Answer
A checkpoint flushes dirty pages to disk, reducing recovery time but increasing I/O load if too frequent.
Quick Answer
WAL checkpoint writes all dirty buffers (modified data pages in shared_buffers) to disk files. This ensures recovery can start from a recent point rather than replaying all WAL from the beginning. Checkpoints happen every checkpoint_timeout (5 min default) or when WAL reaches max_wal_size. Frequent checkpoints: faster recovery but more I/O. Checkpoint duration visible in pg_stat_bgwriter.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ