.

Full Transcript

The range query in Elasticsearch filters documents by checking if a field's value falls within specified limits. First, you choose the field to check. Then you add conditions like 'gte' (greater than or equal) and 'lt' (less than) to define the range. The query runs and returns documents matching these conditions. For example, setting 'age' with 'gte' 30 and 'lt' 40 returns documents where age is between 30 and 39. The execution table shows each step: starting the query, setting the field, adding conditions, executing, and returning results. Variables track the field name, conditions, and final results. Beginners often wonder why both 'gte' and 'lt' are needed; using both narrows the range precisely. If only 'gte' is used, results have no upper limit. The visual quiz checks understanding of these steps and variable changes.

Practice

1. What does a range query in Elasticsearch do?

easy

A. It updates documents with new values.

B. It counts the total number of documents in the index.

C. It finds documents with field values between specified limits.

D. It deletes documents matching a condition.

Solution

1. Step 1: Understand the purpose of range query

   A range query filters documents where a field's value falls within given boundaries like greater than or less than.

2. Step 2: Compare with other query types

   Counting, updating, or deleting documents are different operations, not done by range queries.

3. Final Answer:

   It finds documents with field values between specified limits. -> Option C

4. Quick Check:

   Range query = filter by value limits [OK]

Hint: Range query filters values between limits using gte, lte, gt, lt [OK]

Common Mistakes:

• Confusing range query with count or update operations
• Thinking range query modifies data
• Assuming range query deletes documents

2. Which of the following is the correct syntax for a range query filtering documents where price is greater than or equal to 10 and less than 20?

easy

A. { "range": { "price": { "gte": 10, "lte": 20 } } }

B. { "range": { "price": { "gt": 10, "lte": 20 } } }

C. { "range": { "price": { "gt": 10, "lt": 20 } } }

D. { "range": { "price": { "gte": 10, "lt": 20 } } }

Solution

1. Step 1: Identify the boundary conditions

   The question asks for price >= 10 and price < 20, which means gte:10 and lt:20.

2. Step 2: Match syntax with conditions

   { "range": { "price": { "gte": 10, "lt": 20 } } } uses gte and lt correctly matching the condition.

3. Final Answer:

   { "range": { "price": { "gte": 10, "lt": 20 } } } -> Option D

4. Quick Check:

   gte=10 and lt=20 syntax = { "range": { "price": { "gte": 10, "lt": 20 } } } [OK]

Hint: Match gte/gt and lte/lt exactly to the question limits [OK]

Common Mistakes:

• Mixing up gte with gt or lte with lt
• Using wrong operators for boundaries
• Syntax errors like missing braces

3. Given this Elasticsearch query, what documents will it match?

{ "query": { "range": { "age": { "gt": 30, "lte": 40 } } } }

medium

A. Documents where age is greater than 30 and less than or equal to 40.

B. Documents where age is between 30 and 40 inclusive.

C. Documents where age is greater than or equal to 30 and less than 40.

D. Documents where age is exactly 30 or 40.

Solution

1. Step 1: Interpret the range operators

   "gt": 30 means age > 30 (not including 30), "lte": 40 means age ≤ 40 (including 40).

2. Step 2: Understand the matching documents

   Documents with age greater than 30 and less than or equal to 40 will match.

3. Final Answer:

   Documents where age is greater than 30 and less than or equal to 40. -> Option A

4. Quick Check:

   gt=30 and lte=40 means age >30 and ≤ 40 [OK]

Hint: Remember gt excludes boundary, lte includes boundary [OK]

Common Mistakes:

• Confusing gt with gte or lte with lt
• Assuming boundaries are inclusive when they are not
• Misreading the query operators

4. Identify the error in this range query that tries to find documents with date between '2023-01-01' and '2023-12-31':

{ "range": { "date": { "gte": "2023-01-01", "lt": "2023-12-31" } }

medium

A. The field name 'date' must be inside a 'query' object.

B. The query is missing a closing brace '}' at the end.

C. The range query cannot use 'gte' and 'lt' together.

D. The date format is incorrect; it should be timestamps.

Solution

1. Step 1: Check JSON syntax

   The query is missing the final closing brace '}' to close the outer object.

2. Step 2: Validate other parts

   Date format as string is valid in Elasticsearch; using gte and lt together is allowed; 'date' field can be directly inside range.

3. Final Answer:

   The query is missing a closing brace '}' at the end. -> Option B

4. Quick Check:

   Missing closing brace = syntax error [OK]

Hint: Always check JSON braces and commas carefully [OK]

Common Mistakes:

• Forgetting to close JSON objects
• Assuming date strings must be timestamps
• Thinking gte and lt cannot be combined

5. You want to filter products priced between 50 and 100 inclusive, but exclude those exactly priced at 75. Which Elasticsearch query correctly applies this logic?

hard

A. { "bool": { "must": { "range": { "price": { "gte": 50, "lte": 100 } } }, "must_not": { "term": { "price": 75 } } } }

B. { "range": { "price": { "gte": 50, "lte": 100, "neq": 75 } } }

C. { "range": { "price": { "gt": 50, "lt": 100 } }, "must_not": { "term": { "price": 75 } } }

D. { "bool": { "should": { "range": { "price": { "gte": 50, "lte": 100 } } }, "must_not": { "term": { "price": 75 } } } }

Solution

1. Step 1: Understand the filtering requirements

   We want prices between 50 and 100 inclusive, so gte:50 and lte:100 in a range query.

2. Step 2: Exclude price exactly 75

   Use a bool query with must for range and must_not for term price=75 to exclude it.

3. Step 3: Check options

   { "bool": { "must": { "range": { "price": { "gte": 50, "lte": 100 } } }, "must_not": { "term": { "price": 75 } } } } uses bool with must range and must_not term correctly. { "range": { "price": { "gte": 50, "lte": 100, "neq": 75 } } } uses invalid 'neq'. { "range": { "price": { "gt": 50, "lt": 100 } }, "must_not": { "term": { "price": 75 } } } misses bool wrapper. { "bool": { "should": { "range": { "price": { "gte": 50, "lte": 100 } } }, "must_not": { "term": { "price": 75 } } } } uses should which is incorrect here.

4. Final Answer:

   { "bool": { "must": { "range": { "price": { "gte": 50, "lte": 100 } } }, "must_not": { "term": { "price": 75 } } } } -> Option A

5. Quick Check:

   Use bool must + must_not for inclusive range excluding a value [OK]

Hint: Use bool must for range and must_not to exclude values [OK]

Common Mistakes:

• Using invalid operators like 'neq' in range
• Not wrapping queries in bool for combining conditions
• Using should instead of must for filtering