fix connection drain

Signed-off-by: Aykut Bozkurt <aykut.bozkurt@snowflake.com>

Author: sfc-gh-abozkurt

pg_lake_spatial/tests/pytests/test_gdal.py

@@ -203,11 +203,7 @@ def test_gdal_zip_gml(
     # Querying is currently not supported because WKB is converted by DuckDB
     # Error messages reflect different DuckDB spatial versions
     error = run_query("SELECT shape FROM test_gdal.fdw", user_conn, raise_error=False)
-    assert (
-        "Geometry type 10 not supported" in error
-        or "'MULTICURVE' is not supported" in error
-        or "Unsupported geometry type in WKB" in error
-    )
+    assert "Unsupported geometry type in WKB" in error
 
     user_conn.rollback()
 

pg_lake_table/src/fdw/pg_lake_table.c

@@ -3394,6 +3394,19 @@ fetch_more_data(ForeignScanState *node)
 				fsstate->eof_reached = true;
 			else if (PQresultStatus(res) != PGRES_SINGLE_TUPLE)
 			{
+				/*
+				 * Drain remaining results so the connection processes
+				 * ReadyForQuery and reaches idle state before the error
+				 * unwinds the stack.  Without this, transaction abort cleanup
+				 * sees a busy connection and reports a spurious "lost
+				 * connection to query engine" error.
+				 */
+				PGresult   *remaining = WaitForLastResult(fsstate->conn);
+
+				if (remaining != NULL)
+					PQclear(remaining);
+				fsstate->eof_reached = true;
+
 				ThrowIfPGDuckResultHasError(fsstate->conn, res);
 			}
 		}