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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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70
src/backend/optimizer/path/costsize.c
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@@ -1516,6 +1516,43 @@ cost_ctescan(Path *path, PlannerInfo *root,
path->total_cost = startup_cost + run_cost;
}
/*
* cost_namedtuplestorescan
* Determines and returns the cost of scanning a named tuplestore.
*/
void
cost_namedtuplestorescan(Path *path, PlannerInfo *root,
RelOptInfo *baserel, ParamPathInfo *param_info)
{
Cost startup_cost = 0;
Cost run_cost = 0;
QualCost qpqual_cost;
Cost cpu_per_tuple;
/* Should only be applied to base relations that are Tuplestores */
Assert(baserel->relid > 0);
Assert(baserel->rtekind == RTE_NAMEDTUPLESTORE);
/* Mark the path with the correct row estimate */
if (param_info)
path->rows = param_info->ppi_rows;
else
path->rows = baserel->rows;
/* Charge one CPU tuple cost per row for tuplestore manipulation */
cpu_per_tuple = cpu_tuple_cost;
/* Add scanning CPU costs */
get_restriction_qual_cost(root, baserel, param_info, &qpqual_cost);
startup_cost += qpqual_cost.startup;
cpu_per_tuple += cpu_tuple_cost + qpqual_cost.per_tuple;
run_cost += cpu_per_tuple * baserel->tuples;
path->startup_cost = startup_cost;
path->total_cost = startup_cost + run_cost;
}
/*
* cost_recursive_union
* Determines and returns the cost of performing a recursive union,
@@ -4684,6 +4721,39 @@ set_cte_size_estimates(PlannerInfo *root, RelOptInfo *rel, double cte_rows)
set_baserel_size_estimates(root, rel);
}
/*
* set_namedtuplestore_size_estimates
* Set the size estimates for a base relation that is a tuplestore reference.
*
* The rel's targetlist and restrictinfo list must have been constructed
* already.
*
* We set the same fields as set_baserel_size_estimates.
*/
void
set_namedtuplestore_size_estimates(PlannerInfo *root, RelOptInfo *rel)
{
RangeTblEntry *rte;
/* Should only be applied to base relations that are tuplestore references */
Assert(rel->relid > 0);
rte = planner_rt_fetch(rel->relid, root);
Assert(rte->rtekind == RTE_NAMEDTUPLESTORE);
/*
* Use the estimate provided by the code which is generating the named
* tuplestore. In some cases, the actual number might be available; in
* others the same plan will be re-used, so a "typical" value might be
* estimated and used.
*/
rel->tuples = rte->enrtuples;
if (rel->tuples < 0)
rel->tuples = 1000;
/* Now estimate number of output rows, etc */
set_baserel_size_estimates(root, rel);
}
/*
* set_foreign_size_estimates
* Set the size estimates for a base relation that is a foreign table.