Berkman is among Houston's franchise leaders in home runs, RBIs, walks, runs and slugging percentage.
Oswalt, the MVP of the 2005 NLCS, ranks second in wins and strikeouts in franchise history.
Berkman spent 12 of his 15 seasons in the majors with the Astros after being Houston's first pick in the 1997 draft out of Rice.
For his career, he hit .293 in 1,879 games with 366 home runs and 1,234 RBIs with a .406 on-base percentage and a .537 slugging percentage.
Oswalt finished his 13-season career with a 163-102 record in 365 appearances - 341 starts - with a 3.36 ERA.
Oswalt, a three-time All Star, reached 20 wins in 2004 and 2005 and was a 19-game winner in 2002. After being selected by the Astros in the 23rd round of the 1996 draft, Oswalt was called up to the majors in 2001, finishing that season with a 14-3 record in 28 appearances - 20 starts - with a 2.73 ERA.