I'm using Elixir 1.6.3.
I'm working with the Erlang :ets module in Elixir, and I'm a bit confused by the return value of the :ets.new/2 function.
According to the doc's example, when calling :ets.new(:whatever, []), I should be returned what appears to be an integral value:
iex> table = :ets.new(:buckets_registry, [:set, :protected])
8207
However, when I run the exact same code in iex, I get a reference:
iex(1)> table = :ets.new(:buckets_registry, [:set, :protected])
#Reference<0.1885502827.460455937.234656>
So, has something changed since the documentation was written? Or is it just the same and I'm confused about what a reference is?
Yes, the return value of ets:new was changed from an integer to a reference in Erlang/OTP 20.0. From the README:
OTP-14094 Application(s): stdlib
*** POTENTIAL INCOMPATIBILITY ***
Optimized ETS operations by changing table identifier
type from integer to reference. The reference enables a
more direct mapping to the table with less potential
lock contention and makes especially creation and
deletion of tables scale much better.
The change of the opaque type for the ETS table
identifiers may cause failure in code that make faulty
assumptions about this opaque type.
The number of tables stored at one Erlang node *used*
to be limited. This is no longer the case (except by
memory usage). The previous default limit was about
1400 tables and could be increased by setting the
environment variable ERL_MAX_ETS_TABLES before starting
the Erlang runtime system. This hard limit has been
removed, but it is currently useful to set the
ERL_MAX_ETS_TABLES anyway. It should be set to an
approximate of the maximum amount of tables used. This
since an internal table for named tables is sized using
this value. If large amounts of named tables are used
and ERL_MAX_ETS_TABLES hasn't been increased, the
performance of named table lookup will degrade.