Bug#26827 - table->read_set is set incorrectly,

          causing update of a different column

For efficiency some storage engines do not read a complete record
for update, but only the columns required for selecting the rows.

When updating a row of a partitioned table, modifying a column
that is part of the partition or subpartition expression, then
the row may need to move from one [sub]partition to another one.
This is done by inserting the new row into the target
[sub]partition and deleting the old row from the originating one.
For the insert we need a complete record.

If an above mentioned engine was used for a partitioned table, we
did not have a complete record in update_row(). The implicitly
executed write_row() got an incomplete record.

This is solved by instructing the engine to read a complete record
if one of the columns of the partition or subpartiton is to be
updated.

No testcase. This can be reproduced with Falcon only. The engines
contained in standard 5.1 do always return complete records on
update.


sql/ha_partition.cc:
  Bug#26827 - table->read_set is set incorrectly,
              causing update of a different column
  Setting partition field bits in read_set if a writing
  operation is going on. This replaces the old function
  include_partition_fields_in_used_fields().
  Setting all bits in read_set if write_set contains a column
  used in a partition or subpartition expression.
  Removed include_partition_fields_in_used_fields().
sql/ha_partition.h:
  Bug#26827 - table->read_set is set incorrectly,
              causing update of a different column
  Removed declaration of
  include_partition_fields_in_used_fields().
sql/partition_info.h:
  Bug#26827 - table->read_set is set incorrectly,
              causing update of a different column
  Added a bitmap to partition_info for a quick check of
  columns used in a partition or subpartition expression.
sql/sql_partition.cc:
  Bug#26827 - table->read_set is set incorrectly,
              causing update of a different column
  Initializing the new bitmap with all columns used in a
  partition or subpartition expression.

1 files changed, 33 insertions, 2 deletions

diff --git a/sql/sql_partition.cc b/sql/sql_partition.cc
index ad3cf2d3e7a..a44af968d9f 100644
--- a/sql/sql_partition.cc
+++ b/sql/sql_partition.cc
@@ -523,6 +523,7 @@ static bool set_up_field_array(TABLE *table,
 
   SYNOPSIS
     create_full_part_field_array()
+    thd                  Thread handle
     table                TABLE object for which partition fields are set-up
     part_info            Reference to partitioning data structure
 
@@ -537,11 +538,12 @@ static bool set_up_field_array(TABLE *table,
     This function is called from fix_partition_func
 */
 
-static bool create_full_part_field_array(TABLE *table,
+static bool create_full_part_field_array(THD *thd, TABLE *table,
                                          partition_info *part_info)
 {
   bool result= FALSE;
   Field **ptr;
+  my_bitmap_map *bitmap_buf;
   DBUG_ENTER("create_full_part_field_array");
 
   if (!part_info->is_sub_partitioned())
@@ -578,6 +580,35 @@ static bool create_full_part_field_array(TABLE *table,
     part_info->full_part_field_array= field_array;
     part_info->no_full_part_fields= no_part_fields;
   }
+
+  /*
+    Initialize the set of all fields used in partition and subpartition
+    expression. Required for testing of partition fields in write_set
+    when updating. We need to set all bits in read_set because the row
+    may need to be inserted in a different [sub]partition.
+  */
+  if (!(bitmap_buf= (my_bitmap_map*)
+        thd->alloc(bitmap_buffer_size(table->s->fields))))
+  {
+    mem_alloc_error(bitmap_buffer_size(table->s->fields));
+    result= TRUE;
+    goto end;
+  }
+  if (bitmap_init(&part_info->full_part_field_set, bitmap_buf,
+                  table->s->fields, FALSE))
+  {
+    mem_alloc_error(table->s->fields);
+    result= TRUE;
+    goto end;
+  }
+  /*
+    full_part_field_array may be NULL if storage engine supports native
+    partitioning.
+  */
+  if ((ptr= part_info->full_part_field_array))
+    while (*ptr)
+      bitmap_set_bit(&part_info->full_part_field_set, (*ptr++)->field_index);
+
 end:
   DBUG_RETURN(result);
 }
@@ -1636,7 +1667,7 @@ bool fix_partition_func(THD *thd, TABLE *table,
     my_error(ER_PARTITION_FUNCTION_IS_NOT_ALLOWED, MYF(0));
     goto end;
   }
-  if (unlikely(create_full_part_field_array(table, part_info)))
+  if (unlikely(create_full_part_field_array(thd, table, part_info)))
     goto end;
   if (unlikely(check_primary_key(table)))
     goto end;