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Displaying posts with tag: fractal tree (reset)

Put your MySQL Knowledge to Good Use with Tim Callaghan at Percona Live-London, November 12
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Attending Percona Live in London next week?

Don’t miss the chance to hear Tokutek’s Vice President of Engineering, Tim Callaghan, discuss how to use your MySQL knowledge to become an instant MongoDB Guru and the advantages of using Fractal Tree&#174 indexes in MySQL and MongoDB. Tim will be speaking about these topics in two separate sessions at 12:00pm and 5:00pm on November 12.

For more information on these sessions and Percona Live-London, visit https://www.percona.com/live/london-2013/users/tim-callaghan.

A TokuDB Stall Caused by Conflicting Transactions When Opening a Table
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One of our customers reported that ‘create table select from’ statements stall for a period of time equal to the TokuDB lock timeout.  This indicated a lock conflict between multiple transactions.  In addition, other MySQL clients that were opening unrelated tables were also stalled.  This indicated that some shared mutex is held too long.  We discuss details about this bug and how it was fixed.  The bug fix will be distributed in TokuDB 7.1.0.

Example
Suppose that we set the tokudb lock timeout to 60 seconds just to exaggerate the stall.

mysql> set global tokudb_lock_timeout=60000;
Query OK, 0 rows affected (0.00 sec)

We then create a simple table.

mysql> create table s (id int primary key);
Query OK, 0 rows affected (0.02







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Loading Air Traffic Control Data with TokuDB 4.1.1
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TokuDB has a big advantage over B-trees when trickle loading data into existing tables. However, it is possible to preprocess the data when bulk loading into empty tables or when new indexes are created. TokuDB release 4 now uses a parallel algorithm to speed up these types of bulk insertions. How does the parallel loader performance compare with the serial loader? We use the Air Traffic Control (ATC) data and queries described in a Percona blog and also used in an experiment with TokuDB 2.1.0 to gain some insight.

Our ATC data is about 122M rows in size, is stored in a 40GiB CSV file, and can be found in our Amazon S3 public

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TokuDB speeds up “replace” and “insert ignore” operations by relaxing the affected rows constraint
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In posts on June 30 and July 6, we explained how implementing the commands “replace into” and “insert ignore” with TokuDB’s fractal trees data structures can be two orders of magnitude faster than implementing them with B-trees. Towards the end of each post, we hinted at that there are some caveats that complicate the story a little. In this post, we explain one of the complications: the calculation of affected rows.

MySQL returns the number of rows affected by a “replace” or “insert” statement to the client. For the “replace” statement, the number of affected rows is defined to be

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Showing entries 1 to 4

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