From c096b463eef9e2447e9b68fcfd7354d6debe2bf2 Mon Sep 17 00:00:00 2001
From: Christian Beikov <christian.beikov@gmail.com>
Date: Thu, 29 Apr 2021 13:43:31 +0200
Subject: [PATCH] Emulate null ordering for CockroachDB

---
 .../dialect/CockroachDB192Dialect.java        | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/CockroachDB192Dialect.java b/hibernate-core/src/main/java/org/hibernate/dialect/CockroachDB192Dialect.java
index 1b89423ded..18ad31c338 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/CockroachDB192Dialect.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/CockroachDB192Dialect.java
@@ -14,6 +14,7 @@ import java.util.Map;
 import org.hibernate.JDBCException;
 import org.hibernate.LockMode;
 import org.hibernate.LockOptions;
+import org.hibernate.NullPrecedence;
 import org.hibernate.PessimisticLockException;
 import org.hibernate.boot.model.TypeContributions;
 import org.hibernate.cfg.Environment;
@@ -234,6 +235,25 @@ public class CockroachDB192Dialect extends Dialect {
 		return true;
 	}
 
+	@Override
+	public String renderOrderByElement(String expression, String collation, String order, NullPrecedence nulls) {
+		final StringBuilder orderByElement = new StringBuilder();
+		if ( nulls != NullPrecedence.NONE ) {
+			// Workaround for NULLS FIRST / LAST support.
+			orderByElement.append( "case when " ).append( expression ).append( " is null then " );
+			if ( nulls == NullPrecedence.FIRST ) {
+				orderByElement.append( "0 else 1" );
+			}
+			else {
+				orderByElement.append( "1 else 0" );
+			}
+			orderByElement.append( " end, " );
+		}
+		// Nulls precedence has already been handled so passing NONE value.
+		orderByElement.append( super.renderOrderByElement( expression, collation, order, NullPrecedence.NONE ) );
+		return orderByElement.toString();
+	}
+
 	@Override
 	public String getForUpdateString(String aliases) {
 		return getForUpdateString() + " of " + aliases;