The Commission said the companies' latest promises to safeguard competition in the market made it optimistic that the case will have a satisfactory outcome.
The EU hosted a two-day hearing at the end of last week, giving Oracle the chance to defend its planned deal with Sun.
Since then, officials in the Commission's competition division have been engaged in discussions with Oracle over the weekend about how to allow the deal to go ahead without harming Sun's open source database, MySQL.
In an unusual move for a merger investigation, the Commission issued a statement saying the fact that Oracle had committed to "a series of undertakings to customers, developers and users of MySQL is an important new element to be taken into account in the ongoing proceedings".
Oracle defended the deal during the hearing last week, but did not make any new commitments to address the Commission's concerns.
The commitments to which the Commission referred were given outside the hearing.
More specifically, the Commission said that "Oracle's binding contractual undertakings to storage engine vendors regarding copyright nonassertion and the extension over a period of up to 5 years of the terms and conditions of existing commercial licenses are significant new facts".
Last month the Commission issued a formal statement of objections to Oracle and Sun, saying that the deal would undermine MySQL, an open source rival to the big three proprietary database makers, Oracle, IBM and Microsoft.
Monday's statement from the Commission repeated Competition Commissioner Neelie Kroes' recent comment that she is optimistic that the case can have a satisfactory outcome.
The Commission has to consult national competition officials from the 27 member states of the EU before taking a final decision, but that is usually a formality.
A final decision to grant a conditional approval of the deal is expected in the first half of January. The final deadline for a decision is January 27.
See also: EU reveals objections to Oracle-Sun deal