Re: creating CHECK constraints as NOT VALID

Here's a complete patch with all this stuff, plus doc additions and
simple regression tests for the new ALTER DOMAIN commands.

    Enable CHECK constraints to be declared NOT VALID
    
    This means that they can initially be added to a large existing table
    without checking its initial contents, but new tuples must comply to
    them; a separate pass invoked by ALTER TABLE / VALIDATE can verify
    existing data and ensure it complies with the constraint, at which point
    it is marked validated and becomes a normal part of the table ecosystem.
    
    This patch also enables domains to have unvalidated CHECK constraints
    attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT
    VALID, which can later be validated with ALTER DOMAIN / VALIDATE
    CONSTRAINT.
    
    This patch was sponsored by Enova Financial.

 doc/src/sgml/catalogs.sgml                |    2 +-
 doc/src/sgml/ref/alter_domain.sgml        |   39 +++++-
 doc/src/sgml/ref/alter_table.sgml         |    4 +-
 src/backend/catalog/heap.c                |   13 +-
 src/backend/commands/tablecmds.c          |  227 ++++++++++++++++++++++++-----
 src/backend/commands/typecmds.c           |  140 ++++++++++++++++--
 src/backend/parser/gram.y                 |   22 +++
 src/backend/tcop/utility.c                |    4 +
 src/include/catalog/heap.h                |    1 +
 src/include/commands/typecmds.h           |    1 +
 src/include/nodes/parsenodes.h            |    3 +
 src/test/regress/expected/alter_table.out |   36 +++++
 src/test/regress/expected/domain.out      |   11 ++
 src/test/regress/sql/alter_table.sql      |   29 ++++
 src/test/regress/sql/domain.sql           |   10 ++
 15 files changed, 480 insertions(+), 62 deletions(-)

-- 
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
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