Add config option to always run with a single connection (#1386)

Co-authored-by: Irina Truong <i.chernyavska@gmail.com>

changelog.rst

@@ -12,6 +12,7 @@ Features:
   Also prevents getting stuck in a retry loop.
 * Config option to not restart connection when cancelling a `destructive_warning` query. By default,
   it will now not restart.
+* Config option to always run with a single connection.
 
 Bug fixes:
 ----------

pgcli/main.py

@@ -264,6 +264,9 @@ class PGCli:
         # Initialize completer
         smart_completion = c["main"].as_bool("smart_completion")
         keyword_casing = c["main"]["keyword_casing"]
+        single_connection = single_connection or c["main"].as_bool(
+            "always_use_single_connection"
+        )
         self.settings = {
             "casing_file": get_casing_file(c),
             "generate_casing_file": c["main"].as_bool("generate_casing_file"),

pgcli/pgclirc

@@ -9,6 +9,10 @@ smart_completion = True
 # visible.)
 wider_completion_menu = False
 
+# Do not create new connections for refreshing completions; Equivalent to
+# always running with the --single-connection flag.
+always_use_single_connection = False
+
 # Multi-line mode allows breaking up the sql statements into multiple lines. If
 # this is set to True, then the end of the statements must have a semi-colon.
 # If this is set to False then sql statements can't be split into multiple