Johan review

db_async.py

@@ -7,6 +7,7 @@ import os
 import sqlalchemy
 from databases import Database
 from sqlalchemy import MetaData, Table, Column, Integer, String, Float, DateTime, text
+from sqlalchemy import Index
 
 # Environment: Postgres/TimescaleDB connection URL
 DATABASE_URL = os.getenv("DATABASE_URL", "postgresql://postgres:password@localhost:5432/dereth")
@@ -43,6 +44,12 @@ telemetry_events = Table(
     Column("mem_handles", Integer, nullable=True),
     Column("latency_ms", Float, nullable=True),
 )
+# Composite index to accelerate Grafana queries filtering by character_name then ordering by timestamp
+Index(
+    'ix_telemetry_events_char_ts',
+    telemetry_events.c.character_name,
+    telemetry_events.c.timestamp
+)
 
 # Table for persistent total kills per character
 char_stats = Table(
@@ -108,26 +115,41 @@ async def init_db_async():
     engine = sqlalchemy.create_engine(DATABASE_URL)
     # Reflects metadata definitions into actual database tables via SQLAlchemy
     metadata.create_all(engine)
-    # Enable TimescaleDB extension and convert telemetry_events to hypertable
-    # Use a transactional context to ensure DDL statements are committed
-    with engine.begin() as conn:
-        # Enable or update TimescaleDB extension
-        # Install or confirm TimescaleDB extension to support hypertables
-        try:
-            conn.execute(text("CREATE EXTENSION IF NOT EXISTS timescaledb"))
-        except Exception as e:
-            print(f"Warning: failed to create extension timescaledb: {e}")
-        # Update TimescaleDB extension if an older version exists
-        try:
-            conn.execute(text("ALTER EXTENSION timescaledb UPDATE"))
-        except Exception as e:
-            print(f"Warning: failed to update timescaledb extension: {e}")
-        # Create hypertable for telemetry_events, skip default indexes to avoid collisions
-        # Transform telemetry_events into a hypertable partitioned by timestamp
-        try:
+    # Ensure TimescaleDB extension is installed and telemetry_events is a hypertable
+    # Run DDL in autocommit mode so errors don't abort subsequent statements
+    try:
+        with engine.connect().execution_options(isolation_level="AUTOCOMMIT") as conn:
+            # Install extension if missing
+            try:
+                conn.execute(text("CREATE EXTENSION IF NOT EXISTS timescaledb"))
+            except Exception as e:
+                print(f"Warning: failed to create extension timescaledb: {e}")
+            # Convert to hypertable, migrating existing data and skipping default index creation
+            try:
+                conn.execute(text(
+                    "SELECT create_hypertable('telemetry_events', 'timestamp', "
+                    "if_not_exists => true, migrate_data => true, create_default_indexes => false)"
+                ))
+            except Exception as e:
+                print(f"Warning: failed to create hypertable telemetry_events: {e}")
+    except Exception as e:
+        print(f"Warning: timescale extension/hypertable setup failed: {e}")
+    # Ensure composite index exists for efficient time-series queries by character
+    try:
+        with engine.connect() as conn:
             conn.execute(text(
-                "SELECT create_hypertable('telemetry_events', 'timestamp', \
-                 if_not_exists => true, create_default_indexes => false)"
+                "CREATE INDEX IF NOT EXISTS ix_telemetry_events_char_ts "
+                "ON telemetry_events (character_name, timestamp)"
             ))
-        except Exception as e:
-            print(f"Warning: failed to create hypertable telemetry_events: {e}")
+    except Exception as e:
+        print(f"Warning: failed to create composite index ix_telemetry_events_char_ts: {e}")
+    # Disable parallel workers at the system level to avoid OOMs from large parallel scans
+    try:
+        # Apply settings outside transaction for ALTER SYSTEM
+        conn2 = engine.connect().execution_options(isolation_level="AUTOCOMMIT")
+        conn2.execute(text("ALTER SYSTEM SET max_parallel_workers_per_gather = 0"))
+        conn2.execute(text("ALTER SYSTEM SET max_parallel_workers = 0"))
+        conn2.execute(text("SELECT pg_reload_conf()"))
+        conn2.close()
+    except Exception as e:
+        print(f"Warning: failed to disable parallel workers: {e}")