OREANDA-NEWS. Nasdaq plans to introduce a four- partition matching configuration on April 25, 2016 to improve performance.

As a result, the manner by which Order Reference Numbers are assigned to new orders will be modified. Data recipients may observe:

  • Order Reference Numbers that are out of order
  • Higher maximum Order Reference Numbers

For a given symbol, the order reference numbers will be strictly increasing in time; however, there will no longer be a guarantee that order reference numbers across symbols are strictly increasing. Going forward, order reference numbers across symbols may interleave with one another.

As an example, an Add Order Message for symbol A may be published with Order Reference Number 24, followed by a second Add Order for symbol A with Order Reference Number 28, followed by an Add Order for symbol B with Order Reference Number 15.

In addition, due to the new manner of assigning order reference numbers, the Order Reference Numbers may become significantly higher. Order Reference Numbers are represented as a long integer, and so are not constrained to be smaller than MAX_INTEGER (0x7FFFFFFF =~ 2.14 billion). Historically, Nasdaq Order Reference Numbers have not surpassed MAX_INTEGER; however, with the new assignment methodology it is more likely that MAX_INTEGER will be exceeded.