Fix for bug#20648 We introduce a new field method for knowing "real size", and we now in archive null unused bits of a row to null before writing.

sql/field.cc:
  data_length for field needs to be calculated directly.
sql/field.h:
  The new method data_length() returns the "real" length of the field.
sql/ha_archive.cc:
  Before a write_row() archive nulls space beyond the size of the row in varchars to make sure that compression only sees NULL.

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/field.h b/sql/field.h
index 3306c4123db..2ad564fc753 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -144,6 +144,11 @@ public:
     table, which is located on disk).
   */
   virtual uint32 pack_length_in_rec() const { return pack_length(); }
+
+  /*
+    data_length() return the "real size" of the data in memory.
+  */
+  virtual uint32 data_length(const char *from) { return pack_length(); }
   virtual uint32 sort_length() const { return pack_length(); }
   virtual void reset(void) { bzero(ptr,pack_length()); }
   virtual void reset_fields() {}
@@ -1102,6 +1107,7 @@ public:
   int key_cmp(const byte *str, uint length);
   uint packed_col_length(const char *to, uint length);
   uint max_packed_col_length(uint max_length);
+  uint data_length(const char *from);
   uint size_of() const { return sizeof(*this); }
   enum_field_types real_type() const { return MYSQL_TYPE_VARCHAR; }
   bool has_charset(void) const