Talk:Block nested loop

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This is referenced in the main SQL article.

is block hashing optional?

it's unclear if "block nested loop" always uses block hashing. sources show conflicting evidence

a mariadb article identifies "block nested loop" and "block hash join" as distinct, separate algorithms https://mariadb.com/kb/en/block-based-join-algorithms/

a highly cited research paper "join algorithm costs revisited" specifies blocks are hashed "We assume that the memory based part of the join is based on hashing" https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=733b1e7c0a4d1f12188008e6e6eaa4cb40fd732d

a mysql article on "block nested loop" doesn't mention hashing https://dev.mysql.com/doc/refman/8.4/en/bnl-bka-optimization.html#bnl-optimization

what do you think? Neilc, TiMike is block hashing optional or mandatory in block nested loops? in theory and in practice

Asaf Spiegler (talk) 16:09, 3 December 2024 (UTC)