database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

Implement percent_rank window function

Browse Source
This commit is contained in:
Vicențiu Ciorbaru
2016-03-03 18:45:37 +02:00
parent f638ffef2c
commit b579a626cf
3 changed files with 322 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

111
sql/sql_window.cc
View File

@ -705,6 +705,110 @@ bool compute_window_func_with_frames(Item_window_func *item_win,
}
bool compute_two_pass_window_functions(Item_window_func *item_win,
TABLE *table, READ_RECORD *info)
{
/* Perform first pass. */
// TODO-cvicentiu why not initialize the record for when we need, _in_
// this function.
READ_RECORD *info2= new READ_RECORD();
int err;
bool is_error = false;
bool first_row= true;
clone_read_record(info, info2);
Item_sum_window_with_context *window_func=
static_cast<Item_sum_window_with_context *>(item_win->window_func);
uchar *rowid_buf= (uchar*) my_malloc(table->file->ref_length, MYF(0));
is_error= window_func->create_window_context();
/* Unable to allocate a new context. */
if (is_error)
return true;
Window_context *context = window_func->get_window_context();
/*
The two pass algorithm is as follows:
We have a sorted table according to the partition and order by clauses.
1. Scan through the table till we reach a partition boundary.
2. For each row that we scan, add it to the context.
3. Once the partition boundary is met, do a second scan through the
current partition and use the context information to compute the value for
the window function for that partition.
4. Reset the context.
5. Repeat from 1 till end of table.
*/
bool done = false;
longlong rows_in_current_partition = 0;
// TODO handle end of table updating.
while (!done)
{
if ((err= info->read_record(info)))
{
done = true;
}
bool partition_changed= (done || item_win->check_partition_bound() > -1) ?
true : false;
// The first time we always have a partition changed. Ignore it.
if (first_row)
{
partition_changed= false;
first_row= false;
}
if (partition_changed)
{
/*
We are now looking at the first row for the next partition, or at the
end of the table. Either way, we must remember this position for when
we finish doing the second pass.
*/
table->file->position(table->record[0]);
memcpy(rowid_buf, table->file->ref, table->file->ref_length);
for (longlong row_number = 0; row_number < rows_in_current_partition;
row_number++)
{
if ((err= info2->read_record(info2)))
{
is_error= true;
break;
}
window_func->add();
// Save the window function into the table.
item_win->save_in_field(item_win->result_field, true);
err= table->file->ha_update_row(table->record[1], table->record[0]);
if (err && err != HA_ERR_RECORD_IS_THE_SAME)
{
is_error= true;
break;
}
}
if (is_error)
break;
rows_in_current_partition= 0;
window_func->clear();
context->reset();
// Return to the beginning of the new partition.
table->file->ha_rnd_pos(table->record[0], rowid_buf);
}
rows_in_current_partition++;
context->add_field_to_context(item_win->result_field);
}
window_func->delete_window_context();
delete info2;
my_free(rowid_buf);
return is_error;
}
/*
@brief
This function is called by JOIN::exec to compute window function values
@ -899,6 +1003,13 @@ bool JOIN::process_window_functions(List<Item> *curr_fields_list)
is_error= true;
break;
}
case Item_sum::PERCENT_RANK_FUNC:
case Item_sum::CUME_DIST_FUNC:
{
if (compute_two_pass_window_functions(item_win, tbl, &info))
is_error= true;
break;
}
case Item_sum::COUNT_FUNC:
{
/*