[I] power and log simplifications check the base's nullability but not its value [datafusion]

["RyanLin5967 (via GitHub)" <gi...@apache.org>]

RyanLin5967 opened a new issue, #25209:
URL: https://github.com/apache/datafusion/issues/25209

   ### Describe the bug
   
   Currently, `power`/`log` rewrites check the base's nullability but not its value, so degenerate bases fold wrong.
   
   ### To Reproduce
   
   ```sql
   CREATE VIEW nn AS SELECT * FROM (VALUES (1.0), (0.0), (-2.0), (2.0)) s(a);
   CREATE VIEW nb AS SELECT a FROM (VALUES (1.0),(0.0),(-2.0),(2.0),(NULL)) s(a) WHERE a IS NOT NULL;
   CREATE VIEW t  AS SELECT * FROM (VALUES (2.0), (3.0)) s(b);
   
   SELECT a, log(a, 1.0), log(a, a) FROM nn;
   -- 0.0 and 1.0 on all four rows, a = 1.0, 0.0 and -2.0 included
   
   SELECT a, log(a, 1.0), log(a, a) FROM nb;
   -- NaN NaN / -0.0 NaN / NaN NaN / 0.0 1.0, so only the schema's nullability differs
   
   SELECT b, power(1.0, log(1.0, b)), log(1.0, power(1.0, b)) FROM t;
   -- both b; should be 1.0 and NaN
   
   SELECT count(*) FROM t WHERE power(1.0, log(1.0, b)) = 2.0;
   -- 1, should be 0
   
   SELECT power(1.0, log(1.0, 2.0)), log(1.0, 2.0);
   -- 1.0 and inf, so the all-literal form is evaluated rather than rewritten
   ```
   
   ### Expected behavior
   
   What the nullable-base rows already print: `NaN` where the identity does not hold, and `1.0` for `power(1.0, log(1.0, b))`.
   
   ### Additional context
   
   The four are `power(a, log(a,b))`, `log(a,1)`, `log(a,a)` and `log(a, power(a,b))`, each gated only on `!base_nullable`.
   
   All four hold only for `a > 0, a != 1`.
   
   Reproduced on `datafusion-cli 55.0.0`; `power.rs` is byte-identical on main.
   


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Re: [I] power and log simplifications check the base's nullability but not its value [datafusion]

["RyanLin5967 (via GitHub)" <gi...@apache.org>]

RyanLin5967 closed issue #25209: power and log simplifications check the base's nullability but not its value
URL: https://github.com/apache/datafusion/issues/25209


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Re: [I] power and log simplifications check the base's nullability but not its value [datafusion]

["RyanLin5967 (via GitHub)" <gi...@apache.org>]

RyanLin5967 commented on issue #25209:
URL: https://github.com/apache/datafusion/issues/25209#issuecomment-5640902878

   Duplicate of #25137, which reports the same defect. Closing this one.


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