Stanislav Lukyanov created IGNITE-7908:
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Summary: NULLS LAST works incorrectly for PARTITIONED caches
Key: IGNITE-7908
URL:
https://issues.apache.org/jira/browse/IGNITE-7908 Project: Ignite
Issue Type: Bug
Components: sql
Reporter: Stanislav Lukyanov
When a `SELECT .... ORDER BY ... NULLS LAST` query is executed on a partitioned cache, the null values at the end of the result are interleaved with non-null values.
It seems that for each node participating in the query all null values that are stored on that node are returned immediately after the last non-null value. As a result, non-null values are correctly ordered and null values appear in a few "portions" (the number of "portions" is equal to the number of nodes) among the last values.
Example:
====================
{code:java}
public class NullsLastBug {
public static void main(String[] args) throws Exception {
try (
Ignite srv1 = IgnitionEx.start("examples/config/example-ignite.xml", "server-1");
Ignite srv2 = IgnitionEx.start("examples/config/example-ignite.xml", "server-2");
Ignite srv3 = IgnitionEx.start("examples/config/example-ignite.xml", "server-3")
) {
Ignition.setClientMode(true);
try (Ignite client = IgnitionEx.start("examples/config/example-ignite.xml", "client")) {
IgniteCache<Long, Box> cache = client.getOrCreateCache(
new CacheConfiguration<Long, Box>("cache")
.setCacheMode(CacheMode.PARTITIONED)
.setIndexedTypes(Long.class, Box.class)
);
for (long i = 0; i < 30; i++) {
Long num = (i % 2 != 0) ? i : null;
cache.put(i, new Box(num));
}
SqlFieldsQuery selectAll = new SqlFieldsQuery("SELECT num FROM Box ORDER BY num NULLS LAST");
for (List<?> list : cache.query(selectAll))
System.out.println(list);
}
}
}
}
class Box implements Serializable {
@QuerySqlField(index = true) private Long num;
Box(Long num) {
this.num = num;
}
}
{code}
====================
Output:
====================
{code}
[1]
[3]
[5]
[7]
[9]
[11]
[13]
[15]
[17]
[19]
[21]
[23]
[null]
[null]
[25]
[27]
[null]
[null]
[null]
[null]
[null]
[null]
[null]
[null]
[29]
[null]
[null]
[null]
[null]
[null]
{code}
====================
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