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Enable CHECK constraints to be declared NOT VALID

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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.

An non-validated CHECK constraint is ignored in the planner for
constraint_exclusion purposes; when validated, cached plans are
recomputed so that partitioning starts working right away.

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.

Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various
reviews, and Robert Hass for documentation wording improvement
suggestions.

This patch was sponsored by Enova Financial.
This commit is contained in:
Alvaro Herrera
2011-06-01 18:43:50 -04:00
parent b36927fbe9
commit 897795240c
19 changed files with 581 additions and 70 deletions
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11
src/backend/optimizer/util/plancat.c
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@ -552,7 +552,7 @@ get_relation_data_width(Oid relid, int32 *attr_widths)
/*
* get_relation_constraints
*
* Retrieve the CHECK constraint expressions of the given relation.
* Retrieve the validated CHECK constraint expressions of the given relation.
*
* Returns a List (possibly empty) of constraint expressions. Each one
* has been canonicalized, and its Vars are changed to have the varno
@ -591,6 +591,13 @@ get_relation_constraints(PlannerInfo *root,
{
Node *cexpr;
/*
* If this constraint hasn't been fully validated yet, we must
* ignore it here.
*/
if (!constr->check[i].ccvalid)
continue;
cexpr = stringToNode(constr->check[i].ccbin);
/*
@ -663,7 +670,7 @@ get_relation_constraints(PlannerInfo *root,
*
* Detect whether the relation need not be scanned because it has either
* self-inconsistent restrictions, or restrictions inconsistent with the
* relation's CHECK constraints.
* relation's validated CHECK constraints.
*
* Note: this examines only rel->relid, rel->reloptkind, and
* rel->baserestrictinfo; therefore it can be called before filling in