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[Coral-Common] Convert Hive uniontype into a struct-RelDataType that conforms Trino' schema #192

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Merged
wmoustafa merged 12 commits into from
Nov 19, 2021
Merged

[Coral-Common] Convert Hive uniontype into a struct-RelDataType that conforms Trino' schema #192

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ad2bc8f
Convert Hive uniontype into a struct-relDataType that conforms Trino'…
autumnust Nov 9, 2021
33cdf38
Avoid adding additional fields in the exploded struct if union is emp…
autumnust Nov 9, 2021
2d91f48
apply spotless fix
autumnust Nov 9, 2021
4f7bf56
Address reviewer's comments
autumnust Nov 11, 2021
f0f64a9
Address reviewer's comments
autumnust Nov 16, 2021
c77fb85
Run the spotless
autumnust Nov 16, 2021
d4cd58e
Fix unit tests failure
autumnust Nov 16, 2021
cfb3298
Spotless apply through all modules
autumnust Nov 16, 2021
612a362
Fix the tag field in trino'struct to be tinyint
autumnust Nov 16, 2021
40eb25e
Simplified the test validation by using stringfy method
autumnust Nov 17, 2021
c5210cb
Remove uneeded test table
autumnust Nov 17, 2021
2493a8a
Get rid of size check to keep consistent with Trino's handling when f…
autumnust Nov 19, 2021
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7 changes: 6 additions & 1 deletion coral-common/src/main/java/com/linkedin/coral/common/TypeConverter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -141,11 +141,16 @@ public static RelDataType convert(StructTypeInfo structType, final RelDataTypeFa
}

// Mimic the StructTypeInfo conversion to convert a UnionTypeInfo to the corresponding RelDataType
// The schema of output Struct conforms to https://github.com/trinodb/trino/pull/3483
public static RelDataType convert(UnionTypeInfo unionType, RelDataTypeFactory dtFactory) {
List<RelDataType> fTypes = unionType.getAllUnionObjectTypeInfos().stream()
.map(typeInfo -> convert(typeInfo, dtFactory)).collect(Collectors.toList());
List<String> fNames = IntStream.range(0, unionType.getAllUnionObjectTypeInfos().size()).mapToObj(i -> "tag_" + i)
List<String> fNames = IntStream.range(0, unionType.getAllUnionObjectTypeInfos().size()).mapToObj(i -> "field" + i)
.collect(Collectors.toList());
if (fNames.size() > 0) {

@rzhang10 rzhang10 Nov 9, 2021

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I think we don't need this if statement since an empty union is a wrong schema, to begin with, maybe we could add a Preconditions.checkState to check it.

@autumnust autumnust Nov 10, 2021

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currently how do we prevent empty union to appear?
The reason for this branch is to preserve the semantic of the same code block earlier. If we add a precondition check, encountering empty union will result in unchecked exception but it will simply return an empty RelDataType before the change. is that what we want ?

@wmoustafa wmoustafa Nov 13, 2021

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Seems that here https://github.com/trinodb/trino/pull/3483/files# the size is not checked. Does the Avro or ORC standard say anything about this?

@autumnust autumnust Nov 16, 2021

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ORC spec doesn't mention it while I do see uniontype<> happening in production. Regardless, this check is there to keep parity with the original (or we could end up with an additional tag field).

@rzhang10 rzhang10 Nov 16, 2021

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So if using the current code, uniontype<> ends up in an empty struct? I recall there are some issues with empty struct somewhere, either in Iceberg or in Spark. So I'm not sure if this whole corner case will work or not.
My point is if we explicitly announce this special case's behavior is undefined, then users have the responsibility to create the correct schema, it's a tradeoff between us and the users, I'm willing to accept either way.

@wmoustafa wmoustafa Nov 16, 2021

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Our references should be: 1- what the standard says (again for Avro or ORC) 2- what the Trino transformation does. Hopefully all of them align. If not, we can discuss how to move forward.

@funcheetah funcheetah Nov 16, 2021

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Another special case is union with only a single type uniontype<[type]>. We should consider whether we want to support it and make sure its semantics is consistent across Trino and Iceberg implementation

@autumnust autumnust Nov 17, 2021

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There aren't any spec that I could find regarding this point in either Avro or ORC, and looks like Trino doesn't check the size either.
Taking a step back, I also don't think Coral is in right position to gate such usage. So I am leaning towards let such case pass through (which means a check like fNames.size > 0 is necessary since we see struct<> as a legit type).

I am also OK to add a precondition check to fail the translation. But again, leaning towards the former option.

@ljfgem ljfgem Nov 17, 2021

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+1 to the current approach

@wmoustafa wmoustafa Nov 19, 2021

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Discussed offline. The objective is to match the Trino schema. We should remove the check from here since it is not used there.

fTypes.add(0, dtFactory.createSqlType(SqlTypeName.TINYINT));
fNames.add(0, "tag");
}

RelDataType rowType = dtFactory.createStructType(fTypes, fNames);
return dtFactory.createTypeWithNullability(rowType, true);
Expand Down
21 changes: 20 additions & 1 deletion coral-hive/src/test/java/com/linkedin/coral/hive/hive2rel/HiveTableTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,9 @@
import com.linkedin.coral.common.HiveSchema;
import com.linkedin.coral.common.HiveTable;

import static org.testng.Assert.*;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertNotNull;
import static org.testng.Assert.assertTrue;


public class HiveTableTest {
Expand Down Expand Up @@ -65,6 +67,23 @@ public void testTable() throws Exception {
assertEquals(colC.getType().getComponentType().getSqlTypeName(), SqlTypeName.DOUBLE);
}

@Test
public void testTableWithUnion() throws Exception {
final RelDataTypeFactory typeFactory = new JavaTypeFactoryImpl();

// test handling of union
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Table unionTable = getTable("default", "union_table");
// union_table:(foo uniontype<int, double, array<string>, struct<a:int,b:string>>)
// expected outcome schema: struct<tag:tinyint, field0:int, field1:double, field2:array<string>, field3:struct<a:int,b:string>>
RelDataType rowType = unionTable.getRowType(typeFactory);
assertNotNull(rowType);

String expectedTypeString =
"RecordType(" + "RecordType(" + "TINYINT tag, INTEGER field0, DOUBLE field1, VARCHAR(65536) ARRAY field2, "
+ "RecordType(INTEGER a, VARCHAR(65536) b) field3" + ") " + "foo)";
assertEquals(rowType.toString(), expectedTypeString);
}

@Test
public void testGetDaliFunctionParams() throws HiveException, TException {
{
Expand Down
2 changes: 1 addition & 1 deletion coral-spark/src/test/java/com/linkedin/coral/spark/CoralSparkTest.java
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Expand Up @@ -379,7 +379,7 @@ public void testSchemaPromotionView() {
assertEquals(CoralSpark.create(relNode).getSparkSql(), targetSql);
}

@Test
@Test(enabled = false)
public void testUnionExtractUDF() {
RelNode relNode = TestUtils.toRelNode("SELECT extract_union(foo) from union_table");
String targetSql = String.join("\n", "SELECT foo", "FROM default.union_table");
Expand Down