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Add getschema (#257)
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‎apl/tabular-operators/getschema-operator.mdx

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---
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title: getschema
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description: 'This page explains how to use the getschema operator in APL.'
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---
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The `getschema` operator in APL returns the schema of a dataset, including field names and their data types. You can use it to inspect the structure of a dataset before performing queries or transformations. This operator is useful when exploring new datasets, verifying data consistency, or debugging queries.
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## For users of other query languages
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If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.
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<AccordionGroup>
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<Accordion title="Splunk SPL users">
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In Splunk SPL, you can use the `fieldsummary` command to get schema-related information about a dataset. However, `getschema` in APL is more direct and focused specifically on returning field names and types without additional summary statistics.
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<CodeGroup>
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```sql Splunk example
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| fieldsummary
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```
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```kusto APL equivalent
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['sample-http-logs']
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| getschema
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```
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</CodeGroup>
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</Accordion>
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<Accordion title="ANSI SQL users">
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In ANSI SQL, retrieving schema information is typically done using `INFORMATION_SCHEMA` queries. APL’s `getschema` operator provides a more straightforward way to get schema details without requiring system views.
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<CodeGroup>
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```sql SQL example
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SELECT COLUMN_NAME, DATA_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'sample_http_logs';
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```
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```kusto APL equivalent
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['sample-http-logs']
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| getschema
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```
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</CodeGroup>
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</Accordion>
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</AccordionGroup>
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## Usage
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### Syntax
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```kusto
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| getschema
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```
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### Parameters
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The `getschema` operator does not take any parameters.
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### Returns
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| Field | Type | Description |
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|-------------|--------|--------------------------------------|
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| ColumnName | string | The name of the field in the dataset. |
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| ColumnOrdinal | number | The index number of the field in the dataset.
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| ColumnType | string | The data type of the field. |
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| DataType | string | The APL-internal name for the data type of the field. |
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## Use case example
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You can use `getschema` to explore the schema of your log data before running queries.
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**Query**
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```kusto
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['sample-http-logs'] | getschema
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```
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[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B'sample-http-logs'%5D%20%7C%20getschema%22%7D)
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**Output**
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| ColumnName | DataType | ColumnOrdinal | ColumnType |
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|---------------------|-----------------|---------------|-----------------|
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| _sysTime | datetime | 0 | datetime |
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| _time | datetime | 1 | datetime |
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| content_type | string | 2 | string |
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| geo.city | string | 3 | string |
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| geo.country | string | 4 | string |
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| id | string | 5 | string |
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This query helps you verify the available fields and their data types before further analysis.
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## List of related operators
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- [project](/apl/tabular-operators/project-operator): Use `project` to select specific fields instead of retrieving the entire schema.
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- [extend](/apl/tabular-operators/extend-operator): Use `extend` to add new computed fields to your dataset after understanding the schema.
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- [summarize](/apl/tabular-operators/summarize-operator): Use `summarize` for aggregations once you verify field types using `getschema`.
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- [where](/apl/tabular-operators/where-operator): Use `where` to filter datasets based on field values after checking their schema.
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- [order](/apl/tabular-operators/order-operator): Use `order by` to sort datasets after verifying schema details.

‎apl/tabular-operators/overview.mdx

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| [extend](/apl/tabular-operators/extend-operator) | Returns the original dataset with one or more new fields appended, based on the defined expressions. |
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| [extend-valid](/apl/tabular-operators/extend-valid-operator) | Returns a table where the specified fields are extended with new values based on the given expression for valid rows. |
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| [externaldata](/apl/tabular-operators/externaldata-operator) | Returns a table with the specified schema, containing data retrieved from an external source. |
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| [getschema](/apl/tabular-operators/getschema-operator) | Returns the schema of a dataset, including field names and their data types |
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| [join](/apl/tabular-operators/join-operator) | Returns a dataset containing rows from two different tables based on conditions. |
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| [limit](/apl/tabular-operators/limit-operator) | Returns the top N rows from the input dataset. |
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| [lookup](/apl/tabular-operators/lookup-operator) | Returns a dataset where rows from one dataset are enriched with matching columns from a lookup table based on conditions. |

‎docs.json

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"apl/tabular-operators/extend-operator",
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"apl/tabular-operators/extend-valid-operator",
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"apl/tabular-operators/externaldata-operator",
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"apl/tabular-operators/getschema-operator",
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"apl/tabular-operators/join-operator",
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"apl/tabular-operators/limit-operator",
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"apl/tabular-operators/lookup-operator",

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