You're full of shit, M E M.

Apparently you never heard of Trayvon Martin, in Sanford, Florida.
Obama said "If I had a son, he would have looked like Trayvon", throwing racial kerosine on the fire, undermining law enforcement, stoking violence, and unnecessarily racializing the incident.

Apparently you also never heard of Michael Brown in Ferguson Missouri, and how blacks there, again encouraged by Obama's racializing the incident with racist Eric Holder's DOJ, and having DOJ officials attend Brown's funeral (when in the case of multiple soldiers killed, Obama ignored the deaths and did not attend services.) Arguably, if not for Obama's racially charged rhetoric and actions that encouraged rioting and violence it might never have happened!
And by the way, even Holder's racially partisan DOJ, despite their absolute best efforts to destroy officer Darren Wilson, quietly released a report that found Wilson had acted professionally and done nothing wrong. But Wilson was fired anyway, for no logical reason, other than to appease a black mob.

There was also an incident where a black college professor was caught by police breaking into his own house, and instead of cooperating with police, was arrested because he mouthed off to the officers. Obama again jumped in on the wrong side without knowing the facts and said "The police acted stupidly."
No, they found a guy breaking into a house, who was completely uncooperative when he could have just identified himself, been polite to the officers under the circumstances, and prevented the whole situation.
It was concluded with a ridiculous "Beer summit".

Obama stoked racial tensions throughout his presidency by having Al Sharpton and Black Lives Matter meet him at the White House, on many occasions. With the incendiary level of rhetorric of both Sharpton and BLM, those White House meetings with them have been compared to being the equivalent of if a white president had invited the Ku Klux Klan leadership to the White House. Obama continued to invite Sharpton and BLM to the White House, even after their rhetoric and activism had resulted in multiple police officers being shot and killed in cities nationwide.

It is the overwhelming consensus of poll after poll from the Obama period that racial tensions vastly increased during the Obama years, for obvious reasons, directly related to Obama's words and actions.
Ironic, because Obama was presented in 2008 as a harmless moderate, intended to be a "post-racial" president, whose election would show the nation had moved beyond racial considerations.
But instead, as black historian Thomas Sowell said, Obama campaigned as a moderate, and then governed overseeing a "revenge/payback society", where in addition to the above examples, Obama's DOJ abandoned equal justice under the law, and ignored cases where those victimized were white, and his DOJ would only prosecute cases where the victims were people of color. Most famously throwing an easy slam-dunk case for the Black Panthers voter intimidation case, that would have been an easy and very just conviction, but black racist Eric Holder's DOJ refused to prosecute it. Causing U.S. attorney J.Christian Adams and other U.S. attorneys to resign in protest, to expose the Obama/Holder DOJ's bias.

Yeah, I just can't imagine something like this happening, riots and racial conflict under Obama.

Except that Obama directly caused most of the racial tension during his 8 years.
And those are just the incidents I can recall offhand.

Not to mention his abuses of the IRS, the FISA Court, FBI, DOJ and CIA spying on the Trump campaign and Trump administration after inauguration that according to a Jan 5 2009 memo by then-toorney general Sally Yates, and text messages between Peter Strzok and Lisa Page and other documents, that Obama directly orchestrated these federal abuses of power. Obama should be in jail.