Added support of null keys in HEAP tables

Added ORDER BY optimization

Docs/manual.texi

@@ -750,7 +750,7 @@ Large server clusters using replication are in production use, with
 good results. Work on enhanced replication features is continuing
 in MySQL 4.0.
 
-@item @code{InnoDB} tables -- Gamma
+@item @code{InnoDB} tables -- Stable
 While the @code{InnoDB} transactional table handler is a fairly recent
 addition to @code{MySQL}, it appears to work well and is already being
 used in some large, heavy load production systems.
@@ -3692,9 +3692,6 @@ Allow users to change startup options without taking down the server.
 @item
 Fail safe replication.
 @item
-More functions for full-text search.
-@xref{Fulltext TODO}.
-@item
 New key cache
 @item
 New table definition file format (@code{.frm} files) This will enable us
@@ -3727,9 +3724,6 @@ When using @code{SET CHARACTER SET} we should translate the whole query
 at once and not only strings. This will enable users to use the translated
 characters in database, table and column names.
 @item
-Add a portable interface over @code{gethostbyaddr_r()} so that we can change
-@code{ip_to_hostname()} to not block other threads while doing DNS lookups.
-@item
 Add @code{record_in_range()} method to @code{MERGE} tables to be
 able to choose the right index when there is many to choose from. We should
 also extend the info interface to get the key distribution for each index,
@@ -3861,15 +3855,6 @@ Don't add automatic @code{DEFAULT} values to columns.  Give an error when using
 an @code{INSERT} that doesn't contain a column that doesn't have a
 @code{DEFAULT}.
 @item
-Caching of queries and results. This should be done as a separated
-module that examines each query and if this is query is in the cache
-the cached result should be returned.  When one updates a table one
-should remove as few queries as possible from the cache.
-This should give a big speed bost on machines with much RAM where
-queries are often repeated (like WWW applications).
-One idea would be to only cache queries of type:
-@code{SELECT CACHED ...}
-@item
 Fix @file{libmysql.c} to allow two @code{mysql_query()} commands in a row
 without reading results or give a nice error message when one does this.
 @item
@@ -3934,10 +3919,7 @@ ADD_TO_SET(value,set) and REMOVE_FROM_SET(value,set)
 Add use of @code{t1 JOIN t2 ON ...} and @code{t1 JOIN t2 USING ...}
 Currently, you can only use this syntax with @code{LEFT JOIN}.
 @item
-Add full support for @code{unsigned long long} type.
-@item
-Many more variables for @code{show status}.  Counts for:
-@code{INSERT}/@code{DELETE}/@code{UPDATE} statements. Records reads and
+Many more variables for @code{show status}.  Records reads and
 updated.  Selects on 1 table and selects with joins.  Mean number of
 tables in select. Number of @code{ORDER BY} and @code{GROUP BY} queries.
 @item
@@ -3952,7 +3934,7 @@ should be implemented.
 @item
 Add support for UNICODE.
 @item
-@code{NATURAL JOIN} and @code{UNION JOIN}
+@code{NATURAL JOIN}.
 @item
 Allow @code{select a from crash_me left join crash_me2 using (a)}; In this
 case @code{a} is assumed to come from the @code{crash_me} table.
@@ -4069,8 +4051,6 @@ Use of full calculation names in the order part. (For ACCESS97)
 @code{MINUS}, @code{INTERSECT} and @code{FULL OUTER JOIN}.
 (Currently @code{UNION} (in 4.0) and @code{LEFT OUTER JOIN} are supported)
 @item
-Allow @code{UNIQUE} on fields that can be @code{NULL}.
-@item
 @code{SQL_OPTION MAX_SELECT_TIME=#} to put a time limit on a query.
 @item
 Make the update log to a database.
@@ -24578,6 +24558,7 @@ great tool to find out if this is a problem with your query.
 * Where optimisations::         How MySQL optimises @code{WHERE} clauses
 * DISTINCT optimisation::       How MySQL Optimises @code{DISTINCT}
 * LEFT JOIN optimisation::      How MySQL optimises @code{LEFT JOIN}
+* ORDER BY optimisation::       
 * LIMIT optimisation::          How MySQL optimises @code{LIMIT}
 * Insert speed::                Speed of @code{INSERT} queries
 * Update speed::                Speed of @code{UPDATE} queries
@@ -25171,7 +25152,7 @@ MySQL will stop reading from t2 (for that particular row in t1)
 when the first row in t2 is found.
 
 
-@node LEFT JOIN optimisation, LIMIT optimisation, DISTINCT optimisation, Query Speed
+@node LEFT JOIN optimisation, ORDER BY optimisation, DISTINCT optimisation, Query Speed
 @subsection How MySQL Optimises @code{LEFT JOIN} and @code{RIGHT JOIN}
 
 @findex LEFT JOIN
@@ -25237,7 +25218,119 @@ SELECT * FROM b,a LEFT JOIN c ON (c.key=a.key) LEFT JOIN d (d.key=a.key) WHERE b
 @end example
 
 
-@node LIMIT optimisation, Insert speed, LEFT JOIN optimisation, Query Speed
+@node ORDER BY optimisation, LIMIT optimisation, LEFT JOIN optimisation, Query Speed
+@subsection How MySQL Optimises @code{ORDER BY}
+
+In some cases MySQL can uses index to satisfy an @code{ORDER BY} or
+@code{GROUP BY} request without doing any extra sorting.
+
+The index can also be used even if the @code{ORDER BY} doesn't match the
+index exactly, as long as all the unused index parts and all the extra
+are @code{ORDER BY} columns are constants in the @code{WHERE}
+clause. The following queries will use the index to resolve the
+@code{ORDER BY} / @code{GROUP BY} part:
+
+@example
+SELECT * FROM t1 ORDER BY key_part1,key_part2,...
+SELECT * FROM t1 WHERE key_part1=constant ORDER BY key_part2
+SELECT * FROM t1 WHERE key_part1=constant GROUP BY key_part2
+SELECT * FROM t1 ORDER BY key_part1 DESC,key_part2 DESC
+SELECT * FROM t1 WHERE key_part1=1 ORDER BY key_part1 DESC,key_part2 DESC
+@end example
+
+Some cases where MySQL can NOT use indexes to resolve the @code{ORDER
+BY}: (Note that MySQL will still use indexes to find the rows that
+matches the where clause):
+
+@itemize @bullet
+@item
+You are doing an @code{ORDER BY} on different keys:
+
+@code{SELECT * FROM t1 ORDER BY key1,key2}
+@item
+You are doing an @code{ORDER BY} on not following key parts.
+
+@code{SELECT * FROM t1 WHERE key2=constant ORDER BY key_part2}
+
+@item
+You are mixing @code{ASC} and @code{DESC}.
+
+@code{SELECT * FROM t1 ORDER BY key_part1 DESC,key_part2 ASC}
+
+@item
+The key used to fetch the rows are not the same one that is used to
+do the @code{ORDER BY}:
+
+@code{SELECT * FROM t1 WHERE key2=constant ORDER BY key1}
+
+@item
+You are joining many tables and the columns you are doing an @code{ORDER
+BY} on are not all from the first not-const table that is used to
+retrieve rows (This is the first table in the @code{EXPLAIN} output which
+doesn't use a @code{const} row fetch method).
+
+@item
+You have different @code{ORDER BY} and @code{GROUP BY} expressions.
+
+@item
+The used table index is an index type that doesn't store rows in order.
+(Like index in @code{HEAP} tables).
+@end itemize
+
+
+In the cases where MySQL have to sort the result, it uses the following
+algorithm:
+
+@itemize @bullet
+@item
+Read all rows according to key or by table scanning.
+Rows that doesn't match the WHERE clause are skipped.
+@item
+Store the sort-key in a buffer (of size @code{sort_buffer}).
+@item
+When the buffer gets full, run a qsort on it and store the result
+in a temporary file.  Save a pointer to the sorted block.
+(In the case where all rows fits into the sort buffer, no temporary
+file is created)
+@item
+Repeat the above until all rows have been read.
+@item
+Do a multi-merge of up to @code{MERGEBUFF} (7) regions to one block in
+another temporary file.  Repeat until all blocks from the first file
+are in the second file.
+@item
+Repeat the following until there is less than @code{MERGEBUFF2} (15) 
+blocks left.
+@item
+On the last multi-merge, only the pointer to the row (last part of
+the sort-key) is written to a result file.
+@item
+Now the code in @file{sql/records.cc} will be used to read through them
+in sorted order by using the row pointers in the result file.  To
+optimize this, we read in a big block of row pointers, sort these and
+then we read the rows in the sorted order into a row buffer
+(@code{record_rnd_buffer}) .
+@end itemize
+
+You can with @code{EXPLAIN SELECT ... ORDER BY} check if MySQL can use
+indexes to resolve the query.  If you get @code{Using filesort} in the
+@code{extra} column, then MySQL can't use indexes to resolve the
+@code{ORDER BY}. @xref{EXPLAIN}.
+
+If you want to have a higher @code{ORDER BY} speed, you should first
+see if you can get MySQL to use indexes instead of having to do an extra
+sorting phase. If this is not possible, then you can do:
+
+@itemize @bullet
+@item
+Increase the size of the @code{sort_buffer} variable.
+@item
+Increase the size of the @code{record_rnd_buffer} variable.
+@item
+Change @code{tmpdir} to point to a dedicated disk with lots of empty space.
+@end itemize
+
+@node LIMIT optimisation, Insert speed, ORDER BY optimisation, Query Speed
 @subsection How MySQL Optimises @code{LIMIT}
 
 @findex LIMIT
@@ -25986,19 +26079,9 @@ SELECT MIN(key_part2),MAX(key_part2) FROM table_name where key_part1=10
 
 @item
 Sort or group a table if the sorting or grouping is done on a leftmost
-prefix of a usable key (for example, @code{ORDER BY key_part_1,key_part_2 }). The
-key is read in reverse order if all key parts are followed by @code{DESC}.
-
-The index can also be used even if the @code{ORDER BY} doesn't match the index
-exactly, as long as all the unused index parts and all the extra
-are @code{ORDER BY} columns are constants in the @code{WHERE} clause. The
-following queries will use the index to resolve the @code{ORDER BY} part:
-
-@example
-SELECT * FROM foo ORDER BY key_part1,key_part2,key_part3;
-SELECT * FROM foo WHERE column=constant ORDER BY column, key_part1;
-SELECT * FROM foo WHERE key_part1=const GROUP BY key_part2;
-@end example
+prefix of a usable key (for example, @code{ORDER BY
+key_part_1,key_part_2 }). The key is read in reverse order if all key
+parts are followed by @code{DESC}.  @xref{ORDER BY optimisation}.
 
 @item
 In some cases a query can be optimised to retrieve values without
@@ -33355,7 +33438,12 @@ DELETE [LOW_PRIORITY | QUICK] FROM table_name
 
 or
 
-DELETE [LOW_PRIORITY | QUICK] table_name[.*] [table_name[.*] ...] FROM
+DELETE [LOW_PRIORITY | QUICK] table_name[.*] [,table_name[.*] ...] FROM
+table-references [WHERE where_definition]
+
+or
+
+DELETE [LOW_PRIORITY | QUICK] FROM table_name[.*], [table_name[.*] ...] USING
 table-references [WHERE where_definition]
 @end example
 
@@ -33392,18 +33480,23 @@ TABLE} statement or the @code{myisamchk} utility to reorganise tables.
 @code{OPTIMIZE TABLE} is easier, but @code{myisamchk} is faster.  See
 @ref{OPTIMIZE TABLE, , @code{OPTIMIZE TABLE}} and @ref{Optimisation}.
 
-The multi table delete format is supported starting from MySQL 4.0.0.
+The first multi table delete format is supported starting from MySQL 4.0.0.
+The second multi table delete format is supported starting from MySQL 4.0.2.
 
-The idea is that only matching rows from the tables listed @strong{before} the
-@code{FROM} clause is deleted. The effect is that you can delete rows
-from many tables at the same time and also have additional tables that
-are used for searching.
+The idea is that only matching rows from the tables listed
+@strong{before} the @code{FROM} or before the @code{USING} clause is
+deleted. The effect is that you can delete rows from many tables at the
+same time and also have additional tables that are used for searching.
 
 The @code{.*} after the table names is there just to be compatible with
 @code{Access}:
 
 @example
 DELETE t1,t2 FROM t1,t2,t3 WHERE t1.id=t2.id AND t2.id=t3.id
+
+or
+
+DELETE FROM t1,t2 USING t1,t2,t3 WHERE t1.id=t2.id AND t2.id=t3.id
 @end example
 
 In the above case we delete matching rows just from tables @code{t1} and
@@ -48028,10 +48121,18 @@ Our TODO section contains what we plan to have in 4.0. @xref{TODO MySQL 4.0}.
 
 @itemize @bullet
 @item
+Added support for @code{NULL} keys in HEAP tables.
+@item
+Use index for @code{ORDER BY} in queries of type:
+@code{SELECT * FROM t1 WHERE key_part1=1 ORDER BY key_part1 DESC,key_part2 DESC}
+@item
 Fixed bug in @code{FLUSH QUERY CACHE}.
 @item
 Added @code{CAST()} and @code{CONVERT()} functions.
 @item
+@code{CREATE ... SELECT} on @code{DATE} and @code{TIME} functions now
+create columns of the expected type.
+@item
 Changed order of how keys are created in tables.
 @item
 Added a new columns @code{Null} and @code{Index_type} to @code{SHOW INDEX}.

heap/_check.c

@@ -79,9 +79,11 @@ static int check_one_key(HP_KEYDEF *keydef, uint keynr, ulong records,
   }
   DBUG_PRINT("info",
 	     ("records: %ld   seeks: %d   max links: %d   hitrate: %.2f",
-	      records,seek,max_links,(float) seek / (float) (records ? records : 1)));
+	      records,seek,max_links,
+	      (float) seek / (float) (records ? records : 1)));
   if (print_status)
     printf("Key: %d  records: %ld   seeks: %d   max links: %d   hitrate: %.2f\n",
-	   keynr, records, seek, max_links, (float) seek / (float) records);
+	   keynr, records, seek, max_links,
+	   (float) seek / (float) (records ? records : 1));
   return error;
 }

heap/heapdef.h

@@ -70,6 +70,7 @@ extern int _hp_rec_key_cmp(HP_KEYDEF *keydef,const byte *rec1,
 extern int _hp_key_cmp(HP_KEYDEF *keydef,const byte *rec,
 			   const byte *key);
 extern void _hp_make_key(HP_KEYDEF *keydef,byte *key,const byte *rec);
+extern my_bool hp_if_null_in_key(HP_KEYDEF *keyinfo, const byte *record);
 extern int _hp_close(register HP_INFO *info);
 extern void _hp_clear(HP_SHARE *info);
 

heap/hp_hash.c

@@ -158,11 +158,22 @@ ulong _hp_hashnr(register HP_KEYDEF *keydef, register const byte *key)
   {
     uchar *pos=(uchar*) key;
     key+=seg->length;
+    if (seg->null_bit)
+    {
+      key++;					/* Skipp null byte */
+      if (*pos)					/* Found null */
+      {
+	nr^= (nr << 1) | 1;
+	continue;
+      }
+      pos++;
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       for (; pos < (uchar*) key ; pos++)
       {
-	nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) my_sort_order[(uint) *pos]))+ (nr << 8);
+	nr^=(ulong) ((((uint) nr & 63)+nr2) * 
+		     ((uint) my_sort_order[(uint) *pos])) + (nr << 8);
 	nr2+=3;
       }
     }
@@ -170,7 +181,7 @@ ulong _hp_hashnr(register HP_KEYDEF *keydef, register const byte *key)
     {
       for (; pos < (uchar*) key ; pos++)
       {
-	nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) *pos))+ (nr << 8);
+	nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) *pos)) + (nr << 8);
 	nr2+=3;
       }
     }
@@ -188,11 +199,20 @@ ulong _hp_rec_hashnr(register HP_KEYDEF *keydef, register const byte *rec)
   for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
   {
     uchar *pos=(uchar*) rec+seg->start,*end=pos+seg->length;
+    if (seg->null_bit)
+    {
+      if (rec[seg->null_pos] & seg->null_bit)
+      {
+	nr^= (nr << 1) | 1;
+	continue;
+      }
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       for (; pos < end ; pos++)
       {
-	nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) my_sort_order[(uint) *pos]))+ (nr << 8);
+	nr^=(ulong) ((((uint) nr & 63)+nr2)*
+		     ((uint) my_sort_order[(uint) *pos]))+ (nr << 8);
 	nr2+=3;
       }
     }
@@ -234,6 +254,16 @@ ulong _hp_hashnr(register HP_KEYDEF *keydef, register const byte *key)
   {
     uchar *pos=(uchar*) key;
     key+=seg->length;
+    if (seg->null_bit)
+    {
+      key++;
+      if (*pos)
+      {
+	nr^= (nr << 1) | 1;
+	continue;
+      }
+      pos++;
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       for (; pos < (uchar*) key ; pos++)
@@ -264,6 +294,14 @@ ulong _hp_rec_hashnr(register HP_KEYDEF *keydef, register const byte *rec)
   for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
   {
     uchar *pos=(uchar*) rec+seg->start,*end=pos+seg->length;
+    if (seg->null_bit)
+    {
+      if (rec[seg->null_pos] & seg->null_bit)
+      {
+	nr^= (nr << 1) | 1;
+	continue;
+      }
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       for ( ; pos < end ; pos++)
@@ -295,6 +333,14 @@ int _hp_rec_key_cmp(HP_KEYDEF *keydef, const byte *rec1, const byte *rec2)
 
   for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
   {
+    if (seg->null_bit)
+    {
+      if ((rec1[seg->null_pos] & seg->null_bit) !=
+	  (rec2[seg->null_pos] & seg->null_bit))
+	return 1;
+      if (rec1[seg->null_pos] & seg->null_bit)
+	continue;
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       if (my_sortcmp(rec1+seg->start,rec2+seg->start,seg->length))
@@ -309,14 +355,24 @@ int _hp_rec_key_cmp(HP_KEYDEF *keydef, const byte *rec1, const byte *rec2)
   return 0;
 }
 
-	/* Compare a key in a record to a hole key */
+	/* Compare a key in a record to a whole key */
 
 int _hp_key_cmp(HP_KEYDEF *keydef, const byte *rec, const byte *key)
 {
   HP_KEYSEG *seg,*endseg;
 
-  for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
+  for (seg=keydef->seg,endseg=seg+keydef->keysegs ;
+       seg < endseg ;
+       key+= (seg++)->length)
+  {
+    if (seg->null_bit)
     {
+      int found_null=test(rec[seg->null_pos] & seg->null_bit);
+      if (found_null != (int) *key++)
+	return 1;
+      if (found_null)
+	continue;
+    }
     if (seg->type == HA_KEYTYPE_TEXT)
     {
       if (my_sortcmp(rec+seg->start,key,seg->length))
@@ -327,7 +383,6 @@ int _hp_key_cmp(HP_KEYDEF *keydef, const byte *rec, const byte *key)
       if (bcmp(rec+seg->start,key,seg->length))
 	return 1;
     }
-    key+=seg->length;
   }
   return 0;
 }
@@ -341,7 +396,28 @@ void _hp_make_key(HP_KEYDEF *keydef, byte *key, const byte *rec)
 
   for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
   {
+    if (seg->null_bit)
+      *key++= test(rec[seg->null_pos] & seg->null_bit);
     memcpy(key,rec+seg->start,(size_t) seg->length);
     key+=seg->length;
   }
 }
+
+
+/*
+  Test if any of the key parts are NULL.
+  Return:
+    1 if any of the key parts was NULL
+    0 otherwise
+*/
+
+my_bool hp_if_null_in_key(HP_KEYDEF *keydef, const byte *record)
+{
+  HP_KEYSEG *seg,*endseg;
+  for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
+  {
+    if (seg->null_bit && (record[seg->null_pos] & seg->null_bit))
+      return 1;
+  }
+  return 0;
+}

heap/hp_open.c

@@ -44,7 +44,11 @@ HP_INFO *heap_open(const char *name, int mode, uint keys, HP_KEYDEF *keydef,
       key_segs+= keydef[i].keysegs;
       bzero((char*) &keydef[i].block,sizeof(keydef[i].block));
       for (j=length=0 ; j < keydef[i].keysegs; j++)
+      {
 	length+=keydef[i].seg[j].length;
+	if (keydef[i].seg[j].null_bit)
+	  keydef[i].flag |= HA_NULL_PART_KEY;
+      }
       keydef[i].length=length;
       if (length > max_length)
 	max_length=length;

heap/hp_test2.c

@@ -30,7 +30,7 @@
 #include <signal.h>
 
 #define MAX_RECORDS 100000
-#define MAX_KEYS 3
+#define MAX_KEYS 4
 
 static int get_options(int argc, char *argv[]);
 static int rnd(int max_value);
@@ -40,16 +40,20 @@ static uint flag=0,verbose=0,testflag=0,recant=10000,silent=0;
 static uint keys=MAX_KEYS;
 static uint16 key1[1001];
 static my_bool key3[MAX_RECORDS];
+static int reclength=39;
+
 
 static int calc_check(byte *buf,uint length);
+static void make_record(char *record, uint n1, uint n2, uint n3,
+			const char *mark, uint count);
 
-		/* Huvudprogrammet */
+/* Main program */
 
 int main(int argc, char *argv[])
 {
   register uint i,j;
   uint ant,n1,n2,n3;
-  uint reclength,write_count,update,opt_delete,check2,dupp_keys,found_key;
+  uint write_count,update,opt_delete,check2,dupp_keys,found_key;
   int error;
   ulong pos;
   unsigned long key_check;
@@ -66,7 +70,6 @@ int main(int argc, char *argv[])
   filename2= "test2_2";
   file=file2=0;
   get_options(argc,argv);
-  reclength=37;
 
   write_count=update=opt_delete=0;
   key_check=0;
@@ -77,21 +80,33 @@ int main(int argc, char *argv[])
   keyinfo[0].seg[0].type=HA_KEYTYPE_BINARY;
   keyinfo[0].seg[0].start=0;
   keyinfo[0].seg[0].length=6;
+  keyinfo[0].seg[0].null_bit=0;
   keyinfo[1].seg=keyseg+1;
   keyinfo[1].keysegs=2;
   keyinfo[1].flag=0;
   keyinfo[1].seg[0].type=HA_KEYTYPE_BINARY;
   keyinfo[1].seg[0].start=7;
   keyinfo[1].seg[0].length=6;
+  keyinfo[1].seg[0].null_bit=0;
   keyinfo[1].seg[1].type=HA_KEYTYPE_TEXT;
-  keyinfo[1].seg[1].start=0;			/* Tv}delad nyckel */
+  keyinfo[1].seg[1].start=0;			/* key in two parts */
   keyinfo[1].seg[1].length=6;
+  keyinfo[1].seg[1].null_bit=0;
   keyinfo[2].seg=keyseg+3;
   keyinfo[2].keysegs=1;
   keyinfo[2].flag=HA_NOSAME;
   keyinfo[2].seg[0].type=HA_KEYTYPE_BINARY;
   keyinfo[2].seg[0].start=12;
   keyinfo[2].seg[0].length=8;
+  keyinfo[2].seg[0].null_bit=0;
+  keyinfo[3].keysegs=1;
+  keyinfo[3].flag=HA_NOSAME;
+  keyinfo[3].seg=keyseg+4;
+  keyinfo[3].seg[0].type=HA_KEYTYPE_BINARY;
+  keyinfo[3].seg[0].start=37;
+  keyinfo[3].seg[0].length=1;
+  keyinfo[3].seg[0].null_bit=1;
+  keyinfo[3].seg[0].null_pos=38;
 
   bzero((char*) key1,sizeof(key1));
   bzero((char*) key3,sizeof(key3));
@@ -110,7 +125,7 @@ int main(int argc, char *argv[])
   for (i=0 ; i < recant ; i++)
   {
     n1=rnd(1000); n2=rnd(100); n3=rnd(min(recant*5,MAX_RECORDS));
-    sprintf(record,"%6d:%4d:%8d:Pos: %4d          ",n1,n2,n3,write_count);
+    make_record(record,n1,n2,n3,"Pos",write_count);
 
     if (heap_write(file,record))
     {
@@ -191,7 +206,7 @@ int main(int argc, char *argv[])
   for (i=0 ; i < write_count/10 ; i++)
   {
     n1=rnd(1000); n2=rnd(100); n3=rnd(min(recant*2,MAX_RECORDS));
-    sprintf(record2,"%6d:%4d:%8d:XXX: %4d          ",n1,n2,n3,update);
+    make_record(record2, n1, n2, n3, "XXX", update);
     if (rnd(2) == 1)
     {
       if (heap_scan_init(file))
@@ -654,3 +669,13 @@ static int calc_check(byte *buf, uint length)
     check+= (int) (uchar) *(buf++);
   return check;
 }
+
+static void make_record(char *record, uint n1, uint n2, uint n3,
+			const char *mark, uint count)
+{
+  bfill(record,reclength,' ');
+  sprintf(record,"%6d:%4d:%8d:%3.3s: %4d",
+	  n1,n2,n3,mark,count);
+  record[37]='A';				/* Store A in null key */
+  record[38]=1;					/* set as null */
+}

heap/hp_write.c

@@ -239,7 +239,9 @@ int _hp_write_key(register HP_SHARE *info, HP_KEYDEF *keyinfo,
     }
 
     /* Check if dupplicated keys */
-    if ((keyinfo->flag & HA_NOSAME) && pos == gpos)
+    if ((keyinfo->flag & HA_NOSAME) && pos == gpos &&
+	(!(keyinfo->flag & HA_NULL_PART_KEY) ||
+	 !hp_if_null_in_key(keyinfo, record)))
     {
       pos=empty;
       do

include/heap.h

@@ -78,11 +78,13 @@ typedef struct st_hp_keyseg		/* Key-portion */
   uint start;				/* Start of key in record (from 0) */
   uint length;				/* Keylength */
   uint type;
+  uint null_bit;			/* bit set in row+null_pos */
+  uint null_pos;
 } HP_KEYSEG;
 
 typedef struct st_hp_keydef		/* Key definition with open */
 {
-  uint flag;				/* NOSAME */
+  uint flag;				/* HA_NOSAME |HA_NULL_PART_KEY */
   uint keysegs;				/* Number of key-segment */
   uint length;				/* Length of key (automatic) */
   HP_KEYSEG *seg;

include/my_base.h

@@ -68,7 +68,8 @@ enum ha_rkey_function {
 
 enum ha_key_alg {			
   HA_KEY_ALG_BTREE=0,			/* B-tree, default one          */
-  HA_KEY_ALG_RTREE=1			/* R-tree, for spatial searches */
+  HA_KEY_ALG_RTREE=1,			/* R-tree, for spatial searches */
+  HA_KEY_ALG_HASH=2			/* HASH keys (HEAP tables) */
 };
 
 	/* The following is parameter to ha_extra() */

isam/static.c

@@ -15,7 +15,7 @@
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 /*
-  Static variables for pisam library. All definied here for easy making of
+  Static variables for ISAM library. All definied here for easy making of
   a shared library
 */
 

myisam/mi_static.c

@@ -15,7 +15,7 @@
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 /*
-  Static variables for pisam library. All definied here for easy making of
+  Static variables for MyISAM library. All definied here for easy making of
   a shared library
 */
 

sql/Makefile.am

@@ -51,7 +51,7 @@ noinst_HEADERS =	item.h item_func.h item_sum.h item_cmpfunc.h \
 			sql_manager.h sql_map.h sql_string.h unireg.h \
 			field.h handler.h \
 			ha_isammrg.h ha_isam.h ha_myisammrg.h\
-			ha_heap.h ha_myisam.h ha_berkeley.h ha_innobase.h \
+			ha_heap.h ha_myisam.h ha_berkeley.h ha_innodb.h \
 			opt_range.h opt_ft.h \
 			sql_select.h structs.h table.h sql_udf.h hash_filo.h\
 			lex.h lex_symbol.h sql_acl.h sql_crypt.h  \
@@ -74,7 +74,7 @@ mysqld_SOURCES =	sql_lex.cc sql_handler.cc \
 			time.cc opt_range.cc opt_sum.cc opt_ft.cc \
 		   	records.cc filesort.cc handler.cc \
 		        ha_heap.cc ha_myisam.cc ha_myisammrg.cc \
-	                ha_berkeley.cc ha_innobase.cc \
+	                ha_berkeley.cc ha_innodb.cc \
 			ha_isam.cc ha_isammrg.cc \
 			sql_db.cc sql_table.cc sql_rename.cc sql_crypt.cc \
 			sql_load.cc mf_iocache.cc field_conv.cc sql_show.cc \

sql/ha_berkeley.cc

@@ -1454,6 +1454,37 @@ int ha_berkeley::index_read(byte * buf, const byte * key,
   DBUG_RETURN(error);
 }
 
+/*
+  Read last key is solved by reading the next key and then reading
+  the previous key
+*/
+
+int ha_berkeley::index_read_last(byte * buf, const byte * key, uint key_len)
+{
+  DBT row;
+  int error;
+  KEY *key_info= &table->key_info[active_index];
+  DBUG_ENTER("ha_berkeley::index_read");
+
+  statistic_increment(ha_read_key_count,&LOCK_status);
+  bzero((char*) &row,sizeof(row));
+
+  /* read of partial key */
+  pack_key(&last_key, active_index, key_buff, key, key_len);
+  /* Store for compare */
+  memcpy(key_buff2, key_buff, (key_len=last_key.size));
+  key_info->handler.bdb_return_if_eq= 1;
+  error=read_row(cursor->c_get(cursor, &last_key, &row, DB_SET_RANGE),
+		 (char*) buf, active_index, &row, (DBT*) 0, 0);
+  key_info->handler.bdb_return_if_eq= 0;
+  bzero((char*) &row,sizeof(row));
+  if (read_row(cursor->c_get(cursor, &last_key, &row, DB_PREV),
+	       (char*) buf, active_index, &row, &last_key, 1) ||
+      berkeley_key_cmp(table, key_info, key_buff2, key_len))
+    error=HA_ERR_KEY_NOT_FOUND;
+  DBUG_RETURN(error);
+}
+
 
 int ha_berkeley::index_next(byte * buf)
 {

sql/ha_berkeley.h

@@ -89,7 +89,7 @@ class ha_berkeley: public handler
     int_option_flag(HA_READ_NEXT | HA_READ_PREV |
 		    HA_REC_NOT_IN_SEQ |
 		    HA_KEYPOS_TO_RNDPOS | HA_READ_ORDER | HA_LASTKEY_ORDER |
-		    HA_LONGLONG_KEYS | HA_NULL_KEY | HA_HAVE_KEY_READ_ONLY |
+		    HA_NULL_KEY | HA_HAVE_KEY_READ_ONLY |
 		    HA_BLOB_KEY | HA_NOT_EXACT_COUNT |
 		    HA_PRIMARY_KEY_IN_READ_INDEX | HA_DROP_BEFORE_CREATE |
 		    HA_AUTO_PART_KEY),
@@ -123,6 +123,7 @@ class ha_berkeley: public handler
 		 uint key_len, enum ha_rkey_function find_flag);
   int index_read_idx(byte * buf, uint index, const byte * key,
 		     uint key_len, enum ha_rkey_function find_flag);
+  int index_read_last(byte * buf, const byte * key, uint key_len);
   int index_next(byte * buf);
   int index_next_same(byte * buf, const byte *key, uint keylen);
   int index_prev(byte * buf);

sql/ha_heap.cc

@@ -57,6 +57,7 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
     for (part=0 ; part < pos->key_parts ; part++)
     {
       uint flag=pos->key_part[part].key_type;
+      Field *field=pos->key_part[part].field;
       if (!f_is_packed(flag) &&
 	  f_packtype(flag) == (int) FIELD_TYPE_DECIMAL &&
 	  !(flag & FIELDFLAG_BINARY))
@@ -65,7 +66,17 @@ int ha_heap::open(const char *name, int mode, uint test_if_locked)
 	seg->type= (int) HA_KEYTYPE_BINARY;
       seg->start=(uint) pos->key_part[part].offset;
       seg->length=(uint) pos->key_part[part].length;
-      seg++;
+      if (field->null_ptr)
+      {
+	seg->null_bit=field->null_bit;
+	seg->null_pos= (uint) (field->null_ptr-
+			       (uchar*) table->record[0]);
+      }
+      else
+      {
+	seg->null_bit=0;
+	seg->null_pos=0;
+      }
     }
   }
   mem_per_row += MY_ALIGN(table->reclength+1, sizeof(char*));

sql/ha_heap.h

@@ -36,7 +36,7 @@ class ha_heap: public handler
   ulong option_flag() const
   { return (HA_READ_RND_SAME | HA_NO_INDEX | HA_ONLY_WHOLE_INDEX |
 	    HA_WRONG_ASCII_ORDER | HA_KEYPOS_TO_RNDPOS | HA_NO_BLOBS |
-	    HA_REC_NOT_IN_SEQ); }
+	    HA_NULL_KEY | HA_REC_NOT_IN_SEQ | HA_NOT_READ_PREFIX_LAST); }
   uint max_record_length() const { return HA_MAX_REC_LENGTH; }
   uint max_keys()          const { return MAX_KEY; }
   uint max_key_parts()     const { return MAX_REF_PARTS; }

sql/ha_innobase.cc → sql/ha_innodb.cc

@@ -35,7 +35,7 @@ InnoDB */
 
 #define MAX_ULONG_BIT ((ulong) 1 << (sizeof(ulong)*8-1))
 
-#include "ha_innobase.h"
+#include "ha_innodb.h"
 
 /* We must declare this here because we undef SAFE_MUTEX below */
 pthread_mutex_t innobase_mutex;
@@ -2008,6 +2008,24 @@ ha_innobase::index_read(
 	DBUG_RETURN(error);
 }
 
+
+/*
+  The following functions works like index_read, but it find the last
+  row with the current index prefix.
+  This code is disabled until Heikki has verified that InnoDB support the
+  HA_READ_PREFIX_LAST flag and removed the HA_NOT_READ_PREFIX_LAST
+  flag from ha_innodb.h
+*/
+
+int
+ha_innobase::index_read_last(mysql_byte *buf,
+			     const mysql_byte *key_ptr,
+			     uint key_len)
+{
+  return index_read(buf, key_ptr, key_len, HA_READ_PREFIX_LAST);
+}
+
+
 /************************************************************************
 Changes the active index of a handle. */
 

sql/ha_innobase.h → sql/ha_innodb.h

-/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
-   && Innobase Oy
-
-   -This file is modified from ha_berkeley.h of MySQL distribution-
+/* Copyright (C) 2000 MySQL AB && Innobase Oy
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -17,13 +14,17 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
+/*
+  This file is based on ha_berkeley.h of MySQL distribution
+
+  This file defines the Innodb handler: the interface between MySQL and
+  Innodb
+*/
+
 #ifdef __GNUC__
 #pragma interface			/* gcc class implementation */
 #endif
 
-/* This file defines the Innobase handler: the interface between MySQL and
-Innobase */
-
 typedef struct st_innobase_share {
   THR_LOCK lock;
   pthread_mutex_t mutex;
@@ -32,11 +33,11 @@ typedef struct st_innobase_share {
 } INNOBASE_SHARE;
 
 
-/* The class defining a handle to an Innobase table */
+/* The class defining a handle to an Innodb table */
 class ha_innobase: public handler
 {
 	void*	innobase_prebuilt;	/* (row_prebuilt_t*) prebuilt
-					struct in Innobase, used to save
+					struct in Innodb, used to save
 					CPU */
 	THD*		user_thd;	/* the thread handle of the user
 					currently using the handle; this is
@@ -50,7 +51,7 @@ class ha_innobase: public handler
   	byte*		upd_buff;	/* buffer used in updates */
   	byte*		key_val_buff;	/* buffer used in converting
   					search key values from MySQL format
-  					to Innobase format */
+  					to Innodb format */
 	uint		ref_stored_len;	/* length of the key value stored to
 					'ref' buffer of the handle, if any */
   	ulong 		int_option_flag;
@@ -78,11 +79,11 @@ class ha_innobase: public handler
 			  HA_REC_NOT_IN_SEQ |
 			  HA_KEYPOS_TO_RNDPOS | HA_LASTKEY_ORDER |
 			  HA_HAVE_KEY_READ_ONLY | HA_READ_NOT_EXACT_KEY |
-			  HA_LONGLONG_KEYS | HA_NULL_KEY |
+			  HA_NULL_KEY |
 			  HA_NOT_EXACT_COUNT |
 			  HA_NO_WRITE_DELAYED |
 			  HA_PRIMARY_KEY_IN_READ_INDEX |
-			  HA_DROP_BEFORE_CREATE |
+			  HA_DROP_BEFORE_CREATE | HA_NOT_READ_PREFIX_LAST |
 			  HA_NO_PREFIX_CHAR_KEYS),
 	  last_dup_key((uint) -1),
 	  start_of_scan(0)
@@ -125,6 +126,7 @@ class ha_innobase: public handler
 		       uint key_len, enum ha_rkey_function find_flag);
   	int index_read_idx(byte * buf, uint index, const byte * key,
 			   uint key_len, enum ha_rkey_function find_flag);
+	int index_read_last(byte * buf, const byte * key, uint key_len);
   	int index_next(byte * buf);
   	int index_next_same(byte * buf, const byte *key, uint keylen);
   	int index_prev(byte * buf);

sql/ha_isam.cc

@@ -109,6 +109,15 @@ int ha_isam::index_read_idx(byte * buf, uint index, const byte * key,
   return !error ? 0 : my_errno ? my_errno : -1;
 }
 
+int ha_isam::index_read_last(byte * buf, const byte * key, uint key_len)
+{
+  statistic_increment(ha_read_key_count,&LOCK_status);
+  int error=nisam_rkey(file, buf, active_index, key, key_len,
+		       HA_READ_PREFIX_LAST);
+  table->status=error ? STATUS_NOT_FOUND: 0;
+  return !error ? 0 : my_errno ? my_errno : -1;
+}
+
 int ha_isam::index_next(byte * buf)
 {
   statistic_increment(ha_read_next_count,&LOCK_status);

sql/ha_isam.h

@@ -33,7 +33,7 @@ class ha_isam: public handler
     int_option_flag(HA_READ_NEXT | HA_READ_PREV | HA_READ_RND_SAME |
 		    HA_KEYPOS_TO_RNDPOS | HA_READ_ORDER | HA_LASTKEY_ORDER |
 		    HA_HAVE_KEY_READ_ONLY | HA_READ_NOT_EXACT_KEY |
-		    HA_LONGLONG_KEYS | HA_KEY_READ_WRONG_STR | HA_DUPP_POS |
+		    HA_KEY_READ_WRONG_STR | HA_DUPP_POS |
 		    HA_NOT_DELETE_WITH_CACHE)
     {}
   ~ha_isam() {}
@@ -57,6 +57,7 @@ class ha_isam: public handler
 		 uint key_len, enum ha_rkey_function find_flag);
   int index_read_idx(byte * buf, uint idx, const byte * key,
 		     uint key_len, enum ha_rkey_function find_flag);
+  int index_read_last(byte * buf, const byte * key, uint key_len);
   int index_next(byte * buf);
   int index_prev(byte * buf);
   int index_first(byte * buf);

sql/ha_isammrg.h

@@ -32,8 +32,9 @@ class ha_isammrg: public handler
   ~ha_isammrg() {}
   const char *table_type() const { return "MRG_ISAM"; }
   const char **bas_ext() const;
-  ulong option_flag() const { return HA_READ_RND_SAME | HA_KEYPOS_TO_RNDPOS
-                                                      | HA_REC_NOT_IN_SEQ;}
+  ulong option_flag() const { return (HA_READ_RND_SAME | HA_KEYPOS_TO_RNDPOS |
+				      HA_NOT_READ_PREFIX_LAST |
+				      HA_REC_NOT_IN_SEQ); }
   uint max_record_length() const { return HA_MAX_REC_LENGTH; }
   uint max_keys()          const { return 0; }
   uint max_key_parts()     const { return 0; }

sql/ha_myisam.cc

@@ -777,6 +777,14 @@ int ha_myisam::index_read_idx(byte * buf, uint index, const byte * key,
   return error;
 }
 
+int ha_myisam::index_read_last(byte * buf, const byte * key, uint key_len)
+{
+  statistic_increment(ha_read_key_count,&LOCK_status);
+  int error=mi_rkey(file,buf,active_index, key, key_len, HA_READ_PREFIX_LAST);
+  table->status=error ? STATUS_NOT_FOUND: 0;
+  return error;
+}
+
 int ha_myisam::index_next(byte * buf)
 {
   statistic_increment(ha_read_next_count,&LOCK_status);
@@ -973,7 +981,7 @@ void ha_myisam::update_create_info(HA_CREATE_INFO *create_info)
 }
 
 
-int ha_myisam::create(const char *name, register TABLE *form,
+int ha_myisam::create(const char *name, register TABLE *table,
 		      HA_CREATE_INFO *info)
 {
   int error;
@@ -985,20 +993,20 @@ int ha_myisam::create(const char *name, register TABLE *form,
   MI_KEYDEF *keydef;
   MI_COLUMNDEF *recinfo,*recinfo_pos;
   MI_KEYSEG *keyseg;
-  uint options=form->db_options_in_use;
+  uint options=table->db_options_in_use;
   DBUG_ENTER("ha_myisam::create");
 
   type=HA_KEYTYPE_BINARY;				// Keep compiler happy
   if (!(my_multi_malloc(MYF(MY_WME),
-			&recinfo,(form->fields*2+2)*sizeof(MI_COLUMNDEF),
-			&keydef, form->keys*sizeof(MI_KEYDEF),
+			&recinfo,(table->fields*2+2)*sizeof(MI_COLUMNDEF),
+			&keydef, table->keys*sizeof(MI_KEYDEF),
 			&keyseg,
-			((form->key_parts + form->keys) * sizeof(MI_KEYSEG)),
+			((table->key_parts + table->keys) * sizeof(MI_KEYSEG)),
 			0)))
     DBUG_RETURN(1);
 
-  pos=form->key_info;
-  for (i=0; i < form->keys ; i++, pos++)
+  pos=table->key_info;
+  for (i=0; i < table->keys ; i++, pos++)
   {
     keydef[i].flag= (pos->flags & (HA_NOSAME | HA_FULLTEXT));
     keydef[i].seg=keyseg;
@@ -1041,7 +1049,7 @@ int ha_myisam::create(const char *name, register TABLE *form,
       {
 	keydef[i].seg[j].null_bit=field->null_bit;
 	keydef[i].seg[j].null_pos= (uint) (field->null_ptr-
-					   (uchar*) form->record[0]);
+					   (uchar*) table->record[0]);
       }
       else
       {
@@ -1059,19 +1067,19 @@ int ha_myisam::create(const char *name, register TABLE *form,
 	keydef[i].seg[j].flag|=HA_BLOB_PART;
 	/* save number of bytes used to pack length */
 	keydef[i].seg[j].bit_start= (uint) (field->pack_length() -
-					    form->blob_ptr_size);
+					    table->blob_ptr_size);
       }
     }
     keyseg+=pos->key_parts;
   }
 
   recpos=0; recinfo_pos=recinfo;
-  while (recpos < (uint) form->reclength)
+  while (recpos < (uint) table->reclength)
   {
     Field **field,*found=0;
-    minpos=form->reclength; length=0;
+    minpos=table->reclength; length=0;
 
-    for (field=form->field ; *field ; field++)
+    for (field=table->field ; *field ; field++)
     {
       if ((fieldpos=(*field)->offset()) >= recpos &&
 	  fieldpos <= minpos)
@@ -1117,7 +1125,7 @@ int ha_myisam::create(const char *name, register TABLE *form,
     {
       recinfo_pos->null_bit=found->null_bit;
       recinfo_pos->null_pos= (uint) (found->null_ptr-
-				  (uchar*) form->record[0]);
+				  (uchar*) table->record[0]);
     }
     else
     {
@@ -1132,20 +1140,23 @@ int ha_myisam::create(const char *name, register TABLE *form,
   }
   MI_CREATE_INFO create_info;
   bzero((char*) &create_info,sizeof(create_info));
-  create_info.max_rows=form->max_rows;
-  create_info.reloc_rows=form->min_rows;
+  create_info.max_rows=table->max_rows;
+  create_info.reloc_rows=table->min_rows;
   create_info.auto_increment=(info->auto_increment_value ?
 			      info->auto_increment_value -1 :
 			      (ulonglong) 0);
-  create_info.data_file_length=(ulonglong) form->max_rows*form->avg_row_length;
+  create_info.data_file_length= ((ulonglong) table->max_rows *
+				 table->avg_row_length);
   create_info.raid_type=info->raid_type;
-  create_info.raid_chunks=info->raid_chunks ? info->raid_chunks : RAID_DEFAULT_CHUNKS;
-  create_info.raid_chunksize=info->raid_chunksize ? info->raid_chunksize : RAID_DEFAULT_CHUNKSIZE;
+  create_info.raid_chunks= (info->raid_chunks ? info->raid_chunks :
+			    RAID_DEFAULT_CHUNKS);
+  create_info.raid_chunksize=(info->raid_chunksize ? info->raid_chunksize :
+			      RAID_DEFAULT_CHUNKSIZE);
   create_info.data_file_name= info->data_file_name;
   create_info.index_file_name=info->index_file_name;
 
   error=mi_create(fn_format(buff,name,"","",2+4),
-		  form->keys,keydef,
+		  table->keys,keydef,
 		  (uint) (recinfo_pos-recinfo), recinfo,
 		  0, (MI_UNIQUEDEF*) 0,
 		  &create_info,

sql/ha_myisam.h

@@ -47,7 +47,7 @@ class ha_myisam: public handler
     int_option_flag(HA_READ_NEXT | HA_READ_PREV | HA_READ_RND_SAME |
 		    HA_KEYPOS_TO_RNDPOS | HA_READ_ORDER | HA_LASTKEY_ORDER |
 		    HA_HAVE_KEY_READ_ONLY | HA_READ_NOT_EXACT_KEY |
-		    HA_LONGLONG_KEYS | HA_NULL_KEY |
+		    HA_NULL_KEY |
                     HA_CAN_FULLTEXT | HA_CAN_SQL_HANDLER |
 		    HA_DUPP_POS | HA_BLOB_KEY | HA_AUTO_PART_KEY),
     enable_activate_all_index(1)
@@ -71,6 +71,7 @@ class ha_myisam: public handler
 		 uint key_len, enum ha_rkey_function find_flag);
   int index_read_idx(byte * buf, uint idx, const byte * key,
 		     uint key_len, enum ha_rkey_function find_flag);
+  int index_read_last(byte * buf, const byte * key, uint key_len);
   int index_next(byte * buf);
   int index_prev(byte * buf);
   int index_first(byte * buf);
@@ -78,8 +79,14 @@ class ha_myisam: public handler
   int index_next_same(byte *buf, const byte *key, uint keylen);
   int index_end() { ft_handler=NULL; return 0; }
   int ft_init()
-         { if(!ft_handler) return 1; ft_handler->please->reinit_search(ft_handler); return 0; }
-  FT_INFO *ft_init_ext(uint mode, uint inx,const byte *key, uint keylen, bool presort)
+  {
+    if (!ft_handler)
+      return 1;
+    ft_handler->please->reinit_search(ft_handler);
+    return 0;
+  }
+  FT_INFO *ft_init_ext(uint mode, uint inx,const byte *key, uint keylen,
+		       bool presort)
   { return ft_init_search(mode, file,inx,(byte*) key,keylen,presort); }
   int ft_read(byte *buf);
   int rnd_init(bool scan=1);

sql/ha_myisammrg.cc

@@ -112,6 +112,15 @@ int ha_myisammrg::index_read_idx(byte * buf, uint index, const byte * key,
   return error;
 }
 
+int ha_myisammrg::index_read_last(byte * buf, const byte * key, uint key_len)
+{
+  statistic_increment(ha_read_key_count,&LOCK_status);
+  int error=myrg_rkey(file,buf,active_index, key, key_len,
+		      HA_READ_PREFIX_LAST);
+  table->status=error ? STATUS_NOT_FOUND: 0;
+  return error;
+}
+
 int ha_myisammrg::index_next(byte * buf)
 {
   statistic_increment(ha_read_next_count,&LOCK_status);

sql/ha_myisammrg.h

@@ -38,7 +38,7 @@ class ha_myisammrg: public handler
 	      HA_HAVE_KEY_READ_ONLY |
 	      HA_KEYPOS_TO_RNDPOS | HA_READ_ORDER |
 	      HA_LASTKEY_ORDER | HA_READ_NOT_EXACT_KEY |
-	      HA_LONGLONG_KEYS | HA_NULL_KEY | HA_BLOB_KEY); }
+	      HA_NULL_KEY | HA_BLOB_KEY); }
   uint max_record_length() const { return HA_MAX_REC_LENGTH; }
   uint max_keys()          const { return MI_MAX_KEY; }
   uint max_key_parts()     const { return MAX_REF_PARTS; }
@@ -55,6 +55,7 @@ class ha_myisammrg: public handler
 		 uint key_len, enum ha_rkey_function find_flag);
   int index_read_idx(byte * buf, uint idx, const byte * key,
 		     uint key_len, enum ha_rkey_function find_flag);
+  int index_read_last(byte * buf, const byte * key, uint key_len);
   int index_next(byte * buf);
   int index_prev(byte * buf);
   int index_first(byte * buf);

sql/handler.cc

@@ -33,7 +33,7 @@
 #include "ha_berkeley.h"
 #endif
 #ifdef HAVE_INNOBASE_DB
-#include "ha_innobase.h"
+#include "ha_innodb.h"
 #endif
 #include <myisampack.h>
 #include <errno.h>

sql/handler.h

@@ -55,12 +55,11 @@
 #define HA_REC_NOT_IN_SEQ	64	/* ha_info don't return recnumber;
 					   It returns a position to ha_r_rnd */
 #define HA_ONLY_WHOLE_INDEX	128	/* Can't use part key searches */
-#define HA_RSAME_NO_INDEX	256	/* RSAME can't restore index */
+#define HA_NOT_READ_PREFIX_LAST	256	/* RSAME can't restore index */
 #define HA_WRONG_ASCII_ORDER	512	/* Can't use sorting through key */
 #define HA_HAVE_KEY_READ_ONLY	1024	/* Can read only keys (no record) */
 #define HA_READ_NOT_EXACT_KEY	2048	/* Can read record after/before key */
 #define HA_NO_INDEX		4096	/* No index needed for next/prev */
-#define HA_LONGLONG_KEYS	8192	/* Can have longlong as key */
 #define HA_KEY_READ_WRONG_STR	16384	/* keyread returns converted strings */
 #define HA_NULL_KEY		32768	/* One can have keys with NULL */
 #define HA_DUPP_POS		65536	/* ha_position() gives dupp row */
@@ -256,6 +255,10 @@ public:
   virtual int index_first(byte * buf)=0;
   virtual int index_last(byte * buf)=0;
   virtual int index_next_same(byte *buf, const byte *key, uint keylen);
+  virtual int index_read_last(byte * buf, const byte * key, uint key_len)
+  {
+    return (my_errno=HA_ERR_WRONG_COMMAND);
+  }
   virtual int ft_init()
     { return -1; }
   virtual FT_INFO *ft_init_ext(uint mode,uint inx,const byte *key, uint keylen,

sql/mysqld.cc

@@ -27,7 +27,7 @@
 #include "ha_berkeley.h"
 #endif
 #ifdef HAVE_INNOBASE_DB
-#include "ha_innobase.h"
+#include "ha_innodb.h"
 #endif
 #include "ha_myisam.h"
 #include <nisam.h>

sql/sql_delete.cc

@@ -24,7 +24,7 @@
 
 
 #include "mysql_priv.h"
-#include "ha_innobase.h"
+#include "ha_innodb.h"
 #include "sql_select.h"
 
 int mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds, ORDER *order,

sql/sql_select.cc

@@ -89,15 +89,18 @@ static int join_read_system(JOIN_TAB *tab);
 static int join_read_const(JOIN_TAB *tab);
 static int join_read_key(JOIN_TAB *tab);
 static int join_read_always_key(JOIN_TAB *tab);
+static int join_read_last_key(JOIN_TAB *tab);
 static int join_no_more_records(READ_RECORD *info);
 static int join_read_next(READ_RECORD *info);
 static int join_init_quick_read_record(JOIN_TAB *tab);
 static int test_if_quick_select(JOIN_TAB *tab);
 static int join_init_read_record(JOIN_TAB *tab);
-static int join_init_read_first_with_key(JOIN_TAB *tab);
-static int join_init_read_next_with_key(READ_RECORD *info);
-static int join_init_read_last_with_key(JOIN_TAB *tab);
-static int join_init_read_prev_with_key(READ_RECORD *info);
+static int join_read_first(JOIN_TAB *tab);
+static int join_read_next(READ_RECORD *info);
+static int join_read_next_same(READ_RECORD *info);
+static int join_read_last(JOIN_TAB *tab);
+static int join_read_prev_same(READ_RECORD *info);
+static int join_read_prev(READ_RECORD *info);
 static int join_ft_read_first(JOIN_TAB *tab);
 static int join_ft_read_next(READ_RECORD *info);
 static COND *make_cond_for_table(COND *cond,table_map table,
@@ -2510,7 +2513,7 @@ make_join_readinfo(JOIN *join,uint options)
       tab->quick=0;
       table->file->index_init(tab->ref.key);
       tab->read_first_record= join_read_always_key;
-      tab->read_record.read_record= join_read_next;
+      tab->read_record.read_record= join_read_next_same;
       if (table->used_keys & ((key_map) 1 << tab->ref.key) &&
 	  !table->no_keyread)
       {
@@ -2585,7 +2588,7 @@ make_join_readinfo(JOIN *join,uint options)
 	  {					// Only read index tree
 	    tab->index=find_shortest_key(table, table->used_keys);
 	    tab->table->file->index_init(tab->index);
-	    tab->read_first_record= join_init_read_first_with_key;
+	    tab->read_first_record= join_read_first;
 	    tab->type=JT_NEXT;		// Read with index_first / index_next
 	  }
 	}
@@ -3641,6 +3644,10 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
     {
       if (field->flags & GROUP_FLAG && !using_unique_constraint)
       {
+	/*
+	  We have to reserve one byte here for NULL bits,
+	  as this is updated by 'end_update()'
+	*/
 	*pos++=0;				// Null is stored here
 	recinfo->length=1;
 	recinfo->type=FIELD_NORMAL;
@@ -3730,11 +3737,11 @@ create_tmp_table(THD *thd,TMP_TABLE_PARAM *param,List<Item> &fields,
 	{
 	  /*
 	    To be able to group on NULL, we move the null bit to be
-	     just before the column and extend the key to cover the null bit
+	    just before the column.
+	    The null byte is updated by 'end_update()' 
 	  */
-	  *group_buff= 0;			// Init null byte
-	  key_part_info->offset--;
-	  key_part_info->length++;
+	  key_part_info->null_bit=1;
+	  key_part_info->null_offset= key_part_info->offset-1;
 	  group->field->move_field((char*) group_buff+1, (uchar*) group_buff,
 				   1);
 	}
@@ -4497,6 +4504,35 @@ join_read_always_key(JOIN_TAB *tab)
   return 0;
 }
 
+/*
+  This function is used when optimizing away ORDER BY in 
+  SELECT * FROM t1 WHERE a=1 ORDER BY a DESC,b DESC
+*/
+  
+static int
+join_read_last_key(JOIN_TAB *tab)
+{
+  int error;
+  TABLE *table= tab->table;
+
+  if (cp_buffer_from_ref(&tab->ref))
+    return -1;
+  if ((error=table->file->index_read_last(table->record[0],
+					  tab->ref.key_buff,
+					  tab->ref.key_length)))
+  {
+    if (error != HA_ERR_KEY_NOT_FOUND)
+    {
+      sql_print_error("read_const: Got error %d when reading table %s",error,
+		      table->path);
+      table->file->print_error(error,MYF(0));
+      return 1;
+    }
+    return -1; /* purecov: inspected */
+  }
+  return 0;
+}
+
 
 	/* ARGSUSED */
 static int
@@ -4507,7 +4543,7 @@ join_no_more_records(READ_RECORD *info __attribute__((unused)))
 
 
 static int
-join_read_next(READ_RECORD *info)
+join_read_next_same(READ_RECORD *info)
 {
   int error;
   TABLE *table= info->table;
@@ -4530,6 +4566,37 @@ join_read_next(READ_RECORD *info)
   return 0;
 }
 
+static int
+join_read_prev_same(READ_RECORD *info)
+{
+  int error;
+  TABLE *table= info->table;
+  JOIN_TAB *tab=table->reginfo.join_tab;
+
+  if ((error=table->file->index_prev(table->record[0])))
+  {
+    if (error != HA_ERR_END_OF_FILE)
+    {
+      sql_print_error("read_next: Got error %d when reading table %s",error,
+		      table->path);
+      table->file->print_error(error,MYF(0));
+      error= 1;
+    }
+    else
+    {
+      table->status= STATUS_GARBAGE;
+      error= -1;
+    }
+  }
+  else if (key_cmp(table, tab->ref.key_buff, tab->ref.key,
+		   tab->ref.key_length))
+  {
+    table->status=STATUS_NOT_FOUND;
+    error= 1;
+  }
+  return error;
+}
+
 
 static int
 join_init_quick_read_record(JOIN_TAB *tab)
@@ -4560,7 +4627,7 @@ join_init_read_record(JOIN_TAB *tab)
 }
 
 static int
-join_init_read_first_with_key(JOIN_TAB *tab)
+join_read_first(JOIN_TAB *tab)
 {
   int error;
   TABLE *table=tab->table;
@@ -4571,7 +4638,7 @@ join_init_read_first_with_key(JOIN_TAB *tab)
     table->file->extra(HA_EXTRA_KEYREAD);
   }
   tab->table->status=0;
-  tab->read_record.read_record=join_init_read_next_with_key;
+  tab->read_record.read_record=join_read_next;
   tab->read_record.table=table;
   tab->read_record.file=table->file;
   tab->read_record.index=tab->index;
@@ -4591,8 +4658,9 @@ join_init_read_first_with_key(JOIN_TAB *tab)
   return 0;
 }
 
+
 static int
-join_init_read_next_with_key(READ_RECORD *info)
+join_read_next(READ_RECORD *info)
 {
   int error=info->file->index_next(info->record);
   if (error)
@@ -4609,9 +4677,8 @@ join_init_read_next_with_key(READ_RECORD *info)
   return 0;
 }
 
-
 static int
-join_init_read_last_with_key(JOIN_TAB *tab)
+join_read_last(JOIN_TAB *tab)
 {
   TABLE *table=tab->table;
   int error;
@@ -4621,7 +4688,7 @@ join_init_read_last_with_key(JOIN_TAB *tab)
     table->file->extra(HA_EXTRA_KEYREAD);
   }
   tab->table->status=0;
-  tab->read_record.read_record=join_init_read_prev_with_key;
+  tab->read_record.read_record=join_read_prev;
   tab->read_record.table=table;
   tab->read_record.file=table->file;
   tab->read_record.index=tab->index;
@@ -4641,8 +4708,9 @@ join_init_read_last_with_key(JOIN_TAB *tab)
   return 0;
 }
 
+
 static int
-join_init_read_prev_with_key(READ_RECORD *info)
+join_read_prev(READ_RECORD *info)
 {
   int error=info->file->index_prev(info->record);
   if (error)
@@ -4659,6 +4727,7 @@ join_init_read_prev_with_key(READ_RECORD *info)
   return 0;
 }
 
+
 static int
 join_ft_read_first(JOIN_TAB *tab)
 {
@@ -4734,7 +4803,8 @@ end_send(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
       if (join->select_options & OPTION_FOUND_ROWS)
       {
 	JOIN_TAB *jt=join->join_tab;
-	if ((join->tables == 1) && !join->tmp_table && !join->sort_and_group && !join->send_group_parts && !join->having && !jt->select_cond )
+	if ((join->tables == 1) && !join->tmp_table && !join->sort_and_group
+	    && !join->send_group_parts && !join->having && !jt->select_cond)
 	{
 	  join->select_options ^= OPTION_FOUND_ROWS;
 	  join->send_records = jt->records;
@@ -5315,6 +5385,9 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
 
   if (ref_key >= 0)
   {
+    /*
+      We come here when there is a REF key.
+    */
     int order_direction;
     uint used_key_parts;
     /* Check if we get the rows in requested sorted order by using the key */
@@ -5322,11 +5395,11 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
 	(order_direction = test_if_order_by_key(order,table,ref_key,
 						&used_key_parts)))
     {
-      if (order_direction == -1)
+      if (order_direction == -1)		// If ORDER BY ... DESC
       {
 	if (select && select->quick)
 	{
-	  // ORDER BY ref_key DESC
+	  // ORDER BY range_key DESC
 	  QUICK_SELECT_DESC *tmp=new QUICK_SELECT_DESC(select->quick,
 						       used_key_parts);
 	  if (!tmp || tmp->error)
@@ -5341,11 +5414,15 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
 	{
 	  /*
 	    SELECT * FROM t1 WHERE a=1 ORDER BY a DESC,b DESC
-	    TODO:
-	    Add a new traversal function to read last matching row and
-	    traverse backwards.
+
+	    Use a traversal function that starts by reading the last row
+	    with key part (A) and then traverse the index backwards.
 	  */
-	  DBUG_RETURN(0);
+	  if (table->file->option_flag() & HA_NOT_READ_PREFIX_LAST)
+	    DBUG_RETURN(1);
+	  tab->read_first_record=       join_read_last_key;
+	  tab->read_record.read_record= join_read_prev_same;
+	  /* fall through */
 	}
       }
       DBUG_RETURN(1);			/* No need to sort */
@@ -5377,8 +5454,8 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
 	  if (!no_changes)
 	  {
 	    tab->index=nr;
-	    tab->read_first_record=  (flag > 0 ? join_init_read_first_with_key:
-				      join_init_read_last_with_key);
+	    tab->read_first_record=  (flag > 0 ? join_read_first:
+				      join_read_last);
 	    table->file->index_init(nr);
 	    tab->type=JT_NEXT;	// Read with index_first(), index_next()
 	    if (table->used_keys & ((key_map) 1 << nr))
@@ -6369,7 +6446,8 @@ get_sort_by_table(ORDER *a,ORDER *b,TABLE_LIST *tables)
 static void
 calc_group_buffer(JOIN *join,ORDER *group)
 {
-  uint key_length=0,parts=0;
+  uint key_length=0, parts=0, null_parts=0;
+
   if (group)
     join->group= 1;
   for (; group ; group=group->next)
@@ -6390,10 +6468,11 @@ calc_group_buffer(JOIN *join,ORDER *group)
       key_length+=(*group->item)->max_length;
     parts++;
     if ((*group->item)->maybe_null)
-      key_length++;
+      null_parts++;
   }
-  join->tmp_table_param.group_length=key_length;
+  join->tmp_table_param.group_length=key_length+null_parts;
   join->tmp_table_param.group_parts=parts;
+  join->tmp_table_param.group_null_parts=null_parts;
 }
 
 

sql/sql_select.h

@@ -127,12 +127,13 @@ class TMP_TABLE_PARAM {
   ha_rows end_write_records;
   uint	field_count,sum_func_count,func_count;
   uint  hidden_field_count;
-  uint	group_parts,group_length;
+  uint	group_parts,group_length,group_null_parts;
   uint	quick_group;
   bool  using_indirect_summary_function;
 
   TMP_TABLE_PARAM()
-    :copy_funcs_it(copy_funcs), copy_field(0), group_parts(0), group_length(0)
+    :copy_funcs_it(copy_funcs), copy_field(0), group_parts(0),
+    group_length(0), group_null_parts(0)
   {}
   ~TMP_TABLE_PARAM()
   {