heap: remove NEW_HASH_FUNCTION

This was added in 29fa725 (in 2000) and nothing defines NEW_HASH_FUNCTION. A low collision is the wrong tradeoff, it should be focused on throughput. d405bee shows the existing function is pretty cpu intensive and needs to be improved as well.

Author: grooverdan

storage/heap/hp_hash.c

@@ -209,8 +209,6 @@ void hp_movelink(HASH_INFO *pos, HASH_INFO *next_link, HASH_INFO *newlink)
  return;
 }
 
-#ifndef NEW_HASH_FUNCTION
-
 /* Calc hashvalue for a key */
 
 ulong hp_hashnr(register HP_KEYDEF *keydef, register const uchar *key)
@@ -350,136 +348,6 @@ ulong hp_rec_hashnr(register HP_KEYDEF *keydef, register const uchar *rec)
  return(nr);
 }
 
-#else
-
-/*
- * Fowler/Noll/Vo hash
- *
- * The basis of the hash algorithm was taken from an idea sent by email to the
- * IEEE Posix P1003.2 mailing list from Phong Vo (kpv@research.att.com) and
- * Glenn Fowler (gsf@research.att.com). Landon Curt Noll (chongo@toad.com)
- * later improved on their algorithm.
- *
- * The magic is in the interesting relationship between the special prime
- * 16777619 (2^24 + 403) and 2^32 and 2^8.
- *
- * This hash produces the fewest collisions of any function that we've seen so
- * far, and works well on both numbers and strings.
- */
-
-ulong hp_hashnr(register HP_KEYDEF *keydef, register const uchar *key)
-{
- /*
- Note, if a key consists of a combination of numeric and
- a text columns, it most likely won't work well.
- Making text columns work with NEW_HASH_FUNCTION
- needs also changes in strings/ctype-xxx.c.
- */
- ulong nr= 1, nr2= 4;
- HA_KEYSEG *seg,*endseg;
-
- for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
- {
- uchar *pos=(uchar*) key;
- key+=seg->length;
- if (seg->null_bit)
- {
- key++;
- if (*pos)
- {
-nr^= (nr << 1) | 1;
-/* Add key pack length (2) to key for VARCHAR segments */
- if (seg->type == HA_KEYTYPE_VARTEXT1)
- key+= 2;
-continue;
- }
- pos++;
- }
- if (seg->type == HA_KEYTYPE_TEXT)
- {
- seg->charset->coll->hash_sort(seg->charset, pos, ((uchar*)key)-pos,
- &nr, &nr2);
- }
- else if (seg->type == HA_KEYTYPE_VARTEXT1) /* Any VARCHAR segments */
- {
- uint pack_length= 2; /* Key packing is constant */
- uint length= uint2korr(pos);
- seg->charset->coll->hash_sort(seg->charset, pos+pack_length, length,
- &nr, &nr2);
- key+= pack_length;
- }
- else
- {
- for ( ; pos < (uchar*) key ; pos++)
- {
-nr *=16777619; 
-nr ^=(uint) *pos;
- }
- }
- }
-#ifdef ONLY_FOR_HASH_DEBUGGING
- DBUG_PRINT("exit", ("hash: 0x%lx", nr));
-#endif
- return(nr);
-}
-
-/* Calc hashvalue for a key in a record */
-
-ulong hp_rec_hashnr(register HP_KEYDEF *keydef, register const uchar *rec)
-{
- ulong nr= 1, nr2= 4;
- HA_KEYSEG *seg,*endseg;
-
- for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
- {
- uchar *pos=(uchar*) rec+seg->start;
- if (seg->null_bit)
- {
- if (rec[seg->null_pos] & seg->null_bit)
- {
-nr^= (nr << 1) | 1;
-continue;
- }
- }
- if (seg->type == HA_KEYTYPE_TEXT)
- {
- uint char_length= seg->length; /* TODO: fix to use my_charpos() */
- seg->charset->coll->hash_sort(seg->charset, pos, char_length,
- &nr, &nr2);
- }
- else if (seg->type == HA_KEYTYPE_VARTEXT1) /* Any VARCHAR segments */
- {
- uint pack_length= seg->bit_start;
- uint length= (pack_length == 1 ? (uint) *(uchar*) pos : uint2korr(pos));
- seg->charset->coll->hash_sort(seg->charset, pos+pack_length,
- length, &nr, &nr2);
- }
- else
- {
- uchar *end= pos+seg->length;
- if (seg->type == HA_KEYTYPE_BIT && seg->bit_length)
- {
- uchar bits= get_rec_bits(rec + seg->bit_pos,
- seg->bit_start, seg->bit_length);
-nr *=16777619;
-nr ^=(uint) bits;
- end--;
- }
- for ( ; pos < end ; pos++)
- {
-nr *=16777619; 
-nr ^=(uint) *pos;
- }
- }
- }
-#ifdef ONLY_FOR_HASH_DEBUGGING
- DBUG_PRINT("exit", ("hash: 0x%lx", nr));
-#endif
- return(nr);
-}
-
-#endif
-
 
 /*
  Compare keys for two records. Returns 0 if they are identical