Fix Issue #792 #795
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Fix Issue #792 #795
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The crux of the issue here is that `pgx_sys::Datum::from_datum(d, is_null)` can't ask the input Datum if it thinks it's null (via Datum::is_null(&self)), as nullness isn't a concept Datums encode. A Datum is technically only ever considered null if the accompanying `is_null` argument tells us so. It so happens that if the Datum type is pass-by-reference, and its value is zero, then it's pointing to a NULL, but Postgres doesn't even guarantee us that that is the nullness indicator. Again, only the `is_null` argument does that. As such, when converting a Datum into an Option<Datum>, only listen to the arguments and don't try to infer anything from the input datum's underlying value. This PR includes a few simple tests that are now green with the change to `from.rs`. Thanks to @sumerman for catching this!
The crux of the issue here is that `pgx_sys::Datum::from_datum(d, is_null)` can't ask the input Datum if it thinks it's null (via Datum::is_null(&self)), as nullness isn't a concept Datums encode. A Datum is technically only ever considered null if the accompanying `is_null` argument tells us so. It so happens that if the Datum type is pass-by-reference, and its value is zero, then it's pointing to a NULL, but Postgres doesn't even guarantee us that that is the nullness indicator. Again, only the `is_null` argument does that. As such, when converting a Datum into an Option<Datum>, only listen to the arguments and don't try to infer anything from the input datum's underlying value. This PR includes a few simple tests that are now green with the change to `from.rs`. Thanks to @sumerman for catching this!
thomcc
approved these changes
Oct 20, 2022
|
That check was added because the prior state of affairs was causing segfaults. |
This specific part of it was probably incorrect, however. |
workingjubilee
approved these changes
Oct 20, 2022
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The crux of the issue here is that
pgx_sys::Datum::from_datum(d, is_null)can't ask the input Datum if it thinks it's null (viaDatum::is_null(&self)), as nullness isn't a concept Datums encode.A Datum is technically only ever considered null if the accompanying
is_nullargument tells us so.It so happens that if the
Datumtype is pass-by-reference, and its value is zero, then it's pointing to a NULL, but Postgres doesn't even guarantee us that that is the nullness indicator. Again, only theis_nullargument does that.As such, when converting a
Datuminto anOption<Datum>, only listen to the arguments and don't try to infer anything from the input datum's underlying value.This PR includes a few simple tests that are now green with the change to
from.rs.Thanks to @sumerman for catching this!