~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

 *

 *  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

 */

/**

 * @file

 *

 * Implementation of the JOIN cache

 * 

 * @defgroup Query_Optimizer  Query Optimizer

 * @{

 */

#include "config.h"

#include "drizzled/sql_select.h" /* include join.h */

#include "drizzled/field/blob.h"

#include <algorithm>

using namespace std;

namespace drizzled

{

static uint32_t used_blob_length(CacheField **ptr);

static uint32_t used_blob_length(CacheField **ptr)

{

  uint32_t length,blob_length;

  for (length=0 ; *ptr ; ptr++)

  {

    (*ptr)->blob_length=blob_length=(*ptr)->blob_field->get_length();

    length+=blob_length;

    (*ptr)->blob_field->get_ptr(&(*ptr)->str);

  }

  return length;

}

/*****************************************************************************

  Fill join cache with packed records

  Records are stored in tab->cache.buffer and last record in

  last record is stored with pointers to blobs to support very big

  records

******************************************************************************/

int join_init_cache(Session *session, JoinTable *tables, uint32_t table_count)

{

  unsigned int length, blobs;

  size_t size;

  CacheField *copy,**blob_ptr;

  JoinCache  *cache;

  JoinTable *join_tab;

  cache= &tables[table_count].cache;

  cache->fields=blobs=0;

  join_tab= tables;

  for (unsigned int i= 0; i < table_count ; i++, join_tab++)

  {

    if (!join_tab->used_fieldlength)		/* Not calced yet */

      calc_used_field_length(session, join_tab);

    cache->fields+=join_tab->used_fields;

    blobs+=join_tab->used_blobs;

    /* SemiJoinDuplicateElimination: reserve space for rowid */

    if (join_tab->rowid_keep_flags & JoinTable::KEEP_ROWID)

    {

      cache->fields++;

      join_tab->used_fieldlength += join_tab->table->cursor->ref_length;

    }

  }

  if (!(cache->field=(CacheField*)

        memory::sql_alloc(sizeof(CacheField)*(cache->fields+table_count*2)+(blobs+1)* sizeof(CacheField*))))

  {

    free((unsigned char*) cache->buff);

    cache->buff=0;

    return(1);

  }

  copy=cache->field;

  blob_ptr=cache->blob_ptr=(CacheField**)

    (cache->field+cache->fields+table_count*2);

  length=0;

  for (unsigned int i= 0 ; i < table_count ; i++)

  {

    uint32_t null_fields=0, used_fields;

    Field **f_ptr,*field;

    for (f_ptr= tables[i].table->getFields(), used_fields= tables[i].used_fields; used_fields; f_ptr++)

    {

      field= *f_ptr;

      if (field->isReadSet())

      {

        used_fields--;

        length+=field->fill_cache_field(copy);

        if (copy->blob_field)

          (*blob_ptr++)=copy;

        if (field->maybe_null())

          null_fields++;

        copy->get_rowid= NULL;

        copy++;

      }

    }

    /* Copy null bits from table */

    if (null_fields && tables[i].table->getNullFields())

    {						/* must copy null bits */

      copy->str= tables[i].table->null_flags;

      copy->length= tables[i].table->getShare()->null_bytes;

      copy->strip=0;

      copy->blob_field=0;

      copy->get_rowid= NULL;

      length+=copy->length;

      copy++;

      cache->fields++;

    }

    /* If outer join table, copy null_row flag */

    if (tables[i].table->maybe_null)

    {

      copy->str= (unsigned char*) &tables[i].table->null_row;

      copy->length=sizeof(tables[i].table->null_row);

      copy->strip=0;

      copy->blob_field=0;

      copy->get_rowid= NULL;

      length+=copy->length;

      copy++;

      cache->fields++;

    }

    /* SemiJoinDuplicateElimination: Allocate space for rowid if needed */

    if (tables[i].rowid_keep_flags & JoinTable::KEEP_ROWID)

    {

      copy->str= tables[i].table->cursor->ref;

      copy->length= tables[i].table->cursor->ref_length;

      copy->strip=0;

      copy->blob_field=0;

      copy->get_rowid= NULL;

      if (tables[i].rowid_keep_flags & JoinTable::CALL_POSITION)

      {

        /* We will need to call h->position(): */

        copy->get_rowid= tables[i].table;

        /* And those after us won't have to: */

        tables[i].rowid_keep_flags&=  ~((int)JoinTable::CALL_POSITION);

      }

      copy++;

    }

  }

  cache->length= length+blobs*sizeof(char*);

  cache->blobs= blobs;

  *blob_ptr= NULL;					/* End sequentel */

  size= max((size_t) session->variables.join_buff_size, (size_t)cache->length);

  if (!(cache->buff= (unsigned char*) malloc(size)))

    return 1;

  cache->end= cache->buff+size;

  cache->reset_cache_write();

  return 0;

}

bool JoinCache::store_record_in_cache()

{

  JoinCache *cache= this;

  unsigned char *local_pos;

  CacheField *copy,*end_field;

  bool last_record;

  local_pos= cache->pos;

  end_field= cache->field+cache->fields;

  {

    uint32_t local_length;

    local_length= cache->length;

    if (cache->blobs)

    {

      local_length+= used_blob_length(cache->blob_ptr);

    }

    if ((last_record= (local_length + cache->length > (size_t) (cache->end - local_pos))))

    {

      cache->ptr_record= cache->records;

    }

  }

  /*

    There is room in cache. Put record there

  */

  cache->records++;

  for (copy= cache->field; copy < end_field; copy++)

  {

    if (copy->blob_field)

    {

      if (last_record)

      {

        copy->blob_field->get_image(local_pos, copy->length+sizeof(char*), copy->blob_field->charset());

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

      }

      else

      {

        copy->blob_field->get_image(local_pos, copy->length, // blob length

				    copy->blob_field->charset());

        memcpy(local_pos + copy->length,copy->str,copy->blob_length);  // Blob data

        local_pos+= copy->length+copy->blob_length;

      }

    }

    else

    {

      // SemiJoinDuplicateElimination: Get the rowid into table->ref:

      if (copy->get_rowid)

        copy->get_rowid->cursor->position(copy->get_rowid->getInsertRecord());

      if (copy->strip)

      {

        unsigned char *str, *local_end;

        for (str= copy->str,local_end= str+copy->length; local_end > str && local_end[-1] == ' '; local_end--) {}

        uint32_t local_length= (uint32_t) (local_end - str);

        memcpy(local_pos+2, str, local_length);

        int2store(local_pos, local_length);

        local_pos+= local_length+2;

      }

      else

      {

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

        local_pos+= copy->length;

      }

    }

  }

  cache->pos= local_pos;

  return last_record || (size_t) (cache->end - local_pos) < cache->length;

}

void JoinCache::reset_cache_read()

{

  record_nr= 0;

  pos= buff;

}

void JoinCache::reset_cache_write()

{

  reset_cache_read();

  records= 0;

  ptr_record= UINT32_MAX;

}

/**

  @} (end of group Query_Optimizer)

*/

} /* namespace drizzled */