Minor changes from self review

Signed-off-by: Matt Lord <mattalord@gmail.com>

Author: mattlord

go/test/endtoend/vreplication/config_test.go

@@ -45,7 +45,8 @@ import (
 // default collation as it has to work across versions and the 8.0 default does not exist in 5.7.
 var (
 	// All standard user tables should have a primary key and at least one secondary key.
-	customerTypes         = []string{"'individual'", "'soho'", "'enterprise'"}
+	customerTypes = []string{"'individual'", "'soho'", "'enterprise'"}
+	// We use utf8mb4_general_ci so that we can test with 5.7 and 8.0+.
 	customerTableTemplate = `create table customer(cid int auto_increment, name varchar(128) collate utf8mb4_general_ci, meta json default null,
   industryCategory varchar(100) generated always as (json_extract(meta, _utf8mb4'$.industry')) virtual, typ enum(%s),
   sport set('football','cricket','baseball'), ts timestamp not null default current_timestamp, bits bit(2) default b'11', date1 datetime not null default '0000-00-00 00:00:00',

go/vt/vttablet/tabletserver/vstreamer/rowstreamer.go

@@ -286,7 +286,7 @@ func (rs *rowStreamer) buildSelect(st *binlogdatapb.MinimalTable) (string, error
 		indexHint = fmt.Sprintf(" force index (%s)", escapedPKIndexName)
 	}
 	buf.Myprintf(" from %v%s", sqlparser.NewIdentifierCS(rs.plan.Table.Name), indexHint)
-	if len(rs.lastpk) != 0 { // We're in the copy phase and need to resume
+	if len(rs.lastpk) != 0 { // We're in Nth copy phase cycle and need to resume
 		if len(rs.lastpk) != len(rs.pkColumns) {
 			return "", fmt.Errorf("cannot build a row streamer plan for the %s table as a lastpk value was provided and the number of primary key values within it (%v) does not match the number of primary key columns in the table (%d)",
 				st.Name, rs.lastpk, rs.pkColumns)
@@ -310,14 +310,13 @@ func (rs *rowStreamer) buildSelect(st *binlogdatapb.MinimalTable) (string, error
 			for i, pk := range rs.pkColumns[:lastcol] {
 				buf.Myprintf("%v = ", sqlparser.NewIdentifierCI(rs.plan.Table.Fields[pk].Name))
 				rs.lastpk[i].EncodeSQL(buf)
-				// Only AND expressions are supported.
 				buf.Myprintf(" and ")
 			}
 			buf.Myprintf("%v > ", sqlparser.NewIdentifierCI(rs.plan.Table.Fields[rs.pkColumns[lastcol]].Name))
 			rs.lastpk[lastcol].EncodeSQL(buf)
 			buf.Myprintf(")")
 		}
-	} else if len(rs.plan.whereExprsToPushDown) > 0 { // We're in the running/replicating phase
+	} else if len(rs.plan.whereExprsToPushDown) > 0 { // We're in the first copy phase cycle
 		buf.Myprintf(" where ")
 		addPushdownExpressions()
 	}