Method canOffsetCommitInPlace

src/storage/table/dictionary_column.cpp:231–263

}

bool DictionaryColumn::canOffsetCommitInPlace(const SegmentState& offsetState,
    const SegmentState& dataState, uint64_t numNewStrings, uint64_t totalStringLengthToAdd) const {
    auto totalStringOffsetsAfterUpdate = dataState.metadata.numValues + totalStringLengthToAdd;
    auto offsetCapacity =
        offsetState.metadata.compMeta.numValues(LBUG_PAGE_SIZE, offsetColumn->getDataType()) *
        offsetState.metadata.getNumPages();
    auto numStringsAfterUpdate = offsetState.metadata.numValues + numNewStrings;
    if (numStringsAfterUpdate > offsetCapacity) {
        // Offsets cannot be updated in place
        return false;
    }
    // Indices are limited to 32 bits but in theory could be larger than that since the offset
    // column can grow beyond the node group size.
    //
    // E.g. one big string is written first, followed by NODE_GROUP_SIZE-1 small strings,
    // which are all updated in-place many times (which may fit if the first string is large
    // enough that 2^n minus the first string's size is large enough to fit the other strings,
    // for some n.
    // 32 bits should give plenty of space for updates.
    if (numStringsAfterUpdate > std::numeric_limits<string_index_t>::max()) [[unlikely]] {
        return false;
    }
    if (offsetState.metadata.compMeta.canAlwaysUpdateInPlace()) {
        return true;
    }
    InPlaceUpdateLocalState localUpdateState{};
    if (!offsetState.metadata.compMeta.canUpdateInPlace(
            (const uint8_t*)&totalStringOffsetsAfterUpdate, 0 /*offset*/, 1 /*numValues*/,
            offsetColumn->getDataType().getPhysicalType(), localUpdateState)) {
        return false;
    }
    return true;
}

} // namespace storage
} // namespace lbug