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/*
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is also distributed with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have included with MySQL.
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, version 2.0, 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
@brief
Sorts a database
*/
#include "filesort.h"
#include <m_ctype.h>
#include "sql_sort.h"
#include "probes_mysql.h"
#include "opt_range.h" // QUICK
#include "bounded_queue.h"
#include "filesort_utils.h"
#include "sql_select.h"
#include "debug_sync.h"
#include "opt_trace.h"
#include "sql_optimizer.h" // JOIN
#include "sql_base.h"
#include "opt_costmodel.h"
#include "priority_queue.h"
#include "log.h"
#include "item_sum.h" // Item_sum
#include "json_dom.h" // Json_wrapper
#include "template_utils.h"
#include "pfs_file_provider.h"
#include "mysql/psi/mysql_file.h"
#include <algorithm>
#include <utility>
using std::max;
using std::min;
namespace {
struct Mem_compare
{
Mem_compare() : m_compare_length(0) {}
Mem_compare(const Mem_compare &that)
: m_compare_length(that.m_compare_length)
{
}
bool operator()(const uchar *s1, const uchar *s2) const
{
// memcmp(s1, s2, 0) is guaranteed to return zero.
return memcmp(s1, s2, m_compare_length) < 0;
}
size_t m_compare_length;
};
}
/* functions defined in this file */
static ha_rows find_all_keys(Sort_param *param, QEP_TAB *qep_tab,
Filesort_info *fs_info,
IO_CACHE *buffer_file,
IO_CACHE *chunk_file,
Bounded_queue<uchar *, uchar *, Sort_param,
Mem_compare> *pq,
ha_rows *found_rows);
static int write_keys(Sort_param *param, Filesort_info *fs_info,
uint count, IO_CACHE *buffer_file, IO_CACHE *tempfile);
static void register_used_fields(Sort_param *param);
static int merge_index(Sort_param *param,
Sort_buffer sort_buffer,
Merge_chunk_array chunk_array,
IO_CACHE *tempfile,
IO_CACHE *outfile);
static bool save_index(Sort_param *param, uint count,
Filesort_info *table_sort);
static uint suffix_length(ulong string_length);
static bool check_if_pq_applicable(Opt_trace_context *trace,
Sort_param *param, Filesort_info *info,
TABLE *table,
ha_rows records, ulong memory_available,
bool keep_addon_fields);
void Sort_param::init_for_filesort(Filesort *file_sort,
uint sortlen, TABLE *table,
ulong max_length_for_sort_data,
ha_rows maxrows, bool sort_positions)
{
assert(max_rows == 0); // function should not be called twice
sort_length= sortlen;
ref_length= table->file->ref_length;
if (!(table->file->ha_table_flags() & HA_FAST_KEY_READ) &&
!table->fulltext_searched && !sort_positions)
{
/*
Get the descriptors of all fields whose values are appended
to sorted fields and get its total length in addon_length.
*/
addon_fields=
file_sort->get_addon_fields(max_length_for_sort_data,
table->field, sort_length, &addon_length,
&m_packable_length);
}
if (using_addon_fields())
{
res_length= addon_length;
}
else
{
res_length= ref_length;
/*
The reference to the record is considered
as an additional sorted field
*/
sort_length+= ref_length;
}
/*
Add hash at the end of sort key to order cut values correctly.
Needed for GROUPing, rather than for ORDERing.
*/
if (use_hash)
sort_length+= sizeof(ulonglong);
rec_length= sort_length + addon_length;
max_rows= maxrows;
}
void Sort_param::try_to_pack_addons(ulong max_length_for_sort_data)
{
if (!using_addon_fields() || // no addons, or
using_packed_addons()) // already packed
return;
if (!Addon_fields::can_pack_addon_fields(res_length))
return;
const uint sz= Addon_fields::size_of_length_field;
if (rec_length + sz > max_length_for_sort_data)
return;
// Heuristic: skip packing if potential savings are less than 10 bytes.
if (m_packable_length < (10 + sz))
return;
Addon_fields_array::iterator addonf= addon_fields->begin();
for ( ; addonf != addon_fields->end(); ++addonf)
{
addonf->offset+= sz;
addonf->null_offset+= sz;
}
addon_fields->set_using_packed_addons(true);
m_using_packed_addons= true;
addon_length+= sz;
res_length+= sz;
rec_length+= sz;
}
static void trace_filesort_information(Opt_trace_context *trace,
const st_sort_field *sortorder,
uint s_length)
{
if (!trace->is_started())
return;
Opt_trace_array trace_filesort(trace, "filesort_information");
for (; s_length-- ; sortorder++)
{
Opt_trace_object oto(trace);
oto.add_alnum("direction", sortorder->reverse ? "desc" : "asc");
if (sortorder->field)
{
if (strlen(sortorder->field->table->alias) != 0)
oto.add_utf8_table(sortorder->field->table->pos_in_table_list);
else
oto.add_alnum("table", "intermediate_tmp_table");
oto.add_alnum("field", sortorder->field->field_name ?
sortorder->field->field_name : "tmp_table_column");
}
else
oto.add("expression", sortorder->item);
}
}
/**
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->sort.io_cache or
table->sort.sorted_result, or left in the main filesort buffer.
@param thd Current thread
@param filesort Table and how to sort it
@param sort_positions Set to TRUE if we want to force sorting by position
(Needed by UPDATE/INSERT or ALTER TABLE or
when rowids are required by executor)
@param[out] examined_rows Store number of examined rows here
This is the number of found rows before
applying WHERE condition.
@param[out] found_rows Store the number of found rows here.
This is the number of found rows after
applying WHERE condition.
@param[out] returned_rows Number of rows in the result, could be less than
found_rows if LIMIT is provided.
@note
If we sort by position (like if sort_positions is 1) filesort() will
call table->prepare_for_position().
@returns False if success, true if error
*/
bool filesort(THD *thd, Filesort *filesort, bool sort_positions,
ha_rows *examined_rows, ha_rows *found_rows,
ha_rows *returned_rows)
{
int error;
ulong memory_available= thd->variables.sortbuff_size;
size_t num_chunks;
ha_rows num_rows= HA_POS_ERROR;
IO_CACHE tempfile; // Temporary file for storing intermediate results.
IO_CACHE chunk_file; // For saving Merge_chunk structs.
IO_CACHE *outfile; // Contains the final, sorted result.
Sort_param param;
bool multi_byte_charset;
Bounded_queue<uchar *, uchar *, Sort_param, Mem_compare>
pq((Malloc_allocator<uchar*>
(key_memory_Filesort_info_record_pointers)));
Opt_trace_context * const trace= &thd->opt_trace;
QEP_TAB *const tab= filesort->tab;
TABLE *const table= tab->table();
ha_rows max_rows= filesort->limit;
uint s_length= 0;
DBUG_ENTER("filesort");
if (!(s_length= filesort->make_sortorder()))
DBUG_RETURN(true); /* purecov: inspected */
/*
We need a nameless wrapper, since we may be inside the "steps" of
"join_execution".
*/
Opt_trace_object trace_wrapper(trace);
trace_filesort_information(trace, filesort->sortorder, s_length);
assert(!table->reginfo.join_tab);
assert(tab == table->reginfo.qep_tab);
Item_subselect *const subselect= tab && tab->join() ?
tab->join()->select_lex->master_unit()->item : NULL;
MYSQL_FILESORT_START(const_cast<char*>(table->s->db.str),
const_cast<char*>(table->s->table_name.str));
DEBUG_SYNC(thd, "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.
*/
Filesort_info table_sort= table->sort;
table->sort.io_cache= NULL;
assert(table_sort.sorted_result == NULL);
table_sort.sorted_result_in_fsbuf= false;
outfile= table_sort.io_cache;
my_b_clear(&tempfile);
my_b_clear(&chunk_file);
error= 1;
param.init_for_filesort(filesort,
sortlength(thd, filesort->sortorder, s_length,
&multi_byte_charset,
&param.use_hash),
table,
thd->variables.max_length_for_sort_data,
max_rows, sort_positions);
table_sort.addon_fields= param.addon_fields;
if (tab->quick())
thd->inc_status_sort_range();
else
thd->inc_status_sort_scan();
// If number of rows is not known, use as much of sort buffer as possible.
num_rows= table->file->estimate_rows_upper_bound();
if (multi_byte_charset &&
!(param.tmp_buffer= (char*) my_malloc(key_memory_Sort_param_tmp_buffer,
param.sort_length,MYF(MY_WME))))
goto err;
if (check_if_pq_applicable(trace, &param, &table_sort,
table, num_rows, memory_available,
subselect != NULL))
{
DBUG_PRINT("info", ("filesort PQ is applicable"));
/*
For PQ queries (with limit) we know exactly how many pointers/records
we have in the buffer, so to simplify things, we initialize
all pointers here. (We cannot pack fields anyways, so there is no
point in doing lazy initialization).
*/
table_sort.init_record_pointers();
if (pq.init(param.max_rows,
&param, table_sort.get_sort_keys()))
{
/*
If we fail to init pq, we have to give up:
out of memory means my_malloc() will call my_error().
*/
DBUG_PRINT("info", ("failed to allocate PQ"));
table_sort.free_sort_buffer();
assert(thd->is_error());
goto err;
}
filesort->using_pq= true;
param.using_pq= true;
}
else
{
DBUG_PRINT("info", ("filesort PQ is not applicable"));
filesort->using_pq= false;
param.using_pq= false;
/*
When sorting using priority queue, we cannot use packed addons.
Without PQ, we can try.
*/
param.try_to_pack_addons(thd->variables.max_length_for_sort_data);
/*
We need space for at least one record from each merge chunk, i.e.
param->max_keys_per_buffer >= MERGEBUFF2
See merge_buffers()),
memory_available must be large enough for
param->max_keys_per_buffer * (record + record pointer) bytes
(the main sort buffer, see alloc_sort_buffer()).
Hence this minimum:
*/
const ulong min_sort_memory=
max<ulong>(MIN_SORT_MEMORY,
ALIGN_SIZE(MERGEBUFF2 * (param.rec_length + sizeof(uchar*))));
/*
Cannot depend on num_rows. For external sort, space for upto MERGEBUFF2
rows is required.
*/
if (num_rows < MERGEBUFF2)
num_rows= MERGEBUFF2;
while (memory_available >= min_sort_memory)
{
ha_rows keys= memory_available / (param.rec_length + sizeof(char*));
// If the table is empty, allocate space for one row.
param.max_keys_per_buffer= (uint) min(num_rows > 0 ? num_rows : 1, keys);
table_sort.alloc_sort_buffer(param.max_keys_per_buffer, param.rec_length);
if (table_sort.sort_buffer_size() > 0)
break;
ulong old_memory_available= memory_available;
memory_available= memory_available/4*3;
if (memory_available < min_sort_memory &&
old_memory_available > min_sort_memory)
memory_available= min_sort_memory;
}
if (memory_available < min_sort_memory)
{
my_error(ER_OUT_OF_SORTMEMORY,MYF(ME_ERRORLOG + ME_FATALERROR));
goto err;
}
}
if (open_cached_file(&chunk_file,mysql_tmpdir,TEMP_PREFIX,
DISK_BUFFER_SIZE, MYF(MY_WME)))
goto err;
param.sort_form= table;
param.local_sortorder=
Bounds_checked_array<st_sort_field>(filesort->sortorder, s_length);
// New scope, because subquery execution must be traced within an array.
{
Opt_trace_array ota(trace, "filesort_execution");
num_rows= find_all_keys(&param, tab,
&table_sort,
&chunk_file,
&tempfile,
param.using_pq ? &pq : NULL,
found_rows);
if (num_rows == HA_POS_ERROR)
goto err;
}
num_chunks= static_cast<size_t>(my_b_tell(&chunk_file)) /
sizeof(Merge_chunk);
Opt_trace_object(trace, "filesort_summary")
.add("rows", num_rows)
.add("examined_rows", param.examined_rows)
.add("number_of_tmp_files", num_chunks)
.add("sort_buffer_size", table_sort.sort_buffer_size())
.add_alnum("sort_mode",
param.using_packed_addons() ?
"<sort_key, packed_additional_fields>" :
param.using_addon_fields() ?
"<sort_key, additional_fields>" : "<sort_key, rowid>");
if (num_chunks == 0) // The whole set is in memory
{
if (save_index(&param, (uint) num_rows, &table_sort))
goto err;
}
else
{
// We will need an extra buffer in rr_unpack_from_tempfile()
if (table_sort.using_addon_fields() &&
!(table_sort.addon_fields->allocate_addon_buf(param.addon_length)))
goto err; /* purecov: inspected */
table_sort.read_chunk_descriptors(&chunk_file, num_chunks);
if (table_sort.merge_chunks.is_null())
goto err; /* purecov: inspected */
close_cached_file(&chunk_file);
/* 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.max_keys_per_buffer=
table_sort.sort_buffer_size() / param.rec_length;
if (merge_many_buff(&param,
table_sort.get_raw_buf(),
table_sort.merge_chunks,
&num_chunks,
&tempfile))
goto err;
if (flush_io_cache(&tempfile) ||
reinit_io_cache(&tempfile,READ_CACHE,0L,0,0))
goto err;
if (merge_index(&param,
table_sort.get_raw_buf(),
Merge_chunk_array(table_sort.merge_chunks.begin(),
num_chunks),
&tempfile,
outfile))
goto err;
}
if (num_rows > param.max_rows)
{
// If find_all_keys() produced more results than the query LIMIT.
num_rows= param.max_rows;
}
error= 0;
err:
my_free(param.tmp_buffer);
if (!subselect || !subselect->is_uncacheable())
{
if (!table_sort.sorted_result_in_fsbuf)
table_sort.free_sort_buffer();
my_free(table_sort.merge_chunks.array());
table_sort.merge_chunks= Merge_chunk_array(NULL, 0);
}
close_cached_file(&tempfile);
close_cached_file(&chunk_file);
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)
{
int kill_errno= thd->killed_errno();
assert(thd->is_error() || kill_errno);
/*
We replace the table->sort at the end.
Hence calling free_io_cache to make sure table->sort.io_cache
used for QUICK_INDEX_MERGE_SELECT is free.
*/
free_io_cache(table);
/*
Guard against Bug#11745656 -- KILL QUERY should not send "server shutdown"
to client!
*/
const char *cause= kill_errno
? ((kill_errno == THD::KILL_CONNECTION && !abort_loop)
? ER(THD::KILL_QUERY)
: ER(kill_errno))
: thd->get_stmt_da()->message_text();
const char *msg= ER_THD(thd, ER_FILSORT_ABORT);
my_printf_error(ER_FILSORT_ABORT,
"%s: %s",
MYF(0),
msg,
cause);
if (thd->is_fatal_error)
sql_print_information("%s, host: %s, user: %s, "
"thread: %u, error: %s, query: %-.4096s",
msg,
thd->security_context()->host_or_ip().str,
thd->security_context()->priv_user().str,
thd->thread_id(),
cause,
thd->query().str);
}
else
thd->inc_status_sort_rows(num_rows);
*examined_rows= param.examined_rows;
*returned_rows= num_rows;
/* table->sort.io_cache should be free by this time */
assert(NULL == table->sort.io_cache);
// Assign the copy back!
table->sort= table_sort;
DBUG_PRINT("exit",
("num_rows: %ld examined_rows: %ld found_rows: %ld",
(long) num_rows, (long) *examined_rows, (long) *found_rows));
MYSQL_FILESORT_DONE(error, num_rows);
DBUG_RETURN(error);
} /* filesort */
void filesort_free_buffers(TABLE *table, bool full)
{
DBUG_ENTER("filesort_free_buffers");
my_free(table->sort.sorted_result);
table->sort.sorted_result= NULL;
table->sort.sorted_result_in_fsbuf= false;
if (full)
{
table->sort.free_sort_buffer();
my_free(table->sort.merge_chunks.array());
table->sort.merge_chunks= Merge_chunk_array(NULL, 0);
}
table->sort.addon_fields= NULL;
DBUG_VOID_RETURN;
}
uint Filesort::make_sortorder()
{
uint count;
st_sort_field *sort,*pos;
ORDER *ord;
DBUG_ENTER("make_sortorder");
count=0;
for (ord = order; ord; ord= ord->next)
count++;
if (!sortorder)
sortorder= (st_sort_field*) sql_alloc(sizeof(st_sort_field) * (count + 1));
pos= sort= sortorder;
if (!pos)
DBUG_RETURN(0);
for (ord= order; ord; ord= ord->next, pos++)
{
Item *const item= ord->item[0], *const real_item= item->real_item();
pos->field= 0; pos->item= 0;
if (real_item->type() == Item::FIELD_ITEM)
{
/*
Could be a field, or Item_direct_view_ref/Item_ref wrapping a field
If it is an Item_outer_ref, only_full_group_by has been switched off.
*/
assert
(item->type() == Item::FIELD_ITEM ||
(item->type() == Item::REF_ITEM &&
(down_cast<Item_ref*>(item)->ref_type() == Item_ref::VIEW_REF
|| down_cast<Item_ref*>(item)->ref_type() == Item_ref::OUTER_REF
|| down_cast<Item_ref*>(item)->ref_type() == Item_ref::REF)
));
pos->field= down_cast<Item_field*>(real_item)->field;
}
else if (real_item->type() == Item::SUM_FUNC_ITEM &&
!real_item->const_item())
{
// Aggregate, or Item_aggregate_ref
assert(item->type() == Item::SUM_FUNC_ITEM ||
(item->type() == Item::REF_ITEM &&
static_cast<Item_ref*>(item)->ref_type() ==
Item_ref::AGGREGATE_REF));
pos->field= item->get_tmp_table_field();
}
else if (real_item->type() == Item::COPY_STR_ITEM)
{ // Blob patch
pos->item= static_cast<Item_copy*>(real_item)->get_item();
}
else
pos->item= item;
pos->reverse= (ord->direction == ORDER::ORDER_DESC);
assert(pos->field != NULL || pos->item != NULL);
}
DBUG_RETURN(count);
}
void Filesort_info::read_chunk_descriptors(IO_CACHE *chunk_file, uint count)
{
DBUG_ENTER("Filesort_info::read_chunk_descriptors");
// If we already have a chunk array, we're doing sort in a subquery.
if (!merge_chunks.is_null() &&
merge_chunks.size() < count)
{
my_free(merge_chunks.array()); /* purecov: inspected */
merge_chunks= Merge_chunk_array(NULL, 0); /* purecov: inspected */
}
void *rawmem= merge_chunks.array();
const size_t length= sizeof(Merge_chunk) * count;
if (NULL == rawmem)
{
rawmem= my_malloc(key_memory_Filesort_info_merge, length, MYF(MY_WME));
if (rawmem == NULL)
DBUG_VOID_RETURN; /* purecov: inspected */
}
if (reinit_io_cache(chunk_file, READ_CACHE, 0L, 0, 0) ||
my_b_read(chunk_file, static_cast<uchar*>(rawmem), length))
{
my_free(rawmem); /* purecov: inspected */
rawmem= NULL; /* purecov: inspected */
count= 0; /* purecov: inspected */
}
merge_chunks= Merge_chunk_array(static_cast<Merge_chunk*>(rawmem), count);
DBUG_VOID_RETURN;
}
#ifndef NDEBUG
/*
Print a text, SQL-like record representation into dbug trace.
Note: this function is a work in progress: at the moment
- column read bitmap is ignored (can print garbage for unused columns)
- there is no quoting
*/
static void dbug_print_record(TABLE *table, bool print_rowid)
{
char buff[1024];
Field **pfield;
String tmp(buff,sizeof(buff),&my_charset_bin);
DBUG_LOCK_FILE;
fprintf(DBUG_FILE, "record (");
for (pfield= table->field; *pfield ; pfield++)
fprintf(DBUG_FILE, "%s%s", (*pfield)->field_name, (pfield[1])? ", ":"");
fprintf(DBUG_FILE, ") = ");
fprintf(DBUG_FILE, "(");
for (pfield= table->field; *pfield ; pfield++)
{
Field *field= *pfield;
if (field->is_null()) {
if (fwrite("NULL", sizeof(char), 4, DBUG_FILE) != 4) {
goto unlock_file_and_quit;
}
}
if (field->type() == MYSQL_TYPE_BIT)
(void) field->val_int_as_str(&tmp, 1);
else
field->val_str(&tmp);
if (fwrite(tmp.ptr(),sizeof(char),tmp.length(),DBUG_FILE) != tmp.length()) {
goto unlock_file_and_quit;
}
if (pfield[1]) {
if (fwrite(", ", sizeof(char), 2, DBUG_FILE) != 2) {
goto unlock_file_and_quit;
}
}
}
fprintf(DBUG_FILE, ")");
if (print_rowid)
{
fprintf(DBUG_FILE, " rowid ");
for (uint i=0; i < table->file->ref_length; i++)
{
fprintf(DBUG_FILE, "%x", table->file->ref[i]);
}
}
fprintf(DBUG_FILE, "\n");
unlock_file_and_quit:
DBUG_UNLOCK_FILE;
}
#endif
/// Error handler for filesort.
class Filesort_error_handler : public Internal_error_handler
{
THD *m_thd; ///< The THD in which filesort is executed.
bool m_seen_not_supported; ///< Has a not supported warning has been seen?
public:
/**
Create an error handler and push it onto the error handler
stack. The handler will be automatically popped from the error
handler stack when it is destroyed.
*/
Filesort_error_handler(THD *thd)
: m_thd(thd), m_seen_not_supported(false)
{
thd->push_internal_handler(this);
}
/**
Pop the error handler from the error handler stack, and destroy
it.
*/
~Filesort_error_handler()
{
m_thd->pop_internal_handler();
}
/**
Handle a condition.
The handler will make sure that no more than a single
ER_NOT_SUPPORTED_YET warning will be seen by the higher
layers. This warning is generated by Json_wrapper::make_sort_key()
for every value that it doesn't know how to create a sort key
for. It is sufficient for the higher layers to report this warning
only once per sort.
*/
virtual bool handle_condition(THD *thd,
uint sql_errno,
const char* sqlstate,
Sql_condition::enum_severity_level *level,
const char* msg)
{
if (*level == Sql_condition::SL_WARNING &&
sql_errno == ER_NOT_SUPPORTED_YET)
{
if (m_seen_not_supported)
return true;
m_seen_not_supported= true;
}
return false;
}
};
static const Item::enum_walk walk_subquery=
Item::enum_walk(Item::WALK_POSTFIX | Item::WALK_SUBQUERY);
/**
Search after sort_keys, and write them into tempfile
(if we run out of space in the sort buffer).
All produced sequences are guaranteed to be non-empty.
@param param Sorting parameter
@param select Use this to get source data
@param fs_info Struct containing sort buffer etc.
@param chunk_file File to write Merge_chunks describing sorted segments
in tempfile.
@param tempfile File to write sorted sequences of sortkeys to.
@param pq If !NULL, use it for keeping top N elements
@param [out] found_rows The number of FOUND_ROWS().
For a query with LIMIT, this value will typically
be larger than the function return value.
@note
Basic idea:
@verbatim
while (get_next_sortkey())
{
if (using priority queue)
push sort key into queue
else
{
if (no free space in sort buffer)
{
sort buffer;
dump sorted sequence to 'tempfile';
dump Merge_chunk describing sequence location into 'chunk_file';
}
put sort key into buffer;
if (key was packed)
tell sort buffer the actual number of bytes used;
}
}
if (buffer has some elements && dumped at least once)
sort-dump-dump as above;
else
don't sort, leave sort buffer to be sorted by caller.
@endverbatim
@returns
Number of records written on success.
@returns
HA_POS_ERROR on error.
*/
static ha_rows find_all_keys(Sort_param *param, QEP_TAB *qep_tab,
Filesort_info *fs_info,
IO_CACHE *chunk_file,
IO_CACHE *tempfile,
Bounded_queue<uchar *, uchar *, Sort_param,
Mem_compare> *pq,
ha_rows *found_rows)
{
int error,flag;
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;
bool skip_record;
ha_rows num_records= 0;
const bool packed_addon_fields= param->using_packed_addons();
/*
Set up an error handler for filesort. It is automatically pushed
onto the internal error handler stack upon creation, and will be
popped off the stack automatically when the handler goes out of
scope.
*/
Filesort_error_handler error_handler(thd);
DBUG_ENTER("find_all_keys");
DBUG_PRINT("info",("using: %s",
(qep_tab->condition() ? qep_tab->quick() ? "ranges" : "where":
"every row")));
idx=indexpos=0;
error= 0;
sort_form=param->sort_form;
file=sort_form->file;
ref_length=param->ref_length;
ref_pos= ref_buff;
const bool quick_select= qep_tab->quick() != NULL;
record=0;
*found_rows= 0;
flag= ((file->ha_table_flags() & HA_REC_NOT_IN_SEQ) || quick_select);
if (flag)
ref_pos= &file->ref[0];
next_pos=ref_pos;
if (!quick_select)
{
next_pos=(uchar*) 0; /* Find records in sequence */
DBUG_EXECUTE_IF("bug14365043_1",
DBUG_SET("+d,ha_rnd_init_fail"););
if ((error= file->ha_rnd_init(1)))
{
file->print_error(error, MYF(0));
DBUG_RETURN(HA_POS_ERROR);
}
file->extra_opt(HA_EXTRA_CACHE,
current_thd->variables.read_buff_size);
}
if (quick_select)
{
if ((error= qep_tab->quick()->reset()))
{
file->print_error(error, MYF(0));
DBUG_RETURN(HA_POS_ERROR);
}
}
/* 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 and verify
it's not used
*/
assert(sort_form->tmp_set.n_bits == 0 ||
bitmap_is_clear_all(&sort_form->tmp_set));
// Temporary set for register_used_fields and mark_field_in_map()
sort_form->read_set= &sort_form->tmp_set;
// Include fields used for sorting in the read_set.
register_used_fields(param);
// Include fields used by conditions in the read_set.
if (qep_tab->condition())
{
Mark_field mf(sort_form, MARK_COLUMNS_TEMP);
qep_tab->condition()->walk(&Item::mark_field_in_map,
walk_subquery, (uchar*) &mf);
}
// Include fields used by pushed conditions in the read_set.
if (qep_tab->table()->file->pushed_idx_cond)
{
Mark_field mf(sort_form, MARK_COLUMNS_TEMP);
qep_tab->table()->file->pushed_idx_cond->walk(&Item::mark_field_in_map,
walk_subquery,
(uchar*) &mf);
}
sort_form->column_bitmaps_set(&sort_form->tmp_set, &sort_form->tmp_set);
DEBUG_SYNC(thd, "after_index_merge_phase1");
for (;;)
{
if (quick_select)
{
if ((error= qep_tab->quick()->get_next()))
break;
file->position(sort_form->record[0]);
DBUG_EXECUTE_IF("debug_filesort", dbug_print_record(sort_form, TRUE););
}
else /* Not quick-select */
{
DBUG_EXECUTE_IF("bug19656296", DBUG_SET("+d,ha_rnd_next_deadlock"););
{
error= file->ha_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 (!quick_select)
{
(void) file->extra(HA_EXTRA_NO_CACHE);
file->ha_rnd_end();
}
num_records= HA_POS_ERROR;
goto cleanup;
}
if (error == 0)
param->examined_rows++;
if (!error && !qep_tab->skip_record(thd, &skip_record) && !skip_record)
{
++(*found_rows);
if (pq)
pq->push(ref_pos);
else
{
if (fs_info->isfull())
{
if (write_keys(param, fs_info, idx, chunk_file, tempfile))
{
num_records= HA_POS_ERROR;
goto cleanup;
}
idx= 0;
indexpos++;
}
if (idx == 0)
fs_info->init_next_record_pointer();
uchar *start_of_rec= fs_info->get_next_record_pointer();
const uint rec_sz= param->make_sortkey(start_of_rec, ref_pos);
if (packed_addon_fields && rec_sz != param->rec_length)
fs_info->adjust_next_record_pointer(rec_sz);
idx++;
num_records++;
}
}
/*
Don't try unlocking the row if skip_record reported an error since in
this case the transaction might have been rolled back already.
*/
else if (!thd->is_error())
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)
{
(void) file->extra(HA_EXTRA_NO_CACHE); /* End cacheing of records */
if (!next_pos)
file->ha_rnd_end();
}
if (thd->is_error())
{
num_records= HA_POS_ERROR;
goto cleanup;
}
/* Signal we should use orignal column read and write maps */
sort_form->column_bitmaps_set(save_read_set, save_write_set);
DBUG_PRINT("test",("error: %d indexpos: %d",error,indexpos));
if (error != HA_ERR_END_OF_FILE)
{
myf my_flags;
switch (error) {
case HA_ERR_LOCK_DEADLOCK:
case HA_ERR_LOCK_WAIT_TIMEOUT:
my_flags= MYF(0);
break;
default:
my_flags= MYF(ME_ERRORLOG);
}
file->print_error(error, my_flags);
num_records= HA_POS_ERROR;
goto cleanup;
}
if (indexpos && idx &&
write_keys(param, fs_info, idx, chunk_file, tempfile))
{
num_records= HA_POS_ERROR; // purecov: inspected
goto cleanup;
}
if (pq)
num_records= pq->num_elements();
cleanup:
// Clear tmp_set so it can be used elsewhere
bitmap_clear_all(&sort_form->tmp_set);
DBUG_PRINT("info", ("find_all_keys return %lu", (ulong) num_records));
DBUG_RETURN(num_records);
} /* find_all_keys */
/**
@details
Sort the buffer and write:
-# the sorted sequence to tempfile
-# a Merge_chunk describing the sorted sequence position to chunk_file
@param param Sort parameters
@param fs_info Contains the buffer to be sorted and written.
@param count Number of records to write.
@param chunk_file One 'Merge_chunk' struct will be written into this file.
The Merge_chunk::{file_pos, count} will indicate where
the sorted data was stored.
@param tempfile The sorted sequence will be written into this file.
@returns
0 OK
@returns
1 Error
*/
static int
write_keys(Sort_param *param, Filesort_info *fs_info, uint count,
IO_CACHE *chunk_file, IO_CACHE *tempfile)
{
Merge_chunk merge_chunk;
DBUG_ENTER("write_keys");
fs_info->sort_buffer(param, count);
if (!my_b_inited(tempfile) &&
open_cached_file(tempfile, mysql_tmpdir, TEMP_PREFIX, DISK_BUFFER_SIZE,
MYF(MY_WME)))
DBUG_RETURN(1); /* purecov: inspected */
// Check that we wont have more chunks than we can possibly keep in memory.
if (my_b_tell(chunk_file) + sizeof(Merge_chunk) > (ulonglong)UINT_MAX)
DBUG_RETURN(1); /* purecov: inspected */
merge_chunk.set_file_position(my_b_tell(tempfile));
if (static_cast<ha_rows>(count) > param->max_rows)
{
// Write only SELECT LIMIT rows to the file
count= static_cast<uint>(param->max_rows); /* purecov: inspected */
}
merge_chunk.set_rowcount(static_cast<ha_rows>(count));
const bool packed_addon_fields= param->using_packed_addons();
for (uint ix= 0; ix < count; ++ix)
{
uint rec_length;
uchar *record= fs_info->get_sorted_record(ix);
if (packed_addon_fields)
{
rec_length= param->sort_length +
Addon_fields::read_addon_length(record + param->sort_length);
}
else
rec_length= param->rec_length;
if (my_b_write(tempfile, record, rec_length))
DBUG_RETURN(1); /* purecov: inspected */
}
if (my_b_write(chunk_file, &merge_chunk, sizeof(merge_chunk)))
DBUG_RETURN(1); /* purecov: inspected */
DBUG_RETURN(0);
} /* write_keys */
/**
Store length as suffix in high-byte-first order.
*/
static inline void store_length(uchar *to, size_t 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;
}
}
#ifdef WORDS_BIGENDIAN
const bool Is_big_endian= true;
#else
const bool Is_big_endian= false;
#endif
void copy_native_longlong(uchar *to, size_t to_length,
longlong val, bool is_unsigned)
{
copy_integer<Is_big_endian>(to, to_length,
static_cast<uchar*>(static_cast<void*>(&val)),
sizeof(longlong),
is_unsigned);
}
/**
Make a sort key for the JSON value in an Item.
This function is called by Sort_param::make_sortkey(). We don't want
it to be inlined, since that seemed to have a negative impact on
some performance tests.
@param[in] item The item for which to create a sort key.
@param[out] to Pointer into the buffer to which the sort key should
be written. It will point to where the data portion
of the key should start. For nullable items, this
means right after the NULL indicator byte. The NULL
indicator byte (to[-1]) should be initialized by the
caller to a value that indicates not NULL.
@param[in] length The length of the sort key, not including the NULL
indicator byte at the beginning of the sort key for
nullable items.
@param[in,out] hash The hash key of the JSON values in the current row.
*/
static void MY_ATTRIBUTE((noinline))
make_json_sort_key(Item *item, uchar *to, size_t length, ulonglong *hash)
{
assert(!item->maybe_null || to[-1] == 1);
Json_wrapper wr;
if (item->val_json(&wr))
{
// An error happened when reading the JSON value. Give up.
memset(to, 0, length);
return;
}
if (item->null_value)
{
/*
Got NULL. The sort key should be all zeros. The caller has
already tentatively set the NULL indicator byte at to[-1] to
not-NULL, so we need to clear that byte too.
*/
if (item->maybe_null)
{
memset(to - 1, 0, length + 1);
}
else
{
/* purecov: begin inspected */
DBUG_PRINT("warning",
("Got null on something that shouldn't be null"));
DBUG_ABORT();
memset(to, 0, length);
/* purecov: end */
}
}
else
{
wr.make_sort_key(to, length);
*hash= wr.make_hash_key(hash);
}
}
uint Sort_param::make_sortkey(uchar *to, const uchar *ref_pos)
{
uchar *orig_to= to;
const st_sort_field *sort_field;
ulonglong hash= 0;
for (sort_field= local_sortorder.begin() ;
sort_field != local_sortorder.end() ;
sort_field++)
{
bool maybe_null= false;
if (sort_field->field)
{
Field *field= sort_field->field;
assert(sort_field->field_type == field->type());
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->make_sort_key(to, sort_field->length);
if (sort_field->field_type == MYSQL_TYPE_JSON)
{
assert(use_hash);
unique_hash(field, &hash);
}
}
else
{ // Item
Item *item=sort_field->item;
maybe_null= item->maybe_null;
assert(sort_field->field_type == item->field_type());
switch (sort_field->result_type) {
case STRING_RESULT:
{
if (maybe_null)
*to++= 1;
if (sort_field->field_type == MYSQL_TYPE_JSON)
{
assert(use_hash);
/*
We don't want the code for creating JSON sort keys to be
inlined here, as increasing the size of the surrounding
"else" branch seems to have a negative impact on some
performance tests, even if those tests never execute the
"else" branch.
*/
make_json_sort_key(item, to, sort_field->length, &hash);
break;
}
const CHARSET_INFO *cs=item->collation.collation;
char fill_char= ((cs->state & MY_CS_BINSORT) ? (char) 0 : ' ');
/* 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);
DBUG_PRINT("warning",
("Got null on something that shouldn't be null"));
memset(to, 0, sort_field->length); // Avoid crash
/* purecov: end */
}
break;
}
size_t length= res->length();
if (sort_field->need_strxnfrm)
{
char *from=(char*) res->ptr();
size_t tmp_length MY_ATTRIBUTE((unused));
if ((uchar*) from == to)
{
assert(sort_field->length >= length);
set_if_smaller(length,sort_field->length);
memcpy(tmp_buffer, from, length);
from= tmp_buffer;
}
tmp_length=
cs->coll->strnxfrm(cs, to, sort_field->length,
item->max_char_length(),
(uchar*) from, length,
MY_STRXFRM_PAD_WITH_SPACE |
MY_STRXFRM_PAD_TO_MAXLEN);
assert(tmp_length == sort_field->length);
}
else
{
size_t diff;
uint sort_field_length= sort_field->length -
sort_field->suffix_length;
if (sort_field_length < length)
{
diff= 0;
length= sort_field_length;
}
else
diff= sort_field_length - length;
if (sort_field->suffix_length)
{
/* Store length last in result_string */
store_length(to + sort_field_length, length,
sort_field->suffix_length);
}
my_strnxfrm(cs, to,length,(const uchar*)res->ptr(),length);
cs->cset->fill(cs, (char *)to+length,diff,fill_char);
}
break;
}
case INT_RESULT:
{
longlong value= item->field_type() == MYSQL_TYPE_TIME ?
item->val_time_temporal_result() :
item->is_temporal_with_date() ?
item->val_date_temporal_result() :
item->val_int_result();
if (maybe_null)
{
*to++=1; /* purecov: inspected */
if (item->null_value)
{
if (maybe_null)
memset(to-1, 0, sort_field->length+1);
else
{
DBUG_PRINT("warning",
("Got null on something that shouldn't be null"));
memset(to, 0, sort_field->length);
}
break;
}
}
copy_native_longlong(to, sort_field->length,
value, item->unsigned_flag);
break;
}
case DECIMAL_RESULT:
{
my_decimal dec_buf, *dec_val= item->val_decimal_result(&dec_buf);
if (maybe_null)
{
if (item->null_value)
{
memset(to, 0, sort_field->length+1);
to++;
break;
}
*to++=1;
}
if (sort_field->length < DECIMAL_MAX_FIELD_SIZE)
{
uchar buf[DECIMAL_MAX_FIELD_SIZE];
my_decimal2binary(E_DEC_FATAL_ERROR, dec_val, buf,
item->max_length - (item->decimals ? 1:0),
item->decimals);
memcpy(to, buf, sort_field->length);
}
else
{
my_decimal2binary(E_DEC_FATAL_ERROR, dec_val, 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)
{
memset(to, 0, sort_field->length+1);
to++;
break;
}
*to++=1;
}
if (sort_field->length < sizeof(double))
{
uchar buf[sizeof(double)];
change_double_for_sort(value, buf);
memcpy(to, buf, sort_field->length);
}
else
{
change_double_for_sort(value, to);
}
break;
}
case ROW_RESULT:
default:
// This case should never be choosen
assert(0);
break;
}
}
if (sort_field->reverse)
{ /* Revers key */
if (maybe_null)
to[-1]= ~to[-1];
uint length= sort_field->length;
while (length--)
{
*to = (uchar) (~ *to);
to++;
}
}
else
to+= sort_field->length;
}
if (use_hash)
{
int8store(to, hash);
to+= 8;
}
if (using_addon_fields())
{
/*
Save field values appended to sorted fields.
First null bit indicators are appended then field values follow.
*/
uchar *nulls= to;
uchar *p_len= to;
Addon_fields_array::const_iterator addonf= addon_fields->begin();
uint32 res_len= addonf->offset;
const bool packed_addon_fields= addon_fields->using_packed_addons();
memset(nulls, 0, addonf->offset);
to+= addonf->offset;
for ( ; addonf != addon_fields->end(); ++addonf)
{
Field *field= addonf->field;
if (addonf->null_bit && field->is_null())
{
nulls[addonf->null_offset]|= addonf->null_bit;
if (!packed_addon_fields)
to+= addonf->max_length;
}
else
{
uchar *ptr= field->pack(to, field->ptr);
int sz= static_cast<int>(ptr - to);
res_len += sz;
if (packed_addon_fields)
to+= sz;
else
to+= addonf->max_length;
}
}
if (packed_addon_fields)
Addon_fields::store_addon_length(p_len, res_len);
DBUG_PRINT("info", ("make_sortkey %p %u", orig_to, res_len));
}
else
{
/* Save filepos last */
memcpy(to, ref_pos, ref_length);
to+= ref_length;
}
return to - orig_to;
}
/*
Register fields used by sorting in the sorted table's read set
*/
static void register_used_fields(Sort_param *param)
{
Bounds_checked_array<st_sort_field>::const_iterator sort_field;
TABLE *table=param->sort_form;
MY_BITMAP *bitmap= table->read_set;
Mark_field mf(table, MARK_COLUMNS_TEMP);
for (sort_field= param->local_sortorder.begin() ;
sort_field != param->local_sortorder.end() ;
sort_field++)
{
Field *field;
if ((field= sort_field->field))
{
if (field->table == table)
{
bitmap_set_bit(bitmap, field->field_index);
if (field->is_virtual_gcol())
table->mark_gcol_in_maps(field);
}
}
else
{ // Item
sort_field->item->walk(&Item::mark_field_in_map, walk_subquery,
(uchar *)&mf);
}
}
if (param->using_addon_fields())
{
Addon_fields_array::const_iterator addonf= param->addon_fields->begin();
for ( ; addonf != param->addon_fields->end(); ++addonf)
{
Field *field= addonf->field;
bitmap_set_bit(bitmap, field->field_index);
if (field->is_virtual_gcol())
table->mark_gcol_in_maps(field);
}
}
else
{
/* Save filepos last */
table->prepare_for_position();
}
}
/**
This function is used only if the entire result set fits in memory.
For addon fields, we keep the result in the filesort buffer.
This saves us a lot of memcpy calls.
For row references, we copy the final sorted result into a buffer,
but we do not copy the actual sort-keys, as they are no longer needed.
We could have kept the result in the sort buffere here as well,
but the new buffer - containing only row references - is probably a
lot smaller.
The result data will be unpacked by rr_unpack_from_buffer()
or rr_from_pointers()
@param [in] param Sort parameters.
@param count Number of records
@param [in,out] table_sort Information used by rr_unpack_from_buffer() /
rr_from_pointers()
*/
static bool save_index(Sort_param *param, uint count, Filesort_info *table_sort)
{
uchar *to;
DBUG_ENTER("save_index");
table_sort->sort_buffer(param, count);
if (param->using_addon_fields())
{
table_sort->sorted_result_in_fsbuf= true;
table_sort->set_sort_length(param->sort_length);
DBUG_RETURN(0);
}
table_sort->sorted_result_in_fsbuf= false;
const size_t buf_size= param->res_length * count;
assert(table_sort->sorted_result == NULL);
if (!(to= table_sort->sorted_result=
static_cast<uchar*>(my_malloc(key_memory_Filesort_info_record_pointers,
buf_size, MYF(MY_WME)))))
DBUG_RETURN(1); /* purecov: inspected */
table_sort->sorted_result_end=
table_sort->sorted_result + buf_size;
uint res_length= param->res_length;
uint offset= param->rec_length - res_length;
for (uint ix= 0; ix < count; ++ix)
{
uchar *record= table_sort->get_sorted_record(ix);
memcpy(to, record + offset, res_length);
to+= res_length;
}
DBUG_RETURN(0);
}
/**
Test whether priority queue is worth using to get top elements of an
ordered result set. If it is, then allocates buffer for required amount of
records
@param trace Current trace context.
@param param Sort parameters.
@param filesort_info Filesort information.
@param table Table to sort.
@param num_rows Estimate of number of rows in source record set.
@param memory_available Memory available for sorting.
@param keep_addon_fields Do not try to strip off addon fields.
DESCRIPTION
Given a query like this:
SELECT ... FROM t ORDER BY a1,...,an LIMIT max_rows;
This function tests whether a priority queue should be used to keep
the result. Necessary conditions are:
- estimate that it is actually cheaper than merge-sort
- enough memory to store the <max_rows> records.
If we don't have space for <max_rows> records, but we *do* have
space for <max_rows> keys, we may rewrite 'table' to sort with
references to records instead of additional data.
(again, based on estimates that it will actually be cheaper).
@returns
true - if it's ok to use PQ
false - PQ will be slower than merge-sort, or there is not enough memory.
*/
bool check_if_pq_applicable(Opt_trace_context *trace,
Sort_param *param,
Filesort_info *filesort_info,
TABLE *table, ha_rows num_rows,
ulong memory_available,
bool keep_addon_fields)
{
DBUG_ENTER("check_if_pq_applicable");
/*
How much Priority Queue sort is slower than qsort.
Measurements (see unit test) indicate that PQ is roughly 3 times slower.
*/
const double PQ_slowness= 3.0;
Opt_trace_object trace_filesort(trace,
"filesort_priority_queue_optimization");
if (param->max_rows == HA_POS_ERROR)
{
trace_filesort
.add("usable", false)
.add_alnum("cause", "not applicable (no LIMIT)");
DBUG_RETURN(false);
}
trace_filesort
.add("limit", param->max_rows)
.add("rows_estimate", num_rows)
.add("row_size", param->rec_length)
.add("memory_available", memory_available);
if (param->max_rows + 2 >= UINT_MAX)
{
trace_filesort.add("usable", false).add_alnum("cause", "limit too large");
DBUG_RETURN(false);
}
ulong num_available_keys=
memory_available / (param->rec_length + sizeof(char*));
// We need 1 extra record in the buffer, when using PQ.
param->max_keys_per_buffer= (uint) param->max_rows + 1;
if (num_rows < num_available_keys)
{
// The whole source set fits into memory.
if (param->max_rows < num_rows/PQ_slowness )
{
filesort_info->
alloc_sort_buffer(param->max_keys_per_buffer, param->rec_length);
trace_filesort.add("chosen", true);
DBUG_RETURN(filesort_info->sort_buffer_size() > 0);
}
else
{
// PQ will be slower.
trace_filesort.add("chosen", false)
.add_alnum("cause", "quicksort_is_cheaper");
DBUG_RETURN(false);
}
}
// Do we have space for LIMIT rows in memory?
if (param->max_keys_per_buffer < num_available_keys)
{
filesort_info->alloc_sort_buffer(param->max_keys_per_buffer,
param->rec_length);
trace_filesort.add("chosen", true);
DBUG_RETURN(filesort_info->sort_buffer_size() > 0);
}
// Try to strip off addon fields.
if (!keep_addon_fields && param->using_addon_fields())
{
const ulong row_length=
param->sort_length + param->ref_length + sizeof(char*);
num_available_keys= memory_available / row_length;
Opt_trace_object trace_addon(trace, "strip_additional_fields");
trace_addon.add("row_size", row_length);
// Can we fit all the keys in memory?
if (param->max_keys_per_buffer >= num_available_keys)
{
trace_addon.add("chosen", false).add_alnum("cause", "not_enough_space");
}
else
{
const Cost_model_table *cost_model= table->cost_model();
const double sort_merge_cost=
get_merge_many_buffs_cost_fast(num_rows,
num_available_keys,
row_length, cost_model);
trace_addon.add("sort_merge_cost", sort_merge_cost);
/*
PQ has cost:
(insert + qsort) * log(queue size) * key_compare_cost() +
cost of file lookup afterwards.
The lookup cost is a bit pessimistic: we take table scan cost and
assume that on average we find the row after scanning half of the file.
A better estimate would be lookup cost, but note that we are doing
random lookups here, rather than sequential scan.
*/
const double pq_cpu_cost=
(PQ_slowness * num_rows + param->max_keys_per_buffer) *
cost_model->key_compare_cost(log((double) param->max_keys_per_buffer));
const Cost_estimate scan_cost= table->file->table_scan_cost();
const double pq_io_cost=
param->max_rows * scan_cost.total_cost() / 2.0;
const double pq_cost= pq_cpu_cost + pq_io_cost;
trace_addon.add("priority_queue_cost", pq_cost);
if (sort_merge_cost < pq_cost)
{
trace_addon.add("chosen", false);
DBUG_RETURN(false);
}
trace_addon.add("chosen", true);
filesort_info->alloc_sort_buffer(param->max_keys_per_buffer,
param->sort_length + param->ref_length);
if (filesort_info->sort_buffer_size() > 0)
{
// Make attached data to be references instead of fields.
filesort_info->addon_fields= NULL;
param->addon_fields= NULL;
param->res_length= param->ref_length;
param->sort_length+= param->ref_length;
param->rec_length= param->sort_length;
DBUG_RETURN(true);
}
}
}
DBUG_RETURN(false);
}
/**
Merges buffers to make < MERGEBUFF2 buffers.
@param param Sort parameters.
@param sort_buffer The main memory buffer.
@param chunk_array Array of chunk descriptors to merge.
@param p_num_chunks [out]
output: the number of chunks left in the output file.
@param t_file Where to store the result.
*/
int merge_many_buff(Sort_param *param, Sort_buffer sort_buffer,
Merge_chunk_array chunk_array,
size_t *p_num_chunks, IO_CACHE *t_file)
{
uint i;
IO_CACHE t_file2,*from_file,*to_file,*temp;
DBUG_ENTER("merge_many_buff");
size_t num_chunks= chunk_array.size();
*p_num_chunks= num_chunks;
if (num_chunks <= 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 (num_chunks > 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;
Merge_chunk *last_chunk= chunk_array.begin();;
for (i=0 ; i < num_chunks - MERGEBUFF * 3 / 2 ; i+= MERGEBUFF)
{
if (merge_buffers(param, // param
from_file, // from_file
to_file, // to_file
sort_buffer, // sort_buffer
last_chunk++, // last_chunk [out]
Merge_chunk_array(&chunk_array[i], MERGEBUFF),
0)) // flag
goto cleanup;
}
if (merge_buffers(param,
from_file,
to_file,
sort_buffer,
last_chunk++,
Merge_chunk_array(&chunk_array[i], num_chunks - i),
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);
num_chunks= last_chunk - chunk_array.begin();
}
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);
}
*p_num_chunks= num_chunks;
DBUG_RETURN(num_chunks > MERGEBUFF2); /* Return 1 if interrupted */
} /* merge_many_buff */
/**
Read data to buffer.
@returns
(uint)-1 if something goes wrong
*/
uint read_to_buffer(IO_CACHE *fromfile,
Merge_chunk *merge_chunk,
Sort_param *param)
{
DBUG_ENTER("read_to_buffer");
uint rec_length= param->rec_length;
ha_rows count;
if ((count= min(merge_chunk->max_keys(), merge_chunk->rowcount())))
{
size_t bytes_to_read;
if (param->using_packed_addons())
{
count= merge_chunk->rowcount();
bytes_to_read=
min(merge_chunk->buffer_size(),
static_cast<size_t>(fromfile->end_of_file -
merge_chunk->file_position()));
}
else
bytes_to_read= rec_length * static_cast<size_t>(count);
DBUG_PRINT("info", ("read_to_buffer %p at file_pos %llu bytes %llu",
merge_chunk,
static_cast<ulonglong>(merge_chunk->file_position()),
static_cast<ulonglong>(bytes_to_read)));
if (mysql_file_pread(fromfile->file,
merge_chunk->buffer_start(),
bytes_to_read,
merge_chunk->file_position(), MYF_RW))
DBUG_RETURN((uint) -1); /* purecov: inspected */
size_t num_bytes_read;
if (param->using_packed_addons())
{
/*
The last record read is most likely not complete here.
We need to loop through all the records, reading the length fields,
and then "chop off" the final incomplete record.
*/
uchar *record= merge_chunk->buffer_start();
uint ix= 0;
for (; ix < count; ++ix)
{
if (record + param->sort_length + Addon_fields::size_of_length_field >=
merge_chunk->buffer_end())
break; // Incomplete record.
uchar *plen= record + param->sort_length;
uint res_length= Addon_fields::read_addon_length(plen);
if (plen + res_length >= merge_chunk->buffer_end())
break; // Incomplete record.
assert(res_length > 0);
record+= param->sort_length;
record+= res_length;
}
assert(ix > 0);
count= ix;
num_bytes_read= record - merge_chunk->buffer_start();
DBUG_PRINT("info", ("read %llu bytes of complete records",
static_cast<ulonglong>(bytes_to_read)));
}
else
num_bytes_read= bytes_to_read;
merge_chunk->init_current_key();
merge_chunk->advance_file_position(num_bytes_read);
merge_chunk->decrement_rowcount(count);
merge_chunk->set_mem_count(count);
DBUG_RETURN(num_bytes_read);
}
DBUG_RETURN (0);
} /* read_to_buffer */
namespace {
/**
This struct is used for merging chunks for filesort() and for Unique::get().
For filesort() we use memcmp to compare rows.
For Unique::get() we use the provided compare function.
*/
struct Merge_chunk_less
{
size_t m_len;
Sort_param::chunk_compare_fun m_fun;
Merge_chunk_compare_context *m_arg;
// CTOR for filesort()
explicit Merge_chunk_less(size_t len)
: m_len(len), m_fun(NULL), m_arg(NULL)
{}
// CTOR for Unique::get()
Merge_chunk_less(Sort_param::chunk_compare_fun fun,
Merge_chunk_compare_context *arg)
: m_len(0), m_fun(fun), m_arg(arg)
{}
bool operator()(Merge_chunk *a, Merge_chunk *b)
{
uchar *key1= a->current_key();
uchar *key2= b->current_key();
if (m_len)
return memcmp(key1, key2, m_len) > 0;
if (m_fun)
return (*m_fun)(m_arg, key1, key2) > 0;
// We can actually have zero-length sort key for filesort().
return false;
}
};
} // namespace
/**
Merge buffers to one buffer.
@param param Sort parameter
@param from_file File with source data (Merge_chunks point to this file)
@param to_file File to write the sorted result data.
@param sort_buffer Buffer for data to store up to MERGEBUFF2 sort keys.
@param [out] last_chunk Store here Merge_chunk describing data written to
to_file.
@param chunk_array Array of chunks to merge.
@param flag
@returns
0 OK
@returns
other error
*/
int merge_buffers(Sort_param *param, IO_CACHE *from_file,
IO_CACHE *to_file, Sort_buffer sort_buffer,
Merge_chunk *last_chunk,
Merge_chunk_array chunk_array,
int flag)
{
int error;
uint rec_length,res_length;
size_t sort_length;
ha_rows maxcount;
ha_rows max_rows,org_max_rows;
my_off_t to_start_filepos;
uchar *strpos;
Merge_chunk *merge_chunk;
Sort_param::chunk_compare_fun cmp;
Merge_chunk_compare_context *first_cmp_arg;
volatile THD::killed_state *killed= &current_thd->killed;
THD::killed_state not_killable;
DBUG_ENTER("merge_buffers");
current_thd->inc_status_sort_merge_passes();
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;
const uint offset= (flag == 0) ? 0 : (rec_length - res_length);
maxcount= (ulong) (param->max_keys_per_buffer / chunk_array.size());
to_start_filepos= my_b_tell(to_file);
strpos= sort_buffer.array();
org_max_rows=max_rows= param->max_rows;
/* The following will fire if there is not enough space in sort_buffer */
assert(maxcount!=0);
const bool doing_unique= (param->unique_buff != NULL);
if (doing_unique)
{
cmp= param->compare;
first_cmp_arg= &param->cmp_context;
}
else
{
cmp= NULL;
first_cmp_arg= NULL;
}
Merge_chunk_less mcl=
doing_unique ?
Merge_chunk_less(cmp, first_cmp_arg) :
Merge_chunk_less(sort_length);
Priority_queue<Merge_chunk*,
std::vector<Merge_chunk*, Malloc_allocator<Merge_chunk*> >,
Merge_chunk_less>
queue(mcl,
Malloc_allocator<Merge_chunk*>(key_memory_Filesort_info_merge));
if (queue.reserve(chunk_array.size()))
DBUG_RETURN(1);
for (merge_chunk= chunk_array.begin() ;
merge_chunk != chunk_array.end() ; merge_chunk++)
{
merge_chunk->set_buffer(strpos,
strpos + (sort_buffer.size()/(chunk_array.size())));
merge_chunk->set_max_keys(maxcount);
strpos+=
(uint) (error= (int)read_to_buffer(from_file, merge_chunk, param));
merge_chunk->set_buffer_end(strpos);
if (error == -1)
DBUG_RETURN(error); /* purecov: inspected */
// If less data in buffers than expected
merge_chunk->set_max_keys(merge_chunk->mem_count());
(void) queue.push(merge_chunk);
}
if (doing_unique)
{
assert(!param->using_packed_addons());
/*
Called by Unique::get()
Copy the first argument to param->unique_buff for unique removal.
Store it also in 'to_file'.
*/
merge_chunk= queue.top();
memcpy(param->unique_buff, merge_chunk->current_key(), rec_length);
if (my_b_write(to_file, merge_chunk->current_key(), rec_length))
{
DBUG_RETURN(1); /* purecov: inspected */
}
merge_chunk->advance_current_key(rec_length);
merge_chunk->decrement_mem_count();
if (!--max_rows)
{
error= 0; /* purecov: inspected */
goto end; /* purecov: inspected */
}
// The top chunk may actually contain only a single element
if (merge_chunk->mem_count() == 0)
{
if (!(error= (int) read_to_buffer(from_file, merge_chunk, param)))
{
queue.pop();
reuse_freed_buff(merge_chunk, &queue);
}
else if (error == -1)
DBUG_RETURN(error);
}
queue.update_top(); // Top element has been used
}
while (queue.size() > 1)
{
if (*killed)
{
DBUG_RETURN(1); /* purecov: inspected */
}
for (;;)
{
merge_chunk= queue.top();
if (doing_unique) // Remove duplicates
{
assert(!param->using_packed_addons());
uchar *current_key= merge_chunk->current_key();
if (!(*cmp)(first_cmp_arg, param->unique_buff, current_key))
goto skip_duplicate;
memcpy(param->unique_buff, merge_chunk->current_key(), rec_length);
}
{
param->get_rec_and_res_len(merge_chunk->current_key(),
&rec_length, &res_length);
const uint bytes_to_write= (flag == 0) ? rec_length : res_length;
DBUG_PRINT("info", ("write record at %llu len %u",
my_b_tell(to_file), bytes_to_write));
if (my_b_write(to_file,
merge_chunk->current_key() + offset, bytes_to_write))
{
DBUG_RETURN(1); /* purecov: inspected */
}
if (!--max_rows)
{
error= 0; /* purecov: inspected */
goto end; /* purecov: inspected */
}
}
skip_duplicate:
merge_chunk->advance_current_key(rec_length);
merge_chunk->decrement_mem_count();
if (0 == merge_chunk->mem_count())
{
if (!(error= (int) read_to_buffer(from_file, merge_chunk, param)))
{
queue.pop();
reuse_freed_buff(merge_chunk, &queue);
break; /* One buffer have been removed */
}
else if (error == -1)
DBUG_RETURN(error); /* purecov: inspected */
}
/*
The Merge_chunk at the queue's top had one of its keys consumed, thus
it may now rank differently in the comparison order of the queue, so:
*/
queue.update_top();
}
}
merge_chunk= queue.top();
merge_chunk->set_buffer(sort_buffer.array(),
sort_buffer.array() + sort_buffer.size());
merge_chunk->set_max_keys(param->max_keys_per_buffer);
/*
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 (doing_unique)
{
uchar *current_key= merge_chunk->current_key();
if (!(*cmp)(first_cmp_arg, param->unique_buff, current_key))
{
merge_chunk->advance_current_key(rec_length); // Remove duplicate
merge_chunk->decrement_mem_count();
}
}
do
{
if (merge_chunk->mem_count() > max_rows)
{
merge_chunk->set_mem_count(max_rows); /* Don't write too many records */
merge_chunk->set_rowcount(0); /* Don't read more */
}
max_rows-= merge_chunk->mem_count();
for (uint ix= 0; ix < merge_chunk->mem_count(); ++ix)
{
param->get_rec_and_res_len(merge_chunk->current_key(),
&rec_length, &res_length);
const uint bytes_to_write= (flag == 0) ? rec_length : res_length;
if (my_b_write(to_file,
merge_chunk->current_key() + offset,
bytes_to_write))
{
DBUG_RETURN(1); /* purecov: inspected */
}
merge_chunk->advance_current_key(rec_length);
}
}
while ((error=(int) read_to_buffer(from_file, merge_chunk, param))
!= -1 && error != 0);
end:
last_chunk->set_rowcount(min(org_max_rows-max_rows, param->max_rows));
last_chunk->set_file_position(to_start_filepos);
DBUG_RETURN(error);
} /* merge_buffers */
/* Do a merge to output-file (save only positions) */
static int merge_index(Sort_param *param, Sort_buffer sort_buffer,
Merge_chunk_array chunk_array,
IO_CACHE *tempfile, IO_CACHE *outfile)
{
DBUG_ENTER("merge_index");
if (merge_buffers(param, // param
tempfile, // from_file
outfile, // to_file
sort_buffer, // sort_buffer
chunk_array.begin(), // last_chunk [out]
chunk_array,
1)) // flag
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.
@param thd Thread handler
@param sortorder Order of items to sort
@param s_length Number of items to sort
@param[out] multi_byte_charset Set to 1 if we are using multi-byte charset
(In which case we have to use strxnfrm())
@param[out] use_hash Set to true when make_sortkey should
calculate and append hash for each sort key
@see Sort_param::make_sortkey()
@note
sortorder->length is updated for each sort item.
@n
sortorder->need_strxnfrm is set 1 if we have to use strxnfrm
@return
Total length of sort buffer in bytes
*/
uint
sortlength(THD *thd, st_sort_field *sortorder, uint s_length,
bool *multi_byte_charset, bool *use_hash)
{
uint total_length= 0;
const CHARSET_INFO *cs;
*multi_byte_charset= false;
*use_hash= false;
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())
total_length++; // Place for NULL marker
if (sortorder->field->result_type() == STRING_RESULT &&
!sortorder->field->is_temporal())
{
set_if_smaller(sortorder->length, thd->variables.max_sort_length);
}
sortorder->field_type= sortorder->field->type();
if (sortorder->field_type == MYSQL_TYPE_JSON)
*use_hash= true;
}
else
{
sortorder->result_type= sortorder->item->result_type();
sortorder->field_type= sortorder->item->field_type();
if (sortorder->item->is_temporal())
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;
}
if (sortorder->field_type == MYSQL_TYPE_JSON)
*use_hash= true;
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
assert(0);
break;
}
if (sortorder->item->maybe_null)
total_length++; // Place for NULL marker
}
total_length+= sortorder->length;
}
sortorder->field= NULL; // end marker
DBUG_PRINT("info",("sort_length: %u", total_length));
return total_length;
}
/**
Get descriptors of fields appended to sorted fields and
calculate their total length.
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.
@param max_length_for_sort_data Value of session variable.
@param ptabfield Array of references to the table fields
@param sortlength Total length of sorted fields
@param[out] plength Total length of appended fields
@param[out] ppackable_length Total length of appended fields having a
packable type
@note
The null bits for the appended values are supposed to be put together
and stored into the buffer just ahead of the value of the first field.
@return
Pointer to the layout descriptors for the appended fields, if any
@returns
NULL if we do not store field values with sort data.
*/
Addon_fields *
Filesort::get_addon_fields(ulong max_length_for_sort_data,
Field **ptabfield, uint sortlength, uint *plength,
uint *ppackable_length)
{
Field **pfield;
Field *field;
uint total_length= 0;
uint packable_length= 0;
uint num_fields= 0;
uint null_fields= 0;
TABLE *const table= tab->table();
MY_BITMAP *read_set= table->read_set;
// Locate the effective index for the table to be sorted (if any)
const uint index= tab->effective_index();
/*
filter_covering is true if access is via an index that is covering,
regardless of whether the access is by the covering index or by
index and base table, since the query has to be fulfilled with fields
from that index only.
This information is later used to filter out base columns for virtual
generated columns, since these are only needed when reading the table.
During sorting, trust that values for all generated columns have been
materialized, which means that base columns are no longer necessary.
*/
const bool filter_covering=
index != MAX_KEY &&
table->covering_keys.is_set(index) &&
table->index_contains_some_virtual_gcol(index);
/*
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= *ppackable_length= 0;
for (pfield= ptabfield; (field= *pfield) ; pfield++)
{
if (!bitmap_is_set(read_set, field->field_index))
continue;
// part_of_key is empty for a BLOB, so apply this check before the next.
if (field->flags & BLOB_FLAG)
{
assert(addon_fields == NULL);
return NULL;
}
if (filter_covering && !field->part_of_key.is_set(index))
continue; // See explanation above filter_covering
const uint field_length= field->max_packed_col_length();
total_length+= field_length;
const enum_field_types field_type= field->type();
if (field->maybe_null() ||
field_type == MYSQL_TYPE_STRING ||
field_type == MYSQL_TYPE_VARCHAR ||
field_type == MYSQL_TYPE_VAR_STRING)
packable_length+= field_length;
if (field->maybe_null())
null_fields++;
num_fields++;
}
if (0 == num_fields)
return NULL;
total_length+= (null_fields + 7) / 8;
*ppackable_length= packable_length;
if (total_length + sortlength > max_length_for_sort_data)
{
assert(addon_fields == NULL);
return NULL;
}
if (addon_fields == NULL)
{
void *rawmem1= sql_alloc(sizeof(Addon_fields));
void *rawmem2= sql_alloc(sizeof(Sort_addon_field) * num_fields);
if (rawmem1 == NULL || rawmem2 == NULL)
return NULL; /* purecov: inspected */
Addon_fields_array
addon_array(static_cast<Sort_addon_field*>(rawmem2), num_fields);
addon_fields= new (rawmem1) Addon_fields(addon_array);
}
else
{
/*
Allocate memory only once, reuse descriptor array and buffer.
Set using_packed_addons here, and size/offset details below.
*/
assert(num_fields == addon_fields->num_field_descriptors());
addon_fields->set_using_packed_addons(false);
}
*plength= total_length;
uint length= (null_fields + 7) / 8;
null_fields= 0;
Addon_fields_array::iterator addonf= addon_fields->begin();
for (pfield= ptabfield; (field= *pfield) ; pfield++)
{
if (!bitmap_is_set(read_set, field->field_index))
continue;
if (filter_covering && !field->part_of_key.is_set(index))
continue;
assert(addonf != addon_fields->end());
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->max_length= field->max_packed_col_length();
DBUG_PRINT("info", ("addon_field %s max_length %u",
addonf->field->field_name, addonf->max_length));
length+= addonf->max_length;
addonf++;
}
DBUG_PRINT("info",("addon_length: %d",length));
return addon_fields;
}
/*
** 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,uchar *to)
{
uchar *tmp= to;
if (nr == 0.0)
{ /* Change to zero string */
tmp[0]=(uchar) 128;
memset(tmp+1, 0, sizeof(nr)-1);
}
else
{
#ifdef WORDS_BIGENDIAN
memcpy(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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