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Merge pull request #21948 from kitaisreal/hashed-dictionary-clickhouse-source-preallocate-regression-fix

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HashedDictionary clickhouse source preallocate regression fix
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Maksim Kita 2021-03-22 14:11:19 +03:00 committed by GitHub
commit af25805a70
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1 changed files with 1 additions and 30 deletions
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29
src/Dictionaries/HashedDictionary.cpp
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@ -384,41 +384,12 @@ void HashedDictionary::loadData()
{
if (!source_ptr->hasUpdateField())
{
/// atomic since progress callbac called in parallel
std::atomic<uint64_t> new_size = 0;
auto stream = source_ptr->loadAll();
/// preallocation can be used only when we know number of rows, for this we need:
/// - source clickhouse
/// - no filtering (i.e. lack of <where>), since filtering can filter
/// too much rows and eventually it may allocate memory that will
/// never be used.
bool preallocate = false;
if (const auto & clickhouse_source = dynamic_cast<ClickHouseDictionarySource *>(source_ptr.get()))
{
if (!clickhouse_source->hasWhere())
preallocate = true;
}
if (preallocate)
{
stream->setProgressCallback([&new_size](const Progress & progress)
{
new_size += progress.total_rows_to_read;
});
}
stream->readPrefix();
while (const auto block = stream->read())
{
if (new_size)
{
size_t current_new_size = new_size.exchange(0);
if (current_new_size)
resize(current_new_size);
}
else
resize(block.rows());
blockToAttributes(block);
}