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Fix: sorted DISTINCT with empty string

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This commit is contained in:
Igor Nikonov 2023-01-03 00:18:29 +00:00
parent c5155b8d32
commit b7062c182a
3 changed files with 26 additions and 0 deletions
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24
src/Common/HashTable/ClearableHashSet.h
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@ -48,6 +48,30 @@ struct ClearableHashTableCell : public BaseCell
ClearableHashTableCell(const Key & key_, const State & state) : BaseCell(key_, state), version(state.version) {}
};
using StringRefBaseCell = HashSetCellWithSavedHash<StringRef, DefaultHash<StringRef>, ClearableHashSetState>;
/// specialization for StringRef to allow zero size key (empty string)
template <>
struct ClearableHashTableCell<StringRef, StringRefBaseCell> : public StringRefBaseCell
{
using State = ClearableHashSetState;
using value_type = typename StringRefBaseCell::value_type;
UInt32 version;
bool isZero(const State & state) const { return version != state.version; }
static bool isZero(const StringRef & key_, const State & state_) { return StringRefBaseCell::isZero(key_, state_); }
/// Set the key value to zero.
void setZero() { version = 0; }
/// Do I need to store the zero key separately (that is, can a zero key be inserted into the hash table).
static constexpr bool need_zero_value_storage = true;
ClearableHashTableCell() { } //-V730 /// NOLINT
ClearableHashTableCell(const StringRef & key_, const State & state) : StringRefBaseCell(key_, state), version(state.version) { }
};
template <
typename Key,
typename Hash = DefaultHash<Key>,

1
tests/queries/0_stateless/02515_distinct_zero_size_key_bug_44831.reference Normal file
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@ -0,0 +1 @@
\N

1
tests/queries/0_stateless/02515_distinct_zero_size_key_bug_44831.sql Normal file
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@ -0,0 +1 @@
SELECT DISTINCT NULL, if(number > 0, 't', '') AS res FROM numbers(1) ORDER BY res;