10.3.2 Operands related to HiRDB processing

2) pd_dbsync_altwrite_skip = Y | N
Operand default value
  • Default value in recommended mode: Y
  • Default value in 0904 compatibility mode: N
Specifies the handling of write processing when an update buffer reference request is issued during synchronization point acquisition processing. Normally, such write processing of the update buffer contents into the database is handled by the server process that will execute the transaction that issues the reference request. This operand specifies whether the handling of this write processing is to be skipped.
The following compares the values of this operand:
Comparison itempd_dbsync_altwrite_skip operand value
YN
Database writing method when an update buffer reference request is issued during synchronization point acquisition processingThe server process that will execute the transaction that issues the reference request does not handle writing of the update buffer contents into the database. (The handling is skipped.)The server process that will execute the transaction that issues the reference request handles writing of the update buffer contents into the database. (The handling is not skipped.)
AdvantageBecause the server process that will execute the transaction does not handle the write processing, the performance of the referencing transaction is stable during synchronization point acquisition processing.The amount of time required for synchronization point acquisition processing is reduced because some of the workload is distributed to the referencing transaction.
DisadvantageThe amount of time required for synchronization point acquisition processing increases because none of the workload is distributed to the referencing transaction.There might be adverse effects on the referencing transaction during synchronization point acquisition processing.
Specification guidelines
You can execute the statistics analysis utility to obtain statistical information on the global buffer pool to check the database write processing take-over count (ALTRW) due to reference request hits during synchronization point processing. If this value is large, performance of a referencing transaction is not stable during synchronization point acquisition processing. To achieve stable performance, specify Y. Note that when Y is specified, more time is required for synchronization point acquisition processing; if necessary, you can use the facility for parallel writes in deferred write processing to distribute the write processing workload.