Fixed LP bug #670380.

Lifted the limitation that hash join could not be used over 
varchar fields with non-binary collation.

1 files changed, 251 insertions, 0 deletions

diff --git a/sql/key.cc b/sql/key.cc
index a1793e9e5f4..08502cfe6cc 100644
--- a/sql/key.cc
+++ b/sql/key.cc
@@ -567,3 +567,254 @@ next_loop:
   } while (key_info); /* no more keys to test */
   DBUG_RETURN(0);
 }
+
+
+/**
+  Get hash value for the key from a key buffer 
+
+  @param  key_info       the key descriptor
+  @param  used_key_part  number of key parts used for the key
+  @param  key            pointer to the buffer with the key value
+
+  @datails
+  When hashing we should take special care only of:
+  1. NULLs (and keyparts which can be null so one byte reserved for it);
+  2. Strings for which we have to take into account their collations
+  and the values of their lengths in the prefixes.
+
+  @return  hash value calculated for the key
+*/
+
+ulong key_hashnr(KEY *key_info, uint used_key_parts, const uchar *key)
+{
+  ulong nr=1, nr2=4;
+  KEY_PART_INFO *key_part= key_info->key_part;
+  KEY_PART_INFO *end_key_part= key_part + used_key_parts;
+
+  for (; key_part < end_key_part; key_part++)
+  {
+    uchar *pos= (uchar*)key;
+    CHARSET_INFO *cs;
+    uint length, pack_length;
+    bool is_string= TRUE;
+    LINT_INIT(cs);
+    key+= key_part->length;
+    if (key_part->null_bit)
+    {
+      key++;                       /* Skip null byte */
+      if (*pos)                    /* Found null */
+      {
+        nr^= (nr << 1) | 1;
+        /* Add key pack length to key for VARCHAR segments */
+        switch (key_part->type) {
+        case HA_KEYTYPE_VARTEXT1:
+        case HA_KEYTYPE_VARBINARY1:
+          key++;
+          break;
+        case HA_KEYTYPE_VARTEXT2:
+        case HA_KEYTYPE_VARBINARY2:
+          key+= 2;
+          break;
+        default:
+          ;
+        }
+    continue;
+      }
+      pos++;                       /* Skip null byte */
+    }
+    /* If it is string set parameters of the string */
+    switch (key_part->type) {
+    case HA_KEYTYPE_TEXT:
+      cs= key_part->field->charset();
+      length= key_part->length;
+      pack_length= 0;
+      break;
+    case HA_KEYTYPE_BINARY :
+      cs= &my_charset_bin;
+      length= key_part->length;
+      pack_length= 0;
+      break;
+    case HA_KEYTYPE_VARTEXT1:
+      cs= key_part->field->charset();
+      length= (uint)(pos[0]);
+      pack_length= 1;
+      break;
+    case HA_KEYTYPE_VARBINARY1:
+      cs= &my_charset_bin;
+      length= (uint)(pos[0]);
+      pack_length= 1;
+      break;
+    case HA_KEYTYPE_VARTEXT2:
+      cs= key_part->field->charset();
+      length= uint2korr(pos);
+      pack_length= 2;
+      break;
+    case HA_KEYTYPE_VARBINARY2:
+      cs= &my_charset_bin;
+      length= uint2korr(pos);
+      pack_length= 2;
+      break;
+    default:
+      is_string= FALSE;
+    }
+
+    if (is_string)
+    {
+      if (cs->mbmaxlen > 1)
+      {
+        uint char_length= my_charpos(cs, pos + pack_length,
+                                     pos + pack_length + length,
+                                     length / cs->mbmaxlen);
+        set_if_smaller(length, char_length);
+      }
+      cs->coll->hash_sort(cs, pos+pack_length, length, &nr, &nr2);
+      key+= pack_length;
+    }
+    else
+    {
+      for (; pos < (uchar*)key ; pos++)
+      {
+        nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) *pos)) + (nr << 8);
+        nr2+=3;
+      }
+    }
+  }
+  DBUG_PRINT("exit", ("hash: %lx", nr));
+  return(nr);
+}
+
+
+/**
+  Check whether two keys in the key buffers are equal
+
+  @param key_info        the key descriptor
+  @param  used_key_part  number of key parts used for the keys
+  @param key1            pointer to the buffer with the first key 
+  @param key2            pointer to the buffer with the second key 
+
+  @detail See details of key_hashnr().
+
+  @retval TRUE  keys in the buffers are NOT equal
+  @retval FALSE keys in the buffers are equal
+*/
+
+bool key_buf_cmp(KEY *key_info, uint used_key_parts,
+                 const uchar *key1, const uchar *key2)
+{
+  KEY_PART_INFO *key_part= key_info->key_part;
+  KEY_PART_INFO *end_key_part= key_part + used_key_parts;
+
+  for (; key_part < end_key_part; key_part++)
+  {
+    uchar *pos1= (uchar*)key1;
+    uchar *pos2= (uchar*)key2;
+    CHARSET_INFO *cs;
+    uint length1, length2, pack_length;
+    bool is_string= TRUE;
+    LINT_INIT(cs);
+    key1+= key_part->length;
+    key2+= key_part->length;
+    if (key_part->null_bit)
+    {
+      key1++; key2++;                           /* Skip null byte */
+      if (*pos1 && *pos2)                       /* Both are null */
+      {
+        /* Add key pack length to key for VARCHAR segments */
+        switch (key_part->type) {
+        case HA_KEYTYPE_VARTEXT1:
+        case HA_KEYTYPE_VARBINARY1:
+          key1++; key2++;
+          break;
+        case HA_KEYTYPE_VARTEXT2:
+        case HA_KEYTYPE_VARBINARY2:
+          key1+= 2; key2+= 2;
+          break;
+        default:
+          ;
+        }
+    continue;
+      }
+      if (*pos1 != *pos2)
+        return FALSE;
+      pos1++; pos2++;
+    }
+
+    /* If it is string set parameters of the string */
+    switch (key_part->type) {
+    case HA_KEYTYPE_TEXT:
+      cs= key_part->field->charset();
+      length1= length2= key_part->length;
+      pack_length= 0;
+      break;
+    case HA_KEYTYPE_BINARY :
+      cs= &my_charset_bin;
+      length1= length2= key_part->length;
+      pack_length= 0;
+      break;
+    case HA_KEYTYPE_VARTEXT1:
+      cs= key_part->field->charset();
+      length1= (uint)(pos1[0]);
+      length2= (uint)(pos2[0]);
+      pack_length= 1;
+      break;
+    case HA_KEYTYPE_VARBINARY1:
+      cs= &my_charset_bin;
+      length1= (uint)(pos1[0]);
+      length2= (uint)(pos2[0]);
+      pack_length= 1;
+      break;
+    case HA_KEYTYPE_VARTEXT2:
+      cs= key_part->field->charset();
+      length1= uint2korr(pos1);
+      length2= uint2korr(pos2);
+      pack_length= 2;
+      break;
+    case HA_KEYTYPE_VARBINARY2:
+      cs= &my_charset_bin;
+      length1= uint2korr(pos1);
+      length2= uint2korr(pos2);
+      pack_length= 2;
+      break;
+    default:
+      is_string= FALSE;
+    }
+
+    if (is_string)
+    {
+      /*
+        Compare the strings taking into account length in characters
+        and collation
+      */
+      uint byte_len1= length1, byte_len2= length2;
+      if (cs->mbmaxlen > 1)
+      {
+        uint char_length1= my_charpos(cs, pos1 + pack_length,
+                                      pos1 + pack_length + length1,
+                                      length1 / cs->mbmaxlen);
+        uint char_length2= my_charpos(cs, pos2 + pack_length,
+                                      pos2 + pack_length + length2,
+                                      length2 / cs->mbmaxlen);
+        set_if_smaller(length1, char_length1);
+        set_if_smaller(length2, char_length2);
+      }
+      if (length1 != length2 ||
+          cs->coll->strnncollsp(cs,
+                                pos1 + pack_length, byte_len1,
+                                pos2 + pack_length, byte_len2,
+                                1))
+        return TRUE;
+      key1+= pack_length; key2+= pack_length;
+    }
+    else
+    {
+      /* it is OK to compare non-string byte per byte */
+      for (; pos1 < (uchar*)key1 ; pos1++, pos2++)
+      {
+        if (pos1[0] != pos2[0])
+          return TRUE;
+      }
+    }
+  }
+  return FALSE;
+}
+