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Add infrastructure to support EphemeralNamedRelation references.

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A QueryEnvironment concept is added, which allows new types of
objects to be passed into queries from parsing on through
execution.  At this point, the only thing implemented is a
collection of EphemeralNamedRelation objects -- relations which
can be referenced by name in queries, but do not exist in the
catalogs.  The only type of ENR implemented is NamedTuplestore, but
provision is made to add more types fairly easily.

An ENR can carry its own TupleDesc or reference a relation in the
catalogs by relid.

Although these features can be used without SPI, convenience
functions are added to SPI so that ENRs can easily be used by code
run through SPI.

The initial use of all this is going to be transition tables in
AFTER triggers, but that will be added to each PL as a separate
commit.

An incidental effect of this patch is to produce a more informative
error message if an attempt is made to modify the contents of a CTE
from a referencing DML statement.  No tests previously covered that
possibility, so one is added.

Kevin Grittner and Thomas Munro
Reviewed by Heikki Linnakangas, David Fetter, and Thomas Munro
with valuable comments and suggestions from many others
This commit is contained in:
Kevin Grittner
2017-03-31 23:17:18 -05:00
parent 25dc142a49
commit 18ce3a4ab2
78 changed files with 1598 additions and 122 deletions
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45
src/backend/optimizer/path/allpaths.c
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@ -111,6 +111,8 @@ static void set_tablefunc_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
@ -396,6 +398,9 @@ set_rel_size(PlannerInfo *root, RelOptInfo *rel,
else
set_cte_pathlist(root, rel, rte);
break;
case RTE_NAMEDTUPLESTORE:
set_namedtuplestore_pathlist(root, rel, rte);
break;
default:
elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
break;
@ -464,6 +469,9 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
case RTE_CTE:
/* CTE reference --- fully handled during set_rel_size */
break;
case RTE_NAMEDTUPLESTORE:
/* tuplestore reference --- fully handled during set_rel_size */
break;
default:
elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
break;
@ -639,6 +647,13 @@ set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
* executed only once.
*/
return;
case RTE_NAMEDTUPLESTORE:
/*
* tuplestore cannot be shared, at least without more
* infrastructure to support that.
*/
return;
}
/*
@ -2089,6 +2104,36 @@ set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
add_path(rel, create_ctescan_path(root, rel, required_outer));
}
/*
* set_namedtuplestore_pathlist
* Build the (single) access path for a named tuplestore RTE
*
* There's no need for a separate set_namedtuplestore_size phase, since we
* don't support join-qual-parameterized paths for tuplestores.
*/
static void
set_namedtuplestore_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte)
{
Relids required_outer;
/* Mark rel with estimated output rows, width, etc */
set_namedtuplestore_size_estimates(root, rel);
/*
* We don't support pushing join clauses into the quals of a tuplestore
* scan, but it could still have required parameterization due to LATERAL
* refs in its tlist.
*/
required_outer = rel->lateral_relids;
/* Generate appropriate path */
add_path(rel, create_namedtuplestorescan_path(root, rel, required_outer));
/* Select cheapest path (pretty easy in this case...) */
set_cheapest(rel);
}
/*
* set_worktable_pathlist
* Build the (single) access path for a self-reference CTE RTE