Test with MyISAM tables. Add PXC section to pt-archiver docs.

t/pt-archiver/samples/table14.sql

@@ -0,0 +1,25 @@
+use test;
+
+drop table if exists table_1;
+drop table if exists table_2;
+
+create table table_1(
+   a int not null primary key,
+   b int,
+   c int not null,
+   d varchar(50),
+   key(b)
+) engine=myisam;
+
+create table table_2(
+   a int not null primary key auto_increment,
+   b int,
+   c int not null,
+   d varchar(50)
+) engine=myisam;
+
+insert into table_1 values
+   (1, 2,    3, 4),
+   (2, null, 3, 4),
+   (3, 2,    3, "\t"),
+   (4, 2,    3, "\n");