Sandoval eclipsed Willie Mays' San Francisco record of 16 games with a hit in the ninth inning of Tuesday night's series opener.
Sandoval owns the longest current hitting streak in the Majors and is just four games shy of his own personal best of 22 games. He set that last season from June 19 to July 30.
"It means a lot for me and I'm happy, but I care more that we lost," said Sandoval after the Giants' 4-2 loss to the Reds. "I care more to win the games. For me it's more special to help my team win the game."
Sandoval is hitting .329 this season, second on the team to Buster Posey's average of .382.