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/* Copyright (C) 2001 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; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Function to handle quick removal of duplicates
This code is used when doing multi-table deletes to find the rows in
reference tables that needs to be deleted.
The basic idea is as follows:
Store first all strings in a binary tree, ignoring duplicates.
When the tree uses more memory than 'max_heap_table_size',
write the tree (in sorted order) out to disk and start with a new tree.
When all data has been generated, merge the trees (removing any found
duplicates).
The unique entries will be returned in sort order, to ensure that we do the
deletes in disk order.
*/
#include "mysql_priv.h"
#include "sql_sort.h"
int unique_write_to_file(gptr key, element_count count, Unique *unique)
{
/*
Use unique->size (size of element stored in the tree) and not
unique->tree.size_of_element. The latter is different from unique->size
when tree implementation chooses to store pointer to key in TREE_ELEMENT
(instead of storing the element itself there)
*/
return my_b_write(&unique->file, (byte*) key,
unique->size) ? 1 : 0;
}
int unique_write_to_ptrs(gptr key, element_count count, Unique *unique)
{
memcpy(unique->record_pointers, key, unique->size);
unique->record_pointers+=unique->size;
return 0;
}
Unique::Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
uint size_arg, ulong max_in_memory_size_arg)
:max_in_memory_size(max_in_memory_size_arg), size(size_arg), elements(0)
{
my_b_clear(&file);
init_tree(&tree, max_in_memory_size / 16, 0, size, comp_func, 0, NULL,
comp_func_fixed_arg);
/* If the following fail's the next add will also fail */
my_init_dynamic_array(&file_ptrs, sizeof(BUFFPEK), 16, 16);
max_elements= max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT)+size);
open_cached_file(&file, mysql_tmpdir,TEMP_PREFIX, DISK_BUFFER_SIZE,
MYF(MY_WME));
}
Unique::~Unique()
{
close_cached_file(&file);
delete_tree(&tree);
delete_dynamic(&file_ptrs);
}
/* Write tree to disk; clear tree */
bool Unique::flush()
{
BUFFPEK file_ptr;
elements+= tree.elements_in_tree;
file_ptr.count=tree.elements_in_tree;
file_ptr.file_pos=my_b_tell(&file);
if (tree_walk(&tree, (tree_walk_action) unique_write_to_file,
(void*) this, left_root_right) ||
insert_dynamic(&file_ptrs, (gptr) &file_ptr))
return 1;
delete_tree(&tree);
return 0;
}
/*
Modify the TABLE element so that when one calls init_records()
the rows will be read in priority order.
*/
bool Unique::get(TABLE *table)
{
SORTPARAM sort_param;
table->found_records=elements+tree.elements_in_tree;
if (my_b_tell(&file) == 0)
{
/* Whole tree is in memory; Don't use disk if you don't need to */
if ((record_pointers=table->record_pointers= (byte*)
my_malloc(size * tree.elements_in_tree, MYF(0))))
{
(void) tree_walk(&tree, (tree_walk_action) unique_write_to_ptrs,
this, left_root_right);
return 0;
}
}
/* Not enough memory; Save the result to file */
if (flush())
return 1;
IO_CACHE *outfile=table->io_cache;
BUFFPEK *file_ptr= (BUFFPEK*) file_ptrs.buffer;
uint maxbuffer= file_ptrs.elements - 1;
uchar *sort_buffer;
my_off_t save_pos;
bool error=1;
/* Open cached file if it isn't open */
outfile=table->io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
MYF(MY_ZEROFILL));
if (!outfile || ! my_b_inited(outfile) &&
open_cached_file(outfile,mysql_tmpdir,TEMP_PREFIX,READ_RECORD_BUFFER,
MYF(MY_WME)))
return 1;
reinit_io_cache(outfile,WRITE_CACHE,0L,0,0);
bzero((char*) &sort_param,sizeof(sort_param));
sort_param.max_rows= elements;
sort_param.sort_form=table;
sort_param.sort_length=sort_param.ref_length=size;
sort_param.keys= max_in_memory_size / sort_param.sort_length;
sort_param.not_killable=1;
if (!(sort_buffer=(uchar*) my_malloc((sort_param.keys+1) *
sort_param.sort_length,
MYF(0))))
return 1;
sort_param.unique_buff= sort_buffer+(sort_param.keys*
sort_param.sort_length);
/* Merge the buffers to one file, removing duplicates */
if (merge_many_buff(&sort_param,sort_buffer,file_ptr,&maxbuffer,&file))
goto err;
if (flush_io_cache(&file) ||
reinit_io_cache(&file,READ_CACHE,0L,0,0))
goto err;
if (merge_buffers(&sort_param, &file, outfile, sort_buffer, file_ptr,
file_ptr, file_ptr+maxbuffer,0))
goto err;
error=0;
err:
x_free((gptr) sort_buffer);
if (flush_io_cache(outfile))
error=1;
/* Setup io_cache for reading */
save_pos=outfile->pos_in_file;
if (reinit_io_cache(outfile,READ_CACHE,0L,0,0))
error=1;
outfile->end_of_file=save_pos;
return error;
}
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