On Wed, May 1, 2024 at 1:10 PM Ayush Vatsa <ayushvatsa1...@gmail.com> wrote:
> I'm currently delving into Postgres HLL (HyperLogLog) functionality and have
> encountered an unexpected behavior while executing queries from the
> "cumulative_add_sparse_edge.sql" regress test. This particular test data file
> involves three columns, with the last column representing an HLL
> (HyperLogLog) value derived from the previous HLL value and the current raw
> value.
>
> Upon manual inspection of the query responsible for deriving the last row's
> HLL value, I noticed a discrepancy. When executing the query:
> """
> -- '\x148B481002....' is second last rows hll value
> SELECT hll_add('\x148B481002.....', hll_hashval(2561));
> """
> instead of obtaining the expected value (''\x148B481002....''), I received a
> different output which is ('\x138b48000200410061008100a1 ........').
PostgreSQL has no function called hll_add or hll_hashval, and no
regression test file called cumulative_add_sparse_edge.sql. A quick
Google search suggests that these things are part of citusdata's fork
of PostgreSQL, so you might want to contact them.
--
Robert Haas
EDB: http://www.enterprisedb.com
