> a sequential scan may push ~100GB of other data from memory (shared buffers or page cache).
Small note, if I remember correctly PostgreSQL allocates small buffer within shared_buffers for bulk reads. It is so that single sequential scan won't flush all of shared buffers content.
Similar mechanism exists for a pagecache implementation on Linux. It is divided into generations based on access patterns.
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> a sequential scan may push ~100GB of other data from memory (shared buffers or page cache).
Small note, if I remember correctly PostgreSQL allocates small buffer within shared_buffers for bulk reads. It is so that single sequential scan won't flush all of shared buffers content.
Similar mechanism exists for a pagecache implementation on Linux. It is divided into generations based on access patterns.