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In streaming joins, a traditional hash join (for batch/static data) differs from a symmetric hash join (for unbounded streams). Which of the following statements are true about these join methods?

i) A traditional hash join for two tables (R ⋈ S) typically hashes one entire table (say, S) into memory and then probes with each row from the other table (R).

ii) A symmetric hash join for streams maintains a hash table for each input stream and continuously checks incoming tuples from each side against the stored tuples from the other side.

iii) A single, global hash table can be used to join any number of streams simultaneously without missing any matches.

iv) With two input streams, a symmetric hash join ensures that if a tuple arrives on one stream, it will be matched with any buffered tuples from the other stream that fall into the join window, so no valid pair is missed.

i, iii, iv

i, ii, iv

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ii, iii, iv

i, ii, iii, iv

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