Oracle 5.0 Reference Manual page 1584

Transaction temporary storage.
temporary storage when executing a statement that is part of a Cluster transaction. All records are
released when the statement is completed and the cluster is waiting for the commit or rollback.
The default values for these parameters are adequate for most situations. However, users with a need
to support transactions involving large numbers of rows or operations may need to increase these
values to enable better parallelism in the system, whereas users whose applications require relatively
small transactions can decrease the values to save memory.
•
MaxNoOfConcurrentIndexOperations
Effective Version
MySQL 5.0.0
Restart Type: N
For queries using a unique hash index, another temporary set of operation records is used during
a query's execution phase. This parameter sets the size of that pool of records. Thus, this record is
allocated only while executing a part of a query. As soon as this part has been executed, the record
is released. The state needed to handle aborts and commits is handled by the normal operation
records, where the pool size is set by the parameter MaxNoOfConcurrentOperations.
The default value of this parameter is 8192. Only in rare cases of extremely high parallelism using
unique hash indexes should it be necessary to increase this value. Using a smaller value is possible
and can save memory if the DBA is certain that a high degree of parallelism is not required for the
cluster.
•
MaxNoOfFiredTriggers
Effective Version
MySQL 5.0.0
Restart Type: N
The default value of
some cases it can even be decreased if the DBA feels certain the need for parallelism in the cluster
is not high.
A record is created when an operation is performed that affects a unique hash index. Inserting or
deleting a record in a table with unique hash indexes or updating a column that is part of a unique
hash index fires an insert or a delete in the index table. The resulting record is used to represent this
index table operation while waiting for the original operation that fired it to complete. This operation is
short-lived but can still require a large number of records in its pool for situations with many parallel
write operations on a base table containing a set of unique hash indexes.
•
TransactionBufferMemory
Effective Version
MySQL 5.0.0
Restart Type: N
The memory affected by this parameter is used for tracking operations fired when updating index
tables and reading unique indexes. This memory is used to store the key and column information for
these operations. It is only very rarely that the value for this parameter needs to be altered from the
default.
The default value for
MySQL Cluster Configuration Files
The next set of
Type/Units
integer
Type/Units
integer
MaxNoOfFiredTriggers
Type/Units
bytes
TransactionBufferMemory
1564
parameters is used to determine
[ndbd]
Default
8K
Default
4000
is 4000, which is sufficient for most situations. In
Default
1M
is 1MB.
Range/Values
0 - 4G
Range/Values
0 - 4G
Range/Values
1K - 4G