Details
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Bug
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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None
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None
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None
Description
Here's the SQL to demonstrate the problem:
DROP DATABASE IF EXISTS json_arrayagg_db;CREATE DATABASE json_arrayagg_db; |
USE json_arrayagg_db;CREATE TABLE t1 (a INT, b VARCHAR(80)); |
INSERT INTO t1 VALUES |
(1, "Hello"),(1, "World"), (2, "This"),(2, "Will"), (2, "Work"),(2, "!"), (3, NULL), |
(1, "Hello"),(1, "World"), (2, "This"),(2, "Will"), (2, "Work"),(2, "!"), (3, NULL); |
SELECT JSON_ARRAYAGG(a), JSON_ARRAYAGG(b) FROM t1 GROUP BY a; |
DROP TABLE t1; |
CREATE TABLE t1 (a INT, b VARCHAR(80))ENGINE=COLUMNSTORE; |
INSERT INTO t1 VALUES |
(1, "Hello"),(1, "World"), (2, "This"),(2, "Will"), (2, "Work"),(2, "!"), (3, NULL), |
(1, "Hello"),(1, "World"), (2, "This"),(2, "Will"), (2, "Work"),(2, "!"), (3, NULL); |
SELECT JSON_ARRAYAGG(a), JSON_ARRAYAGG(b) FROM t1 GROUP BY a; |
These queries return different results for row containing "[3,3]" in first column: InnoDBreturns the string "[null,null]" and MCS currently returns NULL (which is empty string in actuality).
The code in question is this:
void JsonArrayAggOrderBy::processRow(const rowgroup::Row& row) |
{
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// check if this is a distinct row |
if (fDistinct && fDistinctMap->find(row.getPointer()) != fDistinctMap->end()) |
return; |
|
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// this row is skipped if any concatenated column is null. |
if (concatColIsNull(row)) |
return; |
...
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It actively skips NULL rows when doing group by aggregation.