new parquet reader/writer with tests. removed old parquet backend

Author: Vedant1

docs/backends.rst

@@ -51,10 +51,3 @@ GUFI
 .. automodule:: dsi.backends.gufi
    :members:
    :special-members: __init__
-
-Parquet
---------
-
-.. automodule:: dsi.backends.parquet
-   :members:
-   :special-members: __init__

docs/cr_intro.rst

@@ -42,7 +42,6 @@ All DSI backends include:
 - DuckDB: In-process SQL database designed for fast queries on large data files
 - GUFI: the `Grand Unified File Index system <https://github.com/mar-file-system/GUFI>`_ ; developed at LANL. 
   GUFI is a fast, secure metadata search across a filesystem accessible to both privileged and unprivileged users.
-- Parquet: a columnar storage format for `Apache Hadoop <https://hadoop.apache.org>`_.
 
 DSI Core
 ~~~~~~~~

dsi/backends/filesystem.py

@@ -78,7 +78,6 @@ class Filesystem(Backend):
     # Declare store types
     GUFI_STORE = "gufi"
     SQLITE_STORE = "sqlite"
-    PARQUET_STORE = "parquet"
 
     # Declare comparison types
     GT = ">"

dsi/backends/parquet.py

@@ -219,9 +219,7 @@ def export_table(self, table_name, filename):
                 elif file_extension.lower() == "csv":
                     self.t.load_module('plugin', "Csv_Writer", "writer", filename = filename, table_name = table_name)
                 elif file_extension.lower() in ['pq', 'parquet']:
-                    table_data = self.t.active_metadata[table_name]
-                    df = pd.DataFrame(table_data)
-                    df.to_parquet(filename, engine='pyarrow', index=False)
+                    self.t.load_module('plugin', "Parquet_Writer", "writer", filename = filename, table_name = table_name)
                 else:
                     success_load = False
         except Exception as e:
@@ -481,14 +479,8 @@ def read(self, args):
                     self.t.load_module('plugin', "YAML1", "reader", filenames = dbfile)
                 elif file_extension.lower() == 'json':
                     self.t.load_module('plugin', "JSON", "reader", filenames = dbfile)
-                elif file_extension.lower() == 'pq' or file_extension.lower() == 'parquet':
-                    self.t.load_module('backend','Parquet','back-write', filename=dbfile)
-                    data = OrderedDict(self.t.artifact_handler(interaction_type="query")) #Parquet's query() returns a normal dict
-                    if table_name is not None:
-                        self.t.active_metadata[table_name] = data
-                    else:
-                        self.t.active_metadata["Parquet"] = data
-                    self.t.unload_module('backend','Parquet','back-write')
+                elif file_extension.lower() in ['pq', 'parquet']:
+                    self.t.load_module('plugin', "Parquet", "reader", filenames = dbfile, table_name = table_name)
         except Exception as e:
             print(f"read ERROR: {e}\n")
             self.t.active_metadata = OrderedDict()

dsi/backends/tests/test_parquet.py

@@ -24,15 +24,15 @@ class Terminal():
     for more information.
     """
     BACKEND_PREFIX = ['dsi.backends']
-    BACKEND_IMPLEMENTATIONS = ['gufi', 'sqlite', 'parquet', 'duckdb', 'hpss']
+    BACKEND_IMPLEMENTATIONS = ['gufi', 'sqlite', 'duckdb', 'hpss']
     PLUGIN_PREFIX = ['dsi.plugins']
     PLUGIN_IMPLEMENTATIONS = ['env', 'file_reader', 'file_writer', 'collection_reader']
     VALID_ENV = ['Hostname', 'SystemKernel', 'GitInfo']
-    VALID_READERS = ['Bueno', 'Csv', 'YAML1', 'TOML1', 'Schema', 'JSON', 'MetadataReader1', 'Ensemble', 'Cloverleaf', 'Dict']
+    VALID_READERS = ['Bueno', 'Csv', 'YAML1', 'TOML1', 'Parquet', 'Schema', 'JSON', 'MetadataReader1', 'Ensemble', 'Cloverleaf', 'Dict']
     VALID_DATACARDS = ['Oceans11Datacard', 'DublinCoreDatacard', 'SchemaOrgDatacard', 'GoogleDatacard']
-    VALID_WRITERS = ['ER_Diagram', 'Table_Plot', 'Csv_Writer']
+    VALID_WRITERS = ['ER_Diagram', 'Table_Plot', 'Csv_Writer', 'Parquet_Writer']
     VALID_PLUGINS = VALID_ENV + VALID_READERS + VALID_WRITERS + VALID_DATACARDS
-    VALID_BACKENDS = ['Gufi', 'Sqlite', 'Parquet', 'DuckDB', 'SqlAlchemy', 'HPSS']
+    VALID_BACKENDS = ['Gufi', 'Sqlite', 'DuckDB', 'SqlAlchemy', 'HPSS']
     VALID_MODULES = VALID_PLUGINS + VALID_BACKENDS
     VALID_MODULE_FUNCTIONS = {'plugin': ['reader', 'writer'], 
                               'backend': ['back-read', 'back-write']}
@@ -503,13 +503,7 @@ def artifact_handler(self, interaction_type, query = None, **kwargs):
             self.logger.info(f"{first_backend.__class__.__name__} backend - {interaction_type.upper()} the data")
         start = datetime.now()
         if interaction_type in ['query', 'get']:
-            # Only used when reading data from Parquet backend in CLI API (Parquet uses query not process) - 
-            # TODO fix this passthrough by updating Parquet to use process_artifacts()
-            # TODO query all backends
-            if len(self.loaded_backends) > 1:
-                if parent_backend == "Filesystem" and ".temp.db" in first_backend.filename:
-                    first_backend = self.loaded_backends[1]
-                    parent_backend = first_backend.__class__.__bases__[0].__name__
+            # TODO query all backends together
             if self.valid_backend(first_backend, parent_backend):
                 if "query" in first_backend.query_artifacts.__code__.co_varnames:
                     self.logger.info(f"Query to get data: {query}")
@@ -1362,8 +1356,6 @@ def valid_backend(self, backend, parent_name):
                 valid = True
             if backend.__class__.__name__ == "DuckDB" and os.path.getsize(backend.filename) > 13000:
                 valid = True
-            if backend.__class__.__name__ == "Parquet" and os.path.getsize(backend.filename) > 100:
-                valid = True
         return valid
 
 

dsi/cli.py

@@ -117,6 +117,7 @@ def list_readers(self):
         print("\nValid Readers for `reader_name` in read():\n" + "-"*50)
         print("Collection           : Loads data from an Ordered Dict. If multiple tables, each table must be a nested OrderedDict.")
         print("CSV                  : Loads data from CSV files (one table per call)")
+        print("Parquet              : Loads data from Parquet - a columnar storage format for Apache Hadoop (one table per call)")
         print("YAML1                : Loads data from YAML files of a certain structure")
         print("TOML1                : Loads data from TOML files of a certain structure")
         print("JSON                 : Loads single-table data from JSON files")
@@ -139,6 +140,7 @@ def read(self, filenames, reader_name, table_name = None):
             The expected input type depends on the selected `reader_name`:
                 - "Collection"           → Ordered Dictionary of table(s)
                 - "CSV"                  → .csv
+                - "Parquet"              → .pq
                 - "YAML1"                → .yaml or .yml
                 - "TOML1"                → .toml
                 - "JSON"                 → .json
@@ -163,7 +165,7 @@ def read(self, filenames, reader_name, table_name = None):
 
             Required when using the `Collection` reader to load an Ordered Dictionary representing only one table.
             
-            Recommended when the input file contains a single table for the `CSV`, `JSON`, or `Ensemble` reader.
+            Recommended when the input file contains a single table for the `CSV`, `Parquet`, `JSON`, or `Ensemble` reader.
         """
         if isinstance(filenames, str) and not os.path.exists(filenames):
             sys.exit("read() ERROR: The input file must be a valid filepath. Please check again.")
@@ -234,6 +236,8 @@ def read(self, filenames, reader_name, table_name = None):
                         self.t.load_module('plugin', 'Bueno', 'reader', filenames=filenames)
                     elif reader_name.lower() == "csv":
                         self.t.load_module('plugin', 'Csv', 'reader', filenames=filenames, table_name=table_name)
+                    elif reader_name.lower() == "parquet":
+                        self.t.load_module('plugin', 'Parquet', 'reader', filenames=filenames, table_name=table_name)
                     elif reader_name.lower() == "yaml1":
                         self.t.load_module('plugin', 'YAML1', 'reader', filenames=filenames)
                     elif reader_name.lower() == "toml1":
@@ -257,7 +261,7 @@ def read(self, filenames, reader_name, table_name = None):
 
             if correct_reader == False:
                 print("read() ERROR: Please check your spelling of the 'reader_name' argument as it does not exist in DSI\n")
-                elg = "Collection, CSV, YAML1, TOML1, JSON, Ensemble, Cloverleaf, Bueno, DublinCoreDatacard, SchemaOrgDatacard"
+                elg = "Collection, CSV, Parquet, YAML1, TOML1, JSON, Ensemble, Cloverleaf, Bueno, DublinCoreDatacard, SchemaOrgDatacard"
                 sys.exit(f"Eligible readers are: {elg}, GoogleDatacard, Oceans11Datacard")
 
         table_keys = [k for k in self.t.new_tables if k not in ("dsi_relations", "dsi_units")]
@@ -672,6 +676,7 @@ def list_writers(self):
         print("ER_Diagram  : Creates a visual ER diagram image based on all tables in DSI.")
         print("Table_Plot  : Generates a plot of numerical data from a specified table.")
         print("Csv         : Exports the data of a specified table to a CSV file.")
+        print("Parquet     : Exports the data of a specified table to a Parquet file.")
         print()
 
     def write(self, filename, writer_name, table_name = None):
@@ -685,6 +690,7 @@ def write(self, filename, writer_name, table_name = None):
                 - "ER_Diagram"   → .png, .pdf, .jpg, .jpeg
                 - "Table_Plot"   → .png, .jpg, .jpeg
                 - "Csv"          → .csv
+                - "Parquet"      → .pq
 
         `writer_name` : str        
             Name of the DSI Writer to export data. 
@@ -695,7 +701,7 @@ def write(self, filename, writer_name, table_name = None):
             For guidance on creating a DSI-compatible Writer, view :ref:`custom_writer`.
 
         `table_name`: str, optional
-            Required when using "Table_Plot" or "Csv" to specify which table to export.
+            Required when using "Table_Plot", "Csv" or "Parquet" to specify which table to export.
         """
         if not self.t.valid_backend(self.main_backend_obj, self.main_backend_obj.__class__.__bases__[0].__name__):
             sys.exit("ERROR: Cannot write() data from an empty backend. Please ensure there is data in it.")
@@ -764,6 +770,8 @@ def write(self, filename, writer_name, table_name = None):
                         self.t.load_module('plugin', 'Table_Plot', 'writer', filename=filename, table_name = table_name)
                     elif writer_name.lower() in ["csv", "csv writer", "csv_writer"]:
                         self.t.load_module('plugin', 'Csv_Writer', 'writer', filename=filename, table_name = table_name)
+                    elif writer_name.lower() in ["parquet", "parquet writer", "parquet_writer"]:
+                        self.t.load_module('plugin', 'Parquet_Writer', 'writer', filename=filename, table_name = table_name)
                     else:
                         correct_writer = False
             except Exception as e:

dsi/core.py

@@ -9,6 +9,7 @@
 try: import tomllib
 except ModuleNotFoundError: import pip._vendor.tomli as tomllib
 import os
+from pyarrow import parquet as pq
 # import ast
 
 from dsi.plugins.metadata import StructuredMetadata
@@ -459,6 +460,52 @@ def add_rows(self) -> None:
 
         self.set_schema_2(self.toml_data)
 
+class Parquet(FileReader):
+    """
+    DSI Reader that loads data stored in a Parquet file as a table. Users can choose to specify the table name upon reading too.
+    """
+    def __init__(self, filenames, table_name = None, **kwargs):
+        """
+        Initializes the Parquet Reader with user specified filenames and an optional table_name.
+
+        `filenames` : str or list of str
+            Required. One or more Parquet file paths to be loaded into DSI.
+            If multiple files are provided, all data must correspond to the same table.
+
+        `table_name` : str, optional
+            Optional name to assign to the loaded table.
+            If not provided, DSI will default to using "Parquet" as the table name.
+        """
+        super().__init__(filenames, **kwargs)
+        self.parquet_data = OrderedDict()
+        if isinstance(filenames, str):
+            self.filenames = [filenames]
+        else:
+            self.filenames = filenames
+        self.table_name = table_name
+    
+    def add_rows(self) -> None:
+        """Parses Parquet data and stores data into a table as an Ordered Dictionary."""
+        total_df = DataFrame()
+        
+        for filename in self.filenames:
+            table = pq.read_table(filename).to_pandas()
+            try:
+                total_df = concat([total_df, table], axis=0, ignore_index=True)
+            except:
+                raise TypeError(f"Error in adding {filename} to the existing Parquet data. Please recheck column names and data structure")
+
+        table_data = OrderedDict(total_df.to_dict(orient='list'))
+        for col, coldata in table_data.items():  # replace NaNs with None
+            table_data[col] = [None if type(item) == float and isnan(item) else item for item in coldata]
+
+        if self.table_name is not None:
+            self.parquet_data[self.table_name] = table_data
+        else:
+            self.parquet_data = table_data
+        
+        self.set_schema_2(self.parquet_data)
+        
 class Ensemble(FileReader):
     """
     DSI Reader that loads ensemble simulation data stored in a CSV file.