From 1a5e3a7215ca7c51fe30e6753b841184564ac104 Mon Sep 17 00:00:00 2001
From: Luka Peschke <mail@lukapeschke.com>
Date: Fri, 20 Dec 2024 10:35:34 +0100
Subject: [PATCH 1/3] fix(resolver): do not copy sort when flattening a join or
 append transform

closes #4063 #4947

Signed-off-by: Luka Peschke <mail@lukapeschke.com>
---
 prqlc/prqlc/src/semantic/resolver/flatten.rs | 21 ++++-
 prqlc/prqlc/tests/integration/sql.rs         | 83 ++++++++++++++++++++
 2 files changed, 103 insertions(+), 1 deletion(-)

diff --git a/prqlc/prqlc/src/semantic/resolver/flatten.rs b/prqlc/prqlc/src/semantic/resolver/flatten.rs
index 7c9afb00a4f9..b96827adc67c 100644
--- a/prqlc/prqlc/src/semantic/resolver/flatten.rs
+++ b/prqlc/prqlc/src/semantic/resolver/flatten.rs
@@ -131,12 +131,31 @@ impl PlFold for Flattener {
                     kind => (self.fold_expr(*t.input)?, fold_transform_kind(self, kind)?),
                 };
 
+                // In case we're appending or joining another pipeline, we do not want to apply the
+                // sub-pipeline's sort, as it may result in column lookup errors. Without this, we
+                // would try to join on `album_id` in the outer pipeline of the following query, but
+                // the column does not exist
+                //
+                // from artists
+                // join side:left (
+                //   from albums
+                //   sort {`album_id`}
+                //   derive {`album_name` = `name`}
+                //   select {`artist_id`, `album_name`}
+                // ) (this.id == that.artist_id)
+                let sort = if matches!(kind, TransformKind::Join { .. } | TransformKind::Append(_))
+                {
+                    vec![]
+                } else {
+                    self.sort.clone()
+                };
+
                 ExprKind::TransformCall(TransformCall {
                     input: Box::new(input),
                     kind: Box::new(kind),
                     partition: self.partition.clone(),
                     frame: self.window.clone(),
-                    sort: self.sort.clone(),
+                    sort,
                 })
             }
             kind => self.fold_expr_kind(kind)?,
diff --git a/prqlc/prqlc/tests/integration/sql.rs b/prqlc/prqlc/tests/integration/sql.rs
index 8d86aa36074e..098f6640aca4 100644
--- a/prqlc/prqlc/tests/integration/sql.rs
+++ b/prqlc/prqlc/tests/integration/sql.rs
@@ -885,6 +885,89 @@ fn test_intersect_07() {
     );
 }
 
+#[test]
+fn test_sort_in_nested_join() {
+    assert_snapshot!(compile(r#"
+    from albums
+    join side:left (
+        from artists
+        sort {-`artist-id`}
+        take 10
+    ) (this.artist_id == that.artist_id) | take 10
+    "#).unwrap(),
+        @r#"
+    WITH table_0 AS (
+      SELECT
+        *
+      FROM
+        artists
+      ORDER BY
+        "artist-id" DESC
+      LIMIT
+        10
+    )
+    SELECT
+      albums.*,
+      table_0.*
+    FROM
+      albums
+      LEFT JOIN table_0 ON albums.artist_id = table_0.artist_id
+    LIMIT
+      10
+    "#
+    );
+}
+
+#[test]
+fn test_sort_in_nested_append() {
+    assert_snapshot!(compile(r#"
+    from `albums`
+    select { `album_id`, `title` }
+    sort {+`album_id`}
+    take 2
+    append (
+        from `albums`
+        select { `album_id`, `title` }
+        sort {-`album_id`}
+        take 2
+    )
+    "#).unwrap(),
+        @r#"
+        WITH table_0 AS (
+          SELECT
+            album_id,
+            title
+          FROM
+            albums
+          ORDER BY
+            album_id DESC
+          LIMIT
+            2
+        )
+        SELECT
+          *
+        FROM
+          (
+            SELECT
+              album_id,
+              title
+            FROM
+              albums
+            ORDER BY
+              album_id
+            LIMIT
+              2
+          ) AS table_1
+        UNION
+        ALL
+        SELECT
+          *
+        FROM
+          table_0
+    "#
+    );
+}
+
 #[test]
 fn test_rn_ids_are_unique() {
     // this is wrong, output will have duplicate y_id and x_id

From 451ad5879e52fa921f426f2bf94cf38bb9b4e9c2 Mon Sep 17 00:00:00 2001
From: Luka Peschke <mail@lukapeschke.com>
Date: Sat, 21 Dec 2024 12:34:06 +0100
Subject: [PATCH 2/3] docs: update changelog

Signed-off-by: Luka Peschke <mail@lukapeschke.com>
---
 CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9275f7c87e43..29f45d786935 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@
 
 **Fixes**:
 
+- Sort steps in sub-pipelines no longer cause a column lookup error (@lukapeschke, #5066)
+
 **Documentation**:
 
 **Web**:
@@ -18,6 +20,8 @@
 
 **New Contributors**:
 
+- @lukapeschke, with #5066
+
 ## 0.13.2
 
 0.13.2 is a tiny release to fix an issue publishing 0.13.1 to crates.io.

From fd41d4705cfa04b2567ef418f8e6cd84e405e903 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 21 Dec 2024 11:34:35 +0000
Subject: [PATCH 3/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 CHANGELOG.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 29f45d786935..c9fb01c5bbaf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,8 @@
 
 **Fixes**:
 
-- Sort steps in sub-pipelines no longer cause a column lookup error (@lukapeschke, #5066)
+- Sort steps in sub-pipelines no longer cause a column lookup error
+  (@lukapeschke, #5066)
 
 **Documentation**: