fix(isthmus): correct strpos parameter order #676
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benbellick
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Jan 16, 2026
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Just two minor comments but otherwise LGTM! Thanks for doing that 🚀
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| List<RexNode> operands = new ArrayList<>(call.getOperands()); | ||
| Collections.swap(operands, 0, 1); |
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Probably not a bad idea to put a comment here just because we have some naked numbers used to reference parameters.
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Is the class Javadoc not sufficient?
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It's probably fine, just my opinion if we wanted to make it extra clear. Feel free to ignore if you disagree.
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| String query = String.format("SELECT STRPOS(%s, %s) > 0 FROM strings", left, right); | ||
| @Test |
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| @Test | |
| @Test | |
| // Verifies POSITION→strpos parameter swap (#662). | |
| // SQL POSITION(substring IN input) must become Substrait strpos(input, substring). |
Just so someone has a reference for the future :)
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@benbellick I changed the comments in both PositionFunctionMapper and StringFunctionTest to (hopefully) make things clearer, along the lines of your suggestions. |
Both SQL STRPOS and POSITION functions are modelled by Calcite as Position. Parameters are substring followed by the input to be searched. This maps to the Substrait strpos function, which has the parameters of input to be searched followed by substring. The default mapping retains the argument order, which results in SQL being translated to incorrect Substrait, and correct Substrait translated to incorrect SQL. Round-trip between Substrait and SQL still works since the parameter order is reversed in both directions, resulting in the correct order again. This change adds a custom function mapper to reverse the order of the first two parameters when converting between Calcite Position and Substrait strpos functions. Signed-off-by: Mark S. Lewis <Mark.S.Lewis@outlook.com>
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Both SQL STRPOS and POSITION functions are modelled by Calcite as Position. Parameters are substring followed by the input to be searched. This maps to the Substrait strpos function, which has the parameters of input to be searched followed by substring. The default mapping retains the argument order, which results in SQL being translated to incorrect Substrait, and correct Substrait translated to incorrect SQL. Round-trip between Substrait and SQL still works since the parameter order is reversed in both directions, resulting in the correct order again.
This change adds a custom function mapper to reverse the order of the first two parameters when converting between Calcite Position and Substrait strpos functions.
Closes #662