Fix for more than 50 fields in Postgres

data_diff/sqeleton/databases/postgresql.py

@@ -1,3 +1,4 @@
+from typing import List
 from ..abcs.database_types import (
     DbPath,
     JSON,
@@ -92,6 +93,10 @@ def quote(self, s: str):
     def to_string(self, s: str):
         return f"{s}::varchar"
 
+    def concat(self, items: List[str]) -> str:
+        joined_exprs = " || ".join(items)
+        return f"({joined_exprs})"
+
     def _convert_db_precision_to_digits(self, p: int) -> int:
         # Subtracting 2 due to wierd precision issues in PostgreSQL
         return super()._convert_db_precision_to_digits(p) - 2

tests/test_postgresql.py

@@ -70,3 +70,47 @@ def test_uuid(self):
         self.connection.query(self.table_src.drop(True))
         self.connection.query(self.table_dst.drop(True))
         mysql_conn.query(self.table_dst.drop(True))
+
+
+class Test100Fields(unittest.TestCase):
+    def setUp(self) -> None:
+        self.connection = get_conn(db.PostgreSQL)
+
+        table_suffix = random_table_suffix()
+
+        self.table_src_name = f"src{table_suffix}"
+        self.table_dst_name = f"dst{table_suffix}"
+
+        self.table_src = table(self.table_src_name)
+        self.table_dst = table(self.table_dst_name)
+
+    def test_100_fields(self):
+        self.connection.query('CREATE EXTENSION IF NOT EXISTS "uuid-ossp";', None)
+
+        columns = [f"col{i}" for i in range(100)]
+        fields = " ,".join(f'"{field}" TEXT' for field in columns)
+
+        queries = [
+            self.table_src.drop(True),
+            self.table_dst.drop(True),
+            f"CREATE TABLE {self.table_src_name} (id uuid DEFAULT uuid_generate_v4 (), {fields})",
+            commit,
+            self.table_src.insert_rows([[f"{x * y}" for x in range(100)] for y in range(10)], columns=columns),
+            commit,
+            self.table_dst.create(self.table_src),
+            commit,
+            self.table_src.insert_rows([[1 for x in range(100)]], columns=columns),
+            commit,
+        ]
+
+        for query in queries:
+            self.connection.query(query)
+
+        a = TableSegment(self.connection, self.table_src.path, ("id",), extra_columns=tuple(columns))
+        b = TableSegment(self.connection, self.table_dst.path, ("id",), extra_columns=tuple(columns))
+
+        differ = HashDiffer()
+        diff = list(differ.diff_tables(a, b))
+        id_ = diff[0][1][0]
+        result = (id_,) + tuple("1" for x in range(100))
+        self.assertEqual(diff, [("-", result)])