fix deadlock handling

lib-sql/indices.sql

@@ -31,6 +31,7 @@ CREATE INDEX IF NOT EXISTS idx_placex_geometry ON placex
 -- Index is needed during import but can be dropped as soon as a full
 -- geometry index is in place. The partial index is almost as big as the full
 -- index.
+---
 DROP INDEX IF EXISTS idx_placex_geometry_lower_rank_ways;
 ---
 CREATE INDEX IF NOT EXISTS idx_placex_geometry_reverse_lookupPolygon
@@ -60,7 +61,6 @@ CREATE INDEX IF NOT EXISTS idx_postcode_postcode
 ---
   DROP INDEX IF EXISTS idx_placex_geometry_address_area_candidates;
   DROP INDEX IF EXISTS idx_placex_geometry_buildings;
-  DROP INDEX IF EXISTS idx_placex_geometry_lower_rank_ways;
   DROP INDEX IF EXISTS idx_placex_wikidata;
   DROP INDEX IF EXISTS idx_placex_rank_address_sector;
   DROP INDEX IF EXISTS idx_placex_rank_boundaries_sector;

src/nominatim_db/db/query_pool.py

@@ -21,6 +21,8 @@
 class QueryPool:
     """ Pool to run SQL queries in parallel asynchronous execution.
 
+        All queries are run in autocommit mode. If parallel execution leads
+        to a deadlock, then the query is repeated.
         The results of the queries is discarded.
     """
     def __init__(self, dsn: str, pool_size: int = 1, **conn_args: Any) -> None:
@@ -50,8 +52,14 @@ async def finish(self) -> None:
         await asyncio.wait(self.pool)
         self.wait_time += time.time() - tstart
 
+        for task in self.pool:
+            excp = task.exception()
+            if excp is not None:
+                raise excp
+
 
     async def _worker_loop(self, dsn: str, **conn_args: Any) -> None:
+        conn_args['autocommit'] = True
         aconn = await psycopg.AsyncConnection.connect(dsn, **conn_args)
         async with aconn:
             async with aconn.cursor() as cur: