somu-imply commented on code in PR #13736:
URL: https://github.com/apache/druid/pull/13736#discussion_r1096228358
##########
docs/querying/sql.md:
##########
@@ -82,6 +83,27 @@ FROM clause, metadata tables are not considered datasources.
They exist only in
For more information about table, lookup, query, and join datasources, refer
to the [Datasources](datasource.md)
documentation.
+## UNNEST
+
+The UNNEST clause unnests values stored in arrays within a column. It's the
SQL equivalent to the [unnest datasource](./datasource.md#unnest).
+
+The following is the general syntax for UNNEST, specifically a query that
returns the column that gets unnested:
+
+```sql
+SELECT target_column FROM datasource, UNNEST(source) as UNNESTED(target_column)
Review Comment:
The same query can be invoked as
```
SELECT foo.target_column FROM datasource, UNNEST(source) as
foo(target_column)
```
The unnested is not a mandatory keyword and user can use any name they want
as a table alias for the unnest. Think of this as unnest is a cross join
between two data sources and each can be aliased as a table name.
##########
docs/querying/sql.md:
##########
@@ -55,6 +55,7 @@ Druid SQL supports SELECT queries with the following
structure:
[ WITH tableName [ ( column1, column2, ... ) ] AS ( query ) ]
SELECT [ ALL | DISTINCT ] { * | exprs }
FROM { <table> | (<subquery>) | <o1> [ INNER | LEFT ] JOIN <o2> ON condition }
+[, UNNEST(<input>) as unnested(<output>) ]
Review Comment:
UNNEST(<input>) as <table_alias>(<output>)
##########
docs/querying/sql-functions.md:
##########
@@ -1357,6 +1357,13 @@ Truncates a numerical expression to a specific number of
decimal digits.
Parses `expr` into a `COMPLEX<json>` object. This operator deserializes JSON
values when processing them, translating stringified JSON into a nested
structure. If the input is not a `VARCHAR` or it is invalid JSON, this function
will result in a `NULL` value.
+## UNNEST
+
+`UNNEST(source)) as UNNESTED (target)`
Review Comment:
This actually should be `UNNEST(source)) as table_alias_name
(column_alias_name)`
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