add an initial mini tutorial

mini_tutorial.py

@@ -0,0 +1,71 @@
+from uc_wrapper import UCClient, FileType, TableType, WriteMode, SchemaEvolution
+import polars as pl
+import os
+
+TUTORIAL_DIR = "/home/codespace/tutorial"
+
+# Create a csv-file to start with.
+df = pl.DataFrame(
+    {
+        "id": [0, 1, 2, 3],
+        "filter_col": [True, True, False, False],
+        "float_col": [1.1, 2.2, 3.3, 4.4],
+    }
+)
+df.write_csv(file=os.path.join(TUTORIAL_DIR, "data.csv"))
+
+# All interaction with Unity Catalog is done through a `UCClient` object.
+client = UCClient()
+
+# We can register the csv-file we created as the table unity.default.csv_table in Unity Catalog
+# with `register_as_table`.
+client.register_as_table(
+    filepath=os.path.join(TUTORIAL_DIR, "data.csv"),
+    catalog="unity",
+    schema="default",
+    name="csv_table",
+    file_type=FileType.CSV,
+)
+
+# Now we can read the created table in as a dataframe.
+df_read = client.read_table(catalog="unity", schema="default", name="csv_table")
+print(df_read)
+
+# Let's then filter the dataframe by filter_col and write the resulting dataframe to a
+# Delta table and register it to Unity Catalog with `create_as_table`. We'll name it
+# unity.default.filtered_delta_table
+df_filtered = df_read.filter(pl.col("filter_col") == True)
+print(df_filtered)
+client.create_as_table(
+    df=df_filtered,
+    catalog="unity",
+    schema="default",
+    name="filtered_delta_table",
+    file_type=FileType.DELTA,
+    table_type=TableType.EXTERNAL,
+    location="file://" + os.path.join(TUTORIAL_DIR, "delta_dir"),
+)
+
+# Let's read back the table to make sure we wrote what we wanted to the Delta table.
+df_read = client.read_table(
+    catalog="unity", schema="default", name="filtered_delta_table"
+)
+print(df_read)
+
+
+# We can write more data to the table with `write_table`. Let's append the entire original
+# dataframe `df` to the Delta table we created.
+client.write_table(
+    df=df,
+    catalog="unity",
+    schema="default",
+    name="filtered_delta_table",
+    mode=WriteMode.APPEND,
+    schema_evolution=SchemaEvolution.STRICT,
+)
+
+# Now let's just verify we actually wrote more data to the Delta table.
+df_read = client.read_table(
+    catalog="unity", schema="default", name="filtered_delta_table"
+)
+print(df_read)