fix python tests back (they always call prepare)

c/driver/postgresql/statement.cc

@@ -1167,12 +1167,14 @@ AdbcStatusCode PostgresStatement::ExecuteQuery(struct ArrowArrayStream* stream,
     return ExecuteBind(stream, rows_affected, error);
   }
 
-  // If we have been requested to prepare the query but there are no parameters to bind,
-  // use the PqResultArrayReader to handle the execution of the query. We don't currently
-  // issue an explicit PGprepare(); however, this is the path we would need to take when
-  // we do implement this (because preparing a query that includes COPY is not supported).
-  // Also take this path if no output is requested (e.g., a CREATE or UPDATE).
-  if (!stream || prepared_) {
+  // Check if we have been explicitly requested to avoid COPY
+  // (make less of a hack before merging)
+  size_t use_copy = 0;
+  GetOption(ADBC_POSTGRESQL_OPTION_USE_COPY, nullptr, &use_copy, nullptr);
+
+  // If we have been requested to avoid COPY or there is no output requested,
+  // execute using the PqResultArrayReader.
+  if (!stream || !use_copy) {
     PqResultArrayReader reader(connection_->conn(), type_resolver_, query_);
     RAISE_ADBC(reader.ToArrayStream(rows_affected, stream, error));
     return ADBC_STATUS_OK;

c/driver/postgresql/statement.h

@@ -33,6 +33,9 @@
 #define ADBC_POSTGRESQL_OPTION_BATCH_SIZE_HINT_BYTES \
   "adbc.postgresql.batch_size_hint_bytes"
 
+#define ADBC_POSTGRESQL_OPTION_USE_COPY \
+  "adbc.postgresql.batch_size_hint_bytes"
+
 namespace adbcpq {
 class PostgresConnection;
 class PostgresStatement;

python/adbc_driver_postgresql/tests/test_dbapi.py

@@ -148,7 +148,7 @@ def test_query_execute_schema(postgres: dbapi.Connection) -> None:
 def test_query_invalid(postgres: dbapi.Connection) -> None:
     with postgres.cursor() as cur:
         with pytest.raises(
-            postgres.ProgrammingError, match="Failed to execute query"
+            postgres.ProgrammingError, match="Failed to prepare query"
         ) as excinfo:
             cur.execute("SELECT * FROM tabledoesnotexist")