HHH-18053 alternative fix for Cockroach duration arithmetic

Signed-off-by: Gavin King <gavin@hibernate.org>

hibernate-core/src/main/java/org/hibernate/dialect/CockroachDialect.java

@@ -80,7 +80,6 @@
 import static org.hibernate.exception.spi.TemplatedViolatedConstraintNameExtractor.extractUsingTemplate;
 import static org.hibernate.query.sqm.TemporalUnit.DAY;
 import static org.hibernate.query.sqm.TemporalUnit.EPOCH;
-import static org.hibernate.query.sqm.TemporalUnit.NATIVE;
 import static org.hibernate.type.SqlTypes.ARRAY;
 import static org.hibernate.type.SqlTypes.BINARY;
 import static org.hibernate.type.SqlTypes.BLOB;
@@ -787,11 +786,15 @@ public String translateExtractField(TemporalUnit unit) {
 
 	/**
 	 * {@code microsecond} is the smallest unit for an {@code interval},
-	 * and the highest precision for a {@code timestamp}.
+	 * and the highest precision for a {@code timestamp}, so we could
+	 * use it as the "native" precision, but it's more convenient to use
+	 * whole seconds (with the fractional part), since we want to use
+	 * {@code extract(epoch from ...)} in our emulation of
+	 * {@code timestampdiff()}.
 	 */
 	@Override
 	public long getFractionalSecondPrecisionInNanos() {
-		return 1_000; //microseconds
+		return 1_000_000_000; //seconds
 	}
 
 	@Override
@@ -865,13 +868,6 @@ public String timestampdiffPattern(TemporalUnit unit, TemporalType fromTemporalT
 		}
 	}
 
-	@Override
-	public String translateDurationField(TemporalUnit unit) {
-		return unit==NATIVE
-				? "microsecond"
-				: super.translateDurationField(unit);
-	}
-
 	@Override
 	public void appendDatetimeFormat(SqlAppender appender, String format) {
 		appender.appendSql( SpannerDialect.datetimeFormat( format ).result() );