enhance: add bitmap index example

Signed-off-by: luzhang <luzhang@zilliz.com>

examples/orm/bitmap_index_example.py

@@ -0,0 +1,52 @@
+from pymilvus import (
+    connections,
+    FieldSchema, CollectionSchema, DataType,
+    Collection,
+)
+
+DIMENSION = 8
+COLLECTION_NAME = "books"
+connections.connect("default", host="localhost", port="19530")
+
+fields = [
+    FieldSchema(name='id', dtype=DataType.INT64, is_primary=True),
+    FieldSchema(name='title', dtype=DataType.VARCHAR, max_length=200),
+    FieldSchema(name='type', dtype=DataType.VARCHAR, max_length=200),
+    FieldSchema(name='embeddings', dtype=DataType.FLOAT_VECTOR, dim=DIMENSION),
+]
+schema = CollectionSchema(fields=fields, enable_dynamic_field=True)
+collection = Collection(name=COLLECTION_NAME, schema=schema)
+
+data_rows = [
+    {
+        "id": 1,
+        "title": "Lord of the Flies",
+        "type": "novel",
+        "embeddings": [0.64, 0.44, 0.13, 0.47, 0.74, 0.03, 0.32, 0.6],
+    },
+    {
+        "id": 2,
+        "title": "Chinese-English dictionary",
+        "type": "reference",
+        "embeddings": [0.9, 0.45, 0.18, 0.43, 0.4, 0.4, 0.7, 0.24],
+    },
+    {
+        "id": 3,
+        "title": "My Childhood",
+        "type": "autobiographical", 
+        "embeddings": [0.43, 0.57, 0.43, 0.88, 0.84, 0.69, 0.27, 0.98],
+    },
+]
+
+collection.insert(data_rows)
+collection.create_index(
+    "embeddings", {"index_type": "FLAT", "metric_type": "L2"})
+
+# create bitmap index for scalar fields.
+collection.create_index(
+    "type", {"index_type": "BITMAP"})
+
+collection.load()
+
+res = collection.query(expr='type in ["reference"]', output_fields=["id", "type"])
+print(res)