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Don't scan partitioned tables.

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Partitioned tables do not contain any data; only their unpartitioned
descendents need to be scanned.  However, the partitioned tables still
need to be locked, even though they're not scanned.  To make that
work, Append and MergeAppend relations now need to carry a list of
(unscanned) partitioned relations that must be locked, and InitPlan
must lock all partitioned result relations.

Aside from the obvious advantage of avoiding some work at execution
time, this has two other advantages.  First, it may improve the
planner's decision-making in some cases since the empty relation
might throw things off.  Second, it paves the way to getting rid of
the storage for partitioned tables altogether.

Amit Langote, reviewed by me.

Discussion: http://postgr.es/m/6837c359-45c4-8044-34d1-736756335a15@lab.ntt.co.jp
This commit is contained in:
Robert Haas
2017-03-21 09:48:04 -04:00
parent d5286aa905
commit d3cc37f1d8
27 changed files with 537 additions and 164 deletions
Download Patch File Download Diff File Expand all files Collapse all files

103
src/backend/optimizer/prep/prepunion.c
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@@ -566,7 +566,7 @@ generate_union_path(SetOperationStmt *op, PlannerInfo *root,
/*
* Append the child results together.
*/
path = (Path *) create_append_path(result_rel, pathlist, NULL, 0);
path = (Path *) create_append_path(result_rel, pathlist, NULL, 0, NIL);
/* We have to manually jam the right tlist into the path; ick */
path->pathtarget = create_pathtarget(root, tlist);
@@ -678,7 +678,7 @@ generate_nonunion_path(SetOperationStmt *op, PlannerInfo *root,
/*
* Append the child results together.
*/
path = (Path *) create_append_path(result_rel, pathlist, NULL, 0);
path = (Path *) create_append_path(result_rel, pathlist, NULL, 0, NIL);
/* We have to manually jam the right tlist into the path; ick */
path->pathtarget = create_pathtarget(root, tlist);
@@ -1364,6 +1364,9 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
List *inhOIDs;
List *appinfos;
ListCell *l;
bool need_append;
PartitionedChildRelInfo *pcinfo;
List *partitioned_child_rels = NIL;
/* Does RT entry allow inheritance? */
if (!rte->inh)
@@ -1435,6 +1438,7 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
/* Scan the inheritance set and expand it */
appinfos = NIL;
need_append = false;
foreach(l, inhOIDs)
{
Oid childOID = lfirst_oid(l);
@@ -1483,36 +1487,46 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
childRTindex = list_length(parse->rtable);
/*
* Build an AppendRelInfo for this parent and child.
* Build an AppendRelInfo for this parent and child, unless the child
* is a partitioned table.
*/
appinfo = makeNode(AppendRelInfo);
appinfo->parent_relid = rti;
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = oldrelation->rd_rel->reltype;
appinfo->child_reltype = newrelation->rd_rel->reltype;
make_inh_translation_list(oldrelation, newrelation, childRTindex,
&appinfo->translated_vars);
appinfo->parent_reloid = parentOID;
appinfos = lappend(appinfos, appinfo);
/*
* Translate the column permissions bitmaps to the child's attnums (we
* have to build the translated_vars list before we can do this). But
* if this is the parent table, leave copyObject's result alone.
*
* Note: we need to do this even though the executor won't run any
* permissions checks on the child RTE. The insertedCols/updatedCols
* bitmaps may be examined for trigger-firing purposes.
*/
if (childOID != parentOID)
if (childrte->relkind != RELKIND_PARTITIONED_TABLE)
{
childrte->selectedCols = translate_col_privs(rte->selectedCols,
need_append = true;
appinfo = makeNode(AppendRelInfo);
appinfo->parent_relid = rti;
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = oldrelation->rd_rel->reltype;
appinfo->child_reltype = newrelation->rd_rel->reltype;
make_inh_translation_list(oldrelation, newrelation, childRTindex,
&appinfo->translated_vars);
appinfo->parent_reloid = parentOID;
appinfos = lappend(appinfos, appinfo);
/*
* Translate the column permissions bitmaps to the child's attnums
* (we have to build the translated_vars list before we can do
* this). But if this is the parent table, leave copyObject's
* result alone.
*
* Note: we need to do this even though the executor won't run any
* permissions checks on the child RTE. The
* insertedCols/updatedCols bitmaps may be examined for
* trigger-firing purposes.
*/
if (childOID != parentOID)
{
childrte->selectedCols = translate_col_privs(rte->selectedCols,
appinfo->translated_vars);
childrte->insertedCols = translate_col_privs(rte->insertedCols,
childrte->insertedCols = translate_col_privs(rte->insertedCols,
appinfo->translated_vars);
childrte->updatedCols = translate_col_privs(rte->updatedCols,
childrte->updatedCols = translate_col_privs(rte->updatedCols,
appinfo->translated_vars);
}
}
else
partitioned_child_rels = lappend_int(partitioned_child_rels,
childRTindex);
/*
* Build a PlanRowMark if parent is marked FOR UPDATE/SHARE.
@@ -1529,7 +1543,13 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
newrc->allMarkTypes = (1 << newrc->markType);
newrc->strength = oldrc->strength;
newrc->waitPolicy = oldrc->waitPolicy;
newrc->isParent = false;
/*
* We mark RowMarks for partitioned child tables as parent RowMarks
* so that the executor ignores them (except their existence means
* that the child tables be locked using appropriate mode).
*/
newrc->isParent = (childrte->relkind == RELKIND_PARTITIONED_TABLE);
/* Include child's rowmark type in parent's allMarkTypes */
oldrc->allMarkTypes |= newrc->allMarkTypes;
@@ -1545,18 +1565,37 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
heap_close(oldrelation, NoLock);
/*
* If all the children were temp tables, pretend it's a non-inheritance
* situation. The duplicate RTE we added for the parent table is
* harmless, so we don't bother to get rid of it; ditto for the useless
* PlanRowMark node.
* If all the children were temp tables or a partitioned parent did not
* have any leaf partitions, pretend it's a non-inheritance situation; we
* don't need Append node in that case. The duplicate RTE we added for
* the parent table is harmless, so we don't bother to get rid of it;
* ditto for the useless PlanRowMark node.
*/
if (list_length(appinfos) < 2)
if (!need_append)
{
/* Clear flag before returning */
rte->inh = false;
return;
}
/*
* We keep a list of objects in root, each of which maps a partitioned
* parent RT index to the list of RT indexes of its partitioned child
* tables. When creating an Append or a ModifyTable path for the parent,
* we copy the child RT index list verbatim to the path so that it could
* be carried over to the executor so that the latter could identify
* the partitioned child tables.
*/
if (partitioned_child_rels != NIL)
{
pcinfo = makeNode(PartitionedChildRelInfo);
Assert(rte->relkind == RELKIND_PARTITIONED_TABLE);
pcinfo->parent_relid = rti;
pcinfo->child_rels = partitioned_child_rels;
root->pcinfo_list = lappend(root->pcinfo_list, pcinfo);
}
/* Otherwise, OK to add to root->append_rel_list */
root->append_rel_list = list_concat(root->append_rel_list, appinfos);
}