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From:Ole John Aske Date:May 22 2012 9:25am
Subject:bzr push into mysql-trunk branch (ole.john.aske:3901 to 3902) WL#5940
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 3902 Ole John Aske	2012-05-22
      WL#5940: Forgot to 'bzr add' the abstract_query_plan files in the previous WL#5940 commit :-(

    added:
      sql/abstract_query_plan.cc
      sql/abstract_query_plan.h
 3901 Ole John Aske	2012-05-22
      WL#5940: Handler extension and optimizer addaption required for pushed joins.
      
       

    modified:
      sql/CMakeLists.txt
      sql/ha_ndbcluster.cc
      sql/ha_ndbcluster.h
      sql/handler.cc
      sql/handler.h
      sql/opt_explain.cc
      sql/opt_explain_format.h
      sql/opt_explain_json.cc
      sql/opt_explain_traditional.cc
      sql/sql_executor.cc
      sql/sql_optimizer.cc
      sql/sql_select.cc
=== added file 'sql/abstract_query_plan.cc'
--- a/sql/abstract_query_plan.cc	1970-01-01 00:00:00 +0000
+++ b/sql/abstract_query_plan.cc	2012-05-22 09:24:50 +0000
@@ -0,0 +1,528 @@
+/*
+   Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
+
+   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
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
+*/
+
+#include "sql_priv.h"
+#include "sql_select.h"
+#include "sql_optimizer.h"
+#include "abstract_query_plan.h"
+
+
+namespace AQP
+{
+
+  /**
+    @param join_tab Array of access methods constituting the nested loop join.
+    @param access_count Length of array.
+  */
+  Join_plan::Join_plan(const JOIN* join)
+   : m_join_tabs(join->join_tab),
+     m_access_count(join->tables),
+     m_table_accesses(NULL)
+  {
+    /*
+      This combination is assumed not to appear. If it does, code must
+      be written to handle it.
+    */
+    DBUG_ASSERT((m_join_tabs[0].use_quick != 2)
+                || (m_join_tabs[0].type == JT_ALL)
+                || (m_join_tabs[0].select == NULL)
+                || (m_join_tabs[0].select->quick == NULL));
+
+    m_table_accesses= new Table_access[m_access_count];
+    for(uint i= 0; i < m_access_count; i++)
+    {
+      m_table_accesses[i].m_join_plan= this; 
+      m_table_accesses[i].m_tab_no= i;
+    }
+  }
+
+  Join_plan::~Join_plan()
+  {
+    delete[] m_table_accesses;
+    m_table_accesses= NULL;
+  }
+
+  /** Get the JOIN_TAB of the n'th table access operation.*/
+  const JOIN_TAB* Join_plan::get_join_tab(uint join_tab_no) const
+  {
+    DBUG_ASSERT(join_tab_no < m_access_count);
+    return m_join_tabs + join_tab_no;
+  }
+
+  /**
+    Determine join type between this table access and some other table
+    access that preceeds it in the join plan..
+  */
+  enum_join_type 
+  Table_access::get_join_type(const Table_access* predecessor) const
+  {
+    DBUG_ENTER("get_join_type");
+    DBUG_ASSERT(get_access_no() > predecessor->get_access_no());
+
+    if (get_join_tab()->table->pos_in_table_list->outer_join != 0)
+    {
+      /*
+        This cover unnested outer joins such as 
+        'select * from t1 left join t2 on t1.attr=t1.pk'.
+       */
+      DBUG_PRINT("info", ("JT_OUTER_JOIN between %s and %s",
+                          predecessor->get_join_tab()->table->alias,
+                          get_join_tab()->table->alias));
+      DBUG_RETURN(JT_OUTER_JOIN);
+    }
+
+    const TABLE_LIST* const child_embedding= 
+      get_join_tab()->table->pos_in_table_list->embedding;
+
+    if (child_embedding == NULL)
+    {
+      // 'this' is not on the inner side of any left join.
+      DBUG_PRINT("info", ("JT_INNER_JOIN between %s and %s",
+                          predecessor->get_join_tab()->table->alias,
+                          get_join_tab()->table->alias));
+      DBUG_RETURN(JT_INNER_JOIN);
+    }
+
+    DBUG_ASSERT(child_embedding->outer_join != 0);
+
+    const TABLE_LIST *predecessor_embedding= 
+      predecessor->get_join_tab()->table->pos_in_table_list->embedding;
+
+    /*
+      This covers the nested join case, i.e:
+      <table reference> LEFT JOIN (<joined table>).
+      
+      TABLE_LIST objects form a tree where TABLE_LIST::emebedding points to
+      the parent object. Now if child_embedding is non null and not an 
+      ancestor of predecessor_embedding in the embedding tree, then 'this'
+      must be on the inner side of some left join where 'predecessor' is on 
+      the outer side.
+     */
+    while (true)
+    {
+      if (predecessor_embedding == child_embedding)
+      {
+        DBUG_PRINT("info", ("JT_INNER_JOIN between %s and %s",
+                            predecessor->get_join_tab()->table->alias,
+                            get_join_tab()->table->alias));
+        DBUG_RETURN(JT_INNER_JOIN);
+      }
+      else if (predecessor_embedding == NULL)
+      {
+        /*
+           We reached the root of the tree without finding child_embedding,
+           so it must be in another branch and hence on the inner side of some
+           left join where 'predecessor' is on the outer side.
+         */
+        DBUG_PRINT("info", ("JT_OUTER_JOIN between %s and %s",
+                            predecessor->get_join_tab()->table->alias,
+                            get_join_tab()->table->alias));
+        DBUG_RETURN(JT_OUTER_JOIN);
+      }
+      // Iterate through ancestors of predecessor_embedding.
+      predecessor_embedding = predecessor_embedding->embedding;
+    }
+  }
+
+  /**
+    Get the number of key values for this operation. It is an error
+    to call this method on an operation that is not an index lookup
+    operation.
+  */
+  uint Table_access::get_no_of_key_fields() const
+  {
+    DBUG_ASSERT(m_access_type == AT_PRIMARY_KEY ||
+                m_access_type == AT_UNIQUE_KEY ||
+                m_access_type == AT_MULTI_PRIMARY_KEY ||
+                m_access_type == AT_MULTI_UNIQUE_KEY ||
+                m_access_type == AT_ORDERED_INDEX_SCAN); // Used as 'range scan'
+    return get_join_tab()->ref.key_parts;
+  }
+
+  /**
+    Get the field_no'th key values for this operation. It is an error
+    to call this method on an operation that is not an index lookup
+    operation.
+  */
+  const Item* Table_access::get_key_field(uint field_no) const
+  {
+    DBUG_ASSERT(field_no < get_no_of_key_fields());
+    return get_join_tab()->ref.items[field_no];
+  }
+
+  /**
+    Get the field_no'th KEY_PART_INFO for this operation. It is an error
+    to call this method on an operation that is not an index lookup
+    operation.
+  */
+  const KEY_PART_INFO* Table_access::get_key_part_info(uint field_no) const
+  {
+    DBUG_ASSERT(field_no < get_no_of_key_fields());
+    const KEY* key= &get_join_tab()->table->key_info[get_join_tab()->ref.key];
+    return &key->key_part[field_no];
+  }
+
+  /**
+    Get the table that this operation accesses.
+  */
+  TABLE* Table_access::get_table() const
+  {
+    return get_join_tab()->table;
+  }
+
+  double Table_access::get_fanout() const
+  {
+    switch (get_access_type())
+    {
+      case AT_PRIMARY_KEY:
+      case AT_UNIQUE_KEY:
+        return 1.0;
+
+      case AT_ORDERED_INDEX_SCAN:
+        DBUG_ASSERT(get_join_tab()->join->best_positions[m_tab_no].records_read>0.0);
+        return get_join_tab()->join->best_positions[m_tab_no].records_read;
+
+      case AT_MULTI_PRIMARY_KEY:
+      case AT_MULTI_UNIQUE_KEY:
+      case AT_MULTI_MIXED:
+        DBUG_ASSERT(get_join_tab()->join->best_positions[m_tab_no].records_read>0.0);
+        return get_join_tab()->join->best_positions[m_tab_no].records_read;
+
+      case AT_TABLE_SCAN:
+        DBUG_ASSERT(get_join_tab()->table->file->stats.records>0.0);
+        return static_cast<double>(get_join_tab()->table->file->stats.records);
+
+      default:
+        return 99999999.0;
+    }
+  }
+
+  /** Get the JOIN_TAB object that corresponds to this operation.*/
+  const JOIN_TAB* Table_access::get_join_tab() const
+  {
+    return m_join_plan->get_join_tab(m_tab_no);
+  }
+
+  /** Get the Item_equal's set relevant for the specified 'Item_field' */
+  Item_equal*
+  Table_access::get_item_equal(const Item_field* field_item) const
+  {
+    DBUG_ASSERT(field_item->type() == Item::FIELD_ITEM);
+
+    COND_EQUAL* const cond_equal = get_join_tab()->join->cond_equal;
+    if (cond_equal!=NULL)
+    {
+      return (field_item->item_equal != NULL)
+               ? field_item->item_equal
+               : const_cast<Item_field*>(field_item)->find_item_equal(cond_equal);
+    }
+    return NULL;
+  }
+
+  /**
+    Write an entry in the trace file about the contents of this object.
+  */
+  void Table_access::dbug_print() const
+  {
+    DBUG_PRINT("info", ("type:%d", get_join_tab()->type));
+    DBUG_PRINT("info", ("ref.key:%d", get_join_tab()->ref.key));
+    DBUG_PRINT("info", ("ref.key_parts:%d", get_join_tab()->ref.key_parts));
+    DBUG_PRINT("info", ("ref.key_length:%d", get_join_tab()->ref.key_length));
+
+    DBUG_PRINT("info", ("order:%p", get_join_tab()->join->order.order));
+    DBUG_PRINT("info", ("skip_sort_order:%d",
+                        get_join_tab()->join->skip_sort_order));
+    DBUG_PRINT("info", ("no_order:%d", get_join_tab()->join->no_order));
+    DBUG_PRINT("info", ("simple_order:%d", get_join_tab()->join->simple_order));
+
+    DBUG_PRINT("info", ("group:%d", get_join_tab()->join->group));
+    DBUG_PRINT("info", ("group_list:%p", get_join_tab()->join->group_list.order));
+    DBUG_PRINT("info", ("simple_group:%d", get_join_tab()->join->simple_group));
+    DBUG_PRINT("info", ("group_optimized_away:%d",
+                        get_join_tab()->join->group_optimized_away));
+
+    DBUG_PRINT("info", ("full_join:%d", get_join_tab()->join->full_join));
+    DBUG_PRINT("info", ("need_tmp:%d", get_join_tab()->join->need_tmp));
+    DBUG_PRINT("info", ("select_distinct:%d",
+                        get_join_tab()->join->select_distinct));
+
+    DBUG_PRINT("info", ("use_quick:%d", get_join_tab()->use_quick));
+    DBUG_PRINT("info", ("index:%d", get_join_tab()->index));
+    DBUG_PRINT("info", ("quick:%p", get_join_tab()->quick));
+    DBUG_PRINT("info", ("select:%p", get_join_tab()->select));
+    if (get_join_tab()->select && get_join_tab()->select->quick)
+    {
+      DBUG_PRINT("info", ("select->quick->get_type():%d",
+                          get_join_tab()->select->quick->get_type()));
+    }
+  }
+
+
+  /**
+    Compute the access type and index (if apliccable) of this operation .
+  */
+  void Table_access::compute_type_and_index() const
+  {
+    DBUG_ENTER("Table_access::compute_type_and_index");
+    const JOIN_TAB* const join_tab= get_join_tab();
+    JOIN* const join= join_tab->join;
+
+    /**
+     * There are some JOIN arguments we don't fully understand or has 
+     * not yet invested time into exploring pushability of:
+     */
+    if (join->procedure)
+    {
+      m_access_type= AT_OTHER;
+      m_other_access_reason = 
+        "'PROCEDURE'-clause post processing cannot be pushed.";
+      DBUG_VOID_RETURN;
+    }
+
+    /**
+     * OLEJA: I think this restriction can be removed
+     * now as WL5558 and other changes has cleaned up the 
+     * ORDER/GROUP BY optimize + execute path.
+     */
+    if (join->group_list && !join->tmp_table_param.quick_group)
+    {
+      m_access_type= AT_OTHER;
+      m_other_access_reason = 
+        "GROUP BY cannot be done using index on grouped columns.";
+      DBUG_VOID_RETURN;
+    }
+
+    /* Tables below 'const_tables' has been const'ified, or entirely
+     * optimized away due to 'impossible WHERE/ON'
+     */
+    if (join_tab < join->join_tab+join->const_tables)
+    {
+      DBUG_PRINT("info", ("Operation %d is const-optimized.", m_tab_no));
+      m_access_type= AT_FIXED;
+      DBUG_VOID_RETURN;
+    }
+
+    /*
+      Identify the type of access operation and the index to use (if any).
+    */
+    switch (join_tab->type)
+    {
+    case JT_EQ_REF:
+      m_index_no= join_tab->ref.key;
+
+      if (m_index_no == static_cast<int>(join_tab->table->s->primary_key))
+      {
+        DBUG_PRINT("info", ("Operation %d is a primary key lookup.", m_tab_no));
+        m_access_type= AT_PRIMARY_KEY;
+      }
+      else
+      {
+        DBUG_PRINT("info", ("Operation %d is a unique index lookup.",
+                            m_tab_no));
+        m_access_type= AT_UNIQUE_KEY;
+      }
+      break;
+
+    case JT_REF:
+    {
+      DBUG_ASSERT(join_tab->ref.key >= 0);
+      DBUG_ASSERT((uint)join_tab->ref.key < MAX_KEY);
+      m_index_no= join_tab->ref.key;
+
+      /*
+        All parts of a key are specified for an unique index -> access is a key lookup.
+      */
+      const KEY *key_info= join_tab->table->s->key_info;
+      if (key_info[m_index_no].key_parts == join_tab->ref.key_parts  &&
+          key_info[m_index_no].flags & HA_NOSAME)
+      {
+        m_access_type= 
+          (m_index_no == static_cast<int32>(join_tab->table->s->primary_key)) 
+              ? AT_PRIMARY_KEY
+              : AT_UNIQUE_KEY;
+        DBUG_PRINT("info", ("Operation %d is an unique key referrence.", m_tab_no));
+      }
+      else
+      {
+        DBUG_ASSERT(join_tab->ref.key_parts > 0);
+        DBUG_ASSERT(join_tab->ref.key_parts <= key_info[m_index_no].key_parts);
+        m_access_type= AT_ORDERED_INDEX_SCAN;
+        DBUG_PRINT("info", ("Operation %d is an ordered index scan.", m_tab_no));
+      }
+      break;
+    }
+    case JT_INDEX_SCAN:
+      DBUG_ASSERT(join_tab->index < MAX_KEY);
+      m_index_no=    join_tab->index;
+      m_access_type= AT_ORDERED_INDEX_SCAN;
+      DBUG_PRINT("info", ("Operation %d is an ordered index scan.", m_tab_no));
+      break;
+
+    case JT_ALL:
+      if (join_tab->use_quick == 2)
+      {
+        /*
+          use_quick == 2 means that the decision on which access method to use
+          will be taken late (as rows from the preceeding operation arrive).
+          This operation is therefor not pushable.
+        */
+        DBUG_PRINT("info",
+                   ("Operation %d has 'use_quick == 2' -> not pushable",
+                    m_tab_no));
+        m_access_type= AT_UNDECIDED;
+        m_index_no=    -1;
+      }
+      else
+      {
+        if (join_tab->select != NULL &&
+            join_tab->select->quick != NULL)
+        {
+          QUICK_SELECT_I *quick= join_tab->select->quick;
+
+          /** QUICK_SELECT results in execution of MRR (Multi Range Read).
+           *  Depending on each range, it may require execution of
+           *  either a PK-lookup or a range scan. To cover both of 
+           *  these we may need to prepare both a pushed lookup join
+           *  and a pushed range scan. Currently we handle it as
+           *  a range scan and convert e PK lookup to a (closed-) range
+           *  whenever required.
+           **/
+
+          const KEY *key_info= join_tab->table->s->key_info;
+          DBUG_EXECUTE("info", quick->dbug_dump(0, TRUE););
+
+          // Temporary assert as we are still investigation the relation between 
+          // 'quick->index == MAX_KEY' and the different quick_types
+          DBUG_ASSERT ((quick->index == MAX_KEY)  ==
+                        ((quick->get_type() == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE) ||
+                         (quick->get_type() == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT) ||
+                         (quick->get_type() == QUICK_SELECT_I::QS_TYPE_ROR_UNION)));
+
+          // JT_INDEX_MERGE: We have a set of qualifying PKs as root of pushed joins
+          if (quick->index == MAX_KEY) 
+          {
+            m_index_no=    join_tab->table->s->primary_key;
+            m_access_type= AT_MULTI_PRIMARY_KEY;    // Multiple PKs are produced by merge
+          }
+
+          // Else JT_RANGE: May be both exact PK and/or index scans when sorted index available
+          else if (quick->index == join_tab->table->s->primary_key)
+          {
+            m_index_no= quick->index;
+            if (key_info[m_index_no].algorithm == HA_KEY_ALG_HASH)
+              m_access_type= AT_MULTI_PRIMARY_KEY; // MRR w/ multiple PK's
+            else
+              m_access_type= AT_MULTI_MIXED;       // MRR w/ both range and PKs
+          }
+          else
+          {
+            m_index_no= quick->index;
+            if (key_info[m_index_no].algorithm == HA_KEY_ALG_HASH)
+              m_access_type= AT_MULTI_UNIQUE_KEY; // MRR with multiple unique keys
+            else
+              m_access_type= AT_MULTI_MIXED;      // MRR w/ both range and unique keys
+          }
+        }
+        else
+        {
+          DBUG_PRINT("info", ("Operation %d is a table scan.", m_tab_no));
+          m_access_type= AT_TABLE_SCAN;
+        }
+      }
+      break;
+
+    case JT_CONST:
+    case JT_SYSTEM:
+    default:
+      /*
+        Other join_types either cannot be pushed or the code analyze them is
+        not yet in place.
+      */
+      DBUG_PRINT("info",
+                 ("Operation %d has join_type %d. -> Not pushable.",
+                  m_tab_no, join_tab->type));
+      m_access_type= AT_OTHER;
+      m_index_no=    -1;
+      m_other_access_reason = "This table access method can not be pushed.";
+      break;
+    }
+    DBUG_VOID_RETURN;
+  }
+  // Table_access::compute_type_and_index()
+
+
+  Table_access::Table_access()
+    :m_join_plan(NULL),
+     m_tab_no(0),
+     m_access_type(AT_VOID),
+     m_other_access_reason(NULL),
+     m_index_no(-1)
+  {}
+
+  /**
+    Check if the results from this operation will joined with results 
+    from the next operation using a join buffer (instead of plain nested loop).
+    @return True if using a join buffer. 
+  */
+  bool Table_access::uses_join_cache() const
+  {
+    return get_join_tab()->next_select == sub_select_cache;
+  }
+
+  /**
+   Check if this table will be presorted to an intermediate record storage
+   before it is joined with its siblings.
+  */
+  bool Table_access::filesort_before_join() const
+  {
+    if (m_access_type == AT_PRIMARY_KEY ||
+        m_access_type == AT_UNIQUE_KEY)
+    {
+      return false;
+    }
+
+    const JOIN_TAB* const join_tab= get_join_tab();
+    JOIN* const join= join_tab->join;
+
+    /**
+     Table will be presorted before joining with child tables, if:
+      1) This is the first non-const table
+      2) There are more tables to be joined
+      3) It is not already decide to write entire join result to temp.
+      4a) The GROUP BY is 'simple' and does not match an orderd index
+      4b) The ORDER BY is 'simple' and does not match an orderd index
+
+     A 'simple' order/group by contain only column references to
+     the first non-const table
+    */
+    if (join_tab == join->join_tab+join->const_tables &&  // First non-const table
+        join->const_tables < join->tables)                // There are more tables
+    {
+      if (join->need_tmp)
+        return false;
+      else if (join->group_list && join->simple_group)
+        return (join->ordered_index_usage!=JOIN::ordered_index_group_by);
+      else if (join->order && join->simple_order)
+        return (join->ordered_index_usage!=JOIN::ordered_index_order_by);
+      else
+        return false;
+    }
+    return false;
+  }
+
+};
+// namespace AQP

=== added file 'sql/abstract_query_plan.h'
--- a/sql/abstract_query_plan.h	1970-01-01 00:00:00 +0000
+++ b/sql/abstract_query_plan.h	2012-05-22 09:24:50 +0000
@@ -0,0 +1,305 @@
+/*
+   Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
+
+   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
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
+*/
+
+#ifndef ABSTRACT_QUERY_PLAN_H_INCLUDED
+#define ABSTRACT_QUERY_PLAN_H_INCLUDED
+
+struct TABLE;
+struct st_join_table;
+typedef st_join_table JOIN_TAB;
+class JOIN;
+class Item;
+class Item_field;
+class Item_equal_iterator;
+
+#include "sql_list.h"
+
+/**
+  Abstract query plan (AQP) is an interface for examining certain aspects of 
+  query plans without accessing mysqld internal classes (JOIN_TAB, SQL_SELECT 
+  etc.) directly.
+
+  AQP maps join execution plans, as represented by mysqld internals, to a set 
+  of facade classes. Non-join operations such as sorting and aggregation is
+  currently *not* modelled in the AQP.
+
+  The AQP models an n-way join as a sequence of the n table access operations
+  that the MySQL server would execute as part of its nested loop join 
+  execution. (Each such table access operation is a scan of a table or index,
+  or an index lookup.) For each lookup operation, it is possible to examine 
+  the expression that represents each field in the key.
+
+  A storage enging will typically use the AQP for finding sections of a join
+  execution plan that may be executed in the engine rather than in mysqld. By 
+  using the AQP rather than the mysqld internals directly, the coupling between
+  the engine and mysqld is reduced.
+*/
+namespace AQP
+{
+  class Table_access;
+
+  /**
+    This class represents a query plan for an n-way join, in the form a 
+    sequence of n table access operations that will execute as a nested loop 
+    join.
+  */
+  class Join_plan : public Sql_alloc
+  {
+    friend class Equal_set_iterator;
+    friend class Table_access;
+  public:
+
+    explicit Join_plan(const JOIN* join);
+
+    ~Join_plan();
+
+    const Table_access* get_table_access(uint access_no) const;
+
+    uint get_access_count() const;
+
+  private:
+    /** 
+      Array of the JOIN_TABs that are the internal representation of table
+      access operations.
+    */
+    const JOIN_TAB* const m_join_tabs;
+
+    /** Number of table access operations. */
+    const uint m_access_count;
+    Table_access* m_table_accesses;
+
+    const JOIN_TAB* get_join_tab(uint join_tab_no) const;
+
+    // No copying.
+    Join_plan(const Join_plan&);
+    Join_plan& operator=(const Join_plan&);
+  }; 
+  // class Join_plan
+
+
+  /**
+    This class is an iterator for iterating over sets of fields (columns) that
+    should have the same value. For example, if the query is
+    SELECT * FROM T1, T2, T3 WHERE T1.b = T2.a AND T2.a = T3.a
+    then there would be such a set of {T1.b, T2.a, T3.a}.
+  */
+  class Equal_set_iterator : public Sql_alloc
+  {
+  public:
+    explicit Equal_set_iterator(Item_equal& item_equal)
+    : m_iterator(item_equal) {}
+
+    const Item_field* next()
+    { return m_iterator++; }
+
+  private:
+    /**
+      This class is implemented in terms of this mysqld internal class.
+     */
+    Item_equal_iterator m_iterator;
+
+    // No copying.
+    Equal_set_iterator(const Equal_set_iterator&);
+    Equal_set_iterator& operator=(const Equal_set_iterator&);
+  }; 
+  // class Equal_set_iterator
+
+  /** The type of a table access operation. */
+  enum enum_access_type
+  {
+    /** For default initialization.*/
+    AT_VOID,
+    /** Value has already been fetched / determined by optimizer.*/
+    AT_FIXED,
+    /** Do a lookup of a single primary key.*/
+    AT_PRIMARY_KEY,
+    /** Do a lookup of a single unique index key.*/
+    AT_UNIQUE_KEY,
+    /** Scan an ordered index with a single upper and lower bound pair.*/
+    AT_ORDERED_INDEX_SCAN,
+    /** Do a multi range read for a set of primary keys.*/
+    AT_MULTI_PRIMARY_KEY,
+    /** Do a multi range read for a set of unique index keys.*/
+    AT_MULTI_UNIQUE_KEY,
+    /** 
+      Do a multi range read for a mix of ranges (for which there is an
+      ordered index), and either primary keys or unique index keys.
+    */
+    AT_MULTI_MIXED,
+    /** Scan a table. (No index is assumed to be used.) */
+    AT_TABLE_SCAN,
+    /** Access method will not be chosen before the execution phase.*/
+    AT_UNDECIDED,
+    /**
+      The access method has properties that prevents it from being pushed to a 
+      storage engine.
+     */
+    AT_OTHER
+  };
+
+  /** The type of join operation require */
+  enum enum_join_type
+  {
+    JT_OUTER_JOIN,
+    JT_INNER_JOIN,
+    JT_SEMI_JOIN
+  };
+
+  /**
+    This class represents an access operation on a table, such as a table
+    scan, or a scan or lookup via an index. A Table_access object is always
+    owned by a Join_plan object, such that the life time of the Table_access 
+    object ends when the life time of the owning Join_plan object ends.
+   */
+  class Table_access : public Sql_alloc
+  {
+    friend class Join_plan;
+    friend inline bool equal(const Table_access*, const Table_access*);
+  public:
+
+    const Join_plan* get_join_plan() const;
+
+    enum_access_type get_access_type() const;
+
+    const char* get_other_access_reason() const;
+
+    enum_join_type get_join_type(const Table_access* parent) const;
+
+    uint get_no_of_key_fields() const;
+
+    const Item* get_key_field(uint field_no) const;
+
+    const KEY_PART_INFO* get_key_part_info(uint field_no) const;
+
+    uint get_access_no() const;
+
+    int get_index_no() const;
+
+    TABLE* get_table() const;
+
+    double get_fanout() const;
+
+    Item_equal* get_item_equal(const Item_field* field_item) const;
+
+    void dbug_print() const;
+
+    bool uses_join_cache() const;
+
+    bool filesort_before_join() const;
+
+  private:
+
+    /** Backref. to the Join_plan which this Table_access is part of */
+    const Join_plan* m_join_plan;
+
+    /** This operation corresponds to m_root_tab[m_tab_no].*/
+    uint m_tab_no;
+
+    /** The type of this operation.*/
+    mutable enum_access_type m_access_type;
+
+    /** 
+      The reason for getting m_access_type==AT_OTHER. Used for explain extended.
+    */
+    mutable const char* m_other_access_reason;
+
+    /** The index to use for this operation (if applicable )*/
+    mutable int m_index_no;
+
+    explicit Table_access();
+
+    const JOIN_TAB* get_join_tab() const;
+
+    void compute_type_and_index() const;
+
+    /** No copying*/
+    Table_access(const Table_access&);
+    Table_access& operator=(const Table_access&);
+  }; 
+  // class Table_access
+
+  /**
+    Get the n'th table access operation.
+    @param access_no The index of the table access operation to fetch.
+    @return The access_no'th table access operation.
+  */
+  inline const Table_access* Join_plan::get_table_access(uint access_no) const
+  {
+    DBUG_ASSERT(access_no < m_access_count);
+    return m_table_accesses + access_no;
+  }
+
+  /**
+     @return The number of table access operations in the nested loop join.
+  */
+  inline uint Join_plan::get_access_count() const
+  { 
+    return m_access_count;
+  }
+
+  /** Get the Join_plan that this Table_access belongs to.*/
+  inline const Join_plan* Table_access::get_join_plan() const
+  {
+    return m_join_plan;
+  }
+
+  /** Get the type of this operation.*/
+  inline enum_access_type Table_access::get_access_type() const
+  {
+    if (m_access_type == AT_VOID)
+      compute_type_and_index();
+    return m_access_type;
+  }
+
+  /** 
+    Get a description of the reason for getting access_type==AT_OTHER. To be 
+    used for informational messages.
+    @return A string that should be assumed to have the same life time as the
+    Table_access object.
+  */
+  inline const char* Table_access::get_other_access_reason() const
+  {
+    if (m_access_type == AT_VOID)
+      compute_type_and_index();
+    return m_other_access_reason;
+  }
+
+  /**
+    @return The number of the index to use for this access operation (
+    or -1 for non-index operations).
+  */
+  inline int Table_access::get_index_no() const
+  {
+    if (m_access_type == AT_VOID)
+      compute_type_and_index();
+	
+    return m_index_no;
+  }
+
+  /** 
+    Get the number of this Table_access within the enclosing Join_plan. 
+    (This number will be in the range 0 to Join_plan::get_access_count() - 1.)
+  */
+  inline uint Table_access::get_access_no() const
+  { 
+    return m_tab_no;
+  }
+
+}; 
+// namespace AQP
+
+#endif

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bzr push into mysql-trunk branch (ole.john.aske:3901 to 3902) WL#5940Ole John Aske22 May