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Got sort-and-read single-pass window function computation to work

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This commit is contained in:
Sergei Petrunia
2016-02-05 14:12:17 +03:00
parent 6399187ebc
commit 346c1a0ad0
5 changed files with 129 additions and 31 deletions
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52
sql/sql_window.cc
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@ -1,7 +1,9 @@
#include "sql_select.h"
#include "item_windowfunc.h"
#include "filesort.h"
#include "sql_base.h"
#include "sql_window.h"
//TODO: why pass List<Window_spec> by value??
bool
@ -258,10 +260,11 @@ bool JOIN::process_window_functions(List<Item> *curr_fields_list)
for (ORDER* curr = spec->order_list.first; curr; curr=curr->next, pos++)
s_order[pos].item = *curr->item;
//psergey-todo: need the below:??
/* This is free'd by free_io_cache call below. */
table[0]->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
MYF(MY_WME | MY_ZEROFILL|
MY_THREAD_SPECIFIC));
Filesort_tracker dummy_tracker(false);
filesort_retval= filesort(thd, table[0], s_order,
total_size,
@ -274,29 +277,38 @@ bool JOIN::process_window_functions(List<Item> *curr_fields_list)
join_tab->records= found_rows;
my_free(s_order);
//psergey-todo: use the created sorted-index to compute the window
//function we're looking at.
handler *file= table[0]->file;
// TODO: We should read in sorted order here, not in rnd_next order!
// note: we can use the same approach as filesort uses to compare
// sort_keys..
READ_RECORD info;
/*
Go through the sorted array and compute the window function
*/
READ_RECORD info;
if (init_read_record(&info, thd, table[0], select, 0, 1, FALSE))
return true;
int err;
while (!(error=info.read_record(&info)))
{
//TODO: What happens for "PARTITION BY (item value...) ?
// TODO: Sort keys are available in the record. Can we just check
// them?
// TODO: how does one check only 'PARTITION BY' part?
}
end_read_record(&info);
item_win->setup_partition_border_check(thd);
// TODO-TODO: also check how the values are read...
int err;
TABLE *tbl= *table;
while (!(err=info.read_record(&info)))
{
store_record(tbl,record[1]);
/*
This will cause window function to compute its value for the
current row :
*/
item_win->advance_window();
/* Put the new value into temptable's field */
item_win->save_in_field(item_win->result_field, true);
err= tbl->file->ha_update_row(tbl->record[1], tbl->record[0]);
if (err && err != HA_ERR_RECORD_IS_THE_SAME)
return true;
}
item_win->set_read_value_from_result_field();
end_read_record(&info);
filesort_free_buffers(table[0], true);
free_io_cache(table[0]);
}
}
}