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[CH-431] not change columns to nulllable in expand operator #433

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@shuai-xu shuai-xu commented Apr 14, 2023

Changelog category (leave one):

  • Bug Fix (user-visible misbehavior in official stable or prestable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

This pr fix the bug that columns type may be changed in expand operator, which will cause memory problem when serialize and deserialize them.
This close #431 .

Felixoid and others added 30 commits April 4, 2022 14:15
…ash_v2

One more try to resurrect build hash
Backport ClickHouse#35733 to 22.3: Added settings for insert of invalid IPv6, IPv4 values
Backport ClickHouse#35820 to 22.3: Avoid processing per-column TTL multiple times
- Allow define version as file
- Add inline cache
- Fix auto_release_type function
exmy and others added 24 commits March 21, 2023 10:35
…ence#354)

ShuffleSplitter improvement: support multiple subdirs
Support full join with join condition

Co-authored-by: shuai.li <shuai.li@kyligence.io>
Support Decimal type in Gluten 
Co-authored-by: shuai.li <shuai.li@kyligence.io>
…like Column 'deviceid' is not presented in input data (Kyligence#388)
Co-authored-by: shuai.li <shuai.li@kyligence.io>
Co-authored-by: shuai.li <shuai.li@kyligence.io>
Co-authored-by: Robert Schulze <robert@clickhouse.com>
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Can one of the admins verify this patch?

@shuai-xu shuai-xu changed the title not change columns to nulllable in expand operator [CH-431] not change columns to nulllable in expand operator Apr 14, 2023
Comment on lines 62 to 76
if (i < aggregating_expressions_columns_.size())
{
// do nothing with the aggregating columns.
cols.push_back(old_col);
continue;
}
if (old_col.type->isNullable())
cols.push_back(old_col);
else
{
auto null_map = DB::ColumnUInt8::create(0, 0);
auto null_col = DB::ColumnNullable::create(old_col.column, std::move(null_map));
auto null_type = std::make_shared<DB::DataTypeNullable>(old_col.type);
cols.push_back(DB::ColumnWithTypeAndName(null_col, null_type, old_col.name));
}
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@lgbo-ustc lgbo-ustc Apr 17, 2023

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The reason for adding nullable here is that , for group by a,b roll up, the column a, b after this expand node could be null. we will have the following cases

a b explain
original a's values original b's values equal to group by a,b
original a's values NULL equal to group by a
NULL NULL equal to group by empty keys

@lwz9103 lwz9103 force-pushed the clickhouse_backend branch 2 times, most recently from dc60d55 to 8066113 Compare May 26, 2023 03:43
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Wrongly converting columns to nullable may cause momory problem