add fix in

digital_land/package/dataset_parquet.py

@@ -258,6 +258,56 @@ def group_parquet_files(
                 f"row count mismatch after grouping: {source_count} source rows vs {batch_count} batch rows"
             )
 
+    def _assign_to_buckets(self, batch_dir, bucket_dir, n_buckets):
+        """
+        Distribute rows from all batch files into n_buckets bucket files based
+        on HASH(fact) % n_buckets. Each unique fact hash always maps to the same
+        bucket, so per-bucket deduplication is equivalent to global deduplication.
+
+        Returns the list of bucket file paths.
+        """
+        digits = max(2, len(str(n_buckets - 1)))
+        bucket_paths = [
+            bucket_dir / f"bucket_{i:0{digits}}.parquet" for i in range(n_buckets)
+        ]
+        for i in range(n_buckets):
+            self.conn.execute(
+                f"""
+                COPY (
+                    SELECT *
+                    FROM read_parquet('{str(batch_dir)}/batch_*.parquet')
+                    WHERE CAST(HASH(fact) AS UBIGINT) % {n_buckets} = {i}
+                ) TO '{bucket_paths[i]}' (FORMAT PARQUET);
+                """
+            )
+        return bucket_paths
+
+    def _deduplicate_buckets(self, bucket_paths, result_dir):
+        """
+        Apply per-fact deduplication to each bucket file, keeping the highest
+        priority and most recent entry for each unique fact hash.
+
+        Returns the list of result file paths.
+        """
+        digits = max(2, len(str(len(bucket_paths) - 1)))
+        result_paths = [
+            result_dir / f"result_{i:0{digits}}.parquet"
+            for i in range(len(bucket_paths))
+        ]
+        for i, bucket_path in enumerate(bucket_paths):
+            self.conn.execute(
+                f"""
+                COPY (
+                    SELECT *
+                    FROM read_parquet('{bucket_path}')
+                    QUALIFY ROW_NUMBER() OVER (
+                        PARTITION BY fact ORDER BY priority, entry_date DESC, entry_number DESC
+                    ) = 1
+                ) TO '{result_paths[i]}' (FORMAT PARQUET);
+                """
+            )
+        return result_paths
+
     def load_facts(self, transformed_parquet_dir):
         """
         This method loads facts into a fact table from a directory containing all transformed files as parquet files
@@ -336,43 +386,23 @@ def load_facts(self, transformed_parquet_dir):
                 logger.info(
                     "Need to use multiple buckets in windowed function for facts"
                 )
-                bucket_dir = transformed_parquet_dir / "bucket"
-                bucket_dir.mkdir(parents=True, exist_ok=True)
-                digits = max(2, len(str(n_buckets - 1)))
-                bucket_paths = [
-                    bucket_dir / f"bucket_{i:0{digits}}.parquet"
-                    for i in range(n_buckets)
-                ]
+                batch_dir = transformed_parquet_dir / "batch"
                 logger.info(
-                    f"Have {len(list(transformed_parquet_dir.glob('batch/batch_*.parquet')))} batch files"
+                    f"Have {len(list(batch_dir.glob('batch_*.parquet')))} batch files"
                 )
 
-                # Loop over each batch file and assign to a bucket file
+                bucket_dir = transformed_parquet_dir / "bucket"
+                bucket_dir.mkdir(parents=True, exist_ok=True)
                 logger.info(f"Assigning to {n_buckets} buckets")
-                for f in transformed_parquet_dir.glob("batch/batch_*.parquet"):
-                    for i in range(n_buckets):
-                        self.conn.execute(
-                            f"""
-                        COPY (
-                            SELECT *
-                            FROM read_parquet('{f}')
-                            WHERE CAST(HASH(fact) AS UBIGINT) % {n_buckets} = {i}
-                        ) TO '{bucket_paths[i]}' (FORMAT PARQUET, APPEND TRUE);
-                        """
-                        )
-
-                logger.info(
-                    f"Have {len(list(bucket_dir.glob('bucket_*.parquet')))} bucket files"
-                )
+                bucket_paths = self._assign_to_buckets(batch_dir, bucket_dir, n_buckets)
+                logger.info(f"Have {len(bucket_paths)} bucket files")
 
-                # temporary diagnostic: total rows across all buckets should equal
-                # total rows across all batch files (deduplication happens later)
+                batch_total = self.conn.execute(
+                    f"SELECT COUNT(*) FROM read_parquet('{str(batch_dir)}/batch_*.parquet')"
+                ).fetchone()[0]
                 bucket_total = self.conn.execute(
                     f"SELECT COUNT(*) FROM read_parquet('{str(bucket_dir)}/bucket_*.parquet')"
                 ).fetchone()[0]
-                batch_total = self.conn.execute(
-                    f"SELECT COUNT(*) FROM read_parquet('{str(transformed_parquet_dir)}/batch/batch_*.parquet')"
-                ).fetchone()[0]
                 logger.info(f"row count in batch files: {batch_total}")
                 logger.info(
                     f"row count in bucket files after assignment: {bucket_total}"
@@ -383,51 +413,27 @@ def load_facts(self, transformed_parquet_dir):
                     )
 
                 process = psutil.Process(os.getpid())
-                mem = process.memory_info().rss / 1024**2  # Memory in MB
+                mem = process.memory_info().rss / 1024**2
                 logger.info(f"[Memory usage] After 'bucketing': {mem:.2f} MB")
 
                 result_dir = transformed_parquet_dir / "result"
                 result_dir.mkdir(parents=True, exist_ok=True)
-                result_paths = [
-                    result_dir / f"result_{i:0{digits}}.parquet"
-                    for i in range(n_buckets)
-                ]
-                for i in range(n_buckets):
-                    bucket_path = bucket_dir / f"bucket_{i:0{digits}}.parquet"
-                    self.conn.execute(
-                        f"""
-                    COPY (
-                        SELECT *
-                        FROM read_parquet('{bucket_path}')
-                        QUALIFY ROW_NUMBER() OVER (
-                            PARTITION BY fact ORDER BY priority, entry_date DESC, entry_number DESC
-                        ) = 1
-                    ) TO '{result_paths[i]}' (FORMAT PARQUET);
-                    """
-                    )
-                logger.info(
-                    f"Have {len(list(transformed_parquet_dir.glob('result_*.parquet')))} result files"
-                )
-
-                # for path in bucket_paths:
-                #     path.unlink(missing_ok=True)
+                result_paths = self._deduplicate_buckets(bucket_paths, result_dir)
+                logger.info(f"Have {len(result_paths)} result files")
 
                 process = psutil.Process(os.getpid())
-                mem = process.memory_info().rss / 1024**2  # Memory in MB
+                mem = process.memory_info().rss / 1024**2
                 logger.info(f"[Memory usage] After 'result': {mem:.2f} MB")
 
                 self.conn.execute(
                     f"""
-                    COPY(
-                        SELECT * FROM
-                    read_parquet('{str(result_dir)}/result_*.parquet')
-                ) TO '{str(output_path)}' (FORMAT PARQUET);
-                """
+                    COPY (
+                        SELECT * FROM read_parquet('{str(result_dir)}/result_*.parquet')
+                    ) TO '{str(output_path)}' (FORMAT PARQUET);
+                    """
                 )
                 logger.info(f"Facts saved to output_path: {output_path}")
                 logger.info(f"output_path exists: {os.path.exists(output_path)}")
-                # for path in result_paths:
-                #     path.unlink(missing_ok=True)
 
             process = psutil.Process(os.getpid())
             mem = process.memory_info().rss / 1024**2  # Memory in MB

tests/integration/package/test_dataset_parquet.py

@@ -1046,3 +1046,135 @@ def test_multi_bucket_load_facts_no_fact_loss(tmp_path):
         f"Expected {n_facts} facts but got {len(df_result)}. "
         "The multi-bucket path silently dropped some facts."
     )
+
+
+def test_assign_to_buckets_creates_correct_files(tmp_path):
+    """
+    Tests that _assign_to_buckets creates exactly n_buckets files in bucket_dir
+    and that the total row count across all bucket files equals the total row
+    count in the batch files (no rows dropped or duplicated during assignment).
+    """
+    n_facts = 30
+    n_buckets = 3
+
+    batch_dir = tmp_path / "batch"
+    batch_dir.mkdir()
+    for i in range(n_facts):
+        pd.DataFrame(
+            {
+                "end_date": [""],
+                "entity": [i + 1],
+                "entry_date": ["2023-01-01"],
+                "entry_number": ["1"],
+                "fact": [f"{'a' * 63}{i}"],
+                "field": ["name"],
+                "priority": ["1"],
+                "reference_entity": [""],
+                "resource": ["resource_abc"],
+                "start_date": [""],
+                "value": [f"value_{i}"],
+            }
+        ).to_parquet(batch_dir / f"batch_{i:02}.parquet", index=False)
+
+    bucket_dir = tmp_path / "bucket"
+    bucket_dir.mkdir()
+
+    package = DatasetParquetPackage(
+        dataset="conservation-area",
+        path=tmp_path / "output",
+        specification_dir=None,
+    )
+    bucket_paths = package._assign_to_buckets(batch_dir, bucket_dir, n_buckets)
+
+    assert (
+        len(bucket_paths) == n_buckets
+    ), f"Expected {n_buckets} bucket files, got {len(bucket_paths)}"
+    assert all(p.exists() for p in bucket_paths), "Not all bucket files were created"
+
+    bucket_total = sum(len(pd.read_parquet(p)) for p in bucket_paths)
+    assert bucket_total == n_facts, (
+        f"Expected {n_facts} total rows across buckets, got {bucket_total}. "
+        "Rows were dropped or duplicated during bucket assignment."
+    )
+
+    # each fact hash should appear in exactly one bucket
+    fact_counts = {}
+    for p in bucket_paths:
+        for fact in pd.read_parquet(p)["fact"]:
+            fact_counts[fact] = fact_counts.get(fact, 0) + 1
+    assert all(
+        v == 1 for v in fact_counts.values()
+    ), "Some fact hashes appear in more than one bucket"
+
+
+def test_deduplicate_buckets_creates_correct_files(tmp_path):
+    """
+    Tests that _deduplicate_buckets creates exactly one result file per bucket
+    and that duplicate fact hashes within a bucket are reduced to a single row,
+    keeping the row with the latest entry_date.
+    """
+    n_buckets = 2
+
+    bucket_dir = tmp_path / "bucket"
+    bucket_dir.mkdir()
+
+    # bucket_00: two rows for the same fact — only the later entry_date should survive
+    pd.DataFrame(
+        {
+            "end_date": ["", ""],
+            "entity": [1, 1],
+            "entry_date": ["2023-01-01", "2023-06-01"],
+            "entry_number": ["1", "2"],
+            "fact": ["fact_aaa", "fact_aaa"],
+            "field": ["name", "name"],
+            "priority": ["1", "1"],
+            "reference_entity": ["", ""],
+            "resource": ["res_a", "res_b"],
+            "start_date": ["", ""],
+            "value": ["old_value", "new_value"],
+        }
+    ).to_parquet(bucket_dir / "bucket_00.parquet", index=False)
+
+    # bucket_01: two distinct facts, no duplicates
+    pd.DataFrame(
+        {
+            "end_date": ["", ""],
+            "entity": [2, 3],
+            "entry_date": ["2023-01-01", "2023-01-01"],
+            "entry_number": ["1", "1"],
+            "fact": ["fact_bbb", "fact_ccc"],
+            "field": ["name", "name"],
+            "priority": ["1", "1"],
+            "reference_entity": ["", ""],
+            "resource": ["res_a", "res_a"],
+            "start_date": ["", ""],
+            "value": ["value_b", "value_c"],
+        }
+    ).to_parquet(bucket_dir / "bucket_01.parquet", index=False)
+
+    result_dir = tmp_path / "result"
+    result_dir.mkdir()
+
+    package = DatasetParquetPackage(
+        dataset="conservation-area",
+        path=tmp_path / "output",
+        specification_dir=None,
+    )
+    bucket_paths = [bucket_dir / "bucket_00.parquet", bucket_dir / "bucket_01.parquet"]
+    result_paths = package._deduplicate_buckets(bucket_paths, result_dir)
+
+    assert (
+        len(result_paths) == n_buckets
+    ), f"Expected {n_buckets} result files, got {len(result_paths)}"
+    assert all(p.exists() for p in result_paths), "Not all result files were created"
+
+    df_00 = pd.read_parquet(result_paths[0])
+    assert (
+        len(df_00) == 1
+    ), "Duplicate fact in bucket_00 should be deduplicated to 1 row"
+    assert (
+        df_00.iloc[0]["value"] == "new_value"
+    ), "The row with the latest entry_date should be kept"
+
+    df_01 = pd.read_parquet(result_paths[1])
+    assert len(df_01) == 2, "bucket_01 has 2 distinct facts, both should be kept"