Spark, Databricks: allow an interval string without a unit

[moshap-firebolt]

Spark's multi-units interval syntax lets the string carry its own units, so no unit follows the literal:

SELECT INTERVAL '1 YEAR 2 DAYS 3 HOURS';
SELECT INTERVAL '2 seconds' * 2;

Both SparkSqlDialect and DatabricksDialect set require_interval_qualifier, so these fail with INTERVAL requires a unit after the literal value. Databricks Runtime parses with Spark's grammar and accepts them too; the Databricks docs show only the qualified form.

This sets require_interval_qualifier to false for both dialects. A unit after a literal is still parsed, so INTERVAL '1' DAY, INTERVAL 12 HOURS and INTERVAL '1-2' YEAR TO MONTH are unchanged. The form this gives up is an expression as the interval value (INTERVAL 1 + 1 DAY), which Spark's grammar does not allow: it takes a literal there.

Tests cover the string forms, the qualified forms, signs and arithmetic for both dialects.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.15%. Comparing base (14cbf75) to head (8231b9a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2614   +/-   ##
=======================================
  Coverage   81.14%   81.15%           
=======================================
  Files          42       42           
  Lines       33736    33736           
  Branches    33736    33736           
=======================================
+ Hits        27376    27379    +3     
+ Misses       2797     2794    -3     
  Partials     3563     3563           

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[LucaCappelletti94]

You could gate unqualified intervals on string literals through a dialect capability, retaining qualifiers for numeric literals and excluding identifiers from literal values.

Setting require_interval_qualifier() to false makes both dialects accept SELECT INTERVAL 1, which Spark 4.0.1 rejects, and misparse SELECT interval FROM t into SELECT INTERVAL FROM AS t, losing the table reference.

I added some red tests to help out.

[LucaCappelletti94]

Suggested change

	}
	}
	#[test]
	fn test_interval_numeric_requires_unit() {
	assert_eq!(
	spark()
	.parse_sql_statements("SELECT INTERVAL 1")
	.unwrap_err()
	.to_string(),
	"sql parser error: INTERVAL requires a unit after the literal value"
	);
	}
	#[test]
	fn test_interval_rejects_value_arithmetic() {
	assert!(spark()
	.parse_sql_statements("SELECT INTERVAL 1 + 1 DAY")
	.is_err());
	}
	#[test]
	fn test_interval_preserves_column_query() {
	let query = spark()
	.run_parser_method("SELECT interval FROM t", |parser| parser.parse_query())
	.unwrap();
	let SetExpr::Select(select) = *query.body else {
	panic!("Expected SELECT");
	};
	assert_eq!(
	select.from,
	vec![TableWithJoins {
	relation: table("t"),
	joins: vec![],
	}]
	);
	assert_eq!(
	select.projection,
	vec![SelectItem::UnnamedExpr(Expr::Identifier(Ident::new(
	"interval"
	)))]
	);
	}

[LucaCappelletti94]

Suggested change

	}
	}
	#[test]
	fn test_interval_numeric_requires_unit() {
	assert_eq!(
	databricks()
	.parse_sql_statements("SELECT INTERVAL 1")
	.unwrap_err()
	.to_string(),
	"sql parser error: INTERVAL requires a unit after the literal value"
	);
	}
	#[test]
	fn test_interval_rejects_value_arithmetic() {
	assert!(databricks()
	.parse_sql_statements("SELECT INTERVAL 1 + 1 DAY")
	.is_err());
	}
	#[test]
	fn test_interval_preserves_column_query() {
	let query = databricks()
	.run_parser_method("SELECT interval FROM t", |parser| parser.parse_query())
	.unwrap();
	let SetExpr::Select(select) = *query.body else {
	panic!("Expected SELECT");
	};
	assert_eq!(
	select.from,
	vec![TableWithJoins {
	relation: table("t"),
	joins: vec![],
	}]
	);
	assert_eq!(
	select.projection,
	vec![SelectItem::UnnamedExpr(Expr::Identifier(Ident::new(
	"interval"
	)))]
	);
	}