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Teach planner to convert simple UNION ALL subqueries into append relations,

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thereby sharing code with the inheritance case.  This puts the UNION-ALL-view
approach to partitioned tables on par with inheritance, so far as constraint
exclusion is concerned: it works either way.  (Still need to update the docs
to say so.)  The definition of "simple UNION ALL" is a little simpler than
I would like --- basically the union arms can only be SELECT * FROM foo
--- but it's good enough for partitioned-table cases.
This commit is contained in:
Tom Lane
2006-02-03 21:08:49 +00:00
parent a25b1decef
commit 8b109ebf14
10 changed files with 888 additions and 388 deletions
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129
src/backend/optimizer/prep/prepunion.c
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@ -4,13 +4,17 @@
* Routines to plan set-operation queries. The filename is a leftover
* from a time when only UNIONs were implemented.
*
* There are two code paths in the planner for set-operation queries.
* If a subquery consists entirely of simple UNION ALL operations, it
* is converted into an "append relation". Otherwise, it is handled
* by the general code in this module (plan_set_operations and its
* subroutines). There is some support code here for the append-relation
* case, but most of the heavy lifting for that is done elsewhere,
* notably in prepjointree.c and allpaths.c.
*
* There is also some code here to support planning of queries that use
* inheritance (SELECT FROM foo*). Although inheritance is radically
* different from set operations as far as the parser representation of
* a query is concerned, we try to handle it identically to the UNION ALL
* case during planning: both are converted to "append rels". (Note that
* UNION ALL is special-cased: other kinds of set operations go through
* a completely different code path.)
* inheritance (SELECT FROM foo*). Inheritance trees are converted into
* append relations, and thenceforth share code with the UNION ALL case.
*
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
@ -18,7 +22,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.129 2006/01/31 21:39:24 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.130 2006/02/03 21:08:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -64,12 +68,13 @@ static List *generate_setop_tlist(List *colTypes, int flag,
static List *generate_append_tlist(List *colTypes, bool flag,
List *input_plans,
List *refnames_tlist);
static bool tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK);
static void expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte,
Index rti);
static void make_translation_lists(Relation oldrelation, Relation newrelation,
Index newvarno,
List **col_mappings, List **translated_vars);
static void make_inh_translation_lists(Relation oldrelation,
Relation newrelation,
Index newvarno,
List **col_mappings,
List **translated_vars);
static Node *adjust_appendrel_attrs_mutator(Node *node,
AppendRelInfo *context);
static Relids adjust_relid_set(Relids relids, Index oldrelid, Index newrelid);
@ -659,41 +664,6 @@ generate_append_tlist(List *colTypes, bool flag,
return tlist;
}
/*
* Does tlist have same datatypes as requested colTypes?
*
* Resjunk columns are ignored if junkOK is true; otherwise presence of
* a resjunk column will always cause a 'false' result.
*/
static bool
tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK)
{
ListCell *l;
ListCell *curColType = list_head(colTypes);
foreach(l, tlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resjunk)
{
if (!junkOK)
return false;
}
else
{
if (curColType == NULL)
return false;
if (exprType((Node *) tle->expr) != lfirst_oid(curColType))
return false;
curColType = lnext(curColType);
}
}
if (curColType != NULL)
return false;
return true;
}
/*
* find_all_inheritors -
@ -896,9 +866,9 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = oldrelation->rd_rel->reltype;
appinfo->child_reltype = newrelation->rd_rel->reltype;
make_translation_lists(oldrelation, newrelation, childRTindex,
&appinfo->col_mappings,
&appinfo->translated_vars);
make_inh_translation_lists(oldrelation, newrelation, childRTindex,
&appinfo->col_mappings,
&appinfo->translated_vars);
appinfo->parent_reloid = parentOID;
appinfos = lappend(appinfos, appinfo);
@ -933,7 +903,7 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
}
/*
* make_translation_lists
* make_inh_translation_lists
* Build the lists of translations from parent Vars to child Vars for
* an inheritance child. We need both a column number mapping list
* and a list of Vars representing the child columns.
@ -941,9 +911,9 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
* For paranoia's sake, we match type as well as attribute name.
*/
static void
make_translation_lists(Relation oldrelation, Relation newrelation,
Index newvarno,
List **col_mappings, List **translated_vars)
make_inh_translation_lists(Relation oldrelation, Relation newrelation,
Index newvarno,
List **col_mappings, List **translated_vars)
{
List *numbers = NIL;
List *vars = NIL;
@ -1123,8 +1093,18 @@ adjust_appendrel_attrs_mutator(Node *node, AppendRelInfo *context)
}
else
{
/* XXX copy some code from ResolveNew */
Assert(false);/* not done yet */
/*
* Build a RowExpr containing the translated variables.
*/
RowExpr *rowexpr;
List *fields;
fields = (List *) copyObject(context->translated_vars);
rowexpr = makeNode(RowExpr);
rowexpr->args = fields;
rowexpr->row_typeid = var->vartype;
rowexpr->row_format = COERCE_IMPLICIT_CAST;
return (Node *) rowexpr;
}
}
/* system attributes don't need any other translation */
@ -1337,45 +1317,6 @@ adjust_appendrel_attr_needed(RelOptInfo *oldrel, AppendRelInfo *appinfo,
return new_attr_needed;
}
/*
* adjust_other_rel_attr_needed
* Adjust an attr_needed[] array to reference a member rel instead of
* the original appendrel
*
* This is exactly like adjust_appendrel_attr_needed except that we disregard
* appinfo->col_mappings and instead assume that the mapping of user
* attributes is one-to-one. This is appropriate for generating an attr_needed
* array that describes another relation to be joined with a member rel.
*/
Relids *
adjust_other_rel_attr_needed(RelOptInfo *oldrel, AppendRelInfo *appinfo,
AttrNumber new_min_attr, AttrNumber new_max_attr)
{
Relids *new_attr_needed;
Index parent_relid = appinfo->parent_relid;
Index child_relid = appinfo->child_relid;
int parent_attr;
/* Create empty result array */
Assert(new_min_attr <= oldrel->min_attr);
Assert(new_max_attr >= oldrel->max_attr);
new_attr_needed = (Relids *)
palloc0((new_max_attr - new_min_attr + 1) * sizeof(Relids));
/* Process user attributes and system attributes */
for (parent_attr = oldrel->min_attr; parent_attr <= oldrel->max_attr;
parent_attr++)
{
Relids attrneeded;
attrneeded = oldrel->attr_needed[parent_attr - oldrel->min_attr];
attrneeded = adjust_relid_set(attrneeded,
parent_relid, child_relid);
new_attr_needed[parent_attr - new_min_attr] = attrneeded;
}
return new_attr_needed;
}
/*
* Adjust the targetlist entries of an inherited UPDATE operation
*