Github user navsan commented on a diff in the pull request:

    https://github.com/apache/incubator-quickstep/pull/100#discussion_r79695417
  
    --- Diff: storage/SplitRowStoreTupleStorageSubBlock.cpp ---
    @@ -88,6 +88,67 @@ inline std::size_t 
CalculateVariableSizeWithRemappedAttributes(
       return total_size;
     }
     
    +
    +/**
    + * A struct which holds the offset information for a non-remapping insert
    + * operation
    + */
    +struct BasicInsertInfo {
    +  BasicInsertInfo(
    +    const CatalogRelationSchema &relation)
    +    : num_attrs_(relation.size()),
    +      num_nullable_attrs_(relation.numNullableAttributes()),
    +      max_var_length_(relation.getMaximumVariableByteLength()),
    +      fixed_len_offset_(BitVector<true>::BytesNeeded(num_nullable_attrs_)),
    +      var_len_offset_(fixed_len_offset_ + relation.getFixedByteLength()),
    +      is_variable_(num_attrs_),
    +      is_nullable_(num_attrs_),
    +      fixed_len_offsets_(num_attrs_),
    +      fixed_len_sizes_(num_attrs_),
    +      var_len_offsets_(num_attrs_) {
    +    attribute_id accessor_attr_id = 0;
    +    for (CatalogRelationSchema::const_iterator attr_it = relation.begin();
    +         attr_it != relation.end();
    +         ++attr_it, ++accessor_attr_id) {
    +      DCHECK_EQ(accessor_attr_id, attr_it->getID());
    +
    +      const int nullable_idx = 
relation.getNullableAttributeIndex(accessor_attr_id);
    +      const int variable_idx = 
relation.getVariableLengthAttributeIndex(accessor_attr_id);
    +      is_nullable_.setBit(accessor_attr_id, nullable_idx != -1);
    +
    +      if (variable_idx == -1) {
    +        is_variable_.setBit(accessor_attr_id, false);
    +        fixed_len_offsets_[accessor_attr_id] = 
relation.getFixedLengthAttributeOffset(accessor_attr_id);
    +        fixed_len_sizes_[accessor_attr_id] = relation.getAttributeById(
    +          accessor_attr_id)->getType().maximumByteLength();
    +        var_len_offsets_[accessor_attr_id] = -1;
    +      } else {
    +        is_variable_.setBit(accessor_attr_id, true);
    +        fixed_len_offsets_[accessor_attr_id] = 0;
    +        fixed_len_sizes_[accessor_attr_id] = 0;
    +        var_len_offsets_[accessor_attr_id] = 
relation.getVariableLengthAttributeIndex(accessor_attr_id);
    +      }
    +    }
    +  }
    +
    +  std::size_t num_attrs_;
    +  std::size_t num_nullable_attrs_;
    +  std::size_t max_var_length_;
    +
    +  // byte offset from the beginning of a tuple to the first fixed length 
attribute
    +  std::uint32_t fixed_len_offset_;
    +  // byte offset from the beginning of a tuple to the first variable 
length offset/length pair
    +  std::uint32_t var_len_offset_;
    +
    +  BitVector<true> is_variable_;
    --- End diff --
    
    Packing these Booleans into a bitvector is needlessly expensive. Just use 
straight up 1-byte bools instead. We only have a few columns, so the space 
overhead is negligible. But doing so will avoid the complexity/cost of bit 
arithmetic to do lookups during insertion.
    [This applies to both the bitmaps.]


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