prefix_search.py
"""
Prefix Search: Help Center with search-as-you-type
===================================================
Real-world use case: A help center where users search for articles
while typing, getting instant results for partial words.
Example: User types "auth" and immediately sees articles about
"authentication", "authorization", "authenticator app", etc.
Without prefix_match: User must type complete words to get matches.
With prefix_match=True: Partial words match, enabling typeahead search.
"""
from agno.knowledge.document import Document
from agno.knowledge.embedder.openai import OpenAIEmbedder
from agno.vectordb.pgvector import PgVector
from agno.vectordb.search import SearchType
# ---------------------------------------------------------------------------
# Setup: Help Center knowledge base with prefix matching
# ---------------------------------------------------------------------------
db_url = "postgresql+psycopg://ai:ai@localhost:5532/ai"
# Help center with prefix search enabled for typeahead
help_center = PgVector(
table_name="help_center_articles",
db_url=db_url,
search_type=SearchType.hybrid,
prefix_match=True, # enables search-as-you-type
embedder=OpenAIEmbedder(id="text-embedding-3-small"),
)
# Same database without prefix matching (for comparison)
help_center_standard = PgVector(
table_name="help_center_articles",
db_url=db_url,
search_type=SearchType.hybrid,
prefix_match=False, # default - exact word match only
embedder=OpenAIEmbedder(id="text-embedding-3-small"),
)
# ---------------------------------------------------------------------------
# Sample help articles
# ---------------------------------------------------------------------------
help_articles = [
Document(
name="auth-setup",
content="Setting up authentication: Configure two-factor authentication (2FA) "
"using an authenticator app like Google Authenticator or Authy.",
),
Document(
name="auth-troubleshoot",
content="Authentication troubleshooting: Common issues with login, "
"password reset, and authentication token expiration.",
),
Document(
name="authorization",
content="Authorization and permissions: How to configure role-based access "
"control (RBAC) and manage user authorization levels.",
),
Document(
name="api-keys",
content="API key management: Generate, rotate, and revoke API keys "
"for programmatic access to your account.",
),
Document(
name="billing",
content="Billing and payments: Update payment methods, view invoices, "
"and manage your subscription plan.",
),
]
# ---------------------------------------------------------------------------
# Demo: Simulate user typing "auth" in search box
# ---------------------------------------------------------------------------
if __name__ == "__main__":
# Setup
help_center.create()
help_center.upsert(documents=help_articles, content_hash="v1")
print("=" * 60)
print("Help Center Search Demo")
print("=" * 60)
# Simulate user typing progressively
search_queries = ["au", "auth", "authent"]
for query in search_queries:
print(f"\nUser types: '{query}'")
print("-" * 40)
# Without prefix matching
print("Standard search (prefix_match=False):")
results = help_center_standard.search(query, limit=2)
for doc in results:
score = doc.meta_data.get("similarity_score", 0)
print(f" [{score:.2f}] {doc.name}: {doc.content[:40]}...")
# With prefix matching
print("\nTypeahead search (prefix_match=True):")
results = help_center.search(query, limit=2)
for doc in results:
score = doc.meta_data.get("similarity_score", 0)
print(f" [{score:.2f}] {doc.name}: {doc.content[:40]}...")
print("\n" + "=" * 60)
print("prefix_match=True finds 'authentication' when user types 'auth'")
print("=" * 60)
Run the Example
1
Set up your virtual environment
uv venv --python 3.12
source .venv/bin/activate
uv venv --python 3.12
.venv\Scripts\activate
2
Install dependencies
uv pip install -U agno openai pgvector psycopg-binary sqlalchemy
3
Run PgVector
docker run -d \
-e POSTGRES_DB=ai \
-e POSTGRES_USER=ai \
-e POSTGRES_PASSWORD=ai \
-e PGDATA=/var/lib/postgresql/data/pgdata \
-v pgvolume:/var/lib/postgresql/data \
-p 5532:5432 \
--name pgvector \
agnohq/pgvector:18
4
Run the example
Save the code above as
prefix_search.py, then run:python prefix_search.py