add --throttle option for batch mode pauses

The --throttle option adds a pause between queries in batch mode, which
can be useful for long or intensive scripts.

Technically we pause between each line of input, which is usually
equivalent to one query.

Author: rolandwalker

changelog.md

@@ -4,6 +4,7 @@ Upcoming (TBD)
 Features
 --------
 * Add a `--checkpoint=` argument to log successful queries in batch mode.
+* Add `--throttle` option for batch mode.
 
 
 Bug Fixes

mycli/main.py

@@ -19,7 +19,7 @@
 from importlib import resources
 import itertools
 from random import choice
-from time import time
+from time import sleep, time
 from urllib.parse import parse_qs, unquote, urlparse
 
 from cli_helpers.tabular_output import TabularOutputFormatter, preprocessors
@@ -1548,6 +1548,7 @@ def get_last_query(self) -> str | None:
 @click.option(
     '--format', 'batch_format', type=click.Choice(['default', 'csv', 'tsv', 'table']), help='Format for batch or --execute output.'
 )
+@click.option('--throttle', type=float, default=0.0, help='Pause in seconds between queries in batch mode.')
 @click.pass_context
 def cli(
     ctx: click.Context,
@@ -1599,6 +1600,7 @@ def cli(
     password_file: str | None,
     noninteractive: bool,
     batch_format: str | None,
+    throttle: float,
 ) -> None:
     """A MySQL terminal client with auto-completion and syntax highlighting.
 
@@ -1931,6 +1933,8 @@ def cli(
                     sys.exit(1)
             try:
                 if warn_confirmed:
+                    if throttle and counter > 1:
+                        sleep(throttle)
                     mycli.run_query(stdin_text, checkpoint=checkpoint, new_line=True)
             except Exception as e:
                 click.secho(str(e), err=True, fg="red")