Previous Topic

Next Topic

Improved Transaction Log Template Copies

The c-tree Server Log Template feature is used as a fast and efficient means of creating transaction logs in high volume systems. An initial transaction log template is created and copied when a new transaction log is required. The original implementation used an operating system file copy command (e.g., cp L0000002.FCT L0000002.FCS) to initiate the copy of the template to the newly named file. This approach required the full contents of the template file to be read. For systems that experience high volume transaction loads where the file is frequently copied, this method could place unnecessary demand on system resources.

An improved efficient method of copying the transaction log template file has been implemented. If an error occurs using this method an error message is output to CTSTATUS.FCS (identified with the "LOG_TEMPLATE_COPY: ..." prefix) and the server then attempts the original log template copy method.

Template Copy Options

The following configuration options can be used to modify the speed of copying of the log template such that the impact of the log template disk write operations impact on c-tree Server performance is reduced.

Copy Sleep Time

LOG_TEMPLATE_COPY_SLEEP_TIME <milliseconds>

This keyword results in the copying of the log template to be paused for the specified number of milliseconds each time it has written the percentage of data specified by the LOG_TEMPLATE_COPY_SLEEP_PCT option to the target transaction log file.

  • Default value: 0 (disabled)
  • Minimum value: 1
  • Maximum value: 1000 (1 second sleep)

Copy Sleep Percentage

LOG_TEMPLATE_COPY_SLEEP_PCT <percent>

This keyword specifies the percentage of data that is written to the target transaction log file after which the copy operation sleeps for the number of milliseconds specified for the LOG_TEMPLATE_COPY_SLEEP_TIME option.

  • Default value: 15
  • Minimum value: 1
  • Maximum value: 99

Example

The following example demonstrates the options that cause the copying of the log template file to sleep for 5 milliseconds after every 20% of the transaction log template file has been copied:

LOG_TEMPLATE_COPY_SLEEP_TIME 5
LOG_TEMPLATE_COPY_SLEEP_PCT 20