From da4792dcd2a4890072ece6dea354d5a3a1253d9c Mon Sep 17 00:00:00 2001
From: findinpath <findinpath@gmail.com>
Date: Thu, 17 Jun 2021 00:31:42 +0200
Subject: [PATCH] Add support for generic parameters in `make_set_digest`
 function

A widely applied usecase  for minhash algorithm is to check the
similarity of two texts.
Therefore the current implementation adds support for creating a
`setdigest` aggregation for (among other types) varchar slices.
---
 .../setdigest/BuildSetDigestAggregation.java  | 17 ++++++++++++++--
 .../sql/query/TestSetDigestFunctions.java     | 20 ++++++++++++++++++-
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/core/trino-main/src/main/java/io/trino/type/setdigest/BuildSetDigestAggregation.java b/core/trino-main/src/main/java/io/trino/type/setdigest/BuildSetDigestAggregation.java
index 6f17380f6057..ecade41a55b5 100644
--- a/core/trino-main/src/main/java/io/trino/type/setdigest/BuildSetDigestAggregation.java
+++ b/core/trino-main/src/main/java/io/trino/type/setdigest/BuildSetDigestAggregation.java
@@ -14,13 +14,15 @@
 
 package io.trino.type.setdigest;
 
+import io.airlift.slice.Slice;
 import io.trino.spi.block.BlockBuilder;
 import io.trino.spi.function.AggregationFunction;
+import io.trino.spi.function.AggregationState;
 import io.trino.spi.function.CombineFunction;
 import io.trino.spi.function.InputFunction;
 import io.trino.spi.function.OutputFunction;
 import io.trino.spi.function.SqlType;
-import io.trino.spi.type.StandardTypes;
+import io.trino.spi.function.TypeParameter;
 
 @AggregationFunction("make_set_digest")
 public final class BuildSetDigestAggregation
@@ -30,7 +32,18 @@ public final class BuildSetDigestAggregation
     private BuildSetDigestAggregation() {}
 
     @InputFunction
-    public static void input(SetDigestState state, @SqlType(StandardTypes.BIGINT) long value)
+    @TypeParameter("T")
+    public static void input(@AggregationState SetDigestState state, @SqlType("T") long value)
+    {
+        if (state.getDigest() == null) {
+            state.setDigest(new SetDigest());
+        }
+        state.getDigest().add(value);
+    }
+
+    @InputFunction
+    @TypeParameter("T")
+    public static void input(@AggregationState SetDigestState state, @SqlType("T") Slice value)
     {
         if (state.getDigest() == null) {
             state.setDigest(new SetDigest());
diff --git a/core/trino-main/src/test/java/io/trino/sql/query/TestSetDigestFunctions.java b/core/trino-main/src/test/java/io/trino/sql/query/TestSetDigestFunctions.java
index b49da9379387..8aec6613ebb2 100644
--- a/core/trino-main/src/test/java/io/trino/sql/query/TestSetDigestFunctions.java
+++ b/core/trino-main/src/test/java/io/trino/sql/query/TestSetDigestFunctions.java
@@ -37,7 +37,7 @@ public void teardown()
     }
 
     @Test
-    public void testCardinality()
+    public void testCardinalityForBigintSetDigest()
     {
         assertThat(assertions.query(
                 "SELECT cardinality(make_set_digest(value)) " +
@@ -45,6 +45,24 @@ public void testCardinality()
                 .matches("VALUES CAST(5 AS BIGINT)");
     }
 
+    @Test
+    public void testCardinalityForVarcharSetDigest()
+    {
+        assertThat(assertions.query(
+                "SELECT cardinality(make_set_digest(value)) " +
+                        "FROM (VALUES 'trino', 'sql', 'everything', 'sql', 'trino') T(value)"))
+                .matches("VALUES CAST(3 AS BIGINT)");
+    }
+
+    @Test
+    public void testCardinalityForDateSetDigest()
+    {
+        assertThat(assertions.query(
+                "SELECT cardinality(make_set_digest(value)) " +
+                        "FROM (VALUES DATE '2001-08-22', DATE '2001-08-22', DATE '2001-08-23') T(value)"))
+                .matches("VALUES CAST(2 AS BIGINT)");
+    }
+
     @Test
     public void testExactIntersectionCardinality()
     {