Oracle 5.0 Reference Manual page 1580

table, cannot be used by other tables.) Performing a node recovery also compresses the partition
because all records are inserted into empty partitions from other live nodes.
The memory space also contains UNDO information: For each update, a copy of
DataMemory
the unaltered record is allocated in the DataMemory. There is also a reference to each copy in
the ordered table indexes. Unique hash indexes are updated only when the unique index columns
are updated, in which case a new entry in the index table is inserted and the old entry is deleted
upon commit. For this reason, it is also necessary to allocate enough memory to handle the largest
transactions performed by applications using the cluster. In any case, performing a few large
transactions holds no advantage over using many smaller ones, for the following reasons:
• Large transactions are not any faster than smaller ones
• Large transactions increase the number of operations that are lost and must be repeated in event
of transaction failure
• Large transactions use more memory
The default value for
reality the maximum size has to be adapted so that the process does not start swapping when the
limit is reached. This limit is determined by the amount of physical RAM available on the machine
and by the amount of memory that the operating system may commit to any one process. 32-bit
operating systems are generally limited to 2–4GB per process; 64-bit operating systems can use
more. For large databases, it may be preferable to use a 64-bit operating system for this reason.
•
IndexMemory
Effective Version
MySQL 5.0.0
Restart Type: N
This parameter controls the amount of storage used for hash indexes in MySQL Cluster. Hash
indexes are always used for primary key indexes, unique indexes, and unique constraints. Note
that when defining a primary key and a unique index, two indexes will be created, one of which is
a hash index used for all tuple accesses as well as lock handling. It is also used to enforce unique
constraints.
The size of the hash index is 25 bytes per record, plus the size of the primary key. For primary keys
larger than 32 bytes another 8 bytes is added.
The default value for
•
StringMemory
Effective Version
MySQL 5.0.0
Restart Type: S
This parameter determines how much memory is allocated for strings such as table names, and
is specified in an
[ndbd]
and inclusive is interpreted as a percent of the maximum default value, which is calculated
0 100
based on a number of factors including the number of tables, maximum table name size, maximum
size of files, MaxNoOfTriggers, maximum column name size, and maximum default column
.FRM
value. In general it is safe to assume that the maximum default value is approximately 5 MB for a
MySQL Cluster having 1000 tables.
MySQL Cluster Configuration Files
is 80MB; the minimum is 1MB. There is no maximum size, but in
DataMemory
Type/Units
bytes
is 18MB. The minimum is 1MB.
IndexMemory
Type/Units
% or bytes
or
[ndbd default]
1560
Default
18M
Default
0
section of the
config.ini
Range/Values
1M - 1T
Range/Values
0 - 4G
file. A value between