pgsql: Add functions min_scale(numeric) and trim_scale(numeric).

Add functions min_scale(numeric) and trim_scale(numeric).

These allow better control of trailing zeroes in numeric values.

Pavel Stehule, based on an old proposal of Marko Tiikkaja's;
review by Karl Pinc

Discussion: https://postgr.es/m/CAFj8pRDjs-navGASeF0Wk74N36YGFJ+v=Ok9_knRa7vDc-qugg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/20d6225d1656102534a73d9675bc531ff0e5203b

Modified Files
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doc/src/sgml/func.sgml                |  32 ++++++++-
src/backend/utils/adt/numeric.c       |  91 ++++++++++++++++++++++++
src/include/catalog/catversion.h      |   2 +-
src/include/catalog/pg_proc.dat       |   7 ++
src/test/regress/expected/numeric.out | 126 ++++++++++++++++++++++++++++++++++
src/test/regress/sql/numeric.sql      |  30 ++++++++
6 files changed, 285 insertions(+), 3 deletions(-)