disk data storage and mediumtext column

[a.noort]

Hello,

Part (or all) of the data of a mediumtext column of a table that is to be stored on a tablespace on disk, seems to be stored in main-memory instead. This results in a table-full error much earlier than expected.

I use MySQL version 5.1.12-beta.

I use the following cluster configuration:

[NDBD DEFAULT]
NoOfReplicas=2
DataMemory=32M
IndexMemory=16M

[TCP DEFAULT]
portnumber=2202

[NDB_MGMD]
hostname=mgmnode
datadir=/var/lib/mysql-cluster

[NDBD]
hostname=ndbd1
datadir=/usr/local/mysql/data

[NDBD]
hostname=ndbd2
datadir=/usr/local/mysql/data

[MYSQLD]
hostname=sqlnode

I created one table in de ndbcluster engine with the following SQL code:

CREATE LOGFILE GROUP lg_test
ADD UNDOFILE 'undo_test.dat'
INITIAL_SIZE 16M
UNDO_BUFFER_SIZE 2M
ENGINE NDB;

CREATE TABLESPACE ts_test
ADD DATAFILE 'data_test.dat'
USE LOGFILE GROUP lg_test
INITIAL_SIZE 32M
ENGINE NDB;

CREATE TABLE testtext (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
data MEDIUMTEXT
)
TABLESPACE ts_test STORAGE DISK
ENGINE NDB;

I tried to insert 1500 rows with 16 kB data in the data field of each row, but got the error "ERROR 1114 (HY000) at line 371: The table 'testtext' is full" when inserting the 1395-th row.

This is not what I would have expected.

My hypothesis is that the data of the MEDIUMTEXT column is stored in main-memory instead of in the tablespace on disk. The fact that the number of free_extents of the 'data_test.dat' file as found in the table information_schema.files, is exactly the same after inserting the rows as it was before, support this hypothesis.

I would like to have the content of the MEDIUMTEXT column in the tablespace on disk, so I can store more data with less main memory.
I want to apply a MySQL cluster for High-Availability only, not for High-Performance, so I do not mind to store the data on disk.

Can someone give some comments on this. Is this a bug, or is it meant to be this way?

Thanks in advance,

Alex