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Fix LowCardinality empty array serialization. #3907

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This commit is contained in:
Nikolai Kochetov 2019-01-09 15:16:03 +03:00
parent 06095340c7
commit cea23a1486
3 changed files with 13 additions and 0 deletions
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4
dbms/src/DataTypes/DataTypeLowCardinality.cpp
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@ -508,6 +508,10 @@ void DataTypeLowCardinality::serializeBinaryBulkWithMultipleStreams(
size_t max_limit = column.size() - offset;
limit = limit ? std::min(limit, max_limit) : max_limit;
/// Do not write anything for empty column. (May happen while writing empty arrays.)
if (limit == 0)
return;
auto sub_column = low_cardinality_column.cutAndCompact(offset, limit);
ColumnPtr positions = sub_column->getIndexesPtr();
ColumnPtr keys = sub_column->getDictionary().getNestedColumn();

2
dbms/tests/queries/0_stateless/00800_low_cardinality_empty_array.reference Normal file
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@ -0,0 +1,2 @@
[]
[]

7
dbms/tests/queries/0_stateless/00800_low_cardinality_empty_array.sql Normal file
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@ -0,0 +1,7 @@
drop table if exists test.lc;
create table test.lc (names Array(LowCardinality(String))) engine=MergeTree order by tuple();
insert into test.lc values ([]);
insert into test.lc select emptyArrayString();
select * from test.lc;
drop table if exists test.lc;