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[common] Fix FLOAT precision checking. (#4656) #4658

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[common] Fix FLOAT precision checking. (#4656) #4658

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10 changes: 6 additions & 4 deletions paimon-common/src/main/java/org/apache/paimon/utils/TypeUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -144,11 +144,13 @@ public static Object castFromStringInternal(String s, DataType type, boolean isC
} else {
// Compatible canal-cdc
Float f = Float.valueOf(s);
if (f.toString().length() != s.length()) {
throw new NumberFormatException(
s + " cannot be cast to float due to precision loss");
} else {
// Validate precision by comparing the rounded value
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float f = Float.parseFloat(s);

if ((double) f == d || Math.abs(f - d) < Math.abs(d * 1e-6)) {
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why use "d * 1e-6"?
what about Double#compare?

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  1. The value 1e-6 (which is 0.000001) is typically a reasonable threshold for floating-point comparisons, it's a balance between precision and practical usability.
  2. This approach helps avoid rejecting values that are within the acceptable precision for FLOAT types in databases like MySQL, while still accounting for the limitations of floating-point precision.

return f;
} else {
// Significant precision loss detected
throw new NumberFormatException(
s + " cannot be cast to FLOAT due to precision loss");
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The exception message need improve. It needs to cover the comparative failure situation.

}
}
case DOUBLE:
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