Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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10.1.2.1
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None
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Low
Description
The division operator '/' may give wrong results when used with NUMRERIC operands.
Example (copied from ij):
CREATE TABLE t (d1 DOUBLE, d2 DOUBLE, n1 NUMERIC(31,11), n2
NUMERIC(31,11));
INSERT INTO t VALUES (1.5, 2.5, 1.5, 2.5);
SELECT d1/d2, n1/n2, n1*(1.0/n2) FROM t;
1 |2 |3
----------------------------------------------------------------
0.6 |0 |0.600000000000000000000000000000
1 row selected
The result in column 2 should not be zero, but 0.6.
It seems there is something wrong with the calculation of the scale. Hint from Satheesh Bandaram:
If you look at NumericTypeCompiler code, which calculates the scale and precision of operation result type, the comments and the code doesn't seem to match. (getScale() method):
NumericTypeCompiler.java
else if (TypeCompiler.DIVIDE_OP.equals(operator))
{ /* ** Take max left scale + right precision - right scale + 1, ** or 4, whichever is biggest */ LanguageConnectionContext lcc = (LanguageConnectionContext) (ContextService.getContext(LanguageConnectionContext.CONTEXT_ID)); // Scale: 31 - left precision + left scale - right scale val = Math.max(NumberDataValue.MAX_DECIMAL_PRECISION_SCALE - lprec + lscale - rscale, 0); }Here val is returning zero for scale, it seems.