bk commit into 5.1 tree (mronstrom:1.2051)

[mikael]

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ChangeSet
  1.2051 05/10/29 19:50:50 mronstrom@stripped +1 -0
  A first step to WL #2537

  sql/sql_partition.cc
    1.32 05/10/29 19:50:20 mronstrom@stripped +53 -13
    A first step to WL #2537

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	mronstrom
# Host:	c-ef09e253.1238-1-64736c10.cust.bredbandsbolaget.se
# Root:	/Users/mikron/wl2537

--- 1.31/sql/sql_partition.cc	2005-10-25 23:48:44 +02:00
+++ 1.32/sql/sql_partition.cc	2005-10-29 19:50:20 +02:00
@@ -1113,14 +1113,16 @@
   SYNOPSIS
     set_indicator_in_key_fields
     key_info                  Reference to find the key fields
+    accept_part_key           Accept only parts of a key
 */
 
-static void set_indicator_in_key_fields(KEY *key_info)
+static void set_indicator_in_key_fields(KEY *key_info, bool accept_part_key)
 {
   KEY_PART_INFO *key_part;
   uint key_parts= key_info->key_parts, i;
   for (i= 0, key_part=key_info->key_part; i < key_parts; i++, key_part++)
-    key_part->field->flags|= GET_FIXED_FIELDS_FLAG;
+    if (accept_part_key || !(key_part->key_part_flag & HA_PART_KEY_SEG))
+      key_part->field->flags|= GET_FIXED_FIELDS_FLAG;
 }
 
 
@@ -1142,6 +1144,7 @@
                                bool *some_fields)
 {
   DBUG_ENTER("check_fields_in_PF");
+
   *all_fields= TRUE;
   *some_fields= FALSE;
   do
@@ -1371,7 +1374,7 @@
 
   if (primary_key < MAX_KEY)
   {
-    set_indicator_in_key_fields(table->key_info+primary_key);
+    set_indicator_in_key_fields(table->key_info+primary_key, TRUE);
     check_fields_in_PF(table->s->part_info->full_part_field_array,
                         &all_fields, &some_fields);
     clear_indicator_in_key_fields(table->key_info+primary_key);
@@ -1411,7 +1414,7 @@
   {
     if (table->key_info[i].flags & HA_NOSAME) //Unique index
     {
-      set_indicator_in_key_fields(table->key_info+i);
+      set_indicator_in_key_fields(table->key_info+i, TRUE);
       check_fields_in_PF(table->s->part_info->full_part_field_array,
                          &all_fields, &some_fields);
       clear_indicator_in_key_fields(table->key_info+i);
@@ -1446,26 +1449,63 @@
   3) Possible if PF is a growing function of the field
   4) Possible if PF is a shrinking function of the field
   OBSERVATION:
-  1) IF f1(A) is a growing function AND f2(A) is a growing function THEN
+  1) Plus operator
+     IF f1(A) is a growing function AND f2(A) is a growing function THEN
      f1(A) + f2(A) is a growing function
-     f1(A) * f2(A) is a growing function if f1(A) >= 0 and f2(A) >= 0
-  2) IF f1(A) is a growing function and f2(A) is a shrinking function THEN
+     IF f1(A) is a shrinking function and f2(A) is a shrinking function THEN
+     f1(A) + f2(A) is a shrinking function
+  2) Minus operator
+     IF f1(A) is a growing function and f2(A) is a shrinking function THEN
+     f1(A) - f2(A) is a growing function
+     IF f1(A) is a shrinking function and f2(A) is a growing function THEN
+     f1(A) - f2(A) is a shrinking function
+  3) Division operator
+     IF f1(A) is a growing function and f2(A) is a shrinking function THEN
      f1(A) / f2(A) is a growing function if f1(A) >= 0 and f2(A) > 0
-  3) IF A is a growing function then a function f(A) that removes the
+  4) Multiplication operator
+     IF (f1(A) is a growing function AND f2(A) is a growing function) OR
+        (f1(A) is a shrinking function AND f2(A) is a shrinking function)
+     THEN
+     f1(A) * f2(A) is a growing function if f1(A) >= 0 and f2(A) >= 0 or
+     if f1(A) <= 0 and f2(A) <= 0
+  5) SHIFT LEFT operator
+     Shift left is a multiplication operator if number of shifts is > 0
+  6) SHIFT RIGHT operator
+     Shift right is a division operator if number of shifts is > 0
+  7) IF A is a growing function then a function f(A) that removes the
      least significant portion of A is a growing function
      E.g. DATE(datetime) is a growing function
      MONTH(datetime) is not a growing/shrinking function
-  4) IF f1(A) is a growing function and f2(A) is a growing function THEN
+  8) IF f1(A) is a growing function and f2(A) is a growing function THEN
      f1(f2(A)) and f2(f1(A)) are also growing functions
-  5) IF f1(A) is a shrinking function and f2(A) is a growing function THEN
+  9) IF f1(A) is a shrinking function and f2(A) is a growing function THEN
      f1(f2(A)) is a shrinking function and f2(f1(A)) is a shrinking function
-  6) f1(A) = A is a growing function
-  7) f1(A) = A*a + b (where a and b are constants) is a growing function
+  10) f1(A) = A is a growing function
+  11) f1(A) = A*a + b (where a and b are constants) is a growing function
 
   By analysing the item tree of the PF we can use these deducements and
   derive whether the PF is a growing function or a shrinking function or
   neither of it.
 
+  Now after all this theory we discover that unfortunately operators can
+  overflow. Thus the analysis above is only of value when there are no
+  overflow errors. Given that the item trees doesn't discover overflows
+  we'll skip the theory for now and leave it here as food for thought
+  for future MySQL Programmers.
+
+  In practice most people will either use a simple integer field for
+  partition function and this cannot overflow and by 10) it is a growing
+  function, thus we support that e.g. PARTITION BY RANGE(a).
+  It is also very popular with date ranges. To support this we support
+  the following function as range capable.
+  DATEDIFF
+  TIMESTAMPDIFF
+  TO_DAYS
+  YEAR
+  YEAR_WEEK
+
+  Later on I'm sure more functions can be added but these are a good start.
+
   If the PF is range capable then a flag is set on the table object
   indicating this to notify that we can use also ranges on the field
   of the PF to deduce a set of partitions if the fields of the PF were
@@ -1523,7 +1563,7 @@
   part_info->some_fields_in_PF.clear_all();
   for (i= 0; i < keys; i++)
   {
-    set_indicator_in_key_fields(table->key_info+i);
+    set_indicator_in_key_fields(table->key_info+i, FALSE);
     check_fields_in_PF(part_info->full_part_field_array,
                        &all_fields, &some_fields);
     if (all_fields)