> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/xql-command-reference-guide/readme/functions/greatest.md). # greatest Use the `greatest()` function to return the largest value from a list of expressions. ## Syntax ```sql greatest(, [, ...]) ``` ## Parameters | Name | Type | Required | Description | | ------------- | --------------------------------- | -------- | ----------------------------------------------------------------------------------- | | `expression1` | integer, float, string, timestamp | Yes | The first value to compare. | | `expression2` | integer, float, string, timestamp | Yes | The second value to compare. | | `...` | integer, float, string, timestamp | No | Additional values to compare. Any number of additional expressions can be provided. | ## Returns **Type**: Same as input type **Description**: The `greatest()` function returns the largest value among all the provided expressions. If any input is `null`, the function may skip `null` values or return `null` depending on the implementation. ## Usage notes * **Input type**: XQL doesn't support NaN or infinite values as input and these value types also can not be returned. * **Multiple Arguments**: The function accepts two or more arguments and returns the maximum value among them. * **Type Consistency**: All arguments should be of compatible types for meaningful comparison. * **Null Handling**: If all inputs are `null`, the function returns `null`. If some inputs are `null`, the function typically returns the greatest non-null value. * **String Comparison**: When comparing strings, the function uses lexicographic (alphabetical) ordering. * **Relationship to least()**: The `greatest()` function is the counterpart of `least()`, which returns the smallest value. * **Common Use Cases**: This function is typically used within the `alter` stage for selecting the maximum value across multiple fields, implementing upper bounds, and data normalization. ## Examples ### Example 1: Find greatest among literal values **Goal**: Find the largest value from a set of numeric literals. **XQL code**: ```sql dataset = xdr_data | limit 1 | alter max_val = greatest(10, 25, 5, 42, 18) | fields max_val ``` **Explanation**: The `greatest()` function compares all five literal values and returns `42`, the largest among them. **Output**: | MAX\_VAL | | -------- | | 42 | ### Example 2: Find greatest value across multiple fields **Goal**: Find the largest value among multiple numeric fields for each record. **XQL code**: ```sql config timeframe = 1d | dataset = sample_xql_raw | alter max_field = greatest(event_id, numeric_value, duration_seconds) | fields event_id, numeric_value, duration_seconds, max_field | limit 3 ``` **Explanation**: This query compares the values of `event_id`, `numeric_value`, and `duration_seconds` for each record and returns the largest value in `max_field`. **Output**: | EVENT\_ID | NUMERIC\_VALUE | DURATION\_SECONDS | MAX\_FIELD | | --------- | -------------- | ----------------- | ---------- | | 101 | 5.0 | 1.5 | 101 | | 102 | 200.0 | 0.8 | 200.0 | | 103 | 50.0 | 10.2 | 103 | ### Example 3: Implement an upper bound using greatest **Goal**: Ensure a value is at least a minimum threshold by using `greatest()` as a lower clamp. **XQL code**: ```sql config timeframe = 1d | dataset = sample_xql_raw | alter clamped_duration = greatest(duration_seconds, 1.0) | fields event_id, duration_seconds, clamped_duration | limit 3 ``` **Explanation**: This query ensures that `clamped_duration` is at least `1.0` by returning the greater of `duration_seconds` and `1.0`. Values below `1.0` are raised to `1.0`, while values above remain unchanged. **Output**: | EVENT\_ID | DURATION\_SECONDS | CLAMPED\_DURATION | | --------- | ----------------- | ----------------- | | 101 | 1.5 | 1.5 | | 102 | 0.8 | 1.0 | | 103 | 10.2 | 10.2 | ## Related articles * **Stages**: [`alter`](/xql-command-reference-guide/readme/stages/alter.md), [`fields`](/xql-command-reference-guide/readme/stages/fields.md), [`limit`](/xql-command-reference-guide/readme/stages/limit.md) * **Functions**: [`least()`](/xql-command-reference-guide/readme/functions/least.md), `max_by()`, [`coalesce()`](/xql-command-reference-guide/readme/functions/coalesce.md) * **Datasets**: [`xdr_data`](https://docs-cortex.paloaltonetworks.com/r/Cortex-XQL-Schema-Reference-Guide/Introduction) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. 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