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Simplify the planner's new representation of indexable clauses a little. 

In commit 1a8d5afb0, I thought it'd be a good idea to define
IndexClause.indexquals as NIL in the most common case where the given
clause (IndexClause.rinfo) is usable exactly as-is.  It'd be more
consistent to define the indexquals in that case as being a one-element
list containing IndexClause.rinfo, but I thought saving the palloc
overhead for making such a list would be worthwhile.

In hindsight, that was a great example of "premature optimization is the
root of all evil": it's complicated everyplace that needs to deal with
the indexquals, requiring duplicative code to handle both the simple
case and the not-simple case.  I'd initially found that tolerable but
it's getting less so as I mop up some areas that I'd not touched in
1a8d5afb0.  In any case, two more pallocs during a planner run are
surely at the noise level (a conclusion confirmed by a bit of
microbenchmarking).  So let's change this decision before it becomes
set in stone, and insist that IndexClause.indexquals always be a valid
list of the actual index quals for the clause.

Discussion: https://postgr.es/m/24586.1550106354@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2019-02-14 19:37:30 -05:00
parent 86eea78694
commit 8fd3fdd85a
4 changed files with 63 additions and 117 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/optimizer/path/indxpath.c
View File

@ -2435,7 +2435,7 @@ match_clause_to_indexcol(PlannerInfo *root,
{
iclause = makeNode(IndexClause);
iclause->rinfo = rinfo;
iclause->indexquals = NIL;
iclause->indexquals = list_make1(rinfo);
iclause->lossy = false;
iclause->indexcol = indexcol;
iclause->indexcols = NIL;
@ -2599,7 +2599,7 @@ match_opclause_to_indexcol(PlannerInfo *root,
{
iclause = makeNode(IndexClause);
iclause->rinfo = rinfo;
iclause->indexquals = NIL;
iclause->indexquals = list_make1(rinfo);
iclause->lossy = false;
iclause->indexcol = indexcol;
iclause->indexcols = NIL;
@ -2819,7 +2819,7 @@ match_saopclause_to_indexcol(RestrictInfo *rinfo,
IndexClause *iclause = makeNode(IndexClause);
iclause->rinfo = rinfo;
iclause->indexquals = NIL;
iclause->indexquals = list_make1(rinfo);
iclause->lossy = false;
iclause->indexcol = indexcol;
iclause->indexcols = NIL;
@ -3078,7 +3078,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
* usable as index quals.
*/
if (var_on_left && !iclause->lossy)
iclause->indexquals = NIL;
iclause->indexquals = list_make1(rinfo);
else
{
/*

30
src/backend/optimizer/plan/createplan.c
View File

@ -3075,11 +3075,8 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
Assert(!rinfo->pseudoconstant);
subquals = lappend(subquals, rinfo->clause);
if (iclause->indexquals)
subindexquals = list_concat(subindexquals,
get_actual_clauses(iclause->indexquals));
else
subindexquals = lappend(subindexquals, rinfo->clause);
subindexquals = list_concat(subindexquals,
get_actual_clauses(iclause->indexquals));
if (rinfo->parent_ec)
subindexECs = lappend(subindexECs, rinfo->parent_ec);
}
@ -4491,33 +4488,18 @@ fix_indexqual_references(PlannerInfo *root, IndexPath *index_path,
{
IndexClause *iclause = lfirst_node(IndexClause, lc);
int indexcol = iclause->indexcol;
ListCell *lc2;
if (iclause->indexquals == NIL)
foreach(lc2, iclause->indexquals)
{
/* rinfo->clause is directly usable as an indexqual */
Node *clause = (Node *) iclause->rinfo->clause;
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
Node *clause = (Node *) rinfo->clause;
stripped_indexquals = lappend(stripped_indexquals, clause);
clause = fix_indexqual_clause(root, index, indexcol,
clause, iclause->indexcols);
fixed_indexquals = lappend(fixed_indexquals, clause);
}
else
{
/* Process the derived indexquals */
ListCell *lc2;
foreach(lc2, iclause->indexquals)
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
Node *clause = (Node *) rinfo->clause;
stripped_indexquals = lappend(stripped_indexquals, clause);
clause = fix_indexqual_clause(root, index, indexcol,
clause, iclause->indexcols);
fixed_indexquals = lappend(fixed_indexquals, clause);
}
}
}
*stripped_indexquals_p = stripped_indexquals;

116
src/backend/utils/adt/selfuncs.c
View File

@ -197,8 +197,6 @@ static bool get_actual_variable_range(PlannerInfo *root,
Oid sortop,
Datum *min, Datum *max);
static RelOptInfo *find_join_input_rel(PlannerInfo *root, Relids relids);
static IndexQualInfo *deconstruct_indexqual(RestrictInfo *rinfo,
IndexOptInfo *index, int indexcol);
static List *add_predicate_to_quals(IndexOptInfo *index, List *indexQuals);
@ -5263,16 +5261,13 @@ get_index_quals(List *indexclauses)
foreach(lc, indexclauses)
{
IndexClause *iclause = lfirst_node(IndexClause, lc);
ListCell *lc2;
if (iclause->indexquals == NIL)
foreach(lc2, iclause->indexquals)
{
/* rinfo->clause is directly usable as an indexqual */
result = lappend(result, iclause->rinfo);
}
else
{
/* report the derived indexquals */
result = list_concat(result, list_copy(iclause->indexquals));
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
result = lappend(result, rinfo);
}
}
return result;
@ -5282,85 +5277,60 @@ List *
deconstruct_indexquals(IndexPath *path)
{
List *result = NIL;
IndexOptInfo *index = path->indexinfo;
ListCell *lc;
foreach(lc, path->indexclauses)
{
IndexClause *iclause = lfirst_node(IndexClause, lc);
int indexcol = iclause->indexcol;
IndexQualInfo *qinfo;
ListCell *lc2;
if (iclause->indexquals == NIL)
foreach(lc2, iclause->indexquals)
{
/* rinfo->clause is directly usable as an indexqual */
qinfo = deconstruct_indexqual(iclause->rinfo, index, indexcol);
result = lappend(result, qinfo);
}
else
{
/* Process the derived indexquals */
ListCell *lc2;
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
Expr *clause = rinfo->clause;
IndexQualInfo *qinfo;
foreach(lc2, iclause->indexquals)
qinfo = (IndexQualInfo *) palloc(sizeof(IndexQualInfo));
qinfo->rinfo = rinfo;
qinfo->indexcol = indexcol;
if (IsA(clause, OpExpr))
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
qinfo = deconstruct_indexqual(rinfo, index, indexcol);
result = lappend(result, qinfo);
qinfo->clause_op = ((OpExpr *) clause)->opno;
qinfo->other_operand = get_rightop(clause);
}
else if (IsA(clause, RowCompareExpr))
{
RowCompareExpr *rc = (RowCompareExpr *) clause;
qinfo->clause_op = linitial_oid(rc->opnos);
qinfo->other_operand = (Node *) rc->rargs;
}
else if (IsA(clause, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
qinfo->clause_op = saop->opno;
qinfo->other_operand = (Node *) lsecond(saop->args);
}
else if (IsA(clause, NullTest))
{
qinfo->clause_op = InvalidOid;
qinfo->other_operand = NULL;
}
else
{
elog(ERROR, "unsupported indexqual type: %d",
(int) nodeTag(clause));
}
result = lappend(result, qinfo);
}
}
return result;
}
static IndexQualInfo *
deconstruct_indexqual(RestrictInfo *rinfo, IndexOptInfo *index, int indexcol)
{
{
Expr *clause;
IndexQualInfo *qinfo;
clause = rinfo->clause;
qinfo = (IndexQualInfo *) palloc(sizeof(IndexQualInfo));
qinfo->rinfo = rinfo;
qinfo->indexcol = indexcol;
if (IsA(clause, OpExpr))
{
qinfo->clause_op = ((OpExpr *) clause)->opno;
qinfo->other_operand = get_rightop(clause);
}
else if (IsA(clause, RowCompareExpr))
{
RowCompareExpr *rc = (RowCompareExpr *) clause;
qinfo->clause_op = linitial_oid(rc->opnos);
qinfo->other_operand = (Node *) rc->rargs;
}
else if (IsA(clause, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
qinfo->clause_op = saop->opno;
qinfo->other_operand = (Node *) lsecond(saop->args);
}
else if (IsA(clause, NullTest))
{
qinfo->clause_op = InvalidOid;
qinfo->other_operand = NULL;
}
else
{
elog(ERROR, "unsupported indexqual type: %d",
(int) nodeTag(clause));
}
return qinfo;
}
}
/*
* Simple function to compute the total eval cost of the "other operands"
* in an IndexQualInfo list. Since we know these will be evaluated just

26
src/include/nodes/pathnodes.h
View File

@ -1185,26 +1185,20 @@ typedef struct IndexPath
* conditions is done by a planner support function attached to the
* indexclause's top-level function or operator.
*
* If indexquals is NIL, it means that rinfo->clause is directly usable as
* an indexqual. Otherwise indexquals contains one or more directly-usable
* indexqual conditions extracted from the given clause. The 'lossy' flag
* indicates whether the indexquals are semantically equivalent to the
* original clause, or form a weaker condition.
*
* Currently, entries in indexquals are RestrictInfos, but they could perhaps
* be bare clauses instead; the only advantage of making them RestrictInfos
* is the possibility of caching cost and selectivity information across
* multiple uses, and it's not clear that that's really worth the price of
* constructing RestrictInfos for them. Note however that the extended-stats
* machinery won't do anything with non-RestrictInfo clauses, so that would
* have to be fixed.
* indexquals is a list of RestrictInfos for the directly-usable index
* conditions associated with this IndexClause. In the simplest case
* it's a one-element list whose member is iclause->rinfo. Otherwise,
* it contains one or more directly-usable indexqual conditions extracted
* from the given clause. The 'lossy' flag indicates whether the
* indexquals are semantically equivalent to the original clause, or
* represent a weaker condition.
*
* Normally, indexcol is the index of the single index column the clause
* works on, and indexcols is NIL. But if the clause is a RowCompareExpr,
* indexcol is the index of the leading column, and indexcols is a list of
* all the affected columns. (Note that indexcols matches up with the
* columns of the actual indexable RowCompareExpr, which might be in
* indexquals rather than rinfo.)
* columns of the actual indexable RowCompareExpr in indexquals, which
* might be different from the original in rinfo.)
*
* An IndexPath's IndexClause list is required to be ordered by index
* column, i.e. the indexcol values must form a nondecreasing sequence.
@ -1214,7 +1208,7 @@ typedef struct IndexClause
{
NodeTag type;
struct RestrictInfo *rinfo; /* original restriction or join clause */
List *indexquals; /* indexqual(s) derived from it, or NIL */
List *indexquals; /* indexqual(s) derived from it */
bool lossy; /* are indexquals a lossy version of clause? */
AttrNumber indexcol; /* index column the clause uses (zero-based) */
List *indexcols; /* multiple index columns, if RowCompare */