Mayor Bill de Blasio sparred for 90 minutes on Tuesday with his two main rivals in a rowdy and rambunctious debate that devolved into shouting, finger-pointing and cut-off microphones.

The candidates talked over each other. The crowd shouted them down. And it ended with an exasperated moderator, Errol Louis of NY1, spinning his finger in the air in a mercy-rule declaration that the debate was done.

“I think that’s going to do it,” Mr. Louis said.

Here are five takeaways from the first mayoral clash between Mr. de Blasio, Assemblywoman Nicole Malliotakis, a Republican, and Bo Dietl, a former police detective running as an independent on the Dump the Mayor line.

1. The debate did not shake up the race

Mr. de Blasio came in as a heavy front-runner — he led his closest challenger, Ms. Malliotakis, by more than 40 percentage points in recent polls — and the political imperative for both his opponents was to take him down a notch. And while they focused almost all of their rhetorical fire on the incumbent — Ms. Malliotakis and Mr. Dietl barely addressed one another — the mayor mostly stayed calm as he swiped away their charges, escaping without any crippling sound bites.