Preserve JOIN token style in formatter

docs/format-contract.md

@@ -36,6 +36,11 @@ Heuristics such as select-list thresholds and line-break preferences are documen
 - Single-quoted string literal contents are preserved as written, including doubled quotes and over-escaped forms.
 - Quoted identifier contents are not recased.
 
+## JOIN Token Preservation
+
+- `JOIN` stays `JOIN`.
+- `INNER JOIN` stays `INNER JOIN`.
+
 ## Parse Fallback vs Strict Mode
 
 Default behavior (`strict = false` / no `--strict`):

docs/style-guide.md

@@ -52,6 +52,7 @@ FROM t;
 - Clause order: `SELECT`, `FROM`, `WHERE`, `GROUP BY`, `HAVING`, `WINDOW` (if any), `QUALIFY` (if supported), `ORDER BY`, `LIMIT`/`FETCH`, `OFFSET`
 - Each clause starts on its own line (except small inline `SELECT`)
 - `FROM` base relation on its own line; each `JOIN` on a new line aligned with `FROM`
+- Join token style is preserved (`JOIN` remains `JOIN`; `INNER JOIN` remains `INNER JOIN`)
 - `ON` is indented one level under its join
 - `WHERE` / `HAVING` / `QUALIFY` break logical conditions across lines
 - `GROUP BY` renders one item per line when more than one expression is present

fixtures/ansi/expected/01.sql

@@ -15,7 +15,7 @@ SELECT
     ORDER BY f.order_ts
   ) AS order_seq
 FROM analytics_space."fact_orders" f
-INNER JOIN analytics_space."dim_customers" c
+JOIN analytics_space."dim_customers" c
   ON c.customer_id = f.customer_id
 LEFT JOIN (
   SELECT

fixtures/ansi/expected/07.sql

@@ -1,5 +1,5 @@
 SELECT *
 FROM dim_customers c
-INNER JOIN fact_orders o USING customer_id
+JOIN fact_orders o USING customer_id
 CROSS JOIN dim_dates d
 NATURAL LEFT JOIN dim_flags f;

fixtures/ansi/out/01.sql

@@ -15,7 +15,7 @@ SELECT
     ORDER BY f.order_ts
   ) AS order_seq
 FROM analytics_space."fact_orders" f
-INNER JOIN analytics_space."dim_customers" c
+JOIN analytics_space."dim_customers" c
   ON c.customer_id = f.customer_id
 LEFT JOIN (
   SELECT

fixtures/ansi/out/07.sql

@@ -1,5 +1,5 @@
 SELECT *
 FROM dim_customers c
-INNER JOIN fact_orders o USING customer_id
+JOIN fact_orders o USING customer_id
 CROSS JOIN dim_dates d
 NATURAL LEFT JOIN dim_flags f;

fixtures/dremio/expected/03.sql

@@ -12,23 +12,32 @@ CREATE TABLE demoCatalog.reporting."tables".orders_partitioned AS
     CASE WHEN o.change_time IS NULL THEN 0 ELSE 1 END AS is_changed,
     CASE WHEN o.cancel_time IS NULL THEN 0 ELSE 1 END AS is_canceled
   FROM demoCatalog.reporting."tables"."orders" o
-  INNER JOIN demoCatalog.reporting."tables"."cart_orders" co
+  JOIN demoCatalog.reporting."tables"."cart_orders" co
     ON co.order_id = o.id
-  INNER JOIN demoCatalog.reporting."tables"."order_revenues" orev
+  JOIN demoCatalog.reporting."tables"."order_revenues" orev
     ON orev.order_id = o.id
-  INNER JOIN demoCatalog.reporting."tables"."sites" s
+  JOIN demoCatalog.reporting."tables"."sites" s
     ON s.id = co.site_id
   LEFT JOIN (
     SELECT
       i.order_id,
       SUM(i.revenue) AS revenue_share
     FROM demoCatalog.reporting."tables"."order_revenue_items" i
-    INNER JOIN demoCatalog.reporting."tables"."product_types" pt
+    JOIN demoCatalog.reporting."tables"."product_types" pt
       ON i.product_type_id = pt.id
     WHERE pt.revenue_group_id = 17
     GROUP BY i.order_id
   ) dist
     ON dist.order_id = o.id
-  WHERE NOT EXISTS (SELECT 1 FROM demoCatalog.reporting."tables"."order_items" AS oi JOIN demoCatalog.reporting."tables"."customer_items" AS ci ON ci.id = oi.customer_item_id WHERE oi.order_id = o.id AND ci.product_type_id = 620)
+  WHERE NOT EXISTS
+      (
+        SELECT
+          1
+        FROM demoCatalog.reporting."tables"."order_items" oi
+        JOIN demoCatalog.reporting."tables"."customer_items" ci
+          ON ci.id = oi.customer_item_id
+        WHERE oi.order_id = o.id
+          AND ci.product_type_id = 620
+      )
     AND (o.is_test_order = FALSE)
 );

fixtures/dremio/expected/04.sql

@@ -13,7 +13,7 @@ SELECT
 FROM arctic_catalog.analytics_space.orders_history o
 AT BRANCH feature_campaign_x
 AS OF TIMESTAMP '2024-10-01 12:00:00'
-INNER JOIN arctic_catalog.analytics_space.order_items_history i
+JOIN arctic_catalog.analytics_space.order_items_history i
   ON i.order_id = o.order_id
   AND i.valid_from <= o.order_ts
   AND (

fixtures/dremio/expected/05.sql

@@ -6,7 +6,7 @@ SELECT
   COUNT(*) AS num_orders,
   AVG(o.order_amount) AS avg_order_value
 FROM arctic_catalog.analytics_space."fact_orders" o
-INNER JOIN arctic_catalog.analytics_space."dim_customers" c
+JOIN arctic_catalog.analytics_space."dim_customers" c
   ON c.customer_id = o.customer_id
 WHERE order_ts >= TIMESTAMP '2024-01-01 00:00:00'
 GROUP BY

fixtures/dremio/expected/07.sql

@@ -14,7 +14,7 @@ SELECT
   SUM(o.order_amount) AS total_revenue,
   AVG(o.order_amount) AS avg_order_value
 FROM arctic_catalog.analytics_space."fact_orders" o
-INNER JOIN arctic_catalog.analytics_space."dim_customers" c
+JOIN arctic_catalog.analytics_space."dim_customers" c
   ON c.customer_id = o.customer_id
 WHERE order_ts >= TIMESTAMP '2024-01-01 00:00:00'
 GROUP BY

fixtures/dremio/expected/11.sql

@@ -7,5 +7,5 @@ SELECT
   o.created_at AS order_created_at,
   coalesce(md5(c.email), '') AS email_hash
 FROM demoCatalog.sales.staging.analytics.orders o
-INNER JOIN demoCatalog.sales.staging.crm.customers c
+JOIN demoCatalog.sales.staging.crm.customers c
   ON c.order_id = o.id;

fixtures/dremio/out/03.sql

@@ -12,23 +12,32 @@ CREATE TABLE demoCatalog.reporting."tables".orders_partitioned AS
     CASE WHEN o.change_time IS NULL THEN 0 ELSE 1 END AS is_changed,
     CASE WHEN o.cancel_time IS NULL THEN 0 ELSE 1 END AS is_canceled
   FROM demoCatalog.reporting."tables"."orders" o
-  INNER JOIN demoCatalog.reporting."tables"."cart_orders" co
+  JOIN demoCatalog.reporting."tables"."cart_orders" co
     ON co.order_id = o.id
-  INNER JOIN demoCatalog.reporting."tables"."order_revenues" orev
+  JOIN demoCatalog.reporting."tables"."order_revenues" orev
     ON orev.order_id = o.id
-  INNER JOIN demoCatalog.reporting."tables"."sites" s
+  JOIN demoCatalog.reporting."tables"."sites" s
     ON s.id = co.site_id
   LEFT JOIN (
     SELECT
       i.order_id,
       SUM(i.revenue) AS revenue_share
     FROM demoCatalog.reporting."tables"."order_revenue_items" i
-    INNER JOIN demoCatalog.reporting."tables"."product_types" pt
+    JOIN demoCatalog.reporting."tables"."product_types" pt
       ON i.product_type_id = pt.id
     WHERE pt.revenue_group_id = 17
     GROUP BY i.order_id
   ) dist
     ON dist.order_id = o.id
-  WHERE NOT EXISTS (SELECT 1 FROM demoCatalog.reporting."tables"."order_items" AS oi JOIN demoCatalog.reporting."tables"."customer_items" AS ci ON ci.id = oi.customer_item_id WHERE oi.order_id = o.id AND ci.product_type_id = 620)
+  WHERE NOT EXISTS
+      (
+        SELECT
+          1
+        FROM demoCatalog.reporting."tables"."order_items" oi
+        JOIN demoCatalog.reporting."tables"."customer_items" ci
+          ON ci.id = oi.customer_item_id
+        WHERE oi.order_id = o.id
+          AND ci.product_type_id = 620
+      )
     AND (o.is_test_order = FALSE)
 );

fixtures/dremio/out/04.sql

@@ -13,7 +13,7 @@ SELECT
 FROM arctic_catalog.analytics_space.orders_history o
 AT BRANCH feature_campaign_x
 AS OF TIMESTAMP '2024-10-01 12:00:00'
-INNER JOIN arctic_catalog.analytics_space.order_items_history i
+JOIN arctic_catalog.analytics_space.order_items_history i
   ON i.order_id = o.order_id
   AND i.valid_from <= o.order_ts
   AND (

fixtures/dremio/out/05.sql

@@ -6,7 +6,7 @@ SELECT
   COUNT(*) AS num_orders,
   AVG(o.order_amount) AS avg_order_value
 FROM arctic_catalog.analytics_space."fact_orders" o
-INNER JOIN arctic_catalog.analytics_space."dim_customers" c
+JOIN arctic_catalog.analytics_space."dim_customers" c
   ON c.customer_id = o.customer_id
 WHERE order_ts >= TIMESTAMP '2024-01-01 00:00:00'
 GROUP BY

fixtures/dremio/out/07.sql

@@ -14,7 +14,7 @@ SELECT
   SUM(o.order_amount) AS total_revenue,
   AVG(o.order_amount) AS avg_order_value
 FROM arctic_catalog.analytics_space."fact_orders" o
-INNER JOIN arctic_catalog.analytics_space."dim_customers" c
+JOIN arctic_catalog.analytics_space."dim_customers" c
   ON c.customer_id = o.customer_id
 WHERE order_ts >= TIMESTAMP '2024-01-01 00:00:00'
 GROUP BY

fixtures/dremio/out/11.sql

@@ -7,5 +7,5 @@ SELECT
   o.created_at AS order_created_at,
   coalesce(md5(c.email), '') AS email_hash
 FROM demoCatalog.sales.staging.analytics.orders o
-INNER JOIN demoCatalog.sales.staging.crm.customers c
+JOIN demoCatalog.sales.staging.crm.customers c
   ON c.order_id = o.id;

src/format/sql/from_join.rs

@@ -242,7 +242,7 @@ fn format_join(
     alias_tracker: &mut super::RelationAliasTracker,
 ) -> Doc {
     let (prefix, constraint, asof_match) = match &join.join_operator {
-        JoinOperator::Join(constraint) => ("INNER JOIN", Some(constraint), None),
+        JoinOperator::Join(constraint) => ("JOIN", Some(constraint), None),
         JoinOperator::Inner(constraint) => ("INNER JOIN", Some(constraint), None),
         JoinOperator::Left(constraint) => ("LEFT JOIN", Some(constraint), None),
         JoinOperator::LeftOuter(constraint) => ("LEFT JOIN", Some(constraint), None),

src/format/sql/mod.rs

@@ -1632,7 +1632,7 @@ WHERE NOT EXISTS (
         let out = format_str(sql, &cfg);
         assert_eq!(
             out.trim(),
-            "CREATE TABLE demoCatalog.reporting.\"tables\".orders_partitioned AS\n(\n  SELECT\n    o.id AS order_id,\n    CURRENT_TIMESTAMP AS sync_time,\n    o.order_number AS order_number,\n    co.site_id AS site_id,\n    s.brand_id AS brand_id,\n    s.country_id AS site_country_id,\n    o.created_at AS created_at,\n    COALESCE(dist.revenue_share, 0) AS distribution_amount,\n    CASE WHEN o.change_time IS NULL THEN 0 ELSE 1 END AS is_changed,\n    CASE WHEN o.cancel_time IS NULL THEN 0 ELSE 1 END AS is_canceled\n  FROM demoCatalog.reporting.\"tables\".\"orders\" o\n  INNER JOIN demoCatalog.reporting.\"tables\".\"cart_orders\" co\n    ON co.order_id = o.id\n  INNER JOIN demoCatalog.reporting.\"tables\".\"order_revenues\" orev\n    ON orev.order_id = o.id\n  INNER JOIN demoCatalog.reporting.\"tables\".\"sites\" s\n    ON s.id = co.site_id\n  LEFT JOIN (\n    SELECT\n      i.order_id,\n      SUM(i.revenue) AS revenue_share\n    FROM demoCatalog.reporting.\"tables\".\"order_revenue_items\" i\n    INNER JOIN demoCatalog.reporting.\"tables\".\"product_types\" pt\n      ON i.product_type_id = pt.id\n    WHERE pt.revenue_group_id = 17\n    GROUP BY i.order_id\n  ) dist\n    ON dist.order_id = o.id\n  WHERE NOT EXISTS\n      (\n        SELECT\n          1\n        FROM demoCatalog.reporting.\"tables\".\"order_items\" oi\n        INNER JOIN demoCatalog.reporting.\"tables\".\"customer_items\" ci\n          ON ci.id = oi.customer_item_id\n        WHERE oi.order_id = o.id\n          AND ci.product_type_id = 620\n      )\n    AND (o.is_test_order = FALSE)\n);"
+            "CREATE TABLE demoCatalog.reporting.\"tables\".orders_partitioned AS\n(\n  SELECT\n    o.id AS order_id,\n    CURRENT_TIMESTAMP AS sync_time,\n    o.order_number AS order_number,\n    co.site_id AS site_id,\n    s.brand_id AS brand_id,\n    s.country_id AS site_country_id,\n    o.created_at AS created_at,\n    COALESCE(dist.revenue_share, 0) AS distribution_amount,\n    CASE WHEN o.change_time IS NULL THEN 0 ELSE 1 END AS is_changed,\n    CASE WHEN o.cancel_time IS NULL THEN 0 ELSE 1 END AS is_canceled\n  FROM demoCatalog.reporting.\"tables\".\"orders\" o\n  JOIN demoCatalog.reporting.\"tables\".\"cart_orders\" co\n    ON co.order_id = o.id\n  JOIN demoCatalog.reporting.\"tables\".\"order_revenues\" orev\n    ON orev.order_id = o.id\n  JOIN demoCatalog.reporting.\"tables\".\"sites\" s\n    ON s.id = co.site_id\n  LEFT JOIN (\n    SELECT\n      i.order_id,\n      SUM(i.revenue) AS revenue_share\n    FROM demoCatalog.reporting.\"tables\".\"order_revenue_items\" i\n    JOIN demoCatalog.reporting.\"tables\".\"product_types\" pt\n      ON i.product_type_id = pt.id\n    WHERE pt.revenue_group_id = 17\n    GROUP BY i.order_id\n  ) dist\n    ON dist.order_id = o.id\n  WHERE NOT EXISTS\n      (\n        SELECT\n          1\n        FROM demoCatalog.reporting.\"tables\".\"order_items\" oi\n        JOIN demoCatalog.reporting.\"tables\".\"customer_items\" ci\n          ON ci.id = oi.customer_item_id\n        WHERE oi.order_id = o.id\n          AND ci.product_type_id = 620\n      )\n    AND (o.is_test_order = FALSE)\n);"
         );
     }
 
@@ -1905,6 +1905,18 @@ INSERT INTO a SELECT * FROM s.t AT BRANCH release AS OF TIMESTAMP '2025-01-01 00
         );
     }
 
+    #[test]
+    fn preserves_join_token_style() {
+        let cfg = FormatterConfig::default();
+        let sql =
+            "SELECT * FROM a JOIN b ON a.id = b.id;\nSELECT * FROM a INNER JOIN b ON a.id = b.id;";
+        let out = format_str(sql, &cfg);
+        assert_eq!(
+            out.trim(),
+            "SELECT *\nFROM a\nJOIN b\n  ON a.id = b.id;\n\nSELECT *\nFROM a\nINNER JOIN b\n  ON a.id = b.id;"
+        );
+    }
+
     #[test]
     fn formats_insert_select() {
         let cfg = FormatterConfig::default();
@@ -2041,7 +2053,7 @@ INSERT INTO a SELECT * FROM s.t AT BRANCH release AS OF TIMESTAMP '2025-01-01 00
         let out = format_str(sql, &cfg);
         assert_eq!(
             out.trim(),
-            "SELECT *\nFROM t\nINNER JOIN u\n  ON t.id = u.id\n  AND t.tenant = u.tenant"
+            "SELECT *\nFROM t\nJOIN u\n  ON t.id = u.id\n  AND t.tenant = u.tenant"
         );
     }
 
@@ -2274,7 +2286,7 @@ SELECT
   o.created_at AS order_created_at,
   COALESCE(MD5(c.email), '') AS email_hash
 FROM demoCatalog.sales.staging.analytics.orders o
-INNER JOIN demoCatalog.sales.staging.crm.customers c
+JOIN demoCatalog.sales.staging.crm.customers c
   ON c.order_id = o.id;"
         );
     }