diff --git a/Cargo.lock b/Cargo.lock
index a92b67ef66..b869f3b195 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -329,7 +329,7 @@ checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 [[package]]
 name = "polyglot-sql"
 version = "0.13.8"
-source = "git+https://github.com/chio-labs/polyglot.git?rev=a7413439c520d7949924149b7ea02fa3817463fc#a7413439c520d7949924149b7ea02fa3817463fc"
+source = "git+https://github.com/chio-labs/polyglot.git?rev=9ff0af282829d92efeeb36b6a820be2271e1da49#9ff0af282829d92efeeb36b6a820be2271e1da49"
 dependencies = [
  "polyglot-sql-ast-derive",
  "polyglot-sql-function-catalogs",
@@ -344,7 +344,7 @@ dependencies = [
 [[package]]
 name = "polyglot-sql-ast-derive"
 version = "0.13.8"
-source = "git+https://github.com/chio-labs/polyglot.git?rev=a7413439c520d7949924149b7ea02fa3817463fc#a7413439c520d7949924149b7ea02fa3817463fc"
+source = "git+https://github.com/chio-labs/polyglot.git?rev=9ff0af282829d92efeeb36b6a820be2271e1da49#9ff0af282829d92efeeb36b6a820be2271e1da49"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -354,7 +354,7 @@ dependencies = [
 [[package]]
 name = "polyglot-sql-function-catalogs"
 version = "0.13.8"
-source = "git+https://github.com/chio-labs/polyglot.git?rev=a7413439c520d7949924149b7ea02fa3817463fc#a7413439c520d7949924149b7ea02fa3817463fc"
+source = "git+https://github.com/chio-labs/polyglot.git?rev=9ff0af282829d92efeeb36b6a820be2271e1da49#9ff0af282829d92efeeb36b6a820be2271e1da49"
 
 [[package]]
 name = "portable-atomic"
diff --git a/Cargo.toml b/Cargo.toml
index 75ba4276c9..5dc0f8aca9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ globset = "0.4"
 mimalloc = { version = "0.1", default-features = false, features = ["local_dynamic_tls"] }
 proc-macro2 = { version = "1", features = ["span-locations"] }
 pyo3 = { version = "0.26", features = ["abi3-py312"] }
-polyglot-sql = { git = "https://github.com/chio-labs/polyglot.git", rev = "a7413439c520d7949924149b7ea02fa3817463fc", default-features = false, features = [
+polyglot-sql = { git = "https://github.com/chio-labs/polyglot.git", rev = "9ff0af282829d92efeeb36b6a820be2271e1da49", default-features = false, features = [
     "ast-tools",
     "builder",
     "dialect-bigquery",
@@ -29,7 +29,7 @@ polyglot-sql = { git = "https://github.com/chio-labs/polyglot.git", rev = "a7413
     "semantic",
     "stacker",
 ] }
-polyglot-sql-function-catalogs = { git = "https://github.com/chio-labs/polyglot.git", rev = "a7413439c520d7949924149b7ea02fa3817463fc", default-features = false, features = [
+polyglot-sql-function-catalogs = { git = "https://github.com/chio-labs/polyglot.git", rev = "9ff0af282829d92efeeb36b6a820be2271e1da49", default-features = false, features = [
     "dialect-duckdb",
 ] }
 quote = "1"
diff --git a/tests/e2e/src/sqlbuild/cli/commands/main/compile/_test_types.py b/tests/e2e/src/sqlbuild/cli/commands/main/compile/_test_types.py
index d6166840c1..3208cd0112 100644
--- a/tests/e2e/src/sqlbuild/cli/commands/main/compile/_test_types.py
+++ b/tests/e2e/src/sqlbuild/cli/commands/main/compile/_test_types.py
@@ -496,6 +496,7 @@ class UnionFixtureCompileScalingTestCase:
     expected_sql_tests: int
     expected_errors: int
     expected_max_scaling_ratio: float
+    input_fixture_row_separator: str = " UNION ALL\n"
 
 
 @dataclass(frozen=True)
diff --git a/tests/e2e/src/sqlbuild/cli/commands/main/compile/helpers.py b/tests/e2e/src/sqlbuild/cli/commands/main/compile/helpers.py
index 40ad9bd6cd..e203868234 100644
--- a/tests/e2e/src/sqlbuild/cli/commands/main/compile/helpers.py
+++ b/tests/e2e/src/sqlbuild/cli/commands/main/compile/helpers.py
@@ -2771,17 +2771,25 @@ class UnionFixtureCompileMeasurement(NamedTuple):
     errors: int
 
 
-def _union_all_fixture_rows(*, row_count: int, status: str) -> str:
-    return " UNION ALL\n".join(
+def _union_all_fixture_rows(*, row_count: int, status: str, separator: str) -> str:
+    return separator.join(
         f"  SELECT {row} AS order_id, CAST({row} AS DOUBLE) AS amount, '{status}' AS status"
         for row in range(row_count)
     )
 
 
 def write_union_fixture_test_project(
-    *, project_dir: Path, sql_test_count: int, fixture_row_count: int
+    *,
+    project_dir: Path,
+    sql_test_count: int,
+    fixture_row_count: int,
+    input_fixture_row_separator: str,
 ) -> None:
-    """Write a DuckDB project whose SQL tests use long UNION ALL fixture chains."""
+    """Write a DuckDB project whose SQL tests use long UNION ALL fixture chains.
+
+    `input_fixture_row_separator` joins the rows of the mocked input fixture; the
+    expected fixture always uses plain `UNION ALL`.
+    """
 
     files: dict[str, str] = {
         "sqlbuild_project.toml": (
@@ -2798,13 +2806,17 @@ def write_union_fixture_test_project(
         ),
     }
     for index in range(sql_test_count):
-        fixture_rows: str = _union_all_fixture_rows(
-            row_count=fixture_row_count, status=f"status_{index:02d}"
+        status: str = f"status_{index:02d}"
+        input_rows: str = _union_all_fixture_rows(
+            row_count=fixture_row_count, status=status, separator=input_fixture_row_separator
+        )
+        expected_rows: str = _union_all_fixture_rows(
+            row_count=fixture_row_count, status=status, separator=" UNION ALL\n"
         )
         files[f"tests/unit/orders_case_{index:02d}.sql"] = (
             f'TEST (name "orders_case_{index:02d}");\n\n'
-            f"WITH\n__ref__base_orders AS (\n{fixture_rows}\n),\n"
-            f"__expected__orders AS (\n{fixture_rows}\n)\nSELECT 1\n"
+            f"WITH\n__ref__base_orders AS (\n{input_rows}\n),\n"
+            f"__expected__orders AS (\n{expected_rows}\n)\nSELECT 1\n"
         )
     prepare_inline_project(
         tmp_path=project_dir.parent, project_name=project_dir.name, repo_files=files
diff --git a/tests/e2e/src/sqlbuild/cli/commands/main/compile/test_compile_performance.py b/tests/e2e/src/sqlbuild/cli/commands/main/compile/test_compile_performance.py
index e74c6cfcee..81e5782b98 100644
--- a/tests/e2e/src/sqlbuild/cli/commands/main/compile/test_compile_performance.py
+++ b/tests/e2e/src/sqlbuild/cli/commands/main/compile/test_compile_performance.py
@@ -140,7 +140,18 @@ def test_given_wide_scan_heavy_projects_when_doubling_sql_size_then_compile_scal
             expected_sql_tests=4,
             expected_errors=0,
             expected_max_scaling_ratio=6.0,
-        )
+        ),
+        UnionFixtureCompileScalingTestCase(
+            description="quadrupling commented UNION ALL input fixture rows keeps SQL test analysis linear",
+            sql_test_count=4,
+            small_fixture_rows=50,
+            large_fixture_rows=200,
+            measured_runs=3,
+            expected_sql_tests=4,
+            expected_errors=0,
+            expected_max_scaling_ratio=6.0,
+            input_fixture_row_separator="\n  -- fixture row\n  UNION ALL\n",
+        ),
     ],
     ids=lambda case: case.description,
 )
@@ -154,11 +165,13 @@ def test_given_sql_tests_with_union_all_fixtures_when_quadrupling_rows_then_anal
         project_dir=small_project_dir,
         sql_test_count=test_case.sql_test_count,
         fixture_row_count=test_case.small_fixture_rows,
+        input_fixture_row_separator=test_case.input_fixture_row_separator,
     )
     write_union_fixture_test_project(
         project_dir=large_project_dir,
         sql_test_count=test_case.sql_test_count,
         fixture_row_count=test_case.large_fixture_rows,
+        input_fixture_row_separator=test_case.input_fixture_row_separator,
     )
     small: UnionFixtureCompileMeasurement = measure_union_fixture_compile(
         project_dir=small_project_dir, runs=test_case.measured_runs