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Oct 1, 2026 · Databases

Why SELECT * 20M Rows Won't OOM MySQL: Streaming Protocol & LRU Protection

The article explains why a MySQL SELECT * query scanning 20 million rows won't cause server-side OOM due to its streaming protocol using a 16KB net_buffer, but warns that full table scans can pollute the Buffer Pool, though InnoDB's midpoint insertion strategy and innodb_old_blocks_time (default 1s) protect hot data from eviction.