Fix MutableArrayData::extend_nulls (#1230) #4343
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tustvold
commented
Jun 2, 2023
| @@ -53,7 +53,7 @@ struct _MutableArrayData<'a> { | |||
| pub null_count: usize, | |||
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| pub len: usize, | |||
| pub null_buffer: MutableBuffer, | |||
| pub null_buffer: Option<MutableBuffer>, | |||
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This does add a branch on append, in practice appending to a null mask is so branch heavy anyway, not to mention already involving a dyn dispatch, I struggle to see how this could have an appreciable performance impact
tustvold
commented
Jun 2, 2023
| self.data.len += len; | ||
| let bit_len = bit_util::ceil(self.data.len, 8); | ||
| let nulls = self.data.null_buffer(); | ||
| nulls.resize(bit_len, 0); | ||
| self.data.null_count += len; | ||
| (self.extend_nulls)(&mut self.data, len); |
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Despite its name this extends the values buffers with nulls, it doesn't do anything to the bit mask
…-data-extend-nulls
alamb
approved these changes
Jun 2, 2023
| pub fn extend_nulls(&mut self, len: usize) { | ||
| // TODO: null_buffer should probably be extended here as well |
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Yup, I remember adding it at the same time as I created #1230 - I then completely forgot about it 😅
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Which issue does this PR close?
Closes #1230
Closes #4324
Rationale for this change
MutableArrayData::extend_nulls doesn't update the null bitmask, and so has never worked correctly. Since #3775 it most likely will result in freeze panicking. It is surprising that nobody has hit this before, although we use
MutableArrayDatain very limited places, andMutableArrayData::extend_nullsin even fewer.What changes are included in this PR?
Are there any user-facing changes?