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mariadb/sql/filesort.cc
igor@olga.mysql.com 2d29a57f2b Fixed bug #28811: crash for a query containing a subquery with 
ORDER BY and LIMIT 1. 
The bug was introduced by the patch for bug 21727. The patch
erroneously skipped initialization of the array of headers
for sorted records for non-first evaluations of the subquery.

To fix the problem a new parameter has been added to the
function make_char_array that performs the initialization.
Now this function is called for any invocation of the 
filesort procedure. Yet it allocates the buffer for sorted
records only if this parameter is NULL.
2007-06-07 22:35:31 -07:00

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/* 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 */
/* Sorts a database */
#include "mysql_priv.h"
#ifdef HAVE_STDDEF_H
#include <stddef.h> /* for macro offsetof */
#endif
#include <m_ctype.h>
#include "sql_sort.h"
#ifndef THREAD
#define SKIP_DBUG_IN_FILESORT
#endif
/* How to write record_ref. */
#define WRITE_REF(file,from) \
if (my_b_write((file),(byte*) (from),param->ref_length)) \
DBUG_RETURN(1);
/* functions defined in this file */
static char **make_char_array(char **old_pos, register uint fields,
uint length, myf my_flag);
static BUFFPEK *read_buffpek_from_file(IO_CACHE *buffer_file, uint count);
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, byte *ref_pos);
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 *table_sort);
static uint suffix_length(ulong 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,
byte *buff);
/*
Sort a table
SYNOPSIS
filesort()
table Table to sort
sortorder How to sort the table
s_length Number of elements in sortorder
select condition to apply to the rows
special Not used.
(This could be used to sort the rows pointed on by
select->file)
examined_rows Store number of examined rows here
IMPLEMENTATION
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
REQUIREMENTS
Before calling filesort, one must have done
table->file->info(HA_STATUS_VARIABLE)
RETURN
HA_POS_ERROR Error
# Number of rows
examined_rows will be set to number of examined rows
The result set is stored in table->io_cache or
table->record_pointers
*/
ha_rows filesort(THD *thd, TABLE *table, SORT_FIELD *sortorder, uint s_length,
SQL_SELECT *select, ha_rows max_rows, ha_rows *examined_rows)
{
int error;
ulong 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;
DBUG_ENTER("filesort");
DBUG_EXECUTE("info",TEST_filesort(sortorder,s_length););
#ifdef SKIP_DBUG_IN_FILESORT
DBUG_PUSH(""); /* No DBUG here */
#endif
FILESORT_INFO table_sort;
TABLE_LIST *tab= table->pos_in_table_list;
Item_subselect *subselect= tab ? tab->containing_subselect() : 0;
/*
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));
table->sort.io_cache= NULL;
outfile= table_sort.io_cache;
my_b_clear(&tempfile);
my_b_clear(&buffpek_pointers);
buffpek=0;
error= 1;
bzero((char*) &param,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->table_flags() & HA_FAST_KEY_READ) &&
!table->fulltext_searched)
{
/*
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= (byte *) 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)
{
statistic_increment(thd->status_var.filesort_range_count, &LOCK_status);
}
else
{
statistic_increment(thd->status_var.filesort_scan_count, &LOCK_status);
}
#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->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=my_malloc(param.sort_length,MYF(MY_WME))))
goto err;
memavl= thd->variables.sortbuff_size;
min_sort_memory= max(MIN_SORT_MEMORY, param.sort_length*MERGEBUFF2);
while (memavl >= min_sort_memory)
{
ulong old_memavl;
ulong 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_OUTOFMEMORY,MYF(ME_ERROR+ME_WAITTANG),
thd->variables.sortbuff_size);
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 &&
!(table_sort.buffpek=
(byte *) read_buffpek_from_file(&buffpek_pointers, maxbuffer)))
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((gptr) sort_keys);
table_sort.sort_keys= 0;
x_free((gptr) 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,
(ulong) records, &LOCK_status);
*examined_rows= param.examined_rows;
#ifdef SKIP_DBUG_IN_FILESORT
DBUG_POP(); /* Ok to DBUG */
#endif
memcpy(&table->sort, &table_sort, sizeof(FILESORT_INFO));
DBUG_PRINT("exit",("records: %ld", (long) records));
DBUG_RETURN(error ? HA_POS_ERROR : records);
} /* filesort */
void filesort_free_buffers(TABLE *table, bool full)
{
if (table->sort.record_pointers)
{
my_free((gptr) table->sort.record_pointers,MYF(0));
table->sort.record_pointers=0;
}
if (full)
{
if (table->sort.sort_keys )
{
x_free((gptr) table->sort.sort_keys);
table->sort.sort_keys= 0;
}
if (table->sort.buffpek)
{
x_free((gptr) 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;
DBUG_ENTER("make_char_array");
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);
}
DBUG_RETURN(old_pos);
} /* make_char_array */
/* Read 'count' number of buffer pointers into memory */
static BUFFPEK *read_buffpek_from_file(IO_CACHE *buffpek_pointers, uint count)
{
ulong length;
BUFFPEK *tmp;
DBUG_ENTER("read_buffpek_from_file");
if (count > UINT_MAX/sizeof(BUFFPEK))
return 0; /* sizeof(BUFFPEK)*count will overflow */
tmp=(BUFFPEK*) my_malloc(length=sizeof(BUFFPEK)*count, MYF(MY_WME));
if (tmp)
{
if (reinit_io_cache(buffpek_pointers,READ_CACHE,0L,0,0) ||
my_b_read(buffpek_pointers, (byte*) tmp, length))
{
my_free((char*) tmp, MYF(0));
tmp=0;
}
}
DBUG_RETURN(tmp);
}
/*
Search after sort_keys and write them into tempfile.
SYNOPSIS
find_all_keys()
param Sorting parameter
select Use this to get source data
sort_keys Array of pointers to sort key + addon buffers.
buffpek_pointers File to write BUFFPEKs describing sorted segments
in tempfile.
tempfile File to write sorted sequences of sortkeys to.
indexfile If !NULL, use it for source data (contains rowids)
NOTE
Basic idea:
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.
All produced sequences are guaranteed to be non-empty.
RETURN
Number of records written on success.
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;
byte *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;
DBUG_ENTER("find_all_keys");
DBUG_PRINT("info",("using: %s",(select?select->quick?"ranges":"where":"every row")));
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->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=(byte*) 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())
DBUG_RETURN(HA_POS_ERROR);
init_read_record(&read_record_info, current_thd, select->quick->head,
select, 1, 1);
}
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,(byte*) 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)
{
DBUG_PRINT("info",("Sort killed by user"));
if (!indexfile && !quick_select)
{
(void) file->extra(HA_EXTRA_NO_CACHE);
file->ha_rnd_end();
}
DBUG_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))
DBUG_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->net.report_error)
DBUG_RETURN(HA_POS_ERROR);
}
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();
}
DBUG_PRINT("test",("error: %d indexpos: %d",error,indexpos));
if (error != HA_ERR_END_OF_FILE)
{
file->print_error(error,MYF(ME_ERROR | ME_WAITTANG)); /* purecov: inspected */
DBUG_RETURN(HA_POS_ERROR); /* purecov: inspected */
}
if (indexpos && idx &&
write_keys(param,sort_keys,idx,buffpek_pointers,tempfile))
DBUG_RETURN(HA_POS_ERROR); /* purecov: inspected */
DBUG_RETURN(my_b_inited(tempfile) ?
(ha_rows) (my_b_tell(tempfile)/param->rec_length) :
idx);
} /* find_all_keys */
/*
Sort the buffer and write:
1) the sorted sequence to tempfile
2) a BUFFPEK describing the sorted sequence position to buffpek_pointers
(was: Skriver en buffert med nycklar till filen)
SYNOPSIS
write_keys()
param Sort parameters
sort_keys Array of pointers to keys to sort
count Number of elements in sort_keys array
buffpek_pointers One 'BUFFPEK' struct will be written into this file.
The BUFFPEK::{file_pos, count} will indicate where
the sorted data was stored.
tempfile The sorted sequence will be written into this file.
RETURN
0 OK
1 Error
*/
static int
write_keys(SORTPARAM *param, register uchar **sort_keys, uint count,
IO_CACHE *buffpek_pointers, IO_CACHE *tempfile)
{
uint sort_length, rec_length;
uchar **end;
BUFFPEK buffpek;
DBUG_ENTER("write_keys");
sort_length= param->sort_length;
rec_length= param->rec_length;
#ifdef MC68000
quicksort(sort_keys,count,sort_length);
#else
my_string_ptr_sort((gptr) sort_keys, (uint) count, sort_length);
#endif
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) > (ulonglong)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, (byte*) *sort_keys, (uint) rec_length))
goto err;
if (my_b_write(buffpek_pointers, (byte*) &buffpek, sizeof(buffpek)))
goto err;
DBUG_RETURN(0);
err:
DBUG_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;
}
}
/* makes a sort-key from record */
static void make_sortkey(register SORTPARAM *param,
register uchar *to, byte *ref_pos)
{
reg3 Field *field;
reg1 SORT_FIELD *sort_field;
reg5 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)
bfill(to,sort_field->length+1,(char) 255);
else
bzero((char*) to,sort_field->length+1);
to+= sort_field->length+1;
continue;
}
else
*to++=1;
}
field->sort_string((char*) to,sort_field->length);
}
else
{ // Item
Item *item=sort_field->item;
maybe_null= item->maybe_null;
switch (sort_field->result_type) {
case STRING_RESULT:
{
CHARSET_INFO *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)
bzero((char*) to-1,sort_field->length+1);
else
{
DBUG_PRINT("warning",
("Got null on something that shouldn't be null"));
bzero((char*) to,sort_field->length); // Avoid crash
}
break;
}
length= res->length();
sort_field_length= sort_field->length - sort_field->suffix_length;
diff=(int) (sort_field_length - length);
if (diff < 0)
{
diff=0; /* purecov: inspected */
length= sort_field_length;
}
if (sort_field->suffix_length)
{
/* Store length last in result_string */
store_length(to + sort_field_length, length,
sort_field->suffix_length);
}
if (sort_field->need_strxnfrm)
{
char *from=(char*) res->ptr();
uint tmp_length;
if ((unsigned char *)from == to)
{
set_if_smaller(length,sort_field->length);
memcpy(param->tmp_buffer,from,length);
from=param->tmp_buffer;
}
tmp_length= my_strnxfrm(cs,to,sort_field->length,
(unsigned char *) from, length);
DBUG_ASSERT(tmp_length == sort_field->length);
}
else
{
my_strnxfrm(cs,(uchar*)to,length,(const uchar*)res->ptr(),length);
cs->cset->fill(cs, (char *)to+length,diff,fill_char);
}
break;
}
case INT_RESULT:
{
longlong value= item->val_int_result();
if (maybe_null)
{
*to++=1; /* purecov: inspected */
if (item->null_value)
{
if (maybe_null)
bzero((char*) to-1,sort_field->length+1);
else
{
DBUG_PRINT("warning",
("Got null on something that shouldn't be null"));
bzero((char*) to,sort_field->length);
}
break;
}
}
#if SIZEOF_LONG_LONG > 4
to[7]= (uchar) value;
to[6]= (uchar) (value >> 8);
to[5]= (uchar) (value >> 16);
to[4]= (uchar) (value >> 24);
to[3]= (uchar) (value >> 32);
to[2]= (uchar) (value >> 40);
to[1]= (uchar) (value >> 48);
if (item->unsigned_flag) /* Fix sign */
to[0]= (uchar) (value >> 56);
else
to[0]= (uchar) (value >> 56) ^ 128; /* Reverse signbit */
#else
to[3]= (uchar) value;
to[2]= (uchar) (value >> 8);
to[1]= (uchar) (value >> 16);
if (item->unsigned_flag) /* Fix sign */
to[0]= (uchar) (value >> 24);
else
to[0]= (uchar) (value >> 24) ^ 128; /* Reverse signbit */
#endif
break;
}
case DECIMAL_RESULT:
{
my_decimal dec_buf, *dec_val= item->val_decimal_result(&dec_buf);
if (maybe_null)
{
if (item->null_value)
{
bzero((char*)to, sort_field->length+1);
to++;
break;
}
*to++=1;
}
my_decimal2binary(E_DEC_FATAL_ERROR, dec_val, (char*)to,
item->max_length - (item->decimals ? 1:0),
item->decimals);
break;
}
case REAL_RESULT:
{
double value= item->val_result();
if (maybe_null)
{
if (item->null_value)
{
bzero((char*) to,sort_field->length+1);
to++;
break;
}
*to++=1;
}
change_double_for_sort(value,(byte*) to);
break;
}
case ROW_RESULT:
default:
// This case should never be choosen
DBUG_ASSERT(0);
break;
}
}
if (sort_field->reverse)
{ /* Revers key */
if (maybe_null)
to[-1]= ~to[-1];
length=sort_field->length;
while (length--)
{
*to = (uchar) (~ *to);
to++;
}
}
else
to+= sort_field->length;
}
if (param->addon_field)
{
/*
Save field values appended to sorted fields.
First null bit indicators are appended then field values follow.
In this implementation we use fixed layout for field values -
the same for all records.
*/
SORT_ADDON_FIELD *addonf= param->addon_field;
uchar *nulls= to;
DBUG_ASSERT(addonf != 0);
bzero((char *) nulls, addonf->offset);
to+= addonf->offset;
for ( ; (field= addonf->field) ; addonf++)
{
if (addonf->null_bit && field->is_null())
{
nulls[addonf->null_offset]|= addonf->null_bit;
#ifdef HAVE_purify
bzero(to, addonf->length);
#endif
}
else
{
#ifdef HAVE_purify
uchar *end= (uchar*) field->pack((char *) to, field->ptr);
uint length= (uint) ((to + addonf->length) - end);
DBUG_ASSERT((int) length >= 0);
if (length)
bzero(end, length);
#else
(void) field->pack((char *) to, field->ptr);
#endif
}
to+= addonf->length;
}
}
else
{
/* Save filepos last */
memcpy((byte*) to, ref_pos, (size_s) param->ref_length);
}
return;
}
static bool save_index(SORTPARAM *param, uchar **sort_keys, uint count,
FILESORT_INFO *table_sort)
{
uint offset,res_length;
byte *to;
DBUG_ENTER("save_index");
my_string_ptr_sort((gptr) sort_keys, (uint) count, param->sort_length);
res_length= param->res_length;
offset= param->rec_length-res_length;
if ((ha_rows) count > param->max_rows)
count=(uint) param->max_rows;
if (!(to= table_sort->record_pointers=
(byte*) my_malloc(res_length*count, MYF(MY_WME))))
DBUG_RETURN(1); /* purecov: inspected */
for (uchar **end= sort_keys+count ; sort_keys != end ; sort_keys++)
{
memcpy(to, *sort_keys+offset, res_length);
to+= res_length;
}
DBUG_RETURN(0);
}
/* Merge buffers to make < MERGEBUFF2 buffers */
int merge_many_buff(SORTPARAM *param, uchar *sort_buffer,
BUFFPEK *buffpek, uint *maxbuffer, IO_CACHE *t_file)
{
register uint i;
IO_CACHE t_file2,*from_file,*to_file,*temp;
BUFFPEK *lastbuff;
DBUG_ENTER("merge_many_buff");
if (*maxbuffer < MERGEBUFF2)
DBUG_RETURN(0); /* purecov: inspected */
if (flush_io_cache(t_file) ||
open_cached_file(&t_file2,mysql_tmpdir,TEMP_PREFIX,DISK_BUFFER_SIZE,
MYF(MY_WME)))
DBUG_RETURN(1); /* purecov: inspected */
from_file= t_file ; to_file= &t_file2;
while (*maxbuffer >= MERGEBUFF2)
{
if (reinit_io_cache(from_file,READ_CACHE,0L,0,0))
goto cleanup;
if (reinit_io_cache(to_file,WRITE_CACHE,0L,0,0))
goto cleanup;
lastbuff=buffpek;
for (i=0 ; i <= *maxbuffer-MERGEBUFF*3/2 ; i+=MERGEBUFF)
{
if (merge_buffers(param,from_file,to_file,sort_buffer,lastbuff++,
buffpek+i,buffpek+i+MERGEBUFF-1,0))
goto cleanup;
}
if (merge_buffers(param,from_file,to_file,sort_buffer,lastbuff++,
buffpek+i,buffpek+ *maxbuffer,0))
break; /* purecov: inspected */
if (flush_io_cache(to_file))
break; /* purecov: inspected */
temp=from_file; from_file=to_file; to_file=temp;
setup_io_cache(from_file);
setup_io_cache(to_file);
*maxbuffer= (uint) (lastbuff-buffpek)-1;
}
cleanup:
close_cached_file(to_file); // This holds old result
if (to_file == t_file)
{
*t_file=t_file2; // Copy result file
setup_io_cache(t_file);
}
DBUG_RETURN(*maxbuffer >= MERGEBUFF2); /* Return 1 if interrupted */
} /* merge_many_buff */
/* Read data to buffer */
/* This returns (uint) -1 if something goes wrong */
uint read_to_buffer(IO_CACHE *fromfile, BUFFPEK *buffpek,
uint rec_length)
{
register uint count;
uint length;
if ((count=(uint) min((ha_rows) buffpek->max_keys,buffpek->count)))
{
if (my_pread(fromfile->file,(byte*) buffpek->base,
(length= rec_length*count),buffpek->file_pos,MYF_RW))
return((uint) -1); /* purecov: inspected */
buffpek->key=buffpek->base;
buffpek->file_pos+= length; /* New filepos */
buffpek->count-= count;
buffpek->mem_count= count;
}
return (count*rec_length);
} /* read_to_buffer */
/*
Put all room used by freed buffer to use in adjacent buffer. Note, that
we can't simply distribute memory evenly between all buffers, because
new areas must not overlap with old ones.
SYNOPSIS
reuse_freed_buff()
queue IN list of non-empty buffers, without freed buffer
reuse IN empty buffer
key_length IN key length
*/
void reuse_freed_buff(QUEUE *queue, BUFFPEK *reuse, uint key_length)
{
uchar *reuse_end= reuse->base + reuse->max_keys * key_length;
for (uint i= 0; i < queue->elements; ++i)
{
BUFFPEK *bp= (BUFFPEK *) queue_element(queue, i);
if (bp->base + bp->max_keys * key_length == reuse->base)
{
bp->max_keys+= reuse->max_keys;
return;
}
else if (bp->base == reuse_end)
{
bp->base= reuse->base;
bp->max_keys+= reuse->max_keys;
return;
}
}
DBUG_ASSERT(0);
}
/*
Merge buffers to one buffer
SYNOPSIS
merge_buffers()
param Sort parameter
from_file File with source data (BUFFPEKs point to this file)
to_file File to write the sorted result data.
sort_buffer Buffer for data to store up to MERGEBUFF2 sort keys.
lastbuff OUT Store here BUFFPEK describing data written to to_file
Fb First element in source BUFFPEKs array
Tb Last element in source BUFFPEKs array
flag
RETURN
0 - OK
other - error
*/
int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
IO_CACHE *to_file, uchar *sort_buffer,
BUFFPEK *lastbuff, BUFFPEK *Fb, BUFFPEK *Tb,
int flag)
{
int error;
uint rec_length,sort_length,res_length,offset;
ulong maxcount;
ha_rows max_rows,org_max_rows;
my_off_t to_start_filepos;
uchar *strpos;
BUFFPEK *buffpek;
QUEUE queue;
qsort2_cmp cmp;
volatile THD::killed_state *killed= &current_thd->killed;
THD::killed_state not_killable;
DBUG_ENTER("merge_buffers");
statistic_increment(current_thd->status_var.filesort_merge_passes,
&LOCK_status);
if (param->not_killable)
{
killed= &not_killable;
not_killable= THD::NOT_KILLED;
}
error=0;
rec_length= param->rec_length;
res_length= param->res_length;
sort_length= param->sort_length;
offset= rec_length-res_length;
maxcount= (ulong) (param->keys/((uint) (Tb-Fb) +1));
to_start_filepos= my_b_tell(to_file);
strpos= (uchar*) sort_buffer;
org_max_rows=max_rows= param->max_rows;
/* The following will fire if there is not enough space in sort_buffer */
DBUG_ASSERT(maxcount!=0);
if (init_queue(&queue, (uint) (Tb-Fb)+1, offsetof(BUFFPEK,key), 0,
(queue_compare) (cmp= get_ptr_compare(sort_length)),
(void*) &sort_length))
DBUG_RETURN(1); /* purecov: inspected */
for (buffpek= Fb ; buffpek <= Tb ; buffpek++)
{
buffpek->base= strpos;
buffpek->max_keys= maxcount;
strpos+= (uint) (error= (int) read_to_buffer(from_file, buffpek,
rec_length));
if (error == -1)
goto err; /* purecov: inspected */
buffpek->max_keys= buffpek->mem_count; // If less data in buffers than expected
queue_insert(&queue, (byte*) buffpek);
}
if (param->unique_buff)
{
/*
Called by Unique::get()
Copy the first argument to param->unique_buff for unique removal.
Store it also in 'to_file'.
This is safe as we know that there is always more than one element
in each block to merge (This is guaranteed by the Unique:: algorithm
*/
buffpek= (BUFFPEK*) queue_top(&queue);
memcpy(param->unique_buff, buffpek->key, rec_length);
if (my_b_write(to_file, (byte*) buffpek->key, rec_length))
{
error=1; goto err; /* purecov: inspected */
}
buffpek->key+= rec_length;
buffpek->mem_count--;
if (!--max_rows)
{
error= 0; /* purecov: inspected */
goto end; /* purecov: inspected */
}
queue_replaced(&queue); // Top element has been used
}
else
cmp= 0; // Not unique
while (queue.elements > 1)
{
if (*killed)
{
error= 1; goto err; /* purecov: inspected */
}
for (;;)
{
buffpek= (BUFFPEK*) queue_top(&queue);
if (cmp) // Remove duplicates
{
if (!(*cmp)(&sort_length, &(param->unique_buff),
(uchar**) &buffpek->key))
goto skip_duplicate;
memcpy(param->unique_buff, (uchar*) buffpek->key, rec_length);
}
if (flag == 0)
{
if (my_b_write(to_file,(byte*) buffpek->key, rec_length))
{
error=1; goto err; /* purecov: inspected */
}
}
else
{
if (my_b_write(to_file, (byte*) buffpek->key+offset, res_length))
{
error=1; goto err; /* purecov: inspected */
}
}
if (!--max_rows)
{
error= 0; /* purecov: inspected */
goto end; /* purecov: inspected */
}
skip_duplicate:
buffpek->key+= rec_length;
if (! --buffpek->mem_count)
{
if (!(error= (int) read_to_buffer(from_file,buffpek,
rec_length)))
{
VOID(queue_remove(&queue,0));
reuse_freed_buff(&queue, buffpek, rec_length);
break; /* One buffer have been removed */
}
else if (error == -1)
goto err; /* purecov: inspected */
}
queue_replaced(&queue); /* Top element has been replaced */
}
}
buffpek= (BUFFPEK*) queue_top(&queue);
buffpek->base= sort_buffer;
buffpek->max_keys= param->keys;
/*
As we know all entries in the buffer are unique, we only have to
check if the first one is the same as the last one we wrote
*/
if (cmp)
{
if (!(*cmp)(&sort_length, &(param->unique_buff), (uchar**) &buffpek->key))
{
buffpek->key+= rec_length; // Remove duplicate
--buffpek->mem_count;
}
}
do
{
if ((ha_rows) buffpek->mem_count > max_rows)
{ /* Don't write too many records */
buffpek->mem_count= (uint) max_rows;
buffpek->count= 0; /* Don't read more */
}
max_rows-= buffpek->mem_count;
if (flag == 0)
{
if (my_b_write(to_file,(byte*) buffpek->key,
(rec_length*buffpek->mem_count)))
{
error= 1; goto err; /* purecov: inspected */
}
}
else
{
register uchar *end;
strpos= buffpek->key+offset;
for (end= strpos+buffpek->mem_count*rec_length ;
strpos != end ;
strpos+= rec_length)
{
if (my_b_write(to_file, (byte *) strpos, res_length))
{
error=1; goto err;
}
}
}
}
while ((error=(int) read_to_buffer(from_file,buffpek, rec_length))
!= -1 && error != 0);
end:
lastbuff->count= min(org_max_rows-max_rows, param->max_rows);
lastbuff->file_pos= to_start_filepos;
err:
delete_queue(&queue);
DBUG_RETURN(error);
} /* merge_buffers */
/* Do a merge to output-file (save only positions) */
static int merge_index(SORTPARAM *param, uchar *sort_buffer,
BUFFPEK *buffpek, uint maxbuffer,
IO_CACHE *tempfile, IO_CACHE *outfile)
{
DBUG_ENTER("merge_index");
if (merge_buffers(param,tempfile,outfile,sort_buffer,buffpek,buffpek,
buffpek+maxbuffer,1))
DBUG_RETURN(1); /* purecov: inspected */
DBUG_RETURN(0);
} /* merge_index */
static uint suffix_length(ulong string_length)
{
if (string_length < 256)
return 1;
if (string_length < 256L*256L)
return 2;
if (string_length < 256L*256L*256L)
return 3;
return 4; // Can't sort longer than 4G
}
/*
Calculate length of sort key
SYNOPSIS
sortlength()
thd Thread handler
sortorder Order of items to sort
uint s_length Number of items to sort
multi_byte_charset (out)
Set to 1 if we are using multi-byte charset
(In which case we have to use strxnfrm())
NOTES
sortorder->length is updated for each sort item
sortorder->need_strxnfrm is set 1 if we have to use strxnfrm
RETURN
Total length of sort buffer in bytes
*/
static uint
sortlength(THD *thd, SORT_FIELD *sortorder, uint s_length,
bool *multi_byte_charset)
{
reg2 uint length;
CHARSET_INFO *cs;
*multi_byte_charset= 0;
length=0;
for (; s_length-- ; sortorder++)
{
sortorder->need_strxnfrm= 0;
sortorder->suffix_length= 0;
if (sortorder->field)
{
cs= sortorder->field->sort_charset();
sortorder->length= sortorder->field->sort_length();
if (use_strnxfrm((cs=sortorder->field->sort_charset())))
{
sortorder->need_strxnfrm= 1;
*multi_byte_charset= 1;
sortorder->length= cs->coll->strnxfrmlen(cs, sortorder->length);
}
if (sortorder->field->maybe_null())
length++; // Place for NULL marker
}
else
{
sortorder->result_type= sortorder->item->result_type();
if (sortorder->item->result_as_longlong())
sortorder->result_type= INT_RESULT;
switch (sortorder->result_type) {
case STRING_RESULT:
sortorder->length=sortorder->item->max_length;
set_if_smaller(sortorder->length, thd->variables.max_sort_length);
if (use_strnxfrm((cs=sortorder->item->collation.collation)))
{
sortorder->length= cs->coll->strnxfrmlen(cs, sortorder->length);
sortorder->need_strxnfrm= 1;
*multi_byte_charset= 1;
}
else if (cs == &my_charset_bin)
{
/* Store length last to be able to sort blob/varbinary */
sortorder->suffix_length= suffix_length(sortorder->length);
sortorder->length+= sortorder->suffix_length;
}
break;
case INT_RESULT:
#if SIZEOF_LONG_LONG > 4
sortorder->length=8; // Size of intern longlong
#else
sortorder->length=4;
#endif
break;
case DECIMAL_RESULT:
sortorder->length=
my_decimal_get_binary_size(sortorder->item->max_length -
(sortorder->item->decimals ? 1 : 0),
sortorder->item->decimals);
break;
case REAL_RESULT:
sortorder->length=sizeof(double);
break;
case ROW_RESULT:
default:
// This case should never be choosen
DBUG_ASSERT(0);
break;
}
if (sortorder->item->maybe_null)
length++; // Place for NULL marker
}
set_if_smaller(sortorder->length, thd->variables.max_sort_length);
length+=sortorder->length;
}
sortorder->field= (Field*) 0; // end marker
DBUG_PRINT("info",("sort_length: %d",length));
return length;
}
/*
Get descriptors of fields appended to sorted fields and
calculate its total length
SYNOPSIS
get_addon_fields()
thd Current thread
ptabfields Array of references to the table fields
sortlength Total length of sorted fields
plength out: Total length of appended fields
DESCRIPTION
The function first finds out what fields are used in the result set.
Then it calculates the length of the buffer to store the values of
these fields together with the value of sort values.
If the calculated length is not greater than max_length_for_sort_data
the function allocates memory for an array of descriptors containing
layouts for the values of the non-sorted fields in the buffer and
fills them.
NOTES
The null bits for the appended values are supposed to be put together
and stored the buffer just ahead of the value of the first field.
RETURN
Pointer to the layout descriptors for the appended fields, if any
NULL - if we do not store field values with sort data.
*/
static SORT_ADDON_FIELD *
get_addon_fields(THD *thd, Field **ptabfield, uint sortlength, uint *plength)
{
Field **pfield;
Field *field;
SORT_ADDON_FIELD *addonf;
uint length= 0;
uint fields= 0;
uint null_fields= 0;
query_id_t query_id= thd->query_id;
/*
If there is a reference to a field in the query add it
to the the set of appended fields.
Note for future refinement:
This this a too strong condition.
Actually we need only the fields referred in the
result set. And for some of them it makes sense to use
the values directly from sorted fields.
*/
*plength= 0;
/*
The following statement is added to avoid sorting in alter_table.
The fact is the filter 'field->query_id != thd->query_id'
doesn't work for alter table
*/
if (thd->lex->sql_command != SQLCOM_SELECT &&
thd->lex->sql_command != SQLCOM_INSERT_SELECT)
return 0;
for (pfield= ptabfield; (field= *pfield) ; pfield++)
{
if (field->query_id != query_id)
continue;
if (field->flags & BLOB_FLAG)
return 0;
length+= field->max_packed_col_length(field->pack_length());
if (field->maybe_null())
null_fields++;
fields++;
}
if (!fields)
return 0;
length+= (null_fields+7)/8;
if (length+sortlength > thd->variables.max_length_for_sort_data ||
!(addonf= (SORT_ADDON_FIELD *) my_malloc(sizeof(SORT_ADDON_FIELD)*
(fields+1), MYF(MY_WME))))
return 0;
*plength= length;
length= (null_fields+7)/8;
null_fields= 0;
for (pfield= ptabfield; (field= *pfield) ; pfield++)
{
if (field->query_id != thd->query_id)
continue;
addonf->field= field;
addonf->offset= length;
if (field->maybe_null())
{
addonf->null_offset= null_fields/8;
addonf->null_bit= 1<<(null_fields & 7);
null_fields++;
}
else
{
addonf->null_offset= 0;
addonf->null_bit= 0;
}
addonf->length= field->max_packed_col_length(field->pack_length());
length+= addonf->length;
addonf++;
}
addonf->field= 0; // Put end marker
DBUG_PRINT("info",("addon_length: %d",length));
return (addonf-fields);
}
/*
Copy (unpack) values appended to sorted fields from a buffer back to
their regular positions specified by the Field::ptr pointers.
SYNOPSIS
unpack_addon_fields()
addon_field Array of descriptors for appended fields
buff Buffer which to unpack the value from
NOTES
The function is supposed to be used only as a callback function
when getting field values for the sorted result set.
RETURN
void.
*/
static void
unpack_addon_fields(struct st_sort_addon_field *addon_field, byte *buff)
{
Field *field;
SORT_ADDON_FIELD *addonf= addon_field;
for ( ; (field= addonf->field) ; addonf++)
{
if (addonf->null_bit && (addonf->null_bit & buff[addonf->null_offset]))
{
field->set_null();
continue;
}
field->set_notnull();
field->unpack(field->ptr, (char *) buff+addonf->offset);
}
}
/*
** functions to change a double or float to a sortable string
** The following should work for IEEE
*/
#define DBL_EXP_DIG (sizeof(double)*8-DBL_MANT_DIG)
void change_double_for_sort(double nr,byte *to)
{
uchar *tmp=(uchar*) to;
if (nr == 0.0)
{ /* Change to zero string */
tmp[0]=(uchar) 128;
bzero((char*) tmp+1,sizeof(nr)-1);
}
else
{
#ifdef WORDS_BIGENDIAN
memcpy_fixed(tmp,&nr,sizeof(nr));
#else
{
uchar *ptr= (uchar*) &nr;
#if defined(__FLOAT_WORD_ORDER) && (__FLOAT_WORD_ORDER == __BIG_ENDIAN)
tmp[0]= ptr[3]; tmp[1]=ptr[2]; tmp[2]= ptr[1]; tmp[3]=ptr[0];
tmp[4]= ptr[7]; tmp[5]=ptr[6]; tmp[6]= ptr[5]; tmp[7]=ptr[4];
#else
tmp[0]= ptr[7]; tmp[1]=ptr[6]; tmp[2]= ptr[5]; tmp[3]=ptr[4];
tmp[4]= ptr[3]; tmp[5]=ptr[2]; tmp[6]= ptr[1]; tmp[7]=ptr[0];
#endif
}
#endif
if (tmp[0] & 128) /* Negative */
{ /* make complement */
uint i;
for (i=0 ; i < sizeof(nr); i++)
tmp[i]=tmp[i] ^ (uchar) 255;
}
else
{ /* Set high and move exponent one up */
ushort exp_part=(((ushort) tmp[0] << 8) | (ushort) tmp[1] |
(ushort) 32768);
exp_part+= (ushort) 1 << (16-1-DBL_EXP_DIG);
tmp[0]= (uchar) (exp_part >> 8);
tmp[1]= (uchar) exp_part;
}
}
}
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