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Re: disk data storage and mediumtext column
Posted by: a.noort
Date: November 29, 2006 04:43AM

Hi Stewart,

Stewart Smith Wrote:
-------------------------------------------------------
> please post SHOW CREATE TABLE for the table, also
> maybe ndb_desc output for the table


SHOW CREATE TABLE for the table:

CREATE TABLE `testtext` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`data` mediumtext,
PRIMARY KEY (`id`)
) /*!50100 TABLESPACE ts_test STORAGE DISK */ ENGINE=ndbcluster DEFAULT CHARSET=latin1

ndb_desc for the table:

-- testtext --
Version: 2
Fragment type: 5
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 2
Number of primary keys: 1
Length of frm data: 259
Row Checksum: 1
Row GCI: 1
TableStatus: Retrieved
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY
data Text(256,4000;8;latin1_swedish_ci) NULL AT=FIXED ST=MEMORY

-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex


NDBT_ProgramExit: 0 - OK

Hmmm, this explains it: the system stores the data column in memory! If I create a similar table with a data column of type varchar, then the data column is stored on disk. See the SQL code and the output of SHOW TABLE CREATE and ndb_desc for that table below.

SHOW CREATE TABLE for the table with data column of type VARCHAR:

CREATE TABLE `test` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`data` varchar(255) NOT NULL DEFAULT '',
PRIMARY KEY (`id`)
) /*!50100 TABLESPACE ts_test STORAGE DISK */ ENGINE=ndbcluster DEFAULT CHARSET=latin1

ndb_desc for the table with data column of type VARCHAR:

-- test --
Version: 1
Fragment type: 5
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 2
Number of primary keys: 1
Length of frm data: 253
Row Checksum: 1
Row GCI: 1
TableStatus: Retrieved
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY
data Varchar(255;latin1_swedish_ci) NOT NULL AT=FIXED ST=DISK

-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex


NDBT_ProgramExit: 0 - OK

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November 23, 2006 08:31AM
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November 27, 2006 03:18AM
Re: disk data storage and mediumtext column
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November 29, 2006 04:43AM


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