feat: add elo tables for house ranking

data_platform/assets/elo/elo.py

@@ -0,0 +1,77 @@
+"""ELO schema and table management assets.
+
+Individual assets for the stateful ELO tables (ratings, comparisons) used
+by the house-elo-ranking application.  The sample_listings table is
+managed as a dbt model in marts.
+"""
+
+from pathlib import Path
+
+from dagster import AssetExecutionContext, MaterializeResult, MetadataValue, asset
+from sqlalchemy import text
+
+from data_platform.helpers import render_sql
+from data_platform.resources import PostgresResource
+
+_SQL_DIR = Path(__file__).parent / "sql"
+_SCHEMA = "elo"
+
+
+def _ensure_schema(conn: object) -> None:
+    """Create the ELO schema if it does not exist."""
+    schema_sql = render_sql(_SQL_DIR, "create_schema.sql", schema=_SCHEMA)
+    conn.execute(text(schema_sql))
+
+
+@asset(
+    deps=["elo_sample_listings"],
+    group_name="elo",
+    description="Creates the ELO ratings table that stores per-listing ELO scores.",
+)
+def elo_ratings(
+    context: AssetExecutionContext,
+    postgres: PostgresResource,
+) -> MaterializeResult:
+    """Ensure the ELO ratings table exists (idempotent)."""
+    table_sql = render_sql(_SQL_DIR, "create_ratings_table.sql", schema=_SCHEMA)
+
+    engine = postgres.get_engine()
+    with engine.begin() as conn:
+        _ensure_schema(conn)
+        conn.execute(text(table_sql))
+
+    context.log.info("ELO ratings table ensured.")
+
+    return MaterializeResult(
+        metadata={
+            "schema": MetadataValue.text(_SCHEMA),
+            "table": MetadataValue.text("ratings"),
+        }
+    )
+
+
+@asset(
+    deps=["elo_sample_listings"],
+    group_name="elo",
+    description="Creates the ELO comparisons table that records pairwise match results.",
+)
+def elo_comparisons(
+    context: AssetExecutionContext,
+    postgres: PostgresResource,
+) -> MaterializeResult:
+    """Ensure the ELO comparisons table exists (idempotent)."""
+    table_sql = render_sql(_SQL_DIR, "create_comparisons_table.sql", schema=_SCHEMA)
+
+    engine = postgres.get_engine()
+    with engine.begin() as conn:
+        _ensure_schema(conn)
+        conn.execute(text(table_sql))
+
+    context.log.info("ELO comparisons table ensured.")
+
+    return MaterializeResult(
+        metadata={
+            "schema": MetadataValue.text(_SCHEMA),
+            "table": MetadataValue.text("comparisons"),
+        }
+    )