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    Make PFMERGE source key optional in docs, add tests with one input key, add... · 9e1b879f
    Binbin authored
    Make PFMERGE source key optional in docs, add tests with one input key, add tests on missing source keys (#11205)
    
    The following two cases will create an empty destkey HLL:
    1. called with no source keys, like `pfmerge destkey`
    2. called with non-existing source keys, like `pfmerge destkey non-existing-source-key`
    
    In the first case, in `PFMERGE`, the dest key is actually one of the source keys too.
    So `PFMERGE k1 k2` is equivalent to `SUNIONSTORE k1 k1 k2`,
    and `PFMERGE k1` is equivalent to `SUNIONSTORE k1 k1`.
    So the first case is reasonable, the source key is actually optional.
    
    And the second case, `PFMERGE` on missing keys should succeed and create an empty dest.
    This is consistent with `PFCOUNT`, and also with `SUNIONSTORE`, no need to change.
    9e1b879f
hyperloglog.tcl 7.49 KB