Efficient Transaction Checkpoints

A checkpoint is a snapshot of the c-tree Server’s transaction state at an instance in time. The server writes checkpoints to the current transaction log at predetermined intervals. The most recent checkpoint entry placed in the c-tree Server’s transaction logs identifies the starting point during the server's automatic recovery.

The interval at which checkpoints are written to the transaction log is determined by the server's CHECKPOINT_INTERVAL configuration keyword. This keyword specifies the number of bytes of data written to the transaction logs after which the server issues a checkpoint. It is ordinarily about one-third (1/3) the size of one of the active log files (Lnnnnnnn.FCS). For high transaction rate systems, FairCom recommends increasing the checkpoint interval so that checkpoints occur less frequently.

Increasing the Interval Between Checkpoints

Follow these steps to increase the interval between checkpoints:

1. Because the server enforces a minimum of three checkpoints per transaction log, increase the size of the transaction logs using the LOG_SPACE keyword. Set LOG_SPACE to 12 times the desired checkpoint interval to accommodate three checkpoints per log for four active transaction logs.
2. Set the CHECKPOINT_INTERVAL setting to the desired checkpoint interval.

Example

To set the checkpoint interval to 20,000,000 bytes, use these server configuration settings:

LOG_SPACE 240

CHECKPOINT_INTERVAL 20000000