[t:2219], small changes to help understanding of code

git-svn-id: file:///svn/mysql/tokudb-engine/src@16241 c7de825b-a66e-492c-adef-691d508d4ae1

storage/tokudb/ha_tokudb.h

@@ -248,7 +248,7 @@ class ha_tokudb : public handler {
     u_int32_t place_key_into_mysql_buff(KEY* key_info, uchar * record, uchar* data);
     void unpack_key(uchar * record, DBT const *key, uint index);
     u_int32_t place_key_into_dbt_buff(KEY* key_info, uchar * buff, const uchar * record, bool* has_null, int key_length);
-    DBT* create_dbt_key_from_key(DBT * key, KEY* key_info, uchar * buff, const uchar * record, bool* has_null, bool pack_pk, int key_length = MAX_KEY_LENGTH);
+    DBT* create_dbt_key_from_key(DBT * key, KEY* key_info, uchar * buff, const uchar * record, bool* has_null, bool dont_pack_pk, int key_length = MAX_KEY_LENGTH);
     DBT *create_dbt_key_from_table(DBT * key, uint keynr, uchar * buff, const uchar * record, bool* has_null, int key_length = MAX_KEY_LENGTH);
     DBT* create_dbt_key_for_lookup(DBT * key, KEY* key_info, uchar * buff, const uchar * record, bool* has_null, int key_length = MAX_KEY_LENGTH);
     DBT *pack_key(DBT * key, uint keynr, uchar * buff, const uchar * key_ptr, uint key_length, int8_t inf_byte);

storage/tokudb/hatoku_cmp.cc

@@ -829,26 +829,18 @@ int create_toku_key_descriptor_for_key(KEY* key, uchar* buf) {
 // Creates a descriptor for a DB. That contains all information necessary 
 // to do both key comparisons and data comparisons (for dup-sort databases). 
 //
-// There are three types of descriptors we care about:
+// There are two types of descriptors we care about:
 // 1) Primary key, (in a no-dup database)
-// 2) secondary key, followed by primary key (for secondary indexes that are
-//      dup-sort databases).
-// 3) clustering keys, which are a secondary key followed by a primary key,
+// 2) secondary keys, which are a secondary key followed by a primary key,
 //      but in a no-dup database.
 //
 // I realize this may be confusing, but here is how it works.
-// All DB's have a key compare, and some have a data compare.
+// All DB's have a key compare.
 // The format of the descriptor must be able to handle both.
 //
-// The descriptor handles having two pieces of information appended
-// to each other. The first piece is used for key comparisons (and used
-// in tokudb_cmp_dbt_key), and the second piece is used for data
-// comparisons (used in tokudb_cmp_dbt_data). These pieces are
-// generated by create_toku_key_descriptor_for_key
-//
 // The first four bytes store an offset into the descriptor to the second piece
-// used for data comparisons. For cases 1 and 3 above, where no data comparison
-// exists, this offset is equal to the entire length of the descriptor.
+// used for data comparisons. So, if in the future we want to append something
+// to the descriptor, we can.
 // 
 //
 int create_toku_key_descriptor(