Use hash join when writing sparkey #1
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When writing to sparkey,
allShardsrepresents every expected shard even if there is no corresponding data inshardsfor that shard number.Starting in Scio 14, possibly related to spotify#5208,
shards.rightOuterJoin(allShards)would fail when a shard contained approximately 2GB or more data, leading to the bug described in spotify#5300:java.lang.OutOfMemoryError: Required array length 2147483639 + 15534 is too large.This PR replaces
rightOuterJoinwithhashFullOuterJoin(note that there is nohashRightOuterJoinimplementation). A hash join is a good fit because the right-hand side contains very little data (only the keys of the shards) and it doesn't need to use an array to represent the large left-hand side's values. As a result shards with more than 2GB data can once again be processed successfully.