pgsql: Add sort support routine for the UUID data type.

Add sort support routine for the UUID data type.

This introduces a simple encoding scheme to produce abbreviated keys:
pack as many bytes of each UUID as will fit into a Datum. On
little-endian machines, a byteswap is also performed; the abbreviated
comparator can therefore just consist of a simple 3-way unsigned integer
comparison.

The purpose of this change is to speed up sorting data on a column
of type UUID.

Peter Geoghegan

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a76ef15d9fc9207a0758e8d6f6700dc8c931a934

Modified Files
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src/backend/utils/adt/uuid.c | 187 +++++++++++++++++++++++++++++++++++++++
src/include/catalog/pg_amproc.h | 1 +
src/include/catalog/pg_proc.h | 2 +
src/include/utils/builtins.h | 1 +
4 files changed, 191 insertions(+)