/**
* @brief Get a value of a column from the rollback segment
*
* @param idx The index of the recored column in the rollback segment
*/
Value RollbackSegmentPool::GetValue(RBSegType rb_seg, const catalog::Schema *schema, int idx) {
auto col_id = GetIdOffsetPair(rb_seg, idx)->col_id;
const ValueType column_type = schema->GetType(col_id);
const char *data_ptr = GetColDataLocation(rb_seg, idx);
const bool is_inlined = schema->IsInlined(col_id);
return Value::InitFromTupleStorage(data_ptr, column_type, is_inlined);
}
/**
* @brief create a rollback segment by selecting columns from a tuple
* @param target_list The columns to be selected
* @param tuple The tuple to construct the RB
*
* TODO: Optimization can be done. We can save copying those columns that are
*already
* in the rollback segment created by the same transaction. What we need to do
*is to add
* a bitmap in the rollback segment indicating columns it contains. After that
*we
* can bypass these columns when making a new rollback segment.
*/
RBSegType RollbackSegmentPool::CreateSegmentFromTuple(
const catalog::Schema *schema, const TargetList &target_list,
const AbstractTuple *tuple) {
PL_ASSERT(schema);
PL_ASSERT(target_list.size() != 0);
size_t col_count = target_list.size();
size_t header_size = pairs_start_offset + col_count * sizeof(ColIdOffsetPair);
size_t data_size = 0;
RBSegType rb_seg = nullptr;
// First figure out the total size of the rollback segment data area
for (auto &target : target_list) {
auto col_id = target.first;
data_size += schema->GetLength(col_id);
}
// Allocate the RBSeg
rb_seg = (RBSegType)pool_.AllocateZeroes(header_size + data_size);
PL_ASSERT(rb_seg);
// Fill in the header
SetNextPtr(rb_seg, nullptr);
SetTimeStamp(rb_seg, MAX_CID);
SetColCount(rb_seg, col_count);
// Fill in the col_id & offset pair and set the data field
size_t offset = 0;
for (size_t idx = 0; idx < target_list.size(); ++idx) {
auto &target = target_list[idx];
auto col_id = target.first;
const bool is_inlined = schema->IsInlined(col_id);
const bool is_inbytes = false;
size_t inline_col_size = schema->GetLength(col_id);
size_t allocate_col_size =
(is_inlined) ? inline_col_size : schema->GetVariableLength(col_id);
SetColIdOffsetPair(rb_seg, idx, target.first, offset);
// Set the value
char *value_location = GetColDataLocation(rb_seg, idx);
Value value = tuple->GetValue(col_id);
PL_ASSERT(schema->GetType(col_id) == value.GetValueType());
value.SerializeToTupleStorageAllocateForObjects(
value_location, is_inlined, allocate_col_size, is_inbytes, &pool_);
// Update the offset
offset += inline_col_size;
}
return rb_seg;
}
