StarRocks/starrocks
DECIMAL(38,18) / DECIMAL(38,18) silently returns NULL due to overflow, while equivalent multiplication works correctly
Fechada
#73.784 aberto em 25 de mai. de 2026
good first issuetype/bug
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Description
Issue
When dividing two DECIMAL(38,18) values (the maximum supported decimal precision in StarRocks), the result silently returns NULL due to precision overflow. The equivalent operation using multiplication with POW(..., -1) returns the correct result.
Steps to reproduce Returns NULL (bug)
SELECT CAST(2672.925686105492400095 AS DECIMAL(38,18))
/ CAST(421.193403692563637349 AS DECIMAL(38,18));
Returns 6.346076796721411 (works)
SELECT CAST(2672.925686105492400095 AS DECIMAL(38,18))
* POW(CAST(421.193403692563637349 AS DECIMAL(38,18)), -1);
Workaround: explicit CAST to DOUBLE before division (works)
SELECT CAST(CAST(2672.925686105492400095 AS DECIMAL(38,18)) AS DOUBLE)
/ CAST(CAST(421.193403692563637349 AS DECIMAL(38,18)) AS DOUBLE);
Expected behavior
The session variable decimal_overflow_to_double should apply to the / operator the same way it applies to *.
Actual behavior
Division of two DECIMAL(38,18) values silently returns NULL. No error, no warning.
Starrocks version: 3.5.14