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https://issues.apache.org/jira/browse/ARROW-2622?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wes McKinney updated ARROW-2622:
--------------------------------
Fix Version/s: 0.13.0
> [C++] Array methods IsNull and IsValid are not complementary
> ------------------------------------------------------------
>
> Key: ARROW-2622
> URL: https://issues.apache.org/jira/browse/ARROW-2622
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Affects Versions: 0.9.0
> Reporter: Thomas Buhrmann
> Priority: Major
> Fix For: 0.13.0
>
>
> Hi, not sure if this is a bug or if I misinterpret the spec. According to the
> latter, "Arrays having a 0 null count may choose to not allocate the null
> bitmap". From this I'd infer that the statement also holds in the other
> direction, i.e. non-allocated bitmaps imply a 0 null count. This would mean
> that if a bitmap is not allocated, IsValid() should always return true. But
> at the moment it's doing this:
> {code:java}
> bool IsNull(int64_t i) const {
> return null_bitmap_data_ != NULLPTR &&
> BitUtil::BitNotSet(null_bitmap_data_, i + data_->offset);
> }
> bool IsValid(int64_t i) const {
> return null_bitmap_data_ != NULLPTR &&
> BitUtil::GetBit(null_bitmap_data_, i + data_->offset);
> }
> {code}
> Which leads to a situation where in the case of non-allocated bitmaps values
> are neither Null nor Valid. Shouldn't it rather be:
> {code:java}
> bool IsValid(int64_t i) const {
> return null_bitmap_data_ == NULLPTR ||
> BitUtil::GetBit(null_bitmap_data_, i + data_->offset);
> }{code}
> ?
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