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Unparse UNNEST projection with the table column alias #15879

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Merged
merged 3 commits into from
May 1, 2025
Merged

Unparse UNNEST projection with the table column alias #15879

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c849d89
add table column alias for unnest projection
goldmedal Apr 28, 2025
a882ab1
fix clippy
goldmedal Apr 28, 2025
cc0f635
fix columns check
goldmedal Apr 28, 2025
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25 changes: 22 additions & 3 deletions datafusion/sql/src/unparser/plan.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ use datafusion_expr::{
UserDefinedLogicalNode,
};
use sqlparser::ast::{self, Ident, OrderByKind, SetExpr, TableAliasColumnDef};
use std::sync::Arc;
use std::{sync::Arc, vec};

/// Convert a DataFusion [`LogicalPlan`] to [`ast::Statement`]
///
Expand Down Expand Up @@ -309,12 +309,13 @@ impl Unparser<'_> {
plan: &LogicalPlan,
relation: &mut RelationBuilder,
lateral: bool,
columns: Vec<Ident>,
) -> Result<()> {
if self.dialect.requires_derived_table_alias() {
if self.dialect.requires_derived_table_alias() || !columns.is_empty() {
self.derive(
plan,
relation,
Some(self.new_table_alias(alias.to_string(), vec![])),
Some(self.new_table_alias(alias.to_string(), columns)),
lateral,
)
} else {
Expand Down Expand Up @@ -392,6 +393,18 @@ impl Unparser<'_> {
}
}

// If it's a unnest projection, we should provide the table column alias
// to provide a column name for the unnest relation.
let columns = if unnest_input_type.is_some() {
p.expr
.iter()
.map(|e| {
self.new_ident_quoted_if_needs(e.schema_name().to_string())
})
.collect()
} else {
vec![]
};
// Projection can be top-level plan for derived table
if select.already_projected() {
return self.derive_with_dialect_alias(
Expand All @@ -401,6 +414,7 @@ impl Unparser<'_> {
unnest_input_type
.filter(|t| matches!(t, UnnestInputType::OuterReference))
.is_some(),
columns,
);
}
self.reconstruct_select_statement(plan, p, select)?;
Expand Down Expand Up @@ -434,6 +448,7 @@ impl Unparser<'_> {
plan,
relation,
false,
vec![],
);
}
if let Some(fetch) = &limit.fetch {
Expand Down Expand Up @@ -472,6 +487,7 @@ impl Unparser<'_> {
plan,
relation,
false,
vec![],
);
}
let Some(query_ref) = query else {
Expand Down Expand Up @@ -543,6 +559,7 @@ impl Unparser<'_> {
plan,
relation,
false,
vec![],
);
}

Expand Down Expand Up @@ -833,6 +850,7 @@ impl Unparser<'_> {
plan,
relation,
false,
vec![],
);
}

Expand Down Expand Up @@ -950,6 +968,7 @@ impl Unparser<'_> {
subquery.subquery.as_ref(),
relation,
true,
vec![],
)
}
}
Expand Down
4 changes: 2 additions & 2 deletions datafusion/sql/tests/cases/plan_to_sql.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -698,7 +698,7 @@ fn roundtrip_statement_with_dialect_27() -> Result<(), DataFusionError> {
sql: "SELECT * FROM UNNEST([1,2,3])",
parser_dialect: GenericDialect {},
unparser_dialect: UnparserDefaultDialect {},
expected: @r#"SELECT "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))" FROM (SELECT UNNEST([1, 2, 3]) AS "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))")"#,
expected: @r#"SELECT "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))" FROM (SELECT UNNEST([1, 2, 3]) AS "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))") AS derived_projection ("UNNEST(make_array(Int64(1),Int64(2),Int64(3)))")"#,
);
Ok(())
}
Expand All @@ -720,7 +720,7 @@ fn roundtrip_statement_with_dialect_29() -> Result<(), DataFusionError> {
sql: "SELECT * FROM UNNEST([1,2,3]), j1",
parser_dialect: GenericDialect {},
unparser_dialect: UnparserDefaultDialect {},
expected: @r#"SELECT "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))", j1.j1_id, j1.j1_string FROM (SELECT UNNEST([1, 2, 3]) AS "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))") CROSS JOIN j1"#,
expected: @r#"SELECT "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))", j1.j1_id, j1.j1_string FROM (SELECT UNNEST([1, 2, 3]) AS "UNNEST(make_array(Int64(1),Int64(2),Int64(3)))") AS derived_projection ("UNNEST(make_array(Int64(1),Int64(2),Int64(3)))") CROSS JOIN j1"#,
);
Ok(())
}
Expand Down