pgsql: Add 'ignore_nulls' option to row_to_json

Add 'ignore_nulls' option to row_to_json

Provide an option to skip NULL values in a row when generating a JSON
object from that row with row_to_json.  This can reduce the size of the
JSON object in cases where columns are NULL without really reducing the
information in the JSON object.

This also makes row_to_json into a single function with default values,
rather than having multiple functions.  In passing, change array_to_json
to also be a single function with default values (we don't add an
'ignore_nulls' option yet- it's not clear that there is a sensible
use-case there, and it hasn't been asked for in any case).

Pavel Stehule

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/95d737ff45a38809130a2c633d9e6bc26c825036

Modified Files
--------------
doc/src/sgml/func.sgml               |    6 ++--
src/backend/catalog/system_views.sql |   14 ++++++++
src/backend/utils/adt/json.c         |   55 +++++++++-----------------------
src/include/catalog/catversion.h     |    2 +-
src/include/catalog/pg_proc.h        |    8 ++---
src/include/utils/json.h             |    2 --
src/test/regress/expected/json.out   |   58 ++++++++++++++++++++++++++++++++++
src/test/regress/sql/json.sql        |   24 ++++++++++++++
8 files changed, 118 insertions(+), 51 deletions(-)