The default character for Variable Substitution clashes with a common PostgreSQL idiom

[Eduardo Bellani]

It is possible to nest dollar-quoted string constants by choosing different tags at each nesting level. This is most commonly used in writing function definitions. For example:

$function$
BEGIN
    RETURN ($1 ~ $q$[\t\r\n\v\\]$q$);
END;
$function$

source

Create or replace FUNCTION fff(p1 int)
  returns void
  LANGUAGE  plpgsql
AS
$$ --<< outer level quote
DECLARE
 v_Qry  VARCHAR(4000);
BEGIN
  v_Qry := format(
$string$ --<< quote for the string constant passed to the format function
    Create or replace FUNCTION fff_DYNAMIC_SQL()
       returns void
       LANGUAGE  plpgsql
    AS 
    $f1$ --<< quoting inside the actual function body
    DECLARE
      v1  INTEGER;
    begin
      v1 := %s;
      RETURN;
    END; 
    $f1$
$string$, p1);
  EXECUTE v_Qry;
  RETURN;
END; 
$$;

source

[David Welch]

The following snippet demonstrates turning off the variable substitution altogether...

      var builder =
          DeployChanges.To
              .PostgresqlDatabase(connectionString)
              .WithScriptsEmbeddedInAssembly(Assembly ?? AppInfo.AppAssembly)
              .JournalToPostgresqlTable("public", "versionTable");

      // This line should substitute an instance of the ScriptExecutor that doesn't do variable substitution
      builder.Configure(c => c.ScriptExecutor = new PostgresqlScriptExecutor(() => c.ConnectionManager, () => c.Log, null, () => false, c.ScriptPreprocessors, () => c.Journal));
      var upgrader = builder.Build();