~drizzle-trunk/drizzle/development

/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008-2009 Sun Microsystems, Inc.

 *

 *  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; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  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 "config.h"

#include <drizzled/join_table.h>

#include <drizzled/field/blob.h>

#include <drizzled/sql_select.h>

namespace drizzled

{

int JoinTable::joinReadConstTable(optimizer::Position *pos)

{

  int error;

  Table *Table= this->table;

  Table->const_table=1;

  Table->null_row=0;

  Table->status=STATUS_NO_RECORD;

  if (this->type == AM_SYSTEM)

  {

    if ((error=this->joinReadSystem()))

    {						// Info for DESCRIBE

      this->info="const row not found";

      /* Mark for EXPLAIN that the row was not found */

      pos->setFanout(0.0);

      pos->clearRefDependMap();

      if (! Table->maybe_null || error > 0)

        return(error);

    }

  }

  else

  {

    if (! Table->key_read && 

        Table->covering_keys.test(this->ref.key) && 

        ! Table->no_keyread &&

        (int) Table->reginfo.lock_type <= (int) TL_READ_WITH_SHARED_LOCKS)

    {

      Table->key_read=1;

      Table->cursor->extra(HA_EXTRA_KEYREAD);

      this->index= this->ref.key;

    }

    error=join_read_const(this);

    if (Table->key_read)

    {

      Table->key_read=0;

      Table->cursor->extra(HA_EXTRA_NO_KEYREAD);

    }

    if (error)

    {

      this->info="unique row not found";

      /* Mark for EXPLAIN that the row was not found */

      pos->setFanout(0.0);

      pos->clearRefDependMap();

      if (!Table->maybe_null || error > 0)

        return(error);

    }

  }

  if (*this->on_expr_ref && !Table->null_row)

  {

    if ((Table->null_row= test((*this->on_expr_ref)->val_int() == 0)))

      Table->mark_as_null_row();

  }

  if (!Table->null_row)

    Table->maybe_null=0;

  /* Check appearance of new constant items in Item_equal objects */

  Join *Join= this->join;

  if (Join->conds)

    update_const_equal_items(Join->conds, this);

  TableList *tbl;

  for (tbl= Join->select_lex->leaf_tables; tbl; tbl= tbl->next_leaf)

  {

    TableList *embedded;

    TableList *embedding= tbl;

    do

    {

      embedded= embedding;

      if (embedded->on_expr)

         update_const_equal_items(embedded->on_expr, this);

      embedding= embedded->getEmbedding();

    }

    while (embedding &&

           embedding->getNestedJoin()->join_list.head() == embedded);

  }

  return(0);

}

void JoinTable::readCachedRecord()

{

  unsigned char *pos;

  uint32_t length;

  bool last_record;

  CacheField *copy,*end_field;

  last_record= this->cache.record_nr++ == this->cache.ptr_record;

  pos= this->cache.pos;

  for (copy= this->cache.field, end_field= copy+this->cache.fields;

       copy < end_field;

       copy++)

  {

    if (copy->blob_field)

    {

      if (last_record)

      {

        copy->blob_field->set_image(pos, copy->length+sizeof(char*),

                  copy->blob_field->charset());

        pos+=copy->length+sizeof(char*);

      }

      else

      {

        copy->blob_field->set_ptr(pos, pos+copy->length);

        pos+=copy->length+copy->blob_field->get_length();

      }

    }

    else

    {

      if (copy->strip)

      {

        length= uint2korr(pos);

        memcpy(copy->str, pos+2, length);

        memset(copy->str+length, ' ', copy->length-length);

        pos+= 2 + length;

      }

      else

      {

        memcpy(copy->str,pos,copy->length);

        pos+=copy->length;

      }

    }

  }

  this->cache.pos=pos;

}

int JoinTable::joinReadSystem()

{

  Table *Table= this->table;

  int error;

  if (Table->status & STATUS_GARBAGE)		// If first read

  {

    if ((error=Table->cursor->read_first_row(table->getInsertRecord(),

					   Table->getShare()->getPrimaryKey())))

    {

      if (error != HA_ERR_END_OF_FILE)

        return Table->report_error(error);

      this->table->mark_as_null_row();

      Table->emptyRecord();			// Make empty record

      return -1;

    }

    Table->storeRecord();

  }

  else if (!Table->status)			// Only happens with left join

    Table->restoreRecord();			// restore old record

  Table->null_row=0;

  return Table->status ? -1 : 0;

}

} /* namespace drizzled */