Add --unbuffered mode

changelog.md

@@ -1,6 +1,11 @@
 TBD
 ==============
 
+Features
+--------
+* Add `--unbuffered` mode which fetches rows as needed, to save memory.
+
+
 Bug Fixes
 --------
 * Fix CamelCase fuzzy matching.

mycli/main.py

@@ -477,6 +477,7 @@ def connect(
         ssh_password: str | None = "",
         ssh_key_filename: str | None = "",
         init_command: str | None = "",
+        unbuffered: bool | None = None,
         password_file: str | None = "",
     ) -> None:
         cnf = {
@@ -563,6 +564,7 @@ def _connect() -> None:
                     ssh_password,
                     ssh_key_filename,
                     init_command,
+                    unbuffered,
                 )
             except pymysql.OperationalError as e1:
                 if e1.args[0] == HANDSHAKE_ERROR and ssl is not None and ssl.get("mode", None) == "auto":
@@ -583,6 +585,7 @@ def _connect() -> None:
                             ssh_password,
                             ssh_key_filename,
                             init_command,
+                            unbuffered,
                         )
                     except Exception as e2:
                         raise e2
@@ -1521,6 +1524,9 @@ def get_last_query(self) -> str | None:
 @click.option("-g", "--login-path", type=str, help="Read this path from the login file.")
 @click.option("-e", "--execute", type=str, help="Execute command and quit.")
 @click.option("--init-command", type=str, help="SQL statement to execute after connecting.")
+@click.option(
+    "--unbuffered", is_flag=True, help="Instead of copying every row of data into a buffer, fetch rows as needed, to save memory."
+)
 @click.option("--charset", type=str, help="Character set for MySQL session.")
 @click.option(
     "--password-file", type=click.Path(), help="File or FIFO path containing the password to connect to the db if not specified otherwise."
@@ -1570,6 +1576,7 @@ def cli(
     ssh_config_path: str,
     ssh_config_host: str | None,
     init_command: str | None,
+    unbuffered: bool | None,
     charset: str | None,
     password_file: str | None,
 ) -> None:
@@ -1807,6 +1814,7 @@ def cli(
         ssh_password=ssh_password,
         ssh_key_filename=ssh_key_filename,
         init_command=combined_init_cmd,
+        unbuffered=unbuffered,
         charset=charset,
         password_file=password_file,
     )

mycli/sqlexecute.py

@@ -162,6 +162,7 @@ def __init__(
         ssh_password: str | None,
         ssh_key_filename: str | None,
         init_command: str | None = None,
+        unbuffered: bool | None = None,
     ) -> None:
         self.dbname = database
         self.user = user
@@ -180,6 +181,7 @@ def __init__(
         self.ssh_password = ssh_password
         self.ssh_key_filename = ssh_key_filename
         self.init_command = init_command
+        self.unbuffered = unbuffered
         self.conn: Connection | None = None
         self.connect()
 
@@ -200,6 +202,7 @@ def connect(
         ssh_password: str | None = None,
         ssh_key_filename: str | None = None,
         init_command: str | None = None,
+        unbuffered: bool | None = None,
     ):
         db = database if database is not None else self.dbname
         user = user if user is not None else self.user
@@ -216,6 +219,7 @@ def connect(
         ssh_password = ssh_password if ssh_password is not None else self.ssh_password
         ssh_key_filename = ssh_key_filename if ssh_key_filename is not None else self.ssh_key_filename
         init_command = init_command if init_command is not None else self.init_command
+        unbuffered = unbuffered if unbuffered is not None else self.unbuffered
         _logger.debug(
             "Connection DB Params: \n"
             "\tdatabase: %r"
@@ -231,7 +235,8 @@ def connect(
             "\tssh_port: %r"
             "\tssh_password: %r"
             "\tssh_key_filename: %r"
-            "\tinit_command: %r",
+            "\tinit_command: %r"
+            "\tunbuffered: %r",
             db,
             user,
             host,
@@ -246,6 +251,7 @@ def connect(
             ssh_password,
             ssh_key_filename,
             init_command,
+            unbuffered,
         )
         conv = conversions.copy()
         conv.update({
@@ -285,6 +291,7 @@ def connect(
             program_name="mycli",
             defer_connect=defer_connect,
             init_command=init_command or None,
+            cursorclass=pymysql.cursors.SSCursor if unbuffered else pymysql.cursors.Cursor,
         )  # type: ignore[misc]
 
         if ssh_host:
@@ -324,6 +331,7 @@ def connect(
         self.charset = charset
         self.ssl = ssl
         self.init_command = init_command
+        self.unbuffered = unbuffered
         # retrieve connection id
         self.reset_connection_id()
         self.server_info = ServerInfo.from_version_string(conn.server_version)  # type: ignore[attr-defined]