I need help understanding the following two release note items (see XXX):

<listitem>
<para>
Create a general mechanism that supports casts to and from the
standard string types (<type>TEXT</type>, <type>VARCHAR</type>,
<type>CHAR</type>) for <emphasis>every</emphasis> datatype, by
invoking the datatype's I/O functions (Tom) XXX examples?
</para>

<para>
These new casts are assignment-only in the to-string direction,
explicit-only in the other direction, and therefore should create no
surprising behavior. Various
datatype-specific casting functions that were equivalent to this
behavior were removed.
</para>
</listitem>

<listitem>
<para>
Allow limited hashing when using two different data types (Tom)
</para>

<para>
This allows hash joins, hash indexes, hashed subplans, and hash
aggregation to be used in situations involving cross-data-type
comparisons, if the data types have compatible hash functions.
Currently, cross-data-type hashing support exists for
<type>smallint</type>/<type>integer</type>/<type>bigint</type>,
and for <type>float4</type>/<type>float8</type>. XXX how do you do
hash aggregate with two different data types
</para>
</listitem>


--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

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