Question

I have a table with about 1.4 billion records, with the following format:

mysql> describe _2009all;
+---------------+--------------+------+-----+---------+-------+
| Field         | Type         | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+-------+
| userId        | int(11)      | YES  | MUL | NULL    |       |
| type          | varchar(50)  | YES  |     | NULL    |       |
| kind          | varchar(50)  | YES  |     | NULL    |       |
| description   | varchar(255) | YES  |     | NULL    |       |
| bundleVersion | varchar(255) | YES  |     | NULL    |       |
| bundleId      | varchar(255) | YES  |     | NULL    |       |
| time          | bigint(20)   | YES  |     | NULL    |       |
+---------------+--------------+------+-----+---------+-------+
7 rows in set (0.02 sec)

The entire database takes up less than 0.4 terabytes, and I have about 1.5 terabytes of free disk space available.

I’m trying to prepare the data for analysis where I look at what each user does over time. So I run the following statement:

create table sorted2009 AS (select * from _2009all order by userid,time);

The statement (obviously) takes a long time to run, but at some point, it exhausts the all the free disk space and I get a “ERROR 3 (HY000): Error writing file” error.

Any ideas on how I can create my sorted table? Thanks in advance.

Clarification

Martin: There is only 1 partition.

Andy: The problem I’m trying to solve is that the results of “select * from _2009all order by userid,time” are something that I’m going to be inspecting a lot over the next few months. Thus, rather than running this query every time I want to inspect the results, I want to put the results in a table for faster access.

I had initially assumed that indexing over time would be a waste of space, since timestamps are mostly unique. But I just added an index to the time field in _2009all, and the index takes up a reasonable amount of space. But now to do the sort over the two indexes (what I assume you mean by “indexed walk”):

mysql> select * from _2009all order by userId,time limit 2;
...
2 rows in set (25 min 36.48 sec)

Yes, I’d say 25 minutes is too long. But if you meant something else by your suggestion, I’m open to alternatives.

bot43:

After adding the index to the time field:

mysql> explain select * from _2009all order by userid,time;
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
| id | select_type | table    | type | possible_keys | key  | key_len | ref  | rows       | Extra          |
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
|  1 | SIMPLE      | _2009all | ALL  | NULL          | NULL | NULL    | NULL | 1384378798 | Using filesort |
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
1 row in set (0.05 sec)

mysql> explain select userId,type,kind,description,bundleVersion,bundleId,time from _2009all order by userid,time
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
| id | select_type | table    | type | possible_keys | key  | key_len | ref  | rows       | Extra          |
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
|  1 | SIMPLE      | _2009all | ALL  | NULL          | NULL | NULL    | NULL | 1384378798 | Using filesort |
+----+-------------+----------+------+---------------+------+---------+------+------------+----------------+
1 row in set (0.00 sec)

Good point about the DBMS storing the table any damn way it feels like it. I guess I need another solution.

Answer 1

What indexes do you have on the table?

Can’t you put a composite index on the two columms?

ALTER TABLE `_2009all` ADD INDEX ( `userId` , `time` ) ;