pgsql: Add array_sample() and array_shuffle() functions.

Add array_sample() and array_shuffle() functions.

These are useful in Monte Carlo applications.

Martin Kalcher, reviewed/adjusted by Daniel Gustafsson and myself

Discussion: https://postgr.es/m/9d160a44-7675-51e8-60cf-6d64b76db831@aboutsource.net

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/888f2ea0a81ff171087bdd1c5c1eeda3b78d73d4

Modified Files
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doc/src/sgml/func.sgml                  |  44 ++++++++-
src/backend/utils/adt/array_userfuncs.c | 166 ++++++++++++++++++++++++++++++++
src/include/catalog/catversion.h        |   2 +-
src/include/catalog/pg_proc.dat         |   6 ++
src/test/regress/expected/arrays.out    |  54 +++++++++++
src/test/regress/sql/arrays.sql         |  14 +++
6 files changed, 284 insertions(+), 2 deletions(-)