A checkpoint marks a significant point in a transaction, when SAP Sybase IQ writes to disk certain information it tracks internally. SAP Sybase IQ uses this information during database recovery.
SAP Sybase IQ uses checkpoints differently than OLTP databases such as SQL Anywhere. OLTP databases tend to have short transactions that affect only a small number of rows. Writing entire pages to disk would be very expensive for them. Instead, OLTP databases generally write to disk at checkpoints, and write only the changed data rows.
SAP Sybase IQ is an OLAP database. A single OLAP transaction can change thousands or millions of rows of data. For this reason, the database server does not wait for a checkpoint to occur to perform physical writes. It writes updated data pages to disk after each transaction commits. For an OLAP database, writing full pages of data to disk is much more effective than writing small amounts of data at arbitrary checkpoints.
Most checkpoints occur automatically. You can also set explicit checkpoints, although you do not need to do so.
When a transaction issues a CHECKPOINT command
When the CHECKPOINT_TIME is exceeded
At the start and end of the backup process
When the database server is shut down
The CHECKPOINT_TIME is the maximum time that can pass between checkpoints. By default, it is 60 minutes. To adjust the checkpoint interval, use the SET OPTION statement. Adjusting the checkpoint time or issuing explicit checkpoints may be unnecessary. Controlling checkpoints is less important in SAP Sybase IQ than in OLTP database products, because SAP Sybase IQ writes the actual data pages after each transaction commits.