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postgres/src/backend/optimizer/path/indxpath.c
Tom Lane d18e334c65 Fix thinko in recent changes to handle ScalarArrayOpExpr as an indexable 
condition: when there are multiple possible index paths involving
ScalarArrayOpExprs, they are logically to be ANDed together not ORed.
This thinko was a direct consequence of trying to put the processing
inside generate_bitmap_or_paths(), which I now see was a bit too cute.
So pull it out and make the callers do it separately (there are only two
that need it anyway).  Partially responds to bug #2441 from Arjen van der Meijden.
There are some additional infelicities exposed by his example, but they
are also in 8.1.x, while this mistake is not.
2006-05-18 17:12:10 +00:00

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/*-------------------------------------------------------------------------
*
* indxpath.c
* Routines to determine which indexes are usable for scanning a
* given relation, and create Paths accordingly.
*
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.205 2006/05/18 17:12:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <math.h>
#include "access/skey.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/predtest.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/var.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/pg_locale.h"
#include "utils/selfuncs.h"
/*
* DoneMatchingIndexKeys() - MACRO
*/
#define DoneMatchingIndexKeys(classes) (classes[0] == InvalidOid)
#define IsBooleanOpclass(opclass) \
((opclass) == BOOL_BTREE_OPS_OID || (opclass) == BOOL_HASH_OPS_OID)
static List *find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, bool isjoininner,
Relids outer_relids,
SaOpControl saop_control);
static List *find_saop_paths(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, bool isjoininner,
Relids outer_relids);
static Path *choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths);
static int bitmap_path_comparator(const void *a, const void *b);
static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths);
static List *pull_indexpath_quals(Path *bitmapqual);
static bool lists_intersect_ptr(List *list1, List *list2);
static bool match_clause_to_indexcol(IndexOptInfo *index,
int indexcol, Oid opclass,
RestrictInfo *rinfo,
Relids outer_relids,
SaOpControl saop_control);
static bool is_indexable_operator(Oid expr_op, Oid opclass,
bool indexkey_on_left);
static bool match_rowcompare_to_indexcol(IndexOptInfo *index,
int indexcol,
Oid opclass,
RowCompareExpr *clause,
Relids outer_relids);
static Relids indexable_outerrelids(RelOptInfo *rel);
static bool matches_any_index(RestrictInfo *rinfo, RelOptInfo *rel,
Relids outer_relids);
static List *find_clauses_for_join(PlannerInfo *root, RelOptInfo *rel,
Relids outer_relids, bool isouterjoin);
static ScanDirection match_variant_ordering(PlannerInfo *root,
IndexOptInfo *index,
List *restrictclauses);
static List *identify_ignorable_ordering_cols(PlannerInfo *root,
IndexOptInfo *index,
List *restrictclauses);
static bool match_index_to_query_keys(PlannerInfo *root,
IndexOptInfo *index,
ScanDirection indexscandir,
List *ignorables);
static bool match_boolean_index_clause(Node *clause, int indexcol,
IndexOptInfo *index);
static bool match_special_index_operator(Expr *clause, Oid opclass,
bool indexkey_on_left);
static Expr *expand_boolean_index_clause(Node *clause, int indexcol,
IndexOptInfo *index);
static List *expand_indexqual_opclause(RestrictInfo *rinfo, Oid opclass);
static RestrictInfo *expand_indexqual_rowcompare(RestrictInfo *rinfo,
IndexOptInfo *index,
int indexcol);
static List *prefix_quals(Node *leftop, Oid opclass,
Const *prefix, Pattern_Prefix_Status pstatus);
static List *network_prefix_quals(Node *leftop, Oid expr_op, Oid opclass,
Datum rightop);
static Datum string_to_datum(const char *str, Oid datatype);
static Const *string_to_const(const char *str, Oid datatype);
/*
* create_index_paths()
* Generate all interesting index paths for the given relation.
* Candidate paths are added to the rel's pathlist (using add_path).
*
* To be considered for an index scan, an index must match one or more
* restriction clauses or join clauses from the query's qual condition,
* or match the query's ORDER BY condition, or have a predicate that
* matches the query's qual condition.
*
* There are two basic kinds of index scans. A "plain" index scan uses
* only restriction clauses (possibly none at all) in its indexqual,
* so it can be applied in any context. An "innerjoin" index scan uses
* join clauses (plus restriction clauses, if available) in its indexqual.
* Therefore it can only be used as the inner relation of a nestloop
* join against an outer rel that includes all the other rels mentioned
* in its join clauses. In that context, values for the other rels'
* attributes are available and fixed during any one scan of the indexpath.
*
* An IndexPath is generated and submitted to add_path() for each plain index
* scan this routine deems potentially interesting for the current query.
*
* We also determine the set of other relids that participate in join
* clauses that could be used with each index. The actually best innerjoin
* path will be generated for each outer relation later on, but knowing the
* set of potential otherrels allows us to identify equivalent outer relations
* and avoid repeated computation.
*
* 'rel' is the relation for which we want to generate index paths
*
* Note: check_partial_indexes() must have been run previously for this rel.
*/
void
create_index_paths(PlannerInfo *root, RelOptInfo *rel)
{
List *indexpaths;
List *bitindexpaths;
ListCell *l;
/* Skip the whole mess if no indexes */
if (rel->indexlist == NIL)
{
rel->index_outer_relids = NULL;
return;
}
/*
* Examine join clauses to see which ones are potentially usable with
* indexes of this rel, and generate the set of all other relids that
* participate in such join clauses. We'll use this set later to
* recognize outer rels that are equivalent for joining purposes.
*/
rel->index_outer_relids = indexable_outerrelids(rel);
/*
* Find all the index paths that are directly usable for this relation
* (ie, are valid without considering OR or JOIN clauses).
*/
indexpaths = find_usable_indexes(root, rel,
rel->baserestrictinfo, NIL,
true, false, NULL, SAOP_FORBID);
/*
* We can submit them all to add_path. (This generates access paths for
* plain IndexScan plans.) However, for the next step we will only want
* the ones that have some selectivity; we must discard anything that was
* generated solely for ordering purposes.
*/
bitindexpaths = NIL;
foreach(l, indexpaths)
{
IndexPath *ipath = (IndexPath *) lfirst(l);
add_path(rel, (Path *) ipath);
if (ipath->indexselectivity < 1.0 &&
!ScanDirectionIsBackward(ipath->indexscandir))
bitindexpaths = lappend(bitindexpaths, ipath);
}
/*
* Generate BitmapOrPaths for any suitable OR-clauses present in the
* restriction list. Add these to bitindexpaths.
*/
indexpaths = generate_bitmap_or_paths(root, rel,
rel->baserestrictinfo, NIL,
false, NULL);
bitindexpaths = list_concat(bitindexpaths, indexpaths);
/*
* Likewise, generate paths using ScalarArrayOpExpr clauses; these can't
* be simple indexscans but they can be used in bitmap scans.
*/
indexpaths = find_saop_paths(root, rel,
rel->baserestrictinfo, NIL,
true, false, NULL);
bitindexpaths = list_concat(bitindexpaths, indexpaths);
/*
* If we found anything usable, generate a BitmapHeapPath for the most
* promising combination of bitmap index paths.
*/
if (bitindexpaths != NIL)
{
Path *bitmapqual;
BitmapHeapPath *bpath;
bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
bpath = create_bitmap_heap_path(root, rel, bitmapqual, false);
add_path(rel, (Path *) bpath);
}
}
/*----------
* find_usable_indexes
* Given a list of restriction clauses, find all the potentially usable
* indexes for the given relation, and return a list of IndexPaths.
*
* The caller actually supplies two lists of restriction clauses: some
* "current" ones and some "outer" ones. Both lists can be used freely
* to match keys of the index, but an index must use at least one of the
* "current" clauses to be considered usable. The motivation for this is
* examples like
* WHERE (x = 42) AND (... OR (y = 52 AND z = 77) OR ....)
* While we are considering the y/z subclause of the OR, we can use "x = 42"
* as one of the available index conditions; but we shouldn't match the
* subclause to any index on x alone, because such a Path would already have
* been generated at the upper level. So we could use an index on x,y,z
* or an index on x,y for the OR subclause, but not an index on just x.
* When dealing with a partial index, a match of the index predicate to
* one of the "current" clauses also makes the index usable.
*
* If istoplevel is true (indicating we are considering the top level of a
* rel's restriction clauses), we will include indexes in the result that
* have an interesting sort order, even if they have no matching restriction
* clauses.
*
* 'rel' is the relation for which we want to generate index paths
* 'clauses' is the current list of clauses (RestrictInfo nodes)
* 'outer_clauses' is the list of additional upper-level clauses
* 'istoplevel' is true if clauses are the rel's top-level restriction list
* (outer_clauses must be NIL when this is true)
* 'isjoininner' is true if forming an inner indexscan (so some of the
* given clauses are join clauses)
* 'outer_relids' identifies the outer side of the join (pass NULL
* if not isjoininner)
* 'saop_control' indicates whether ScalarArrayOpExpr clauses can be used
*
* Note: check_partial_indexes() must have been run previously.
*----------
*/
static List *
find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, bool isjoininner,
Relids outer_relids,
SaOpControl saop_control)
{
List *result = NIL;
List *all_clauses = NIL; /* not computed till needed */
ListCell *ilist;
foreach(ilist, rel->indexlist)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist);
IndexPath *ipath;
List *restrictclauses;
List *index_pathkeys;
List *useful_pathkeys;
bool useful_predicate;
bool found_clause;
bool index_is_ordered;
/*
* Ignore partial indexes that do not match the query. If a partial
* index is marked predOK then we know it's OK; otherwise, if we are
* at top level we know it's not OK (since predOK is exactly whether
* its predicate could be proven from the toplevel clauses).
* Otherwise, we have to test whether the added clauses are sufficient
* to imply the predicate. If so, we could use the index in the
* current context.
*
* We set useful_predicate to true iff the predicate was proven using
* the current set of clauses. This is needed to prevent matching a
* predOK index to an arm of an OR, which would be a legal but
* pointlessly inefficient plan. (A better plan will be generated by
* just scanning the predOK index alone, no OR.)
*/
useful_predicate = false;
if (index->indpred != NIL)
{
if (index->predOK)
{
if (istoplevel)
{
/* we know predicate was proven from these clauses */
useful_predicate = true;
}
}
else
{
if (istoplevel)
continue; /* no point in trying to prove it */
/* Form all_clauses if not done already */
if (all_clauses == NIL)
all_clauses = list_concat(list_copy(clauses),
outer_clauses);
if (!predicate_implied_by(index->indpred, all_clauses))
continue; /* can't use it at all */
if (!predicate_implied_by(index->indpred, outer_clauses))
useful_predicate = true;
}
}
/*
* 1. Match the index against the available restriction clauses.
* found_clause is set true only if at least one of the current
* clauses was used (and, if saop_control is SAOP_REQUIRE, it
* has to have been a ScalarArrayOpExpr clause).
*/
restrictclauses = group_clauses_by_indexkey(index,
clauses,
outer_clauses,
outer_relids,
saop_control,
&found_clause);
/*
* Not all index AMs support scans with no restriction clauses. We
* can't generate a scan over an index with amoptionalkey = false
* unless there's at least one restriction clause.
*/
if (restrictclauses == NIL && !index->amoptionalkey)
continue;
/*
* 2. Compute pathkeys describing index's ordering, if any, then see
* how many of them are actually useful for this query. This is not
* relevant unless we are at top level.
*/
index_is_ordered = OidIsValid(index->ordering[0]);
if (istoplevel && index_is_ordered && !isjoininner)
{
index_pathkeys = build_index_pathkeys(root, index,
ForwardScanDirection,
true);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
}
else
useful_pathkeys = NIL;
/*
* 3. Generate an indexscan path if there are relevant restriction
* clauses in the current clauses, OR the index ordering is
* potentially useful for later merging or final output ordering, OR
* the index has a predicate that was proven by the current clauses.
*/
if (found_clause || useful_pathkeys != NIL || useful_predicate)
{
ipath = create_index_path(root, index,
restrictclauses,
useful_pathkeys,
index_is_ordered ?
ForwardScanDirection :
NoMovementScanDirection,
isjoininner);
result = lappend(result, ipath);
}
/*
* 4. If the index is ordered, and there is a requested query ordering
* that we failed to match, consider variant ways of achieving the
* ordering. Again, this is only interesting at top level.
*/
if (istoplevel && index_is_ordered && !isjoininner &&
root->query_pathkeys != NIL &&
pathkeys_useful_for_ordering(root, useful_pathkeys) == 0)
{
ScanDirection scandir;
scandir = match_variant_ordering(root, index, restrictclauses);
if (!ScanDirectionIsNoMovement(scandir))
{
ipath = create_index_path(root, index,
restrictclauses,
root->query_pathkeys,
scandir,
false);
result = lappend(result, ipath);
}
}
}
return result;
}
/*
* find_saop_paths
* Find all the potential indexpaths that make use of ScalarArrayOpExpr
* clauses. The executor only supports these in bitmap scans, not
* plain indexscans, so we need to segregate them from the normal case.
* Otherwise, same API as find_usable_indexes().
* Returns a list of IndexPaths.
*/
static List *
find_saop_paths(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, bool isjoininner,
Relids outer_relids)
{
bool have_saop = false;
ListCell *l;
/*
* Since find_usable_indexes is relatively expensive, don't bother to
* run it unless there are some top-level ScalarArrayOpExpr clauses.
*/
foreach(l, clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
Assert(IsA(rinfo, RestrictInfo));
if (IsA(rinfo->clause, ScalarArrayOpExpr))
{
have_saop = true;
break;
}
}
if (!have_saop)
return NIL;
return find_usable_indexes(root, rel,
clauses, outer_clauses,
istoplevel, isjoininner,
outer_relids,
SAOP_REQUIRE);
}
/*
* generate_bitmap_or_paths
* Look through the list of clauses to find OR clauses, and generate
* a BitmapOrPath for each one we can handle that way. Return a list
* of the generated BitmapOrPaths.
*
* outer_clauses is a list of additional clauses that can be assumed true
* for the purpose of generating indexquals, but are not to be searched for
* ORs. (See find_usable_indexes() for motivation.)
*/
List *
generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool isjoininner,
Relids outer_relids)
{
List *result = NIL;
List *all_clauses;
ListCell *l;
/*
* We can use both the current and outer clauses as context for
* find_usable_indexes
*/
all_clauses = list_concat(list_copy(clauses), outer_clauses);
foreach(l, clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
List *pathlist;
Path *bitmapqual;
ListCell *j;
Assert(IsA(rinfo, RestrictInfo));
/* Ignore RestrictInfos that aren't ORs */
if (!restriction_is_or_clause(rinfo))
continue;
/*
* We must be able to match at least one index to each of the arms of
* the OR, else we can't use it.
*/
pathlist = NIL;
foreach(j, ((BoolExpr *) rinfo->orclause)->args)
{
Node *orarg = (Node *) lfirst(j);
List *indlist;
/* OR arguments should be ANDs or sub-RestrictInfos */
if (and_clause(orarg))
{
List *andargs = ((BoolExpr *) orarg)->args;
indlist = find_usable_indexes(root, rel,
andargs,
all_clauses,
false,
isjoininner,
outer_relids,
SAOP_ALLOW);
/* Recurse in case there are sub-ORs */
indlist = list_concat(indlist,
generate_bitmap_or_paths(root, rel,
andargs,
all_clauses,
isjoininner,
outer_relids));
}
else
{
Assert(IsA(orarg, RestrictInfo));
Assert(!restriction_is_or_clause((RestrictInfo *) orarg));
indlist = find_usable_indexes(root, rel,
list_make1(orarg),
all_clauses,
false,
isjoininner,
outer_relids,
SAOP_ALLOW);
}
/*
* If nothing matched this arm, we can't do anything with this OR
* clause.
*/
if (indlist == NIL)
{
pathlist = NIL;
break;
}
/*
* OK, pick the most promising AND combination, and add it to
* pathlist.
*/
bitmapqual = choose_bitmap_and(root, rel, indlist);
pathlist = lappend(pathlist, bitmapqual);
}
/*
* If we have a match for every arm, then turn them into a
* BitmapOrPath, and add to result list.
*/
if (pathlist != NIL)
{
bitmapqual = (Path *) create_bitmap_or_path(root, rel, pathlist);
result = lappend(result, bitmapqual);
}
}
return result;
}
/*
* choose_bitmap_and
* Given a nonempty list of bitmap paths, AND them into one path.
*
* This is a nontrivial decision since we can legally use any subset of the
* given path set. We want to choose a good tradeoff between selectivity
* and cost of computing the bitmap.
*
* The result is either a single one of the inputs, or a BitmapAndPath
* combining multiple inputs.
*/
static Path *
choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel, List *paths)
{
int npaths = list_length(paths);
Path **patharray;
Cost costsofar;
List *qualsofar;
ListCell *lastcell;
int i;
ListCell *l;
Assert(npaths > 0); /* else caller error */
if (npaths == 1)
return (Path *) linitial(paths); /* easy case */
/*
* In theory we should consider every nonempty subset of the given paths.
* In practice that seems like overkill, given the crude nature of the
* estimates, not to mention the possible effects of higher-level AND and
* OR clauses. As a compromise, we sort the paths by selectivity. We
* always take the first, and sequentially add on paths that result in a
* lower estimated cost.
*
* We also make some effort to detect directly redundant input paths, as
* can happen if there are multiple possibly usable indexes. (Another
* way it can happen is that best_inner_indexscan will find the same OR
* join clauses that create_or_index_quals has pulled OR restriction
* clauses out of, and then both versions show up as duplicate paths.) We
* consider an index redundant if any of its index conditions were already
* used by earlier indexes. (We could use predicate_implied_by to have a
* more intelligent, but much more expensive, check --- but in most cases
* simple pointer equality should suffice, since after all the index
* conditions are all coming from the same RestrictInfo lists.)
*
* You might think the condition for redundancy should be "all index
* conditions already used", not "any", but this turns out to be wrong.
* For example, if we use an index on A, and then come to an index with
* conditions on A and B, the only way that the second index can be later
* in the selectivity-order sort is if the condition on B is completely
* non-selective. In any case, we'd surely be drastically misestimating
* the selectivity if we count the same condition twice.
*
* XXX is there any risk of throwing away a useful partial index here
* because we don't explicitly look at indpred? At least in simple cases,
* the partial index will sort before competing non-partial indexes and so
* it makes the right choice, but perhaps we need to work harder.
*
* Note: outputting the selected sub-paths in selectivity order is a good
* thing even if we weren't using that as part of the selection method,
* because it makes the short-circuit case in MultiExecBitmapAnd() more
* likely to apply.
*/
/* Convert list to array so we can apply qsort */
patharray = (Path **) palloc(npaths * sizeof(Path *));
i = 0;
foreach(l, paths)
{
patharray[i++] = (Path *) lfirst(l);
}
qsort(patharray, npaths, sizeof(Path *), bitmap_path_comparator);
paths = list_make1(patharray[0]);
costsofar = bitmap_and_cost_est(root, rel, paths);
qualsofar = pull_indexpath_quals(patharray[0]);
lastcell = list_head(paths); /* for quick deletions */
for (i = 1; i < npaths; i++)
{
Path *newpath = patharray[i];
List *newqual;
Cost newcost;
newqual = pull_indexpath_quals(newpath);
if (lists_intersect_ptr(newqual, qualsofar))
continue; /* consider it redundant */
/* tentatively add newpath to paths, so we can estimate cost */
paths = lappend(paths, newpath);
newcost = bitmap_and_cost_est(root, rel, paths);
if (newcost < costsofar)
{
/* keep newpath in paths, update subsidiary variables */
costsofar = newcost;
qualsofar = list_concat(qualsofar, newqual);
lastcell = lnext(lastcell);
}
else
{
/* reject newpath, remove it from paths list */
paths = list_delete_cell(paths, lnext(lastcell), lastcell);
}
Assert(lnext(lastcell) == NULL);
}
if (list_length(paths) == 1)
return (Path *) linitial(paths); /* no need for AND */
return (Path *) create_bitmap_and_path(root, rel, paths);
}
/* qsort comparator to sort in increasing selectivity order */
static int
bitmap_path_comparator(const void *a, const void *b)
{
Path *pa = *(Path *const *) a;
Path *pb = *(Path *const *) b;
Cost acost;
Cost bcost;
Selectivity aselec;
Selectivity bselec;
Selectivity diff;
cost_bitmap_tree_node(pa, &acost, &aselec);
cost_bitmap_tree_node(pb, &bcost, &bselec);
/*
* Since selectivities are often pretty crude, don't put blind faith
* in them; if the selectivities are within 1% of being the same, treat
* them as equal and sort by cost instead.
*/
diff = aselec - bselec;
if (diff < -0.01)
return -1;
if (diff > 0.01)
return 1;
if (acost < bcost)
return -1;
if (acost > bcost)
return 1;
return 0;
}
/*
* Estimate the cost of actually executing a BitmapAnd with the given
* inputs.
*/
static Cost
bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
{
BitmapAndPath apath;
Path bpath;
/* Set up a dummy BitmapAndPath */
apath.path.type = T_BitmapAndPath;
apath.path.parent = rel;
apath.bitmapquals = paths;
cost_bitmap_and_node(&apath, root);
/* Now we can do cost_bitmap_heap_scan */
cost_bitmap_heap_scan(&bpath, root, rel, (Path *) &apath, false);
return bpath.total_cost;
}
/*
* pull_indexpath_quals
*
* Given the Path structure for a plain or bitmap indexscan, extract a
* list of RestrictInfo nodes for all the indexquals used in the Path.
*
* This is sort of a simplified version of make_restrictinfo_from_bitmapqual;
* here, we are not trying to produce an accurate representation of the AND/OR
* semantics of the Path, but just find out all the base conditions used.
*
* The result list contains pointers to the RestrictInfos used in the Path,
* but all the list cells are freshly built, so it's safe to destructively
* modify the list (eg, by concat'ing it with other lists).
*/
static List *
pull_indexpath_quals(Path *bitmapqual)
{
List *result = NIL;
ListCell *l;
if (IsA(bitmapqual, BitmapAndPath))
{
BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
foreach(l, apath->bitmapquals)
{
List *sublist;
sublist = pull_indexpath_quals((Path *) lfirst(l));
result = list_concat(result, sublist);
}
}
else if (IsA(bitmapqual, BitmapOrPath))
{
BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
foreach(l, opath->bitmapquals)
{
List *sublist;
sublist = pull_indexpath_quals((Path *) lfirst(l));
result = list_concat(result, sublist);
}
}
else if (IsA(bitmapqual, IndexPath))
{
IndexPath *ipath = (IndexPath *) bitmapqual;
result = list_copy(ipath->indexclauses);
}
else
elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
return result;
}
/*
* lists_intersect_ptr
* Detect whether two lists have a nonempty intersection,
* using pointer equality to compare members.
*
* This possibly should go into list.c, but it doesn't yet have any use
* except in choose_bitmap_and.
*/
static bool
lists_intersect_ptr(List *list1, List *list2)
{
ListCell *cell1;
foreach(cell1, list1)
{
void *datum1 = lfirst(cell1);
ListCell *cell2;
foreach(cell2, list2)
{
if (lfirst(cell2) == datum1)
return true;
}
}
return false;
}
/****************************************************************************
* ---- ROUTINES TO CHECK RESTRICTIONS ----
****************************************************************************/
/*
* group_clauses_by_indexkey
* Find restriction clauses that can be used with an index.
*
* Returns a list of sublists of RestrictInfo nodes for clauses that can be
* used with this index. Each sublist contains clauses that can be used
* with one index key (in no particular order); the top list is ordered by
* index key. (This is depended on by expand_indexqual_conditions().)
*
* We can use clauses from either the current clauses or outer_clauses lists,
* but *found_clause is set TRUE only if we used at least one clause from
* the "current clauses" list. See find_usable_indexes() for motivation.
*
* outer_relids determines what Vars will be allowed on the other side
* of a possible index qual; see match_clause_to_indexcol().
*
* 'saop_control' indicates whether ScalarArrayOpExpr clauses can be used.
* When it's SAOP_REQUIRE, *found_clause is set TRUE only if we used at least
* one ScalarArrayOpExpr from the current clauses list.
*
* If the index has amoptionalkey = false, we give up and return NIL when
* there are no restriction clauses matching the first index key. Otherwise,
* we return NIL if there are no restriction clauses matching any index key.
* A non-NIL result will have one (possibly empty) sublist for each index key.
*
* Example: given an index on (A,B,C), we would return ((C1 C2) () (C3 C4))
* if we find that clauses C1 and C2 use column A, clauses C3 and C4 use
* column C, and no clauses use column B.
*
* Note: in some circumstances we may find the same RestrictInfos coming
* from multiple places. Defend against redundant outputs by using
* list_append_unique_ptr (pointer equality should be good enough).
*/
List *
group_clauses_by_indexkey(IndexOptInfo *index,
List *clauses, List *outer_clauses,
Relids outer_relids,
SaOpControl saop_control,
bool *found_clause)
{
List *clausegroup_list = NIL;
bool found_outer_clause = false;
int indexcol = 0;
Oid *classes = index->classlist;
*found_clause = false; /* default result */
if (clauses == NIL && outer_clauses == NIL)
return NIL; /* cannot succeed */
do
{
Oid curClass = classes[0];
List *clausegroup = NIL;
ListCell *l;
/* check the current clauses */
foreach(l, clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
Assert(IsA(rinfo, RestrictInfo));
if (match_clause_to_indexcol(index,
indexcol,
curClass,
rinfo,
outer_relids,
saop_control))
{
clausegroup = list_append_unique_ptr(clausegroup, rinfo);
if (saop_control != SAOP_REQUIRE ||
IsA(rinfo->clause, ScalarArrayOpExpr))
*found_clause = true;
}
}
/* check the outer clauses */
foreach(l, outer_clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
Assert(IsA(rinfo, RestrictInfo));
if (match_clause_to_indexcol(index,
indexcol,
curClass,
rinfo,
outer_relids,
saop_control))
{
clausegroup = list_append_unique_ptr(clausegroup, rinfo);
found_outer_clause = true;
}
}
/*
* If no clauses match this key, check for amoptionalkey restriction.
*/
if (clausegroup == NIL && !index->amoptionalkey && indexcol == 0)
return NIL;
clausegroup_list = lappend(clausegroup_list, clausegroup);
indexcol++;
classes++;
} while (!DoneMatchingIndexKeys(classes));
if (!*found_clause && !found_outer_clause)
return NIL; /* no indexable clauses anywhere */
return clausegroup_list;
}
/*
* match_clause_to_indexcol()
* Determines whether a restriction clause matches a column of an index.
*
* To match a normal index, the clause:
*
* (1) must be in the form (indexkey op const) or (const op indexkey);
* and
* (2) must contain an operator which is in the same class as the index
* operator for this column, or is a "special" operator as recognized
* by match_special_index_operator().
*
* Our definition of "const" is pretty liberal: we allow Vars belonging
* to the caller-specified outer_relids relations (which had better not
* include the relation whose index is being tested). outer_relids should
* be NULL when checking simple restriction clauses, and the outer side
* of the join when building a join inner scan. Other than that, the
* only thing we don't like is volatile functions.
*
* Note: in most cases we already know that the clause as a whole uses
* vars from the interesting set of relations. The reason for the
* outer_relids test is to reject clauses like (a.f1 OP (b.f2 OP a.f3));
* that's not processable by an indexscan nestloop join on A, whereas
* (a.f1 OP (b.f2 OP c.f3)) is.
*
* Presently, the executor can only deal with indexquals that have the
* indexkey on the left, so we can only use clauses that have the indexkey
* on the right if we can commute the clause to put the key on the left.
* We do not actually do the commuting here, but we check whether a
* suitable commutator operator is available.
*
* It is also possible to match RowCompareExpr clauses to indexes (but
* currently, only btree indexes handle this). In this routine we will
* report a match if the first column of the row comparison matches the
* target index column. This is sufficient to guarantee that some index
* condition can be constructed from the RowCompareExpr --- whether the
* remaining columns match the index too is considered in
* expand_indexqual_rowcompare().
*
* It is also possible to match ScalarArrayOpExpr clauses to indexes, when
* the clause is of the form "indexkey op ANY (arrayconst)". Since the
* executor can only handle these in the context of bitmap index scans,
* our caller specifies whether to allow these or not.
*
* For boolean indexes, it is also possible to match the clause directly
* to the indexkey; or perhaps the clause is (NOT indexkey).
*
* 'index' is the index of interest.
* 'indexcol' is a column number of 'index' (counting from 0).
* 'opclass' is the corresponding operator class.
* 'rinfo' is the clause to be tested (as a RestrictInfo node).
* 'saop_control' indicates whether ScalarArrayOpExpr clauses can be used.
*
* Returns true if the clause can be used with this index key.
*
* NOTE: returns false if clause is an OR or AND clause; it is the
* responsibility of higher-level routines to cope with those.
*/
static bool
match_clause_to_indexcol(IndexOptInfo *index,
int indexcol,
Oid opclass,
RestrictInfo *rinfo,
Relids outer_relids,
SaOpControl saop_control)
{
Expr *clause = rinfo->clause;
Node *leftop,
*rightop;
Relids left_relids;
Relids right_relids;
Oid expr_op;
bool plain_op;
/* First check for boolean-index cases. */
if (IsBooleanOpclass(opclass))
{
if (match_boolean_index_clause((Node *) clause, indexcol, index))
return true;
}
/*
* Clause must be a binary opclause, or possibly a ScalarArrayOpExpr
* (which is always binary, by definition). Or it could be a
* RowCompareExpr, which we pass off to match_rowcompare_to_indexcol().
*/
if (is_opclause(clause))
{
leftop = get_leftop(clause);
rightop = get_rightop(clause);
if (!leftop || !rightop)
return false;
left_relids = rinfo->left_relids;
right_relids = rinfo->right_relids;
expr_op = ((OpExpr *) clause)->opno;
plain_op = true;
}
else if (saop_control != SAOP_FORBID &&
clause && IsA(clause, ScalarArrayOpExpr))
{
ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
/* We only accept ANY clauses, not ALL */
if (!saop->useOr)
return false;
leftop = (Node *) linitial(saop->args);
rightop = (Node *) lsecond(saop->args);
left_relids = NULL; /* not actually needed */
right_relids = pull_varnos(rightop);
expr_op = saop->opno;
plain_op = false;
}
else if (clause && IsA(clause, RowCompareExpr))
{
return match_rowcompare_to_indexcol(index, indexcol, opclass,
(RowCompareExpr *) clause,
outer_relids);
}
else
return false;
/*
* Check for clauses of the form: (indexkey operator constant) or
* (constant operator indexkey). See above notes about const-ness.
*/
if (match_index_to_operand(leftop, indexcol, index) &&
bms_is_subset(right_relids, outer_relids) &&
!contain_volatile_functions(rightop))
{
if (is_indexable_operator(expr_op, opclass, true))
return true;
/*
* If we didn't find a member of the index's opclass, see whether it
* is a "special" indexable operator.
*/
if (plain_op &&
match_special_index_operator(clause, opclass, true))
return true;
return false;
}
if (plain_op &&
match_index_to_operand(rightop, indexcol, index) &&
bms_is_subset(left_relids, outer_relids) &&
!contain_volatile_functions(leftop))
{
if (is_indexable_operator(expr_op, opclass, false))
return true;
/*
* If we didn't find a member of the index's opclass, see whether it
* is a "special" indexable operator.
*/
if (match_special_index_operator(clause, opclass, false))
return true;
return false;
}
return false;
}
/*
* is_indexable_operator
* Does the operator match the specified index opclass?
*
* If the indexkey is on the right, what we actually want to know
* is whether the operator has a commutator operator that matches
* the opclass.
*/
static bool
is_indexable_operator(Oid expr_op, Oid opclass, bool indexkey_on_left)
{
/* Get the commuted operator if necessary */
if (!indexkey_on_left)
{
expr_op = get_commutator(expr_op);
if (expr_op == InvalidOid)
return false;
}
/* OK if the (commuted) operator is a member of the index's opclass */
return op_in_opclass(expr_op, opclass);
}
/*
* match_rowcompare_to_indexcol()
* Handles the RowCompareExpr case for match_clause_to_indexcol(),
* which see for comments.
*/
static bool
match_rowcompare_to_indexcol(IndexOptInfo *index,
int indexcol,
Oid opclass,
RowCompareExpr *clause,
Relids outer_relids)
{
Node *leftop,
*rightop;
Oid expr_op;
/* Forget it if we're not dealing with a btree index */
if (index->relam != BTREE_AM_OID)
return false;
/*
* We could do the matching on the basis of insisting that the opclass
* shown in the RowCompareExpr be the same as the index column's opclass,
* but that does not work well for cross-type comparisons (the opclass
* could be for the other datatype). Also it would fail to handle indexes
* using reverse-sort opclasses. Instead, match if the operator listed in
* the RowCompareExpr is the < <= > or >= member of the index opclass
* (after commutation, if the indexkey is on the right).
*/
leftop = (Node *) linitial(clause->largs);
rightop = (Node *) linitial(clause->rargs);
expr_op = linitial_oid(clause->opnos);
/*
* These syntactic tests are the same as in match_clause_to_indexcol()
*/
if (match_index_to_operand(leftop, indexcol, index) &&
bms_is_subset(pull_varnos(rightop), outer_relids) &&
!contain_volatile_functions(rightop))
{
/* OK, indexkey is on left */
}
else if (match_index_to_operand(rightop, indexcol, index) &&
bms_is_subset(pull_varnos(leftop), outer_relids) &&
!contain_volatile_functions(leftop))
{
/* indexkey is on right, so commute the operator */
expr_op = get_commutator(expr_op);
if (expr_op == InvalidOid)
return false;
}
else
return false;
/* We're good if the operator is the right type of opclass member */
switch (get_op_opclass_strategy(expr_op, opclass))
{
case BTLessStrategyNumber:
case BTLessEqualStrategyNumber:
case BTGreaterEqualStrategyNumber:
case BTGreaterStrategyNumber:
return true;
}
return false;
}
/****************************************************************************
* ---- ROUTINES TO DO PARTIAL INDEX PREDICATE TESTS ----
****************************************************************************/
/*
* check_partial_indexes
* Check each partial index of the relation, and mark it predOK or not
* depending on whether the predicate is satisfied for this query.
*/
void
check_partial_indexes(PlannerInfo *root, RelOptInfo *rel)
{
List *restrictinfo_list = rel->baserestrictinfo;
ListCell *ilist;
/*
* Note: if Postgres tried to optimize queries by forming equivalence
* classes over equi-joined attributes (i.e., if it recognized that a
* qualification such as "where a.b=c.d and a.b=5" could make use of an
* index on c.d), then we could use that equivalence class info here with
* joininfo lists to do more complete tests for the usability of a partial
* index. For now, the test only uses restriction clauses (those in
* baserestrictinfo). --Nels, Dec '92
*
* XXX as of 7.1, equivalence class info *is* available. Consider
* improving this code as foreseen by Nels.
*/
foreach(ilist, rel->indexlist)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist);
if (index->indpred == NIL)
continue; /* ignore non-partial indexes */
index->predOK = predicate_implied_by(index->indpred,
restrictinfo_list);
}
}
/****************************************************************************
* ---- ROUTINES TO CHECK JOIN CLAUSES ----
****************************************************************************/
/*
* indexable_outerrelids
* Finds all other relids that participate in any indexable join clause
* for the specified table. Returns a set of relids.
*/
static Relids
indexable_outerrelids(RelOptInfo *rel)
{
Relids outer_relids = NULL;
ListCell *l;
/*
* Examine each joinclause in the joininfo list to see if it matches any
* key of any index. If so, add the clause's other rels to the result.
*/
foreach(l, rel->joininfo)
{
RestrictInfo *joininfo = (RestrictInfo *) lfirst(l);
Relids other_rels;
other_rels = bms_difference(joininfo->required_relids, rel->relids);
if (matches_any_index(joininfo, rel, other_rels))
outer_relids = bms_join(outer_relids, other_rels);
else
bms_free(other_rels);
}
return outer_relids;
}
/*
* matches_any_index
* Workhorse for indexable_outerrelids: see if a joinclause can be
* matched to any index of the given rel.
*/
static bool
matches_any_index(RestrictInfo *rinfo, RelOptInfo *rel, Relids outer_relids)
{
ListCell *l;
Assert(IsA(rinfo, RestrictInfo));
if (restriction_is_or_clause(rinfo))
{
foreach(l, ((BoolExpr *) rinfo->orclause)->args)
{
Node *orarg = (Node *) lfirst(l);
/* OR arguments should be ANDs or sub-RestrictInfos */
if (and_clause(orarg))
{
ListCell *j;
/* Recurse to examine AND items and sub-ORs */
foreach(j, ((BoolExpr *) orarg)->args)
{
RestrictInfo *arinfo = (RestrictInfo *) lfirst(j);
if (matches_any_index(arinfo, rel, outer_relids))
return true;
}
}
else
{
/* Recurse to examine simple clause */
Assert(IsA(orarg, RestrictInfo));
Assert(!restriction_is_or_clause((RestrictInfo *) orarg));
if (matches_any_index((RestrictInfo *) orarg, rel,
outer_relids))
return true;
}
}
return false;
}
/* Normal case for a simple restriction clause */
foreach(l, rel->indexlist)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(l);
int indexcol = 0;
Oid *classes = index->classlist;
do
{
Oid curClass = classes[0];
if (match_clause_to_indexcol(index,
indexcol,
curClass,
rinfo,
outer_relids,
SAOP_ALLOW))
return true;
indexcol++;
classes++;
} while (!DoneMatchingIndexKeys(classes));
}
return false;
}
/*
* best_inner_indexscan
* Finds the best available inner indexscan for a nestloop join
* with the given rel on the inside and the given outer_relids outside.
* May return NULL if there are no possible inner indexscans.
*
* We ignore ordering considerations (since a nestloop's inner scan's order
* is uninteresting). Also, we consider only total cost when deciding which
* of two possible paths is better --- this assumes that all indexpaths have
* negligible startup cost. (True today, but someday we might have to think
* harder.) Therefore, there is only one dimension of comparison and so it's
* sufficient to return a single "best" path.
*
* Note: create_index_paths() must have been run previously for this rel,
* else the result will always be NULL.
*/
Path *
best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel,
Relids outer_relids, JoinType jointype)
{
Path *cheapest;
bool isouterjoin;
List *clause_list;
List *indexpaths;
List *bitindexpaths;
ListCell *l;
InnerIndexscanInfo *info;
MemoryContext oldcontext;
/*
* Nestloop only supports inner, left, and IN joins.
*/
switch (jointype)
{
case JOIN_INNER:
case JOIN_IN:
case JOIN_UNIQUE_OUTER:
isouterjoin = false;
break;
case JOIN_LEFT:
isouterjoin = true;
break;
default:
return NULL;
}
/*
* If there are no indexable joinclauses for this rel, exit quickly.
*/
if (bms_is_empty(rel->index_outer_relids))
return NULL;
/*
* Otherwise, we have to do path selection in the memory context of the
* given rel, so that any created path can be safely attached to the rel's
* cache of best inner paths. (This is not currently an issue for normal
* planning, but it is an issue for GEQO planning.)
*/
oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
/*
* Intersect the given outer_relids with index_outer_relids to find the
* set of outer relids actually relevant for this rel. If there are none,
* again we can fail immediately.
*/
outer_relids = bms_intersect(rel->index_outer_relids, outer_relids);
if (bms_is_empty(outer_relids))
{
bms_free(outer_relids);
MemoryContextSwitchTo(oldcontext);
return NULL;
}
/*
* Look to see if we already computed the result for this set of relevant
* outerrels. (We include the isouterjoin status in the cache lookup key
* for safety. In practice I suspect this is not necessary because it
* should always be the same for a given innerrel.)
*/
foreach(l, rel->index_inner_paths)
{
info = (InnerIndexscanInfo *) lfirst(l);
if (bms_equal(info->other_relids, outer_relids) &&
info->isouterjoin == isouterjoin)
{
bms_free(outer_relids);
MemoryContextSwitchTo(oldcontext);
return info->best_innerpath;
}
}
/*
* Find all the relevant restriction and join clauses.
*
* Note: because we include restriction clauses, we will find indexscans
* that could be plain indexscans, ie, they don't require the join context
* at all. This may seem redundant, but we need to include those scans in
* the input given to choose_bitmap_and() to be sure we find optimal AND
* combinations of join and non-join scans. The worst case is that we
* might return a "best inner indexscan" that's really just a plain
* indexscan, causing some redundant effort in joinpath.c.
*/
clause_list = find_clauses_for_join(root, rel, outer_relids, isouterjoin);
/*
* Find all the index paths that are usable for this join, except for
* stuff involving OR and ScalarArrayOpExpr clauses.
*/
indexpaths = find_usable_indexes(root, rel,
clause_list, NIL,
false, true,
outer_relids,
SAOP_FORBID);
/*
* Generate BitmapOrPaths for any suitable OR-clauses present in the
* clause list.
*/
bitindexpaths = generate_bitmap_or_paths(root, rel,
clause_list, NIL,
true,
outer_relids);
/*
* Likewise, generate paths using ScalarArrayOpExpr clauses; these can't
* be simple indexscans but they can be used in bitmap scans.
*/
bitindexpaths = list_concat(bitindexpaths,
find_saop_paths(root, rel,
clause_list, NIL,
false, true,
outer_relids));
/*
* Include the regular index paths in bitindexpaths.
*/
bitindexpaths = list_concat(bitindexpaths, list_copy(indexpaths));
/*
* If we found anything usable, generate a BitmapHeapPath for the most
* promising combination of bitmap index paths.
*/
if (bitindexpaths != NIL)
{
Path *bitmapqual;
BitmapHeapPath *bpath;
bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
bpath = create_bitmap_heap_path(root, rel, bitmapqual, true);
indexpaths = lappend(indexpaths, bpath);
}
/*
* Now choose the cheapest member of indexpaths.
*/
cheapest = NULL;
foreach(l, indexpaths)
{
Path *path = (Path *) lfirst(l);
if (cheapest == NULL ||
compare_path_costs(path, cheapest, TOTAL_COST) < 0)
cheapest = path;
}
/* Cache the result --- whether positive or negative */
info = makeNode(InnerIndexscanInfo);
info->other_relids = outer_relids;
info->isouterjoin = isouterjoin;
info->best_innerpath = cheapest;
rel->index_inner_paths = lcons(info, rel->index_inner_paths);
MemoryContextSwitchTo(oldcontext);
return cheapest;
}
/*
* find_clauses_for_join
* Generate a list of clauses that are potentially useful for
* scanning rel as the inner side of a nestloop join.
*
* We consider both join and restriction clauses. Any joinclause that uses
* only otherrels in the specified outer_relids is fair game. But there must
* be at least one such joinclause in the final list, otherwise we return NIL
* indicating that there isn't any potential win here.
*/
static List *
find_clauses_for_join(PlannerInfo *root, RelOptInfo *rel,
Relids outer_relids, bool isouterjoin)
{
List *clause_list = NIL;
Relids join_relids;
ListCell *l;
/* Look for joinclauses that are usable with given outer_relids */
join_relids = bms_union(rel->relids, outer_relids);
foreach(l, rel->joininfo)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
/* Can't use pushed-down join clauses in outer join */
if (isouterjoin && rinfo->is_pushed_down)
continue;
if (!bms_is_subset(rinfo->required_relids, join_relids))
continue;
clause_list = lappend(clause_list, rinfo);
}
bms_free(join_relids);
/* if no join clause was matched then forget it, per comments above */
if (clause_list == NIL)
return NIL;
/*
* We can also use any plain restriction clauses for the rel. We put
* these at the front of the clause list for the convenience of
* remove_redundant_join_clauses, which can never remove non-join clauses
* and hence won't be able to get rid of a non-join clause if it appears
* after a join clause it is redundant with.
*/
clause_list = list_concat(list_copy(rel->baserestrictinfo), clause_list);
/*
* We may now have clauses that are known redundant. Get rid of 'em.
*/
if (list_length(clause_list) > 1)
{
clause_list = remove_redundant_join_clauses(root,
clause_list,
isouterjoin);
}
return clause_list;
}
/****************************************************************************
* ---- ROUTINES TO HANDLE PATHKEYS ----
****************************************************************************/
/*
* match_variant_ordering
* Try to match an index's ordering to the query's requested ordering
*
* This is used when the index is ordered but a naive comparison fails to
* match its ordering (pathkeys) to root->query_pathkeys. It may be that
* we need to scan the index backwards. Also, a less naive comparison can
* help for both forward and backward indexscans. Columns of the index
* that have an equality restriction clause can be ignored in the match;
* that is, an index on (x,y) can be considered to match the ordering of
* ... WHERE x = 42 ORDER BY y;
*
* Note: it would be possible to similarly ignore useless ORDER BY items;
* that is, an index on just y could be considered to match the ordering of
* ... WHERE x = 42 ORDER BY x, y;
* But proving that this is safe would require finding a btree opclass
* containing both the = operator and the < or > operator in the ORDER BY
* item. That's significantly more expensive than what we do here, since
* we'd have to look at restriction clauses unrelated to the current index
* and search for opclasses without any hint from the index. The practical
* use-cases seem to be mostly covered by ignoring index columns, so that's
* all we do for now.
*
* Inputs:
* 'index' is the index of interest.
* 'restrictclauses' is the list of sublists of restriction clauses
* matching the columns of the index (NIL if none)
*
* If able to match the requested query pathkeys, returns either
* ForwardScanDirection or BackwardScanDirection to indicate the proper index
* scan direction. If no match, returns NoMovementScanDirection.
*/
static ScanDirection
match_variant_ordering(PlannerInfo *root,
IndexOptInfo *index,
List *restrictclauses)
{
List *ignorables;
/*
* Forget the whole thing if not a btree index; our check for ignorable
* columns assumes we are dealing with btree opclasses. (It'd be possible
* to factor out just the try for backwards indexscan, but considering
* that we presently have no orderable indexes except btrees anyway, it's
* hardly worth contorting this code for that case.)
*
* Note: if you remove this, you probably need to put in a check on
* amoptionalkey to prevent possible clauseless scan on an index that
* won't cope.
*/
if (index->relam != BTREE_AM_OID)
return NoMovementScanDirection;
/*
* Figure out which index columns can be optionally ignored because they
* have an equality constraint. This is the same set for either forward
* or backward scan, so we do it just once.
*/
ignorables = identify_ignorable_ordering_cols(root, index,
restrictclauses);
/*
* Try to match to forward scan, then backward scan. However, we can skip
* the forward-scan case if there are no ignorable columns, because
* find_usable_indexes() would have found the match already.
*/
if (ignorables &&
match_index_to_query_keys(root, index, ForwardScanDirection,
ignorables))
return ForwardScanDirection;
if (match_index_to_query_keys(root, index, BackwardScanDirection,
ignorables))
return BackwardScanDirection;
return NoMovementScanDirection;
}
/*
* identify_ignorable_ordering_cols
* Determine which index columns can be ignored for ordering purposes
*
* Returns an integer List of column numbers (1-based) of ignorable
* columns. The ignorable columns are those that have equality constraints
* against pseudoconstants.
*/
static List *
identify_ignorable_ordering_cols(PlannerInfo *root,
IndexOptInfo *index,
List *restrictclauses)
{
List *result = NIL;
int indexcol = 0; /* note this is 0-based */
ListCell *l;
/* restrictclauses is either NIL or has a sublist per column */
foreach(l, restrictclauses)
{
List *sublist = (List *) lfirst(l);
Oid opclass = index->classlist[indexcol];
ListCell *l2;
foreach(l2, sublist)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l2);
OpExpr *clause = (OpExpr *) rinfo->clause;
Oid clause_op;
int op_strategy;
bool varonleft;
bool ispc;
/* First check for boolean-index cases. */
if (IsBooleanOpclass(opclass))
{
if (match_boolean_index_clause((Node *) clause, indexcol,
index))
{
/*
* The clause means either col = TRUE or col = FALSE; we
* do not care which, it's an equality constraint either
* way.
*/
result = lappend_int(result, indexcol + 1);
break;
}
}
/* Otherwise, ignore if not a binary opclause */
if (!is_opclause(clause) || list_length(clause->args) != 2)
continue;
/* Determine left/right sides and check the operator */
clause_op = clause->opno;
if (match_index_to_operand(linitial(clause->args), indexcol,
index))
{
/* clause_op is correct */
varonleft = true;
}
else
{
Assert(match_index_to_operand(lsecond(clause->args), indexcol,
index));
/* Must flip operator to get the opclass member */
clause_op = get_commutator(clause_op);
varonleft = false;
}
if (!OidIsValid(clause_op))
continue; /* ignore non match, per next comment */
op_strategy = get_op_opclass_strategy(clause_op, opclass);
/*
* You might expect to see Assert(op_strategy != 0) here, but you
* won't: the clause might contain a special indexable operator
* rather than an ordinary opclass member. Currently none of the
* special operators are very likely to expand to an equality
* operator; we do not bother to check, but just assume no match.
*/
if (op_strategy != BTEqualStrategyNumber)
continue;
/* Now check that other side is pseudoconstant */
if (varonleft)
ispc = is_pseudo_constant_clause_relids(lsecond(clause->args),
rinfo->right_relids);
else
ispc = is_pseudo_constant_clause_relids(linitial(clause->args),
rinfo->left_relids);
if (ispc)
{
result = lappend_int(result, indexcol + 1);
break;
}
}
indexcol++;
}
return result;
}
/*
* match_index_to_query_keys
* Check a single scan direction for "intelligent" match to query keys
*
* 'index' is the index of interest.
* 'indexscandir' is the scan direction to consider
* 'ignorables' is an integer list of indexes of ignorable index columns
*
* Returns TRUE on successful match (ie, the query_pathkeys can be considered
* to match this index).
*/
static bool
match_index_to_query_keys(PlannerInfo *root,
IndexOptInfo *index,
ScanDirection indexscandir,
List *ignorables)
{
List *index_pathkeys;
ListCell *index_cell;
int index_col;
ListCell *r;
/* Get the pathkeys that exactly describe the index */
index_pathkeys = build_index_pathkeys(root, index, indexscandir, false);
/*
* Can we match to the query's requested pathkeys? The inner loop skips
* over ignorable index columns while trying to match.
*/
index_cell = list_head(index_pathkeys);
index_col = 0;
foreach(r, root->query_pathkeys)
{
List *rsubkey = (List *) lfirst(r);
for (;;)
{
List *isubkey;
if (index_cell == NULL)
return false;
isubkey = (List *) lfirst(index_cell);
index_cell = lnext(index_cell);
index_col++; /* index_col is now 1-based */
/*
* Since we are dealing with canonicalized pathkeys, pointer
* comparison is sufficient to determine a match.
*/
if (rsubkey == isubkey)
break; /* matched current query pathkey */
if (!list_member_int(ignorables, index_col))
return false; /* definite failure to match */
/* otherwise loop around and try to match to next index col */
}
}
return true;
}
/****************************************************************************
* ---- PATH CREATION UTILITIES ----
****************************************************************************/
/*
* flatten_clausegroups_list
* Given a list of lists of RestrictInfos, flatten it to a list
* of RestrictInfos.
*
* This is used to flatten out the result of group_clauses_by_indexkey()
* to produce an indexclauses list. The original list structure mustn't
* be altered, but it's OK to share copies of the underlying RestrictInfos.
*/
List *
flatten_clausegroups_list(List *clausegroups)
{
List *allclauses = NIL;
ListCell *l;
foreach(l, clausegroups)
allclauses = list_concat(allclauses, list_copy((List *) lfirst(l)));
return allclauses;
}
/****************************************************************************
* ---- ROUTINES TO CHECK OPERANDS ----
****************************************************************************/
/*
* match_index_to_operand()
* Generalized test for a match between an index's key
* and the operand on one side of a restriction or join clause.
*
* operand: the nodetree to be compared to the index
* indexcol: the column number of the index (counting from 0)
* index: the index of interest
*/
bool
match_index_to_operand(Node *operand,
int indexcol,
IndexOptInfo *index)
{
int indkey;
/*
* Ignore any RelabelType node above the operand. This is needed to be
* able to apply indexscanning in binary-compatible-operator cases. Note:
* we can assume there is at most one RelabelType node;
* eval_const_expressions() will have simplified if more than one.
*/
if (operand && IsA(operand, RelabelType))
operand = (Node *) ((RelabelType *) operand)->arg;
indkey = index->indexkeys[indexcol];
if (indkey != 0)
{
/*
* Simple index column; operand must be a matching Var.
*/
if (operand && IsA(operand, Var) &&
index->rel->relid == ((Var *) operand)->varno &&
indkey == ((Var *) operand)->varattno)
return true;
}
else
{
/*
* Index expression; find the correct expression. (This search could
* be avoided, at the cost of complicating all the callers of this
* routine; doesn't seem worth it.)
*/
ListCell *indexpr_item;
int i;
Node *indexkey;
indexpr_item = list_head(index->indexprs);
for (i = 0; i < indexcol; i++)
{
if (index->indexkeys[i] == 0)
{
if (indexpr_item == NULL)
elog(ERROR, "wrong number of index expressions");
indexpr_item = lnext(indexpr_item);
}
}
if (indexpr_item == NULL)
elog(ERROR, "wrong number of index expressions");
indexkey = (Node *) lfirst(indexpr_item);
/*
* Does it match the operand? Again, strip any relabeling.
*/
if (indexkey && IsA(indexkey, RelabelType))
indexkey = (Node *) ((RelabelType *) indexkey)->arg;
if (equal(indexkey, operand))
return true;
}
return false;
}
/****************************************************************************
* ---- ROUTINES FOR "SPECIAL" INDEXABLE OPERATORS ----
****************************************************************************/
/*----------
* These routines handle special optimization of operators that can be
* used with index scans even though they are not known to the executor's
* indexscan machinery. The key idea is that these operators allow us
* to derive approximate indexscan qual clauses, such that any tuples
* that pass the operator clause itself must also satisfy the simpler
* indexscan condition(s). Then we can use the indexscan machinery
* to avoid scanning as much of the table as we'd otherwise have to,
* while applying the original operator as a qpqual condition to ensure
* we deliver only the tuples we want. (In essence, we're using a regular
* index as if it were a lossy index.)
*
* An example of what we're doing is
* textfield LIKE 'abc%'
* from which we can generate the indexscanable conditions
* textfield >= 'abc' AND textfield < 'abd'
* which allow efficient scanning of an index on textfield.
* (In reality, character set and collation issues make the transformation
* from LIKE to indexscan limits rather harder than one might think ...
* but that's the basic idea.)
*
* Another thing that we do with this machinery is to provide special
* smarts for "boolean" indexes (that is, indexes on boolean columns
* that support boolean equality). We can transform a plain reference
* to the indexkey into "indexkey = true", or "NOT indexkey" into
* "indexkey = false", so as to make the expression indexable using the
* regular index operators. (As of Postgres 8.1, we must do this here
* because constant simplification does the reverse transformation;
* without this code there'd be no way to use such an index at all.)
*
* Three routines are provided here:
*
* match_special_index_operator() is just an auxiliary function for
* match_clause_to_indexcol(); after the latter fails to recognize a
* restriction opclause's operator as a member of an index's opclass,
* it asks match_special_index_operator() whether the clause should be
* considered an indexqual anyway.
*
* match_boolean_index_clause() similarly detects clauses that can be
* converted into boolean equality operators.
*
* expand_indexqual_conditions() converts a list of lists of RestrictInfo
* nodes (with implicit AND semantics across list elements) into
* a list of clauses that the executor can actually handle. For operators
* that are members of the index's opclass this transformation is a no-op,
* but clauses recognized by match_special_index_operator() or
* match_boolean_index_clause() must be converted into one or more "regular"
* indexqual conditions.
*----------
*/
/*
* match_boolean_index_clause
* Recognize restriction clauses that can be matched to a boolean index.
*
* This should be called only when IsBooleanOpclass() recognizes the
* index's operator class. We check to see if the clause matches the
* index's key.
*/
static bool
match_boolean_index_clause(Node *clause,
int indexcol,
IndexOptInfo *index)
{
/* Direct match? */
if (match_index_to_operand(clause, indexcol, index))
return true;
/* NOT clause? */
if (not_clause(clause))
{
if (match_index_to_operand((Node *) get_notclausearg((Expr *) clause),
indexcol, index))
return true;
}
/*
* Since we only consider clauses at top level of WHERE, we can convert
* indexkey IS TRUE and indexkey IS FALSE to index searches as well. The
* different meaning for NULL isn't important.
*/
else if (clause && IsA(clause, BooleanTest))
{
BooleanTest *btest = (BooleanTest *) clause;
if (btest->booltesttype == IS_TRUE ||
btest->booltesttype == IS_FALSE)
if (match_index_to_operand((Node *) btest->arg,
indexcol, index))
return true;
}
return false;
}
/*
* match_special_index_operator
* Recognize restriction clauses that can be used to generate
* additional indexscanable qualifications.
*
* The given clause is already known to be a binary opclause having
* the form (indexkey OP pseudoconst) or (pseudoconst OP indexkey),
* but the OP proved not to be one of the index's opclass operators.
* Return 'true' if we can do something with it anyway.
*/
static bool
match_special_index_operator(Expr *clause, Oid opclass,
bool indexkey_on_left)
{
bool isIndexable = false;
Node *rightop;
Oid expr_op;
Const *patt;
Const *prefix = NULL;
Const *rest = NULL;
/*
* Currently, all known special operators require the indexkey on the
* left, but this test could be pushed into the switch statement if some
* are added that do not...
*/
if (!indexkey_on_left)
return false;
/* we know these will succeed */
rightop = get_rightop(clause);
expr_op = ((OpExpr *) clause)->opno;
/* again, required for all current special ops: */
if (!IsA(rightop, Const) ||
((Const *) rightop)->constisnull)
return false;
patt = (Const *) rightop;
switch (expr_op)
{
case OID_TEXT_LIKE_OP:
case OID_BPCHAR_LIKE_OP:
case OID_NAME_LIKE_OP:
/* the right-hand const is type text for all of these */
isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Like,
&prefix, &rest) != Pattern_Prefix_None;
break;
case OID_BYTEA_LIKE_OP:
isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Like,
&prefix, &rest) != Pattern_Prefix_None;
break;
case OID_TEXT_ICLIKE_OP:
case OID_BPCHAR_ICLIKE_OP:
case OID_NAME_ICLIKE_OP:
/* the right-hand const is type text for all of these */
isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Like_IC,
&prefix, &rest) != Pattern_Prefix_None;
break;
case OID_TEXT_REGEXEQ_OP:
case OID_BPCHAR_REGEXEQ_OP:
case OID_NAME_REGEXEQ_OP:
/* the right-hand const is type text for all of these */
isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Regex,
&prefix, &rest) != Pattern_Prefix_None;
break;
case OID_TEXT_ICREGEXEQ_OP:
case OID_BPCHAR_ICREGEXEQ_OP:
case OID_NAME_ICREGEXEQ_OP:
/* the right-hand const is type text for all of these */
isIndexable = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC,
&prefix, &rest) != Pattern_Prefix_None;
break;
case OID_INET_SUB_OP:
case OID_INET_SUBEQ_OP:
isIndexable = true;
break;
}
if (prefix)
{
pfree(DatumGetPointer(prefix->constvalue));
pfree(prefix);
}
/* done if the expression doesn't look indexable */
if (!isIndexable)
return false;
/*
* Must also check that index's opclass supports the operators we will
* want to apply. (A hash index, for example, will not support ">=".)
* Currently, only btree supports the operators we need.
*
* We insist on the opclass being the specific one we expect, else we'd do
* the wrong thing if someone were to make a reverse-sort opclass with the
* same operators.
*/
switch (expr_op)
{
case OID_TEXT_LIKE_OP:
case OID_TEXT_ICLIKE_OP:
case OID_TEXT_REGEXEQ_OP:
case OID_TEXT_ICREGEXEQ_OP:
/* text operators will be used for varchar inputs, too */
isIndexable =
(opclass == TEXT_PATTERN_BTREE_OPS_OID) ||
(opclass == TEXT_BTREE_OPS_OID && lc_collate_is_c()) ||
(opclass == VARCHAR_PATTERN_BTREE_OPS_OID) ||
(opclass == VARCHAR_BTREE_OPS_OID && lc_collate_is_c());
break;
case OID_BPCHAR_LIKE_OP:
case OID_BPCHAR_ICLIKE_OP:
case OID_BPCHAR_REGEXEQ_OP:
case OID_BPCHAR_ICREGEXEQ_OP:
isIndexable =
(opclass == BPCHAR_PATTERN_BTREE_OPS_OID) ||
(opclass == BPCHAR_BTREE_OPS_OID && lc_collate_is_c());
break;
case OID_NAME_LIKE_OP:
case OID_NAME_ICLIKE_OP:
case OID_NAME_REGEXEQ_OP:
case OID_NAME_ICREGEXEQ_OP:
isIndexable =
(opclass == NAME_PATTERN_BTREE_OPS_OID) ||
(opclass == NAME_BTREE_OPS_OID && lc_collate_is_c());
break;
case OID_BYTEA_LIKE_OP:
isIndexable = (opclass == BYTEA_BTREE_OPS_OID);
break;
case OID_INET_SUB_OP:
case OID_INET_SUBEQ_OP:
isIndexable = (opclass == INET_BTREE_OPS_OID ||
opclass == CIDR_BTREE_OPS_OID);
break;
}
return isIndexable;
}
/*
* expand_indexqual_conditions
* Given a list of sublists of RestrictInfo nodes, produce a flat list
* of index qual clauses. Standard qual clauses (those in the index's
* opclass) are passed through unchanged. Boolean clauses and "special"
* index operators are expanded into clauses that the indexscan machinery
* will know what to do with. RowCompare clauses are simplified if
* necessary to create a clause that is fully checkable by the index.
*
* The input list is ordered by index key, and so the output list is too.
* (The latter is not depended on by any part of the core planner, I believe,
* but parts of the executor require it, and so do the amcostestimate
* functions.)
*/
List *
expand_indexqual_conditions(IndexOptInfo *index, List *clausegroups)
{
List *resultquals = NIL;
ListCell *clausegroup_item;
int indexcol = 0;
Oid *classes = index->classlist;
if (clausegroups == NIL)
return NIL;
clausegroup_item = list_head(clausegroups);
do
{
Oid curClass = classes[0];
ListCell *l;
foreach(l, (List *) lfirst(clausegroup_item))
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
Expr *clause = rinfo->clause;
/* First check for boolean cases */
if (IsBooleanOpclass(curClass))
{
Expr *boolqual;
boolqual = expand_boolean_index_clause((Node *) clause,
indexcol,
index);
if (boolqual)
{
resultquals = lappend(resultquals,
make_restrictinfo(boolqual,
true,
false,
NULL));
continue;
}
}
/*
* Else it must be an opclause (usual case), ScalarArrayOp, or
* RowCompare
*/
if (is_opclause(clause))
{
resultquals = list_concat(resultquals,
expand_indexqual_opclause(rinfo,
curClass));
}
else if (IsA(clause, ScalarArrayOpExpr))
{
/* no extra work at this time */
resultquals = lappend(resultquals, rinfo);
}
else if (IsA(clause, RowCompareExpr))
{
resultquals = lappend(resultquals,
expand_indexqual_rowcompare(rinfo,
index,
indexcol));
}
else
elog(ERROR, "unsupported indexqual type: %d",
(int) nodeTag(clause));
}
clausegroup_item = lnext(clausegroup_item);
indexcol++;
classes++;
} while (clausegroup_item != NULL && !DoneMatchingIndexKeys(classes));
Assert(clausegroup_item == NULL); /* else more groups than indexkeys */
return resultquals;
}
/*
* expand_boolean_index_clause
* Convert a clause recognized by match_boolean_index_clause into
* a boolean equality operator clause.
*
* Returns NULL if the clause isn't a boolean index qual.
*/
static Expr *
expand_boolean_index_clause(Node *clause,
int indexcol,
IndexOptInfo *index)
{
/* Direct match? */
if (match_index_to_operand(clause, indexcol, index))
{
/* convert to indexkey = TRUE */
return make_opclause(BooleanEqualOperator, BOOLOID, false,
(Expr *) clause,
(Expr *) makeBoolConst(true, false));
}
/* NOT clause? */
if (not_clause(clause))
{
Node *arg = (Node *) get_notclausearg((Expr *) clause);
/* It must have matched the indexkey */
Assert(match_index_to_operand(arg, indexcol, index));
/* convert to indexkey = FALSE */
return make_opclause(BooleanEqualOperator, BOOLOID, false,
(Expr *) arg,
(Expr *) makeBoolConst(false, false));
}
if (clause && IsA(clause, BooleanTest))
{
BooleanTest *btest = (BooleanTest *) clause;
Node *arg = (Node *) btest->arg;
/* It must have matched the indexkey */
Assert(match_index_to_operand(arg, indexcol, index));
if (btest->booltesttype == IS_TRUE)
{
/* convert to indexkey = TRUE */
return make_opclause(BooleanEqualOperator, BOOLOID, false,
(Expr *) arg,
(Expr *) makeBoolConst(true, false));
}
if (btest->booltesttype == IS_FALSE)
{
/* convert to indexkey = FALSE */
return make_opclause(BooleanEqualOperator, BOOLOID, false,
(Expr *) arg,
(Expr *) makeBoolConst(false, false));
}
/* Oops */
Assert(false);
}
return NULL;
}
/*
* expand_indexqual_opclause --- expand a single indexqual condition
* that is an operator clause
*
* The input is a single RestrictInfo, the output a list of RestrictInfos
*/
static List *
expand_indexqual_opclause(RestrictInfo *rinfo, Oid opclass)
{
Expr *clause = rinfo->clause;
/* we know these will succeed */
Node *leftop = get_leftop(clause);
Node *rightop = get_rightop(clause);
Oid expr_op = ((OpExpr *) clause)->opno;
Const *patt = (Const *) rightop;
Const *prefix = NULL;
Const *rest = NULL;
Pattern_Prefix_Status pstatus;
List *result;
switch (expr_op)
{
/*
* LIKE and regex operators are not members of any index opclass,
* so if we find one in an indexqual list we can assume that it
* was accepted by match_special_index_operator().
*/
case OID_TEXT_LIKE_OP:
case OID_BPCHAR_LIKE_OP:
case OID_NAME_LIKE_OP:
case OID_BYTEA_LIKE_OP:
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like,
&prefix, &rest);
result = prefix_quals(leftop, opclass, prefix, pstatus);
break;
case OID_TEXT_ICLIKE_OP:
case OID_BPCHAR_ICLIKE_OP:
case OID_NAME_ICLIKE_OP:
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC,
&prefix, &rest);
result = prefix_quals(leftop, opclass, prefix, pstatus);
break;
case OID_TEXT_REGEXEQ_OP:
case OID_BPCHAR_REGEXEQ_OP:
case OID_NAME_REGEXEQ_OP:
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex,
&prefix, &rest);
result = prefix_quals(leftop, opclass, prefix, pstatus);
break;
case OID_TEXT_ICREGEXEQ_OP:
case OID_BPCHAR_ICREGEXEQ_OP:
case OID_NAME_ICREGEXEQ_OP:
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC,
&prefix, &rest);
result = prefix_quals(leftop, opclass, prefix, pstatus);
break;
case OID_INET_SUB_OP:
case OID_INET_SUBEQ_OP:
result = network_prefix_quals(leftop, expr_op, opclass,
patt->constvalue);
break;
default:
result = list_make1(rinfo);
break;
}
return result;
}
/*
* expand_indexqual_rowcompare --- expand a single indexqual condition
* that is a RowCompareExpr
*
* It's already known that the first column of the row comparison matches
* the specified column of the index. We can use additional columns of the
* row comparison as index qualifications, so long as they match the index
* in the "same direction", ie, the indexkeys are all on the same side of the
* clause and the operators are all the same-type members of the opclasses.
* If all the columns of the RowCompareExpr match in this way, we just use it
* as-is. Otherwise, we build a shortened RowCompareExpr (if more than one
* column matches) or a simple OpExpr (if the first-column match is all
* there is). In these cases the modified clause is always "<=" or ">="
* even when the original was "<" or ">" --- this is necessary to match all
* the rows that could match the original. (We are essentially building a
* lossy version of the row comparison when we do this.)
*/
static RestrictInfo *
expand_indexqual_rowcompare(RestrictInfo *rinfo,
IndexOptInfo *index,
int indexcol)
{
RowCompareExpr *clause = (RowCompareExpr *) rinfo->clause;
bool var_on_left;
int op_strategy;
Oid op_subtype;
bool op_recheck;
int matching_cols;
Oid expr_op;
List *opclasses;
List *subtypes;
List *new_ops;
ListCell *largs_cell;
ListCell *rargs_cell;
ListCell *opnos_cell;
/* We have to figure out (again) how the first col matches */
var_on_left = match_index_to_operand((Node *) linitial(clause->largs),
indexcol, index);
Assert(var_on_left ||
match_index_to_operand((Node *) linitial(clause->rargs),
indexcol, index));
expr_op = linitial_oid(clause->opnos);
if (!var_on_left)
expr_op = get_commutator(expr_op);
get_op_opclass_properties(expr_op, index->classlist[indexcol],
&op_strategy, &op_subtype, &op_recheck);
/* Build lists of the opclasses and operator subtypes in case needed */
opclasses = list_make1_oid(index->classlist[indexcol]);
subtypes = list_make1_oid(op_subtype);
/*
* See how many of the remaining columns match some index column
* in the same way. A note about rel membership tests: we assume
* that the clause as a whole is already known to use only Vars from
* the indexed relation and possibly some acceptable outer relations.
* So the "other" side of any potential index condition is OK as long
* as it doesn't use Vars from the indexed relation.
*/
matching_cols = 1;
largs_cell = lnext(list_head(clause->largs));
rargs_cell = lnext(list_head(clause->rargs));
opnos_cell = lnext(list_head(clause->opnos));
while (largs_cell != NULL)
{
Node *varop;
Node *constop;
int i;
expr_op = lfirst_oid(opnos_cell);
if (var_on_left)
{
varop = (Node *) lfirst(largs_cell);
constop = (Node *) lfirst(rargs_cell);
}
else
{
varop = (Node *) lfirst(rargs_cell);
constop = (Node *) lfirst(largs_cell);
/* indexkey is on right, so commute the operator */
expr_op = get_commutator(expr_op);
if (expr_op == InvalidOid)
break; /* operator is not usable */
}
if (bms_is_member(index->rel->relid, pull_varnos(constop)))
break; /* no good, Var on wrong side */
if (contain_volatile_functions(constop))
break; /* no good, volatile comparison value */
/*
* The Var side can match any column of the index. If the user
* does something weird like having multiple identical index
* columns, we insist the match be on the first such column,
* to avoid confusing the executor.
*/
for (i = 0; i < index->ncolumns; i++)
{
if (match_index_to_operand(varop, i, index))
break;
}
if (i >= index->ncolumns)
break; /* no match found */
/* Now, do we have the right operator for this column? */
if (get_op_opclass_strategy(expr_op, index->classlist[i])
!= op_strategy)
break;
/* Add opclass and subtype to lists */
get_op_opclass_properties(expr_op, index->classlist[i],
&op_strategy, &op_subtype, &op_recheck);
opclasses = lappend_oid(opclasses, index->classlist[i]);
subtypes = lappend_oid(subtypes, op_subtype);
/* This column matches, keep scanning */
matching_cols++;
largs_cell = lnext(largs_cell);
rargs_cell = lnext(rargs_cell);
opnos_cell = lnext(opnos_cell);
}
/* Return clause as-is if it's all usable as index quals */
if (matching_cols == list_length(clause->opnos))
return rinfo;
/*
* We have to generate a subset rowcompare (possibly just one OpExpr).
* The painful part of this is changing < to <= or > to >=, so deal with
* that first.
*/
if (op_strategy == BTLessEqualStrategyNumber ||
op_strategy == BTGreaterEqualStrategyNumber)
{
/* easy, just use the same operators */
new_ops = list_truncate(list_copy(clause->opnos), matching_cols);
}
else
{
ListCell *opclasses_cell;
ListCell *subtypes_cell;
if (op_strategy == BTLessStrategyNumber)
op_strategy = BTLessEqualStrategyNumber;
else if (op_strategy == BTGreaterStrategyNumber)
op_strategy = BTGreaterEqualStrategyNumber;
else
elog(ERROR, "unexpected strategy number %d", op_strategy);
new_ops = NIL;
forboth(opclasses_cell, opclasses, subtypes_cell, subtypes)
{
expr_op = get_opclass_member(lfirst_oid(opclasses_cell),
lfirst_oid(subtypes_cell),
op_strategy);
if (!OidIsValid(expr_op)) /* should not happen */
elog(ERROR, "could not find member %d of opclass %u",
op_strategy, lfirst_oid(opclasses_cell));
if (!var_on_left)
{
expr_op = get_commutator(expr_op);
if (!OidIsValid(expr_op)) /* should not happen */
elog(ERROR, "could not find commutator of member %d of opclass %u",
op_strategy, lfirst_oid(opclasses_cell));
}
new_ops = lappend_oid(new_ops, expr_op);
}
}
/* If we have more than one matching col, create a subset rowcompare */
if (matching_cols > 1)
{
RowCompareExpr *rc = makeNode(RowCompareExpr);
if (var_on_left)
rc->rctype = (RowCompareType) op_strategy;
else
rc->rctype = (op_strategy == BTLessEqualStrategyNumber) ?
ROWCOMPARE_GE : ROWCOMPARE_LE;
rc->opnos = new_ops;
rc->opclasses = list_truncate(list_copy(clause->opclasses),
matching_cols);
rc->largs = list_truncate((List *) copyObject(clause->largs),
matching_cols);
rc->rargs = list_truncate((List *) copyObject(clause->rargs),
matching_cols);
return make_restrictinfo((Expr *) rc, true, false, NULL);
}
else
{
Expr *opexpr;
opexpr = make_opclause(linitial_oid(new_ops), BOOLOID, false,
copyObject(linitial(clause->largs)),
copyObject(linitial(clause->rargs)));
return make_restrictinfo(opexpr, true, false, NULL);
}
}
/*
* Given a fixed prefix that all the "leftop" values must have,
* generate suitable indexqual condition(s). opclass is the index
* operator class; we use it to deduce the appropriate comparison
* operators and operand datatypes.
*/
static List *
prefix_quals(Node *leftop, Oid opclass,
Const *prefix_const, Pattern_Prefix_Status pstatus)
{
List *result;
Oid datatype;
Oid oproid;
Expr *expr;
Const *greaterstr;
Assert(pstatus != Pattern_Prefix_None);
switch (opclass)
{
case TEXT_BTREE_OPS_OID:
case TEXT_PATTERN_BTREE_OPS_OID:
datatype = TEXTOID;
break;
case VARCHAR_BTREE_OPS_OID:
case VARCHAR_PATTERN_BTREE_OPS_OID:
datatype = VARCHAROID;
break;
case BPCHAR_BTREE_OPS_OID:
case BPCHAR_PATTERN_BTREE_OPS_OID:
datatype = BPCHAROID;
break;
case NAME_BTREE_OPS_OID:
case NAME_PATTERN_BTREE_OPS_OID:
datatype = NAMEOID;
break;
case BYTEA_BTREE_OPS_OID:
datatype = BYTEAOID;
break;
default:
/* shouldn't get here */
elog(ERROR, "unexpected opclass: %u", opclass);
return NIL;
}
/*
* If necessary, coerce the prefix constant to the right type. The given
* prefix constant is either text or bytea type.
*/
if (prefix_const->consttype != datatype)
{
char *prefix;
switch (prefix_const->consttype)
{
case TEXTOID:
prefix = DatumGetCString(DirectFunctionCall1(textout,
prefix_const->constvalue));
break;
case BYTEAOID:
prefix = DatumGetCString(DirectFunctionCall1(byteaout,
prefix_const->constvalue));
break;
default:
elog(ERROR, "unexpected const type: %u",
prefix_const->consttype);
return NIL;
}
prefix_const = string_to_const(prefix, datatype);
pfree(prefix);
}
/*
* If we found an exact-match pattern, generate an "=" indexqual.
*/
if (pstatus == Pattern_Prefix_Exact)
{
oproid = get_opclass_member(opclass, InvalidOid,
BTEqualStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no = operator for opclass %u", opclass);
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) prefix_const);
result = list_make1(make_restrictinfo(expr, true, false, NULL));
return result;
}
/*
* Otherwise, we have a nonempty required prefix of the values.
*
* We can always say "x >= prefix".
*/
oproid = get_opclass_member(opclass, InvalidOid,
BTGreaterEqualStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no >= operator for opclass %u", opclass);
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) prefix_const);
result = list_make1(make_restrictinfo(expr, true, false, NULL));
/*-------
* If we can create a string larger than the prefix, we can say
* "x < greaterstr".
*-------
*/
greaterstr = make_greater_string(prefix_const);
if (greaterstr)
{
oproid = get_opclass_member(opclass, InvalidOid,
BTLessStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no < operator for opclass %u", opclass);
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) greaterstr);
result = lappend(result, make_restrictinfo(expr, true, false, NULL));
}
return result;
}
/*
* Given a leftop and a rightop, and a inet-class sup/sub operator,
* generate suitable indexqual condition(s). expr_op is the original
* operator, and opclass is the index opclass.
*/
static List *
network_prefix_quals(Node *leftop, Oid expr_op, Oid opclass, Datum rightop)
{
bool is_eq;
Oid datatype;
Oid opr1oid;
Oid opr2oid;
Datum opr1right;
Datum opr2right;
List *result;
Expr *expr;
switch (expr_op)
{
case OID_INET_SUB_OP:
datatype = INETOID;
is_eq = false;
break;
case OID_INET_SUBEQ_OP:
datatype = INETOID;
is_eq = true;
break;
default:
elog(ERROR, "unexpected operator: %u", expr_op);
return NIL;
}
/*
* create clause "key >= network_scan_first( rightop )", or ">" if the
* operator disallows equality.
*/
if (is_eq)
{
opr1oid = get_opclass_member(opclass, InvalidOid,
BTGreaterEqualStrategyNumber);
if (opr1oid == InvalidOid)
elog(ERROR, "no >= operator for opclass %u", opclass);
}
else
{
opr1oid = get_opclass_member(opclass, InvalidOid,
BTGreaterStrategyNumber);
if (opr1oid == InvalidOid)
elog(ERROR, "no > operator for opclass %u", opclass);
}
opr1right = network_scan_first(rightop);
expr = make_opclause(opr1oid, BOOLOID, false,
(Expr *) leftop,
(Expr *) makeConst(datatype, -1, opr1right,
false, false));
result = list_make1(make_restrictinfo(expr, true, false, NULL));
/* create clause "key <= network_scan_last( rightop )" */
opr2oid = get_opclass_member(opclass, InvalidOid,
BTLessEqualStrategyNumber);
if (opr2oid == InvalidOid)
elog(ERROR, "no <= operator for opclass %u", opclass);
opr2right = network_scan_last(rightop);
expr = make_opclause(opr2oid, BOOLOID, false,
(Expr *) leftop,
(Expr *) makeConst(datatype, -1, opr2right,
false, false));
result = lappend(result, make_restrictinfo(expr, true, false, NULL));
return result;
}
/*
* Handy subroutines for match_special_index_operator() and friends.
*/
/*
* Generate a Datum of the appropriate type from a C string.
* Note that all of the supported types are pass-by-ref, so the
* returned value should be pfree'd if no longer needed.
*/
static Datum
string_to_datum(const char *str, Oid datatype)
{
/*
* We cheat a little by assuming that textin() will do for bpchar and
* varchar constants too...
*/
if (datatype == NAMEOID)
return DirectFunctionCall1(namein, CStringGetDatum(str));
else if (datatype == BYTEAOID)
return DirectFunctionCall1(byteain, CStringGetDatum(str));
else
return DirectFunctionCall1(textin, CStringGetDatum(str));
}
/*
* Generate a Const node of the appropriate type from a C string.
*/
static Const *
string_to_const(const char *str, Oid datatype)
{
Datum conval = string_to_datum(str, datatype);
return makeConst(datatype, ((datatype == NAMEOID) ? NAMEDATALEN : -1),
conval, false, false);
}
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