~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2006 MySQL AB  

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/**

  @file

  @brief

  Sorts a database

*/

#include <drizzled/server_includes.h>

#include "sql_sort.h"

#include <drizzled/drizzled_error_messages.h>

	/* functions defined in this file */

static char **make_char_array(char **old_pos, register uint fields,

                              uint length, myf my_flag);

static uchar *read_buffpek_from_file(IO_CACHE *buffer_file, uint count,

                                     uchar *buf);

static ha_rows find_all_keys(SORTPARAM *param,SQL_SELECT *select,

			     uchar * *sort_keys, IO_CACHE *buffer_file,

			     IO_CACHE *tempfile,IO_CACHE *indexfile);

static int write_keys(SORTPARAM *param,uchar * *sort_keys,

		      uint count, IO_CACHE *buffer_file, IO_CACHE *tempfile);

static void make_sortkey(SORTPARAM *param,uchar *to, uchar *ref_pos);

static void register_used_fields(SORTPARAM *param);

static int merge_index(SORTPARAM *param,uchar *sort_buffer,

		       BUFFPEK *buffpek,

		       uint maxbuffer,IO_CACHE *tempfile,

		       IO_CACHE *outfile);

static bool save_index(SORTPARAM *param,uchar **sort_keys, uint count, 

                       filesort_info_st *table_sort);

static uint suffix_length(uint32_t string_length);

static uint sortlength(THD *thd, SORT_FIELD *sortorder, uint s_length,

		       bool *multi_byte_charset);

static SORT_ADDON_FIELD *get_addon_fields(THD *thd, Field **ptabfield,

                                          uint sortlength, uint *plength);

static void unpack_addon_fields(struct st_sort_addon_field *addon_field,

                                uchar *buff);

/**

  Sort a table.

  Creates a set of pointers that can be used to read the rows

  in sorted order. This should be done with the functions

  in records.cc.

  Before calling filesort, one must have done

  table->file->info(HA_STATUS_VARIABLE)

  The result set is stored in table->io_cache or

  table->record_pointers.

  @param thd           Current thread

  @param table		Table to sort

  @param sortorder	How to sort the table

  @param s_length	Number of elements in sortorder

  @param select		condition to apply to the rows

  @param max_rows	Return only this many rows

  @param sort_positions	Set to 1 if we want to force sorting by position

			(Needed by UPDATE/INSERT or ALTER Table)

  @param examined_rows	Store number of examined rows here

  @todo

    check why we do this (param.keys--)

  @note

    If we sort by position (like if sort_positions is 1) filesort() will

    call table->prepare_for_position().

  @retval

    HA_POS_ERROR	Error

  @retval

    \#			Number of rows

  @retval

    examined_rows	will be set to number of examined rows

*/

ha_rows filesort(THD *thd, Table *table, SORT_FIELD *sortorder, uint s_length,

		 SQL_SELECT *select, ha_rows max_rows,

                 bool sort_positions, ha_rows *examined_rows)

{

  int error;

  uint32_t memavl, min_sort_memory;

  uint maxbuffer;

  BUFFPEK *buffpek;

  ha_rows records= HA_POS_ERROR;

  uchar **sort_keys= 0;

  IO_CACHE tempfile, buffpek_pointers, *selected_records_file, *outfile; 

  SORTPARAM param;

  bool multi_byte_charset;

  filesort_info_st table_sort;

  TableList *tab= table->pos_in_table_list;

  Item_subselect *subselect= tab ? tab->containing_subselect() : 0;

  DRIZZLE_FILESORT_START();

  /*

   Release InnoDB's adaptive hash index latch (if holding) before

   running a sort.

  */

  ha_release_temporary_latches(thd);

  /* 

    Don't use table->sort in filesort as it is also used by 

    QUICK_INDEX_MERGE_SELECT. Work with a copy and put it back at the end 

    when index_merge select has finished with it.

  */

  memcpy(&table_sort, &table->sort, sizeof(filesort_info_st));

  table->sort.io_cache= NULL;

  outfile= table_sort.io_cache;

  my_b_clear(&tempfile);

  my_b_clear(&buffpek_pointers);

  buffpek=0;

  error= 1;

  memset(&param, 0, sizeof(param));

  param.sort_length= sortlength(thd, sortorder, s_length, &multi_byte_charset);

  param.ref_length= table->file->ref_length;

  param.addon_field= 0;

  param.addon_length= 0;

  if (!(table->file->ha_table_flags() & HA_FAST_KEY_READ) && !sort_positions)

  {

    /* 

      Get the descriptors of all fields whose values are appended 

      to sorted fields and get its total length in param.spack_length.

    */

    param.addon_field= get_addon_fields(thd, table->field, 

                                        param.sort_length,

                                        &param.addon_length);

  }

  table_sort.addon_buf= 0;

  table_sort.addon_length= param.addon_length;

  table_sort.addon_field= param.addon_field;

  table_sort.unpack= unpack_addon_fields;

  if (param.addon_field)

  {

    param.res_length= param.addon_length;

    if (!(table_sort.addon_buf= (uchar *) my_malloc(param.addon_length,

                                                    MYF(MY_WME))))

      goto err;

  }

  else

  {

    param.res_length= param.ref_length;

    /* 

      The reference to the record is considered 

      as an additional sorted field

    */

    param.sort_length+= param.ref_length;

  }

  param.rec_length= param.sort_length+param.addon_length;

  param.max_rows= max_rows;

  if (select && select->quick)

  {

    status_var_increment(thd->status_var.filesort_range_count);

  }

  else

  {

    status_var_increment(thd->status_var.filesort_scan_count);

  }

#ifdef CAN_TRUST_RANGE

  if (select && select->quick && select->quick->records > 0L)

  {

    records=min((ha_rows) (select->quick->records*2+EXTRA_RECORDS*2),

		table->file->stats.records)+EXTRA_RECORDS;

    selected_records_file=0;

  }

  else

#endif

  {

    records= table->file->estimate_rows_upper_bound();

    /*

      If number of records is not known, use as much of sort buffer 

      as possible. 

    */

    if (records == HA_POS_ERROR)

      records--;  // we use 'records+1' below.

    selected_records_file= 0;

  }

  if (multi_byte_charset &&

      !(param.tmp_buffer= (char*) my_malloc(param.sort_length,MYF(MY_WME))))

    goto err;

  memavl= thd->variables.sortbuff_size;

  min_sort_memory= max((uint)MIN_SORT_MEMORY, param.sort_length*MERGEBUFF2);

  while (memavl >= min_sort_memory)

  {

    uint32_t old_memavl;

    uint32_t keys= memavl/(param.rec_length+sizeof(char*));

    param.keys=(uint) min(records+1, keys);

    if ((table_sort.sort_keys=

	 (uchar **) make_char_array((char **) table_sort.sort_keys,

                                    param.keys, param.rec_length, MYF(0))))

      break;

    old_memavl=memavl;

    if ((memavl=memavl/4*3) < min_sort_memory && old_memavl > min_sort_memory)

      memavl= min_sort_memory;

  }

  sort_keys= table_sort.sort_keys;

  if (memavl < min_sort_memory)

  {

    my_error(ER_OUT_OF_SORTMEMORY,MYF(ME_ERROR+ME_WAITTANG));

    goto err;

  }

  if (open_cached_file(&buffpek_pointers,mysql_tmpdir,TEMP_PREFIX,

		       DISK_BUFFER_SIZE, MYF(MY_WME)))

    goto err;

  param.keys--;  			/* TODO: check why we do this */

  param.sort_form= table;

  param.end=(param.local_sortorder=sortorder)+s_length;

  if ((records=find_all_keys(&param,select,sort_keys, &buffpek_pointers,

			     &tempfile, selected_records_file)) ==

      HA_POS_ERROR)

    goto err;

  maxbuffer= (uint) (my_b_tell(&buffpek_pointers)/sizeof(*buffpek));

  if (maxbuffer == 0)			// The whole set is in memory

  {

    if (save_index(&param,sort_keys,(uint) records, &table_sort))

      goto err;

  }

  else

  {

    if (table_sort.buffpek && table_sort.buffpek_len < maxbuffer)

    {

      x_free(table_sort.buffpek);

      table_sort.buffpek= 0;

    }

    if (!(table_sort.buffpek=

          (uchar *) read_buffpek_from_file(&buffpek_pointers, maxbuffer,

                                 table_sort.buffpek)))

      goto err;

    buffpek= (BUFFPEK *) table_sort.buffpek;

    table_sort.buffpek_len= maxbuffer;

    close_cached_file(&buffpek_pointers);

	/* Open cached file if it isn't open */

    if (! my_b_inited(outfile) &&

	open_cached_file(outfile,mysql_tmpdir,TEMP_PREFIX,READ_RECORD_BUFFER,

			  MYF(MY_WME)))

      goto err;

    if (reinit_io_cache(outfile,WRITE_CACHE,0L,0,0))

      goto err;

    /*

      Use also the space previously used by string pointers in sort_buffer

      for temporary key storage.

    */

    param.keys=((param.keys*(param.rec_length+sizeof(char*))) /

		param.rec_length-1);

    maxbuffer--;				// Offset from 0

    if (merge_many_buff(&param,(uchar*) sort_keys,buffpek,&maxbuffer,

			&tempfile))

      goto err;

    if (flush_io_cache(&tempfile) ||

	reinit_io_cache(&tempfile,READ_CACHE,0L,0,0))

      goto err;

    if (merge_index(&param,(uchar*) sort_keys,buffpek,maxbuffer,&tempfile,

		    outfile))

      goto err;

  }

  if (records > param.max_rows)

    records=param.max_rows;

  error =0;

 err:

  if (param.tmp_buffer)

    x_free(param.tmp_buffer);

  if (!subselect || !subselect->is_uncacheable())

  {

    x_free((uchar*) sort_keys);

    table_sort.sort_keys= 0;

    x_free((uchar*) buffpek);

    table_sort.buffpek= 0;

    table_sort.buffpek_len= 0;

  }

  close_cached_file(&tempfile);

  close_cached_file(&buffpek_pointers);

  if (my_b_inited(outfile))

  {

    if (flush_io_cache(outfile))

      error=1;

    {

      my_off_t save_pos=outfile->pos_in_file;

      /* For following reads */

      if (reinit_io_cache(outfile,READ_CACHE,0L,0,0))

	error=1;

      outfile->end_of_file=save_pos;

    }

  }

  if (error)

    my_message(ER_FILSORT_ABORT, ER(ER_FILSORT_ABORT),

               MYF(ME_ERROR+ME_WAITTANG));

  else

    statistic_add(thd->status_var.filesort_rows,

		  (uint32_t) records, &LOCK_status);

  *examined_rows= param.examined_rows;

  memcpy(&table->sort, &table_sort, sizeof(filesort_info_st));

  DRIZZLE_FILESORT_END();

  return(error ? HA_POS_ERROR : records);

} /* filesort */

void filesort_free_buffers(Table *table, bool full)

{

  if (table->sort.record_pointers)

  {

    my_free((uchar*) table->sort.record_pointers,MYF(0));

    table->sort.record_pointers=0;

  }

  if (full)

  {

    if (table->sort.sort_keys )

    {

      x_free((uchar*) table->sort.sort_keys);

      table->sort.sort_keys= 0;

    }

    if (table->sort.buffpek)

    {

      x_free((uchar*) table->sort.buffpek);

      table->sort.buffpek= 0;

      table->sort.buffpek_len= 0;

    }

  }

  if (table->sort.addon_buf)

  {

    my_free((char *) table->sort.addon_buf, MYF(0));

    my_free((char *) table->sort.addon_field, MYF(MY_ALLOW_ZERO_PTR));

    table->sort.addon_buf=0;

    table->sort.addon_field=0;

  }

}

/** Make a array of string pointers. */

static char **make_char_array(char **old_pos, register uint fields,

                              uint length, myf my_flag)

{

  register char **pos;

  char *char_pos;

  if (old_pos ||

      (old_pos= (char**) my_malloc((uint) fields*(length+sizeof(char*)),

				   my_flag)))

  {

    pos=old_pos; char_pos=((char*) (pos+fields)) -length;

    while (fields--) *(pos++) = (char_pos+= length);

  }

  return(old_pos);

} /* make_char_array */

/** Read 'count' number of buffer pointers into memory. */

static uchar *read_buffpek_from_file(IO_CACHE *buffpek_pointers, uint count,

                                     uchar *buf)

{

  uint32_t length= sizeof(BUFFPEK)*count;

  uchar *tmp= buf;

  if (count > UINT_MAX/sizeof(BUFFPEK))

    return 0; /* sizeof(BUFFPEK)*count will overflow */

  if (!tmp)

    tmp= (uchar *)my_malloc(length, MYF(MY_WME));

  if (tmp)

  {

    if (reinit_io_cache(buffpek_pointers,READ_CACHE,0L,0,0) ||

	my_b_read(buffpek_pointers, (uchar*) tmp, length))

    {

      my_free((char*) tmp, MYF(0));

      tmp=0;

    }

  }

  return(tmp);

}

/**

  Search after sort_keys and write them into tempfile.

  All produced sequences are guaranteed to be non-empty.

  @param param             Sorting parameter

  @param select            Use this to get source data

  @param sort_keys         Array of pointers to sort key + addon buffers.

  @param buffpek_pointers  File to write BUFFPEKs describing sorted segments

                           in tempfile.

  @param tempfile          File to write sorted sequences of sortkeys to.

  @param indexfile         If !NULL, use it for source data (contains rowids)

  @note

    Basic idea:

    @verbatim

     while (get_next_sortkey())

     {

       if (no free space in sort_keys buffers)

       {

         sort sort_keys buffer;

         dump sorted sequence to 'tempfile';

         dump BUFFPEK describing sequence location into 'buffpek_pointers';

       }

       put sort key into 'sort_keys';

     }

     if (sort_keys has some elements && dumped at least once)

       sort-dump-dump as above;

     else

       don't sort, leave sort_keys array to be sorted by caller.

  @endverbatim

  @retval

    Number of records written on success.

  @retval

    HA_POS_ERROR on error.

*/

static ha_rows find_all_keys(SORTPARAM *param, SQL_SELECT *select,

			     uchar **sort_keys,

			     IO_CACHE *buffpek_pointers,

			     IO_CACHE *tempfile, IO_CACHE *indexfile)

{

  int error,flag,quick_select;

  uint idx,indexpos,ref_length;

  uchar *ref_pos,*next_pos,ref_buff[MAX_REFLENGTH];

  my_off_t record;

  Table *sort_form;

  THD *thd= current_thd;

  volatile THD::killed_state *killed= &thd->killed;

  handler *file;

  MY_BITMAP *save_read_set, *save_write_set;

  idx=indexpos=0;

  error=quick_select=0;

  sort_form=param->sort_form;

  file=sort_form->file;

  ref_length=param->ref_length;

  ref_pos= ref_buff;

  quick_select=select && select->quick;

  record=0;

  flag= ((!indexfile && file->ha_table_flags() & HA_REC_NOT_IN_SEQ)

	 || quick_select);

  if (indexfile || flag)

    ref_pos= &file->ref[0];

  next_pos=ref_pos;

  if (! indexfile && ! quick_select)

  {

    next_pos=(uchar*) 0;			/* Find records in sequence */

    file->ha_rnd_init(1);

    file->extra_opt(HA_EXTRA_CACHE,

		    current_thd->variables.read_buff_size);

  }

  READ_RECORD read_record_info;

  if (quick_select)

  {

    if (select->quick->reset())

      return(HA_POS_ERROR);

    init_read_record(&read_record_info, current_thd, select->quick->head,

                     select, 1, 1);

  }

  /* Remember original bitmaps */

  save_read_set=  sort_form->read_set;

  save_write_set= sort_form->write_set;

  /* Set up temporary column read map for columns used by sort */

  bitmap_clear_all(&sort_form->tmp_set);

  /* Temporary set for register_used_fields and register_field_in_read_map */

  sort_form->read_set= &sort_form->tmp_set;

  register_used_fields(param);

  if (select && select->cond)

    select->cond->walk(&Item::register_field_in_read_map, 1,

                       (uchar*) sort_form);

  sort_form->column_bitmaps_set(&sort_form->tmp_set, &sort_form->tmp_set);

  for (;;)

  {

    if (quick_select)

    {

      if ((error= read_record_info.read_record(&read_record_info)))

      {

        error= HA_ERR_END_OF_FILE;

        break;

      }

      file->position(sort_form->record[0]);

    }

    else					/* Not quick-select */

    {

      if (indexfile)

      {

	if (my_b_read(indexfile,(uchar*) ref_pos,ref_length)) /* purecov: deadcode */

	{

	  error= my_errno ? my_errno : -1;		/* Abort */

	  break;

	}

	error=file->rnd_pos(sort_form->record[0],next_pos);

      }

      else

      {

	error=file->rnd_next(sort_form->record[0]);

	if (!flag)

	{

	  my_store_ptr(ref_pos,ref_length,record); // Position to row

	  record+= sort_form->s->db_record_offset;

	}

	else if (!error)

	  file->position(sort_form->record[0]);

      }

      if (error && error != HA_ERR_RECORD_DELETED)

	break;

    }

    if (*killed)

    {

      if (!indexfile && !quick_select)

      {

        (void) file->extra(HA_EXTRA_NO_CACHE);

        file->ha_rnd_end();

      }

      return(HA_POS_ERROR);		/* purecov: inspected */

    }

    if (error == 0)

      param->examined_rows++;

    if (error == 0 && (!select || select->skip_record() == 0))

    {

      if (idx == param->keys)

      {

	if (write_keys(param,sort_keys,idx,buffpek_pointers,tempfile))

	  return(HA_POS_ERROR);

	idx=0;

	indexpos++;

      }

      make_sortkey(param,sort_keys[idx++],ref_pos);

    }

    else

      file->unlock_row();

    /* It does not make sense to read more keys in case of a fatal error */

    if (thd->is_error())

      break;

  }

  if (quick_select)

  {

    /*

      index_merge quick select uses table->sort when retrieving rows, so free

      resoures it has allocated.

    */

    end_read_record(&read_record_info);

  }

  else

  {

    (void) file->extra(HA_EXTRA_NO_CACHE);	/* End cacheing of records */

    if (!next_pos)

      file->ha_rnd_end();

  }

  if (thd->is_error())

    return(HA_POS_ERROR);

  /* Signal we should use orignal column read and write maps */

  sort_form->column_bitmaps_set(save_read_set, save_write_set);

  if (error != HA_ERR_END_OF_FILE)

  {

    file->print_error(error,MYF(ME_ERROR | ME_WAITTANG)); /* purecov: inspected */

    return(HA_POS_ERROR);			/* purecov: inspected */

  }

  if (indexpos && idx &&

      write_keys(param,sort_keys,idx,buffpek_pointers,tempfile))

    return(HA_POS_ERROR);			/* purecov: inspected */

  return(my_b_inited(tempfile) ?

	      (ha_rows) (my_b_tell(tempfile)/param->rec_length) :

	      idx);

} /* find_all_keys */

/**

  @details

  Sort the buffer and write:

  -# the sorted sequence to tempfile

  -# a BUFFPEK describing the sorted sequence position to buffpek_pointers

    (was: Skriver en buffert med nycklar till filen)

  @param param             Sort parameters

  @param sort_keys         Array of pointers to keys to sort

  @param count             Number of elements in sort_keys array

  @param buffpek_pointers  One 'BUFFPEK' struct will be written into this file.

                           The BUFFPEK::{file_pos, count} will indicate where

                           the sorted data was stored.

  @param tempfile          The sorted sequence will be written into this file.

  @retval

    0 OK

  @retval

    1 Error

*/

static int

write_keys(SORTPARAM *param, register uchar **sort_keys, uint count,

           IO_CACHE *buffpek_pointers, IO_CACHE *tempfile)

{

  size_t sort_length, rec_length;

  uchar **end;

  BUFFPEK buffpek;

  sort_length= param->sort_length;

  rec_length= param->rec_length;

  my_string_ptr_sort((uchar*) sort_keys, (uint) count, sort_length);

  if (!my_b_inited(tempfile) &&

      open_cached_file(tempfile, mysql_tmpdir, TEMP_PREFIX, DISK_BUFFER_SIZE,

                       MYF(MY_WME)))

    goto err;                                   /* purecov: inspected */

  /* check we won't have more buffpeks than we can possibly keep in memory */

  if (my_b_tell(buffpek_pointers) + sizeof(BUFFPEK) > (uint64_t)UINT_MAX)

    goto err;

  buffpek.file_pos= my_b_tell(tempfile);

  if ((ha_rows) count > param->max_rows)

    count=(uint) param->max_rows;               /* purecov: inspected */

  buffpek.count=(ha_rows) count;

  for (end=sort_keys+count ; sort_keys != end ; sort_keys++)

    if (my_b_write(tempfile, (uchar*) *sort_keys, (uint) rec_length))

      goto err;

  if (my_b_write(buffpek_pointers, (uchar*) &buffpek, sizeof(buffpek)))

    goto err;

  return(0);

err:

  return(1);

} /* write_keys */

/**

  Store length as suffix in high-byte-first order.

*/

static inline void store_length(uchar *to, uint length, uint pack_length)

{

  switch (pack_length) {

  case 1:

    *to= (uchar) length;

    break;

  case 2:

    mi_int2store(to, length);

    break;

  case 3:

    mi_int3store(to, length);

    break;

  default:

    mi_int4store(to, length);

    break;

  }

}

/** Make a sort-key from record. */

static void make_sortkey(register SORTPARAM *param,

			 register uchar *to, uchar *ref_pos)

{

  register Field *field;

  register SORT_FIELD *sort_field;

  register uint length;

  for (sort_field=param->local_sortorder ;

       sort_field != param->end ;

       sort_field++)

  {

    bool maybe_null=0;

    if ((field=sort_field->field))

    {						// Field

      if (field->maybe_null())

      {

	if (field->is_null())

	{

	  if (sort_field->reverse)

	    memset(to, 255, sort_field->length+1);

	  else

	    memset(to, 0, sort_field->length+1);

	  to+= sort_field->length+1;

	  continue;

	}

	else

	  *to++=1;

      }

      field->sort_string(to, sort_field->length);

    }

    else

    {						// Item

      Item *item=sort_field->item;

      maybe_null= item->maybe_null;

      switch (sort_field->result_type) {

      case STRING_RESULT:

      {

        const CHARSET_INFO * const cs=item->collation.collation;

        char fill_char= ((cs->state & MY_CS_BINSORT) ? (char) 0 : ' ');

        int diff;

        uint sort_field_length;

        if (maybe_null)

          *to++=1;

        /* All item->str() to use some extra byte for end null.. */

        String tmp((char*) to,sort_field->length+4,cs);

        String *res= item->str_result(&tmp);

        if (!res)

        {

          if (maybe_null)

            memset(to-1, 0, sort_field->length+1);

          else

          {

            /* purecov: begin deadcode */

            /*

              This should only happen during extreme conditions if we run out

              of memory or have an item marked not null when it can be null.

              This code is here mainly to avoid a hard crash in this case.

            */

            assert(0);

            memset(to, 0, sort_field->length);	// Avoid crash