add DuckDB explorer: creates views over S3 parquets for local querying

prepara_gui.py

@@ -0,0 +1,62 @@
+import os
+import duckdb
+import boto3
+from dotenv import load_dotenv
+
+load_dotenv()
+
+S3_ENDPOINT = os.environ["HETZNER_S3_ENDPOINT"]          # https://hel1.your-objectstorage.com
+S3_BUCKET   = os.environ["HETZNER_S3_BUCKET"]            # baseldosdados
+ACCESS_KEY  = os.environ["AWS_ACCESS_KEY_ID"]
+SECRET_KEY  = os.environ["AWS_SECRET_ACCESS_KEY"]
+
+# Strip protocol for DuckDB httpfs (expects bare hostname)
+s3_host = S3_ENDPOINT.removeprefix("https://").removeprefix("http://")
+
+con = duckdb.connect('basedosdados.duckdb')
+
+con.execute("INSTALL httpfs; LOAD httpfs;")
+con.execute(f"""
+    CREATE OR REPLACE PERSISTENT SECRET hetzner (
+        TYPE S3,
+        KEY_ID '{ACCESS_KEY}',
+        SECRET '{SECRET_KEY}',
+        ENDPOINT '{s3_host}',
+        URL_STYLE 'path'
+    );
+""")
+
+# List all dataset/table prefixes in the bucket
+s3 = boto3.client(
+    's3',
+    endpoint_url=S3_ENDPOINT,
+    aws_access_key_id=ACCESS_KEY,
+    aws_secret_access_key=SECRET_KEY,
+)
+paginator = s3.get_paginator('list_objects_v2')
+
+datasets = {}
+for page in paginator.paginate(Bucket=S3_BUCKET, Delimiter='/'):
+    for prefix in page.get('CommonPrefixes', []):
+        dataset = prefix['Prefix'].rstrip('/')
+        datasets[dataset] = []
+        for page2 in paginator.paginate(Bucket=S3_BUCKET,
+                                        Prefix=dataset + '/',
+                                        Delimiter='/'):
+            for p in page2.get('CommonPrefixes', []):
+                table = p['Prefix'].rstrip('/').split('/')[-1]
+                datasets[dataset].append(table)
+
+# Create schemas and views
+for dataset, tables in datasets.items():
+    con.execute(f"CREATE SCHEMA IF NOT EXISTS {dataset}")
+    for table in tables:
+        path = f"s3://{S3_BUCKET}/{dataset}/{table}/*.parquet"
+        con.execute(f"""
+            CREATE OR REPLACE VIEW {dataset}.{table} AS
+            SELECT * FROM '{path}'
+        """)
+        print(f"✓ {dataset}.{table}")
+
+con.close()
+print("Done! Open with: duckdb --ui basedosdados.duckdb")