postgresql/src/backend/optimizer/path/indxpath.c

3462 lines
105 KiB
C

/*-------------------------------------------------------------------------
*
* indxpath.c
* Routines to determine which indexes are usable for scanning a
* given relation, and create Paths accordingly.
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/path/indxpath.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <math.h>
#include "access/skey.h"
#include "access/sysattr.h"
#include "catalog/pg_am.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_opfamily.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/bytea.h"
#include "utils/lsyscache.h"
#include "utils/pg_locale.h"
#include "utils/selfuncs.h"
#define IsBooleanOpfamily(opfamily) \
((opfamily) == BOOL_BTREE_FAM_OID || (opfamily) == BOOL_HASH_FAM_OID)
#define IndexCollMatchesExprColl(idxcollation, exprcollation) \
((idxcollation) == InvalidOid || (idxcollation) == (exprcollation))
/* Whether to use ScalarArrayOpExpr to build index qualifications */
typedef enum
{
SAOP_PER_AM, /* Use ScalarArrayOpExpr if amsearcharray */
SAOP_ALLOW, /* Use ScalarArrayOpExpr for all indexes */
SAOP_REQUIRE /* Require ScalarArrayOpExpr to be used */
} SaOpControl;
/* Whether we are looking for plain indexscan, bitmap scan, or either */
typedef enum
{
ST_INDEXSCAN, /* must support amgettuple */
ST_BITMAPSCAN, /* must support amgetbitmap */
ST_ANYSCAN /* either is okay */
} ScanTypeControl;
/* Per-path data used within choose_bitmap_and() */
typedef struct
{
Path *path; /* IndexPath, BitmapAndPath, or BitmapOrPath */
List *quals; /* the WHERE clauses it uses */
List *preds; /* predicates of its partial index(es) */
Bitmapset *clauseids; /* quals+preds represented as a bitmapset */
} PathClauseUsage;
static List *find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, RelOptInfo *outer_rel,
SaOpControl saop_control, ScanTypeControl scantype);
static List *find_saop_paths(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, RelOptInfo *outer_rel);
static Path *choose_bitmap_and(PlannerInfo *root, RelOptInfo *rel,
List *paths, RelOptInfo *outer_rel);
static int path_usage_comparator(const void *a, const void *b);
static Cost bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel,
Path *ipath, RelOptInfo *outer_rel);
static Cost bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel,
List *paths, RelOptInfo *outer_rel);
static PathClauseUsage *classify_index_clause_usage(Path *path,
List **clauselist);
static void find_indexpath_quals(Path *bitmapqual, List **quals, List **preds);
static int find_list_position(Node *node, List **nodelist);
static bool check_index_only(RelOptInfo *rel, IndexOptInfo *index);
static List *group_clauses_by_indexkey(IndexOptInfo *index,
List *clauses, List *outer_clauses,
Relids outer_relids,
SaOpControl saop_control,
bool *found_clause);
static bool match_clause_to_indexcol(IndexOptInfo *index,
int indexcol,
RestrictInfo *rinfo,
Relids outer_relids,
SaOpControl saop_control);
static bool is_indexable_operator(Oid expr_op, Oid opfamily,
bool indexkey_on_left);
static bool match_rowcompare_to_indexcol(IndexOptInfo *index,
int indexcol,
Oid opfamily,
Oid idxcollation,
RowCompareExpr *clause,
Relids outer_relids);
static List *match_index_to_pathkeys(IndexOptInfo *index, List *pathkeys);
static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
int indexcol, Expr *clause, Oid pk_opfamily);
static Relids indexable_outerrelids(PlannerInfo *root, 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 bool match_boolean_index_clause(Node *clause, int indexcol,
IndexOptInfo *index);
static bool match_special_index_operator(Expr *clause,
Oid opfamily, Oid idxcollation,
bool indexkey_on_left);
static Expr *expand_boolean_index_clause(Node *clause, int indexcol,
IndexOptInfo *index);
static List *expand_indexqual_opclause(RestrictInfo *rinfo,
Oid opfamily, Oid idxcollation);
static RestrictInfo *expand_indexqual_rowcompare(RestrictInfo *rinfo,
IndexOptInfo *index,
int indexcol);
static List *prefix_quals(Node *leftop, Oid opfamily, Oid collation,
Const *prefix, Pattern_Prefix_Status pstatus);
static List *network_prefix_quals(Node *leftop, Oid expr_op, Oid opfamily,
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(root, 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, NULL, SAOP_PER_AM, ST_ANYSCAN);
/*
* Submit all the ones that can form plain IndexScan plans to add_path.
* (A plain IndexPath might represent either a plain IndexScan or an
* IndexOnlyScan, but for our purposes here the distinction does not
* matter. However, some of the indexes might support only bitmap scans,
* and those we mustn't submit to add_path here.) Also, pick out the ones
* that might be useful as bitmap scans. For that, we must discard
* indexes that don't support bitmap scans, and we also are only
* interested in paths that have some selectivity; we should discard
* anything that was generated solely for ordering purposes.
*/
bitindexpaths = NIL;
foreach(l, indexpaths)
{
IndexPath *ipath = (IndexPath *) lfirst(l);
if (ipath->indexinfo->amhasgettuple)
add_path(rel, (Path *) ipath);
if (ipath->indexinfo->amhasgetbitmap &&
(ipath->path.pathkeys == NIL ||
ipath->indexselectivity < 1.0))
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,
NULL);
bitindexpaths = list_concat(bitindexpaths, indexpaths);
/*
* Likewise, generate paths using executor-managed 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, 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, NULL);
bpath = create_bitmap_heap_path(root, rel, bitmapqual, NULL);
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)
* 'outer_rel' is the outer side of the join if forming an inner indexscan
* (so some of the given clauses are join clauses); NULL if not
* 'saop_control' indicates whether ScalarArrayOpExpr clauses can be used
* 'scantype' indicates whether we need plain or bitmap scan support
*
* 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, RelOptInfo *outer_rel,
SaOpControl saop_control, ScanTypeControl scantype)
{
Relids outer_relids = outer_rel ? outer_rel->relids : NULL;
bool possibly_useful_pathkeys = has_useful_pathkeys(root, rel);
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 *orderbyclauses;
List *index_pathkeys;
List *useful_pathkeys;
bool useful_predicate;
bool found_clause;
bool index_is_ordered;
bool index_only_scan;
/*
* Check that index supports the desired scan type(s)
*/
switch (scantype)
{
case ST_INDEXSCAN:
if (!index->amhasgettuple)
continue;
break;
case ST_BITMAPSCAN:
if (!index->amhasgetbitmap)
continue;
break;
case ST_ANYSCAN:
/* either or both are OK */
break;
}
/*
* If we're doing find_saop_paths(), we can skip indexes that support
* ScalarArrayOpExpr natively. We already generated all the potential
* indexpaths for them, so no need to do anything more.
*/
if (saop_control == SAOP_REQUIRE && index->amsearcharray)
continue;
/*
* 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 = (index->sortopfamily != NULL);
if (index_is_ordered && possibly_useful_pathkeys &&
istoplevel && outer_rel == NULL)
{
index_pathkeys = build_index_pathkeys(root, index,
ForwardScanDirection);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
orderbyclauses = NIL;
}
else if (index->amcanorderbyop && possibly_useful_pathkeys &&
istoplevel && outer_rel == NULL && scantype != ST_BITMAPSCAN)
{
/* see if we can generate ordering operators for query_pathkeys */
orderbyclauses = match_index_to_pathkeys(index,
root->query_pathkeys);
if (orderbyclauses)
useful_pathkeys = root->query_pathkeys;
else
useful_pathkeys = NIL;
}
else
{
useful_pathkeys = NIL;
orderbyclauses = NIL;
}
/*
* 3. Check if an index-only scan is possible.
*/
index_only_scan = check_index_only(rel, index);
/*
* 4. 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,
* OR an index-only scan is possible.
*/
if (found_clause || useful_pathkeys != NIL || useful_predicate ||
index_only_scan)
{
ipath = create_index_path(root, index,
restrictclauses,
orderbyclauses,
useful_pathkeys,
index_is_ordered ?
ForwardScanDirection :
NoMovementScanDirection,
index_only_scan,
outer_rel);
result = lappend(result, ipath);
}
/*
* 5. If the index is ordered, a backwards scan might be interesting.
* Again, this is only interesting at top level.
*/
if (index_is_ordered && possibly_useful_pathkeys &&
istoplevel && outer_rel == NULL)
{
index_pathkeys = build_index_pathkeys(root, index,
BackwardScanDirection);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
if (useful_pathkeys != NIL)
{
ipath = create_index_path(root, index,
restrictclauses,
NIL,
useful_pathkeys,
BackwardScanDirection,
index_only_scan,
outer_rel);
result = lappend(result, ipath);
}
}
}
return result;
}
/*
* find_saop_paths
* Find all the potential indexpaths that make use of executor-managed
* 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, RelOptInfo *outer_rel)
{
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, outer_rel,
SAOP_REQUIRE, ST_BITMAPSCAN);
}
/*
* 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.) outer_rel is the outer
* side when we are considering a nestloop inner indexpath.
*/
List *
generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
RelOptInfo *outer_rel)
{
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,
outer_rel,
SAOP_ALLOW,
ST_BITMAPSCAN);
/* Recurse in case there are sub-ORs */
indlist = list_concat(indlist,
generate_bitmap_or_paths(root, rel,
andargs,
all_clauses,
outer_rel));
}
else
{
Assert(IsA(orarg, RestrictInfo));
Assert(!restriction_is_or_clause((RestrictInfo *) orarg));
indlist = find_usable_indexes(root, rel,
list_make1(orarg),
all_clauses,
false,
outer_rel,
SAOP_ALLOW,
ST_BITMAPSCAN);
}
/*
* 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, outer_rel);
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, RelOptInfo *outer_rel)
{
int npaths = list_length(paths);
PathClauseUsage **pathinfoarray;
PathClauseUsage *pathinfo;
List *clauselist;
List *bestpaths = NIL;
Cost bestcost = 0;
int i,
j;
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. Moreover, it's completely impractical if there are a large
* number of paths, since the work would grow as O(2^N).
*
* As a heuristic, we first check for paths using exactly the same sets of
* WHERE clauses + index predicate conditions, and reject all but the
* cheapest-to-scan in any such group. This primarily gets rid of indexes
* that include the interesting columns but also irrelevant columns. (In
* situations where the DBA has gone overboard on creating variant
* indexes, this can make for a very large reduction in the number of
* paths considered further.)
*
* We then sort the surviving paths with the cheapest-to-scan first, and
* for each path, consider using that path alone as the basis for a bitmap
* scan. Then we consider bitmap AND scans formed from that path plus
* each subsequent (higher-cost) path, adding on a subsequent path if it
* results in a reduction in the estimated total scan cost. This means we
* consider about O(N^2) rather than O(2^N) path combinations, which is
* quite tolerable, especially given than N is usually reasonably small
* because of the prefiltering step. The cheapest of these is returned.
*
* We will only consider AND combinations in which no two indexes use the
* same WHERE clause. This is a bit of a kluge: it's needed because
* costsize.c and clausesel.c aren't very smart about redundant clauses.
* They will usually double-count the redundant clauses, producing a
* too-small selectivity that makes a redundant AND step look like it
* reduces the total cost. Perhaps someday that code will be smarter and
* we can remove this limitation. (But note that this also defends
* against flat-out duplicate input paths, which can happen because
* best_inner_indexscan will find the same OR join clauses that
* create_or_index_quals has pulled OR restriction clauses out of.)
*
* For the same reason, we reject AND combinations in which an index
* predicate clause duplicates another clause. Here we find it necessary
* to be even stricter: we'll reject a partial index if any of its
* predicate clauses are implied by the set of WHERE clauses and predicate
* clauses used so far. This covers cases such as a condition "x = 42"
* used with a plain index, followed by a clauseless scan of a partial
* index "WHERE x >= 40 AND x < 50". The partial index has been accepted
* only because "x = 42" was present, and so allowing it would partially
* double-count selectivity. (We could use predicate_implied_by on
* regular qual clauses too, to have a more intelligent, but much more
* expensive, check for redundancy --- but in most cases simple equality
* seems to suffice.)
*/
/*
* Extract clause usage info and detect any paths that use exactly the
* same set of clauses; keep only the cheapest-to-scan of any such groups.
* The surviving paths are put into an array for qsort'ing.
*/
pathinfoarray = (PathClauseUsage **)
palloc(npaths * sizeof(PathClauseUsage *));
clauselist = NIL;
npaths = 0;
foreach(l, paths)
{
Path *ipath = (Path *) lfirst(l);
pathinfo = classify_index_clause_usage(ipath, &clauselist);
for (i = 0; i < npaths; i++)
{
if (bms_equal(pathinfo->clauseids, pathinfoarray[i]->clauseids))
break;
}
if (i < npaths)
{
/* duplicate clauseids, keep the cheaper one */
Cost ncost;
Cost ocost;
Selectivity nselec;
Selectivity oselec;
cost_bitmap_tree_node(pathinfo->path, &ncost, &nselec);
cost_bitmap_tree_node(pathinfoarray[i]->path, &ocost, &oselec);
if (ncost < ocost)
pathinfoarray[i] = pathinfo;
}
else
{
/* not duplicate clauseids, add to array */
pathinfoarray[npaths++] = pathinfo;
}
}
/* If only one surviving path, we're done */
if (npaths == 1)
return pathinfoarray[0]->path;
/* Sort the surviving paths by index access cost */
qsort(pathinfoarray, npaths, sizeof(PathClauseUsage *),
path_usage_comparator);
/*
* For each surviving index, consider it as an "AND group leader", and see
* whether adding on any of the later indexes results in an AND path with
* cheaper total cost than before. Then take the cheapest AND group.
*/
for (i = 0; i < npaths; i++)
{
Cost costsofar;
List *qualsofar;
Bitmapset *clauseidsofar;
ListCell *lastcell;
pathinfo = pathinfoarray[i];
paths = list_make1(pathinfo->path);
costsofar = bitmap_scan_cost_est(root, rel, pathinfo->path, outer_rel);
qualsofar = list_concat(list_copy(pathinfo->quals),
list_copy(pathinfo->preds));
clauseidsofar = bms_copy(pathinfo->clauseids);
lastcell = list_head(paths); /* for quick deletions */
for (j = i + 1; j < npaths; j++)
{
Cost newcost;
pathinfo = pathinfoarray[j];
/* Check for redundancy */
if (bms_overlap(pathinfo->clauseids, clauseidsofar))
continue; /* consider it redundant */
if (pathinfo->preds)
{
bool redundant = false;
/* we check each predicate clause separately */
foreach(l, pathinfo->preds)
{
Node *np = (Node *) lfirst(l);
if (predicate_implied_by(list_make1(np), qualsofar))
{
redundant = true;
break; /* out of inner foreach loop */
}
}
if (redundant)
continue;
}
/* tentatively add new path to paths, so we can estimate cost */
paths = lappend(paths, pathinfo->path);
newcost = bitmap_and_cost_est(root, rel, paths, outer_rel);
if (newcost < costsofar)
{
/* keep new path in paths, update subsidiary variables */
costsofar = newcost;
qualsofar = list_concat(qualsofar,
list_copy(pathinfo->quals));
qualsofar = list_concat(qualsofar,
list_copy(pathinfo->preds));
clauseidsofar = bms_add_members(clauseidsofar,
pathinfo->clauseids);
lastcell = lnext(lastcell);
}
else
{
/* reject new path, remove it from paths list */
paths = list_delete_cell(paths, lnext(lastcell), lastcell);
}
Assert(lnext(lastcell) == NULL);
}
/* Keep the cheapest AND-group (or singleton) */
if (i == 0 || costsofar < bestcost)
{
bestpaths = paths;
bestcost = costsofar;
}
/* some easy cleanup (we don't try real hard though) */
list_free(qualsofar);
}
if (list_length(bestpaths) == 1)
return (Path *) linitial(bestpaths); /* no need for AND */
return (Path *) create_bitmap_and_path(root, rel, bestpaths);
}
/* qsort comparator to sort in increasing index access cost order */
static int
path_usage_comparator(const void *a, const void *b)
{
PathClauseUsage *pa = *(PathClauseUsage *const *) a;
PathClauseUsage *pb = *(PathClauseUsage *const *) b;
Cost acost;
Cost bcost;
Selectivity aselec;
Selectivity bselec;
cost_bitmap_tree_node(pa->path, &acost, &aselec);
cost_bitmap_tree_node(pb->path, &bcost, &bselec);
/*
* If costs are the same, sort by selectivity.
*/
if (acost < bcost)
return -1;
if (acost > bcost)
return 1;
if (aselec < bselec)
return -1;
if (aselec > bselec)
return 1;
return 0;
}
/*
* Estimate the cost of actually executing a bitmap scan with a single
* index path (no BitmapAnd, at least not at this level).
*/
static Cost
bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel,
Path *ipath, RelOptInfo *outer_rel)
{
Path bpath;
cost_bitmap_heap_scan(&bpath, root, rel, ipath, outer_rel);
return bpath.total_cost;
}
/*
* Estimate the cost of actually executing a BitmapAnd scan with the given
* inputs.
*/
static Cost
bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel,
List *paths, RelOptInfo *outer_rel)
{
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, outer_rel);
return bpath.total_cost;
}
/*
* classify_index_clause_usage
* Construct a PathClauseUsage struct describing the WHERE clauses and
* index predicate clauses used by the given indexscan path.
* We consider two clauses the same if they are equal().
*
* At some point we might want to migrate this info into the Path data
* structure proper, but for the moment it's only needed within
* choose_bitmap_and().
*
* *clauselist is used and expanded as needed to identify all the distinct
* clauses seen across successive calls. Caller must initialize it to NIL
* before first call of a set.
*/
static PathClauseUsage *
classify_index_clause_usage(Path *path, List **clauselist)
{
PathClauseUsage *result;
Bitmapset *clauseids;
ListCell *lc;
result = (PathClauseUsage *) palloc(sizeof(PathClauseUsage));
result->path = path;
/* Recursively find the quals and preds used by the path */
result->quals = NIL;
result->preds = NIL;
find_indexpath_quals(path, &result->quals, &result->preds);
/* Build up a bitmapset representing the quals and preds */
clauseids = NULL;
foreach(lc, result->quals)
{
Node *node = (Node *) lfirst(lc);
clauseids = bms_add_member(clauseids,
find_list_position(node, clauselist));
}
foreach(lc, result->preds)
{
Node *node = (Node *) lfirst(lc);
clauseids = bms_add_member(clauseids,
find_list_position(node, clauselist));
}
result->clauseids = clauseids;
return result;
}
/*
* find_indexpath_quals
*
* Given the Path structure for a plain or bitmap indexscan, extract lists
* of all the indexquals and index predicate conditions used in the Path.
* These are appended to the initial contents of *quals and *preds (hence
* caller should initialize those to NIL).
*
* 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 lists contain pointers to the expressions used in the Path,
* but all the list cells are freshly built, so it's safe to destructively
* modify the lists (eg, by concat'ing with other lists).
*/
static void
find_indexpath_quals(Path *bitmapqual, List **quals, List **preds)
{
if (IsA(bitmapqual, BitmapAndPath))
{
BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
ListCell *l;
foreach(l, apath->bitmapquals)
{
find_indexpath_quals((Path *) lfirst(l), quals, preds);
}
}
else if (IsA(bitmapqual, BitmapOrPath))
{
BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
ListCell *l;
foreach(l, opath->bitmapquals)
{
find_indexpath_quals((Path *) lfirst(l), quals, preds);
}
}
else if (IsA(bitmapqual, IndexPath))
{
IndexPath *ipath = (IndexPath *) bitmapqual;
*quals = list_concat(*quals, get_actual_clauses(ipath->indexclauses));
*preds = list_concat(*preds, list_copy(ipath->indexinfo->indpred));
}
else
elog(ERROR, "unrecognized node type: %d", nodeTag(bitmapqual));
}
/*
* find_list_position
* Return the given node's position (counting from 0) in the given
* list of nodes. If it's not equal() to any existing list member,
* add it at the end, and return that position.
*/
static int
find_list_position(Node *node, List **nodelist)
{
int i;
ListCell *lc;
i = 0;
foreach(lc, *nodelist)
{
Node *oldnode = (Node *) lfirst(lc);
if (equal(node, oldnode))
return i;
i++;
}
*nodelist = lappend(*nodelist, node);
return i;
}
/*
* check_index_only
* Determine whether an index-only scan is possible for this index.
*/
static bool
check_index_only(RelOptInfo *rel, IndexOptInfo *index)
{
bool result;
Bitmapset *attrs_used = NULL;
Bitmapset *index_attrs = NULL;
ListCell *lc;
int i;
/* Index-only scans must be enabled, and AM must be capable of it */
if (!enable_indexonlyscan)
return false;
if (!index->amcanreturn)
return false;
/*
* Check that all needed attributes of the relation are available from
* the index.
*
* XXX this is overly conservative for partial indexes, since we will
* consider attributes involved in the index predicate as required even
* though the predicate won't need to be checked at runtime. (The same
* is true for attributes used only in index quals, if we are certain
* that the index is not lossy.) However, it would be quite expensive
* to determine that accurately at this point, so for now we take the
* easy way out.
*/
/*
* Add all the attributes needed for joins or final output. Note: we must
* look at reltargetlist, not the attr_needed data, because attr_needed
* isn't computed for inheritance child rels.
*/
pull_varattnos((Node *) rel->reltargetlist, rel->relid, &attrs_used);
/* Add all the attributes used by restriction clauses. */
foreach(lc, rel->baserestrictinfo)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
}
/* Construct a bitmapset of columns stored in the index. */
for (i = 0; i < index->ncolumns; i++)
{
int attno = index->indexkeys[i];
/*
* For the moment, we just ignore index expressions. It might be nice
* to do something with them, later.
*/
if (attno == 0)
continue;
index_attrs =
bms_add_member(index_attrs,
attno - FirstLowInvalidHeapAttributeNumber);
}
/* Do we have all the necessary attributes? */
result = bms_is_subset(attrs_used, index_attrs);
bms_free(attrs_used);
bms_free(index_attrs);
return result;
}
/****************************************************************************
* ---- 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).
*/
static 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;
*found_clause = false; /* default result */
if (clauses == NIL && outer_clauses == NIL)
return NIL; /* cannot succeed */
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
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,
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,
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);
}
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 family as the index
* operator for this column, or is a "special" operator as recognized
* by match_special_index_operator();
* and
* (3) must match the collation of the index, if collation is relevant.
*
* 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.
*
* If the index has a collation, the clause must have the same collation.
* For collation-less indexes, we assume it doesn't matter; this is
* necessary for cases like "hstore ? text", wherein hstore's operators
* don't care about collation but the clause will get marked with a
* collation anyway because of the text argument. (This logic is
* embodied in the macro IndexCollMatchesExprColl.)
*
* 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 not
* all indexes handle these natively, and the executor implements them
* only 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).
* 'rinfo' is the clause to be tested (as a RestrictInfo node).
* 'outer_relids' lists rels whose Vars can be considered pseudoconstant.
* '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,
RestrictInfo *rinfo,
Relids outer_relids,
SaOpControl saop_control)
{
Expr *clause = rinfo->clause;
Oid opfamily = index->opfamily[indexcol];
Oid idxcollation = index->indexcollations[indexcol];
Node *leftop,
*rightop;
Relids left_relids;
Relids right_relids;
Oid expr_op;
Oid expr_coll;
bool plain_op;
/*
* Never match pseudoconstants to indexes. (Normally this could not
* happen anyway, since a pseudoconstant clause couldn't contain a Var,
* but what if someone builds an expression index on a constant? It's not
* totally unreasonable to do so with a partial index, either.)
*/
if (rinfo->pseudoconstant)
return false;
/* First check for boolean-index cases. */
if (IsBooleanOpfamily(opfamily))
{
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().
* Or, if the index supports it, we can handle IS NULL/NOT NULL clauses.
*/
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;
expr_coll = ((OpExpr *) clause)->inputcollid;
plain_op = true;
}
else if (clause && IsA(clause, ScalarArrayOpExpr) &&
(index->amsearcharray || saop_control != SAOP_PER_AM))
{
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;
expr_coll = saop->inputcollid;
plain_op = false;
}
else if (clause && IsA(clause, RowCompareExpr))
{
return match_rowcompare_to_indexcol(index, indexcol,
opfamily, idxcollation,
(RowCompareExpr *) clause,
outer_relids);
}
else if (index->amsearchnulls && IsA(clause, NullTest))
{
NullTest *nt = (NullTest *) clause;
if (!nt->argisrow &&
match_index_to_operand((Node *) nt->arg, indexcol, index))
return true;
return false;
}
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 (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
is_indexable_operator(expr_op, opfamily, true))
return true;
/*
* If we didn't find a member of the index's opfamily, see whether it
* is a "special" indexable operator.
*/
if (plain_op &&
match_special_index_operator(clause, opfamily, idxcollation, 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 (IndexCollMatchesExprColl(idxcollation, expr_coll) &&
is_indexable_operator(expr_op, opfamily, false))
return true;
/*
* If we didn't find a member of the index's opfamily, see whether it
* is a "special" indexable operator.
*/
if (match_special_index_operator(clause, opfamily, idxcollation, false))
return true;
return false;
}
return false;
}
/*
* is_indexable_operator
* Does the operator match the specified index opfamily?
*
* If the indexkey is on the right, what we actually want to know
* is whether the operator has a commutator operator that matches
* the opfamily.
*/
static bool
is_indexable_operator(Oid expr_op, Oid opfamily, 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 opfamily */
return op_in_opfamily(expr_op, opfamily);
}
/*
* 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 opfamily,
Oid idxcollation,
RowCompareExpr *clause,
Relids outer_relids)
{
Node *leftop,
*rightop;
Oid expr_op;
Oid expr_coll;
/* 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 opfamily
* shown in the RowCompareExpr be the same as the index column's opfamily,
* but that could fail in the presence of reverse-sort opfamilies: it'd be
* a matter of chance whether RowCompareExpr had picked the forward or
* reverse-sort family. So look only at the operator, and match if it is
* a member of the index's opfamily (after commutation, if the indexkey is
* on the right). We'll worry later about whether any additional
* operators are matchable to the index.
*/
leftop = (Node *) linitial(clause->largs);
rightop = (Node *) linitial(clause->rargs);
expr_op = linitial_oid(clause->opnos);
expr_coll = linitial_oid(clause->inputcollids);
/* Collations must match, if relevant */
if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
return false;
/*
* 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 opfamily member */
switch (get_op_opfamily_strategy(expr_op, opfamily))
{
case BTLessStrategyNumber:
case BTLessEqualStrategyNumber:
case BTGreaterEqualStrategyNumber:
case BTGreaterStrategyNumber:
return true;
}
return false;
}
/****************************************************************************
* ---- ROUTINES TO CHECK ORDERING OPERATORS ----
****************************************************************************/
/*
* match_index_to_pathkeys
* Test whether an index can produce output ordered according to the
* given pathkeys using "ordering operators".
*
* If it can, return a list of suitable ORDER BY expressions, each of the form
* "indexedcol operator pseudoconstant". If not, return NIL.
*/
static List *
match_index_to_pathkeys(IndexOptInfo *index, List *pathkeys)
{
List *orderbyexprs = NIL;
ListCell *lc1;
/* Only indexes with the amcanorderbyop property are interesting here */
if (!index->amcanorderbyop)
return NIL;
foreach(lc1, pathkeys)
{
PathKey *pathkey = (PathKey *) lfirst(lc1);
bool found = false;
ListCell *lc2;
/*
* Note: for any failure to match, we just return NIL immediately.
* There is no value in matching just some of the pathkeys.
*/
/* Pathkey must request default sort order for the target opfamily */
if (pathkey->pk_strategy != BTLessStrategyNumber ||
pathkey->pk_nulls_first)
return NIL;
/* If eclass is volatile, no hope of using an indexscan */
if (pathkey->pk_eclass->ec_has_volatile)
return NIL;
/* Try to match eclass member expression(s) to index */
foreach(lc2, pathkey->pk_eclass->ec_members)
{
EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2);
int indexcol;
/* No possibility of match if it references other relations */
if (!bms_equal(member->em_relids, index->rel->relids))
continue;
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
Expr *expr;
expr = match_clause_to_ordering_op(index,
indexcol,
member->em_expr,
pathkey->pk_opfamily);
if (expr)
{
orderbyexprs = lappend(orderbyexprs, expr);
found = true;
break;
}
}
if (found) /* don't want to look at remaining members */
break;
}
if (!found) /* fail if no match for this pathkey */
return NIL;
}
return orderbyexprs; /* success! */
}
/*
* match_clause_to_ordering_op
* Determines whether an ordering operator expression matches an
* index column.
*
* This is similar to, but simpler than, match_clause_to_indexcol.
* We only care about simple OpExpr cases. The input is a bare
* expression that is being ordered by, which must be of the form
* (indexkey op const) or (const op indexkey) where op is an ordering
* operator for the column's opfamily.
*
* 'index' is the index of interest.
* 'indexcol' is a column number of 'index' (counting from 0).
* 'clause' is the ordering expression to be tested.
* 'pk_opfamily' is the btree opfamily describing the required sort order.
*
* Note that we currently do not consider the collation of the ordering
* operator's result. In practical cases the result type will be numeric
* and thus have no collation, and it's not very clear what to match to
* if it did have a collation. The index's collation should match the
* ordering operator's input collation, not its result.
*
* If successful, return 'clause' as-is if the indexkey is on the left,
* otherwise a commuted copy of 'clause'. If no match, return NULL.
*/
static Expr *
match_clause_to_ordering_op(IndexOptInfo *index,
int indexcol,
Expr *clause,
Oid pk_opfamily)
{
Oid opfamily = index->opfamily[indexcol];
Oid idxcollation = index->indexcollations[indexcol];
Node *leftop,
*rightop;
Oid expr_op;
Oid expr_coll;
Oid sortfamily;
bool commuted;
/*
* Clause must be a binary opclause.
*/
if (!is_opclause(clause))
return NULL;
leftop = get_leftop(clause);
rightop = get_rightop(clause);
if (!leftop || !rightop)
return NULL;
expr_op = ((OpExpr *) clause)->opno;
expr_coll = ((OpExpr *) clause)->inputcollid;
/*
* We can forget the whole thing right away if wrong collation.
*/
if (!IndexCollMatchesExprColl(idxcollation, expr_coll))
return NULL;
/*
* Check for clauses of the form: (indexkey operator constant) or
* (constant operator indexkey).
*/
if (match_index_to_operand(leftop, indexcol, index) &&
!contain_var_clause(rightop) &&
!contain_volatile_functions(rightop))
{
commuted = false;
}
else if (match_index_to_operand(rightop, indexcol, index) &&
!contain_var_clause(leftop) &&
!contain_volatile_functions(leftop))
{
/* Might match, but we need a commuted operator */
expr_op = get_commutator(expr_op);
if (expr_op == InvalidOid)
return NULL;
commuted = true;
}
else
return NULL;
/*
* Is the (commuted) operator an ordering operator for the opfamily? And
* if so, does it yield the right sorting semantics?
*/
sortfamily = get_op_opfamily_sortfamily(expr_op, opfamily);
if (sortfamily != pk_opfamily)
return NULL;
/* We have a match. Return clause or a commuted version thereof. */
if (commuted)
{
OpExpr *newclause = makeNode(OpExpr);
/* flat-copy all the fields of clause */
memcpy(newclause, clause, sizeof(OpExpr));
/* commute it */
newclause->opno = expr_op;
newclause->opfuncid = InvalidOid;
newclause->args = list_make2(rightop, leftop);
clause = (Expr *) newclause;
}
return clause;
}
/****************************************************************************
* ---- ROUTINES TO DO PARTIAL INDEX PREDICATE TESTS ----
****************************************************************************/
/*
* check_partial_indexes
* Check each partial index of the relation, and mark it predOK if
* the index's predicate is satisfied for this query.
*
* Note: it is possible for this to get re-run after adding more restrictions
* to the rel; so we might be able to prove more indexes OK. We assume that
* adding more restrictions can't make an index not OK.
*/
void
check_partial_indexes(PlannerInfo *root, RelOptInfo *rel)
{
List *restrictinfo_list = rel->baserestrictinfo;
ListCell *ilist;
foreach(ilist, rel->indexlist)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist);
if (index->indpred == NIL)
continue; /* ignore non-partial indexes */
if (index->predOK)
continue; /* don't repeat work if already proven OK */
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(PlannerInfo *root, RelOptInfo *rel)
{
Relids outer_relids = NULL;
bool is_child_rel = (rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
ListCell *lc1;
/*
* 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(lc1, rel->joininfo)
{
RestrictInfo *joininfo = (RestrictInfo *) lfirst(lc1);
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);
}
/*
* We also have to look through the query's EquivalenceClasses to see if
* any of them could generate indexable join conditions for this rel.
*/
if (rel->has_eclass_joins)
{
foreach(lc1, root->eq_classes)
{
EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
Relids other_rels = NULL;
bool found_index = false;
ListCell *lc2;
/*
* Won't generate joinclauses if const or single-member (the
* latter test covers the volatile case too)
*/
if (cur_ec->ec_has_const || list_length(cur_ec->ec_members) <= 1)
continue;
/*
* Note we don't test ec_broken; if we did, we'd need a separate
* code path to look through ec_sources. Checking the members
* anyway is OK as a possibly-overoptimistic heuristic.
*/
/*
* No point in searching if rel not mentioned in eclass (but we
* can't tell that for a child rel).
*/
if (!is_child_rel &&
!bms_is_subset(rel->relids, cur_ec->ec_relids))
continue;
/*
* Scan members, looking for both an index match and join
* candidates
*/
foreach(lc2, cur_ec->ec_members)
{
EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
/* Join candidate? */
if (!cur_em->em_is_child &&
!bms_overlap(cur_em->em_relids, rel->relids))
{
other_rels = bms_add_members(other_rels,
cur_em->em_relids);
continue;
}
/* Check for index match (only need one) */
if (!found_index &&
bms_equal(cur_em->em_relids, rel->relids) &&
eclass_matches_any_index(cur_ec, cur_em, rel))
found_index = true;
}
if (found_index)
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;
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
if (match_clause_to_indexcol(index,
indexcol,
rinfo,
outer_relids,
SAOP_ALLOW))
return true;
}
}
return false;
}
/*
* eclass_matches_any_index
* Workhorse for indexable_outerrelids: see if an EquivalenceClass member
* can be matched to any index column of the given rel.
*
* This is also exported for use by find_eclass_clauses_for_index_join.
*/
bool
eclass_matches_any_index(EquivalenceClass *ec, EquivalenceMember *em,
RelOptInfo *rel)
{
ListCell *l;
foreach(l, rel->indexlist)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(l);
int indexcol;
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
Oid curFamily = index->opfamily[indexcol];
Oid curCollation = index->indexcollations[indexcol];
/*
* If it's a btree index, we can reject it if its opfamily isn't
* compatible with the EC, since no clause generated from the EC
* could be used with the index. For non-btree indexes, we can't
* easily tell whether clauses generated from the EC could be used
* with the index, so only check for expression match. This might
* mean we return "true" for a useless index, but that will just
* cause some wasted planner cycles; it's better than ignoring
* useful indexes.
*
* We insist on collation match for all index types, though.
*/
if ((index->relam != BTREE_AM_OID ||
list_member_oid(ec->ec_opfamilies, curFamily)) &&
IndexCollMatchesExprColl(curCollation, ec->ec_collation) &&
match_index_to_operand((Node *) em->em_expr, indexcol, index))
return true;
}
}
return false;
}
/*
* best_inner_indexscan
* Finds the best available inner indexscans for a nestloop join
* with the given rel on the inside and the given outer_rel outside.
*
* *cheapest_startup gets the path with least startup cost
* *cheapest_total gets the path with least total cost (often the same path)
* Both are set to NULL if there are no possible inner indexscans.
*
* We ignore ordering considerations, since a nestloop's inner scan's order
* is uninteresting. Hence startup cost and total cost are the only figures
* of merit to consider.
*
* Note: create_index_paths() must have been run previously for this rel,
* else the results will always be NULL.
*/
void
best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel,
RelOptInfo *outer_rel, JoinType jointype,
Path **cheapest_startup, Path **cheapest_total)
{
Relids outer_relids;
bool isouterjoin;
List *clause_list;
List *indexpaths;
List *bitindexpaths;
List *allindexpaths;
ListCell *l;
InnerIndexscanInfo *info;
MemoryContext oldcontext;
/* Initialize results for failure returns */
*cheapest_startup = *cheapest_total = NULL;
/*
* Nestloop only supports inner, left, semi, and anti joins.
*/
switch (jointype)
{
case JOIN_INNER:
case JOIN_SEMI:
isouterjoin = false;
break;
case JOIN_LEFT:
case JOIN_ANTI:
isouterjoin = true;
break;
default:
return;
}
/*
* If there are no indexable joinclauses for this rel, exit quickly.
*/
if (bms_is_empty(rel->index_outer_relids))
return;
/*
* Otherwise, we have to do path selection in the main planning context,
* 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(root->planner_cxt);
/*
* 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_rel->relids);
if (bms_is_empty(outer_relids))
{
bms_free(outer_relids);
MemoryContextSwitchTo(oldcontext);
return;
}
/*
* 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 combination of rels.)
*
* NOTE: because we cache on outer_relids rather than outer_rel->relids,
* we will report the same paths and hence path cost for joins with
* different sets of irrelevant rels on the outside. Now that cost_index
* is sensitive to outer_rel->rows, this is not really right. However the
* error is probably not large. Is it worth establishing a separate cache
* entry for each distinct outer_rel->relids set to get this right?
*/
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);
*cheapest_startup = info->cheapest_startup_innerpath;
*cheapest_total = info->cheapest_total_innerpath;
return;
}
}
/*
* 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. Also, even if the "best inner
* indexscan" is just a plain indexscan, it will have a different cost
* estimate because of cache effects.
*/
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 executor-managed ScalarArrayOpExpr clauses.
*/
allindexpaths = find_usable_indexes(root, rel,
clause_list, NIL,
false, outer_rel,
SAOP_PER_AM,
ST_ANYSCAN);
/*
* Include the ones that are usable as plain indexscans in indexpaths, and
* include the ones that are usable as bitmap scans in bitindexpaths.
*/
indexpaths = bitindexpaths = NIL;
foreach(l, allindexpaths)
{
IndexPath *ipath = (IndexPath *) lfirst(l);
if (ipath->indexinfo->amhasgettuple)
indexpaths = lappend(indexpaths, ipath);
if (ipath->indexinfo->amhasgetbitmap)
bitindexpaths = lappend(bitindexpaths, ipath);
}
/*
* Generate BitmapOrPaths for any suitable OR-clauses present in the
* clause list.
*/
bitindexpaths = list_concat(bitindexpaths,
generate_bitmap_or_paths(root, rel,
clause_list, NIL,
outer_rel));
/*
* Likewise, generate paths using executor-managed 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, outer_rel));
/*
* 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, outer_rel);
bpath = create_bitmap_heap_path(root, rel, bitmapqual, outer_rel);
indexpaths = lappend(indexpaths, bpath);
}
/*
* Now choose the cheapest members of indexpaths.
*/
if (indexpaths != NIL)
{
*cheapest_startup = *cheapest_total = (Path *) linitial(indexpaths);
for_each_cell(l, lnext(list_head(indexpaths)))
{
Path *path = (Path *) lfirst(l);
if (compare_path_costs(path, *cheapest_startup, STARTUP_COST) < 0)
*cheapest_startup = path;
if (compare_path_costs(path, *cheapest_total, TOTAL_COST) < 0)
*cheapest_total = path;
}
}
/* Cache the results --- whether positive or negative */
info = makeNode(InnerIndexscanInfo);
info->other_relids = outer_relids;
info->isouterjoin = isouterjoin;
info->cheapest_startup_innerpath = *cheapest_startup;
info->cheapest_total_innerpath = *cheapest_total;
rel->index_inner_paths = lcons(info, rel->index_inner_paths);
MemoryContextSwitchTo(oldcontext);
}
/*
* 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. Note
* we'll take anything that's applicable to the join whether it has
* anything to do with an index or not; since we're only building a list,
* it's not worth filtering more finely here.
*/
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);
/*
* Also check to see if any EquivalenceClasses can produce a relevant
* joinclause. Since all such clauses are effectively pushed-down, this
* doesn't apply to outer joins.
*/
if (!isouterjoin && rel->has_eclass_joins)
clause_list = list_concat(clause_list,
find_eclass_clauses_for_index_join(root,
rel,
outer_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 */
clause_list = list_concat(list_copy(rel->baserestrictinfo), clause_list);
return clause_list;
}
/*
* relation_has_unique_index_for
* Determine whether the relation provably has at most one row satisfying
* a set of equality conditions, because the conditions constrain all
* columns of some unique index.
*
* The conditions are provided as a list of RestrictInfo nodes, where the
* caller has already determined that each condition is a mergejoinable
* equality with an expression in this relation on one side, and an
* expression not involving this relation on the other. The transient
* outer_is_left flag is used to identify which side we should look at:
* left side if outer_is_left is false, right side if it is true.
*/
bool
relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel,
List *restrictlist)
{
ListCell *ic;
/* Short-circuit the easy case */
if (restrictlist == NIL)
return false;
/* Examine each index of the relation ... */
foreach(ic, rel->indexlist)
{
IndexOptInfo *ind = (IndexOptInfo *) lfirst(ic);
int c;
/*
* If the index is not unique or if it's a partial index that doesn't
* match the query, it's useless here.
*/
if (!ind->unique || (ind->indpred != NIL && !ind->predOK))
continue;
/*
* Try to find each index column in the list of conditions. This is
* O(n^2) or worse, but we expect all the lists to be short.
*/
for (c = 0; c < ind->ncolumns; c++)
{
ListCell *lc;
foreach(lc, restrictlist)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Node *rexpr;
/*
* The condition's equality operator must be a member of the
* index opfamily, else it is not asserting the right kind of
* equality behavior for this index. We check this first
* since it's probably cheaper than match_index_to_operand().
*/
if (!list_member_oid(rinfo->mergeopfamilies, ind->opfamily[c]))
continue;
/*
* XXX at some point we may need to check collations here too.
* For the moment we assume all collations reduce to the same
* notion of equality.
*/
/* OK, see if the condition operand matches the index key */
if (rinfo->outer_is_left)
rexpr = get_rightop(rinfo->clause);
else
rexpr = get_leftop(rinfo->clause);
if (match_index_to_operand(rexpr, c, ind))
break; /* found a match; column is unique */
}
if (lc == NULL)
break; /* no match; this index doesn't help us */
}
/* Matched all columns of this index? */
if (c == ind->ncolumns)
return true;
}
return false;
}
/****************************************************************************
* ---- 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
*
* Note that we aren't interested in collations here; the caller must check
* for a collation match, if it's dealing with an operator where that matters.
*/
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 opfamily,
* 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 opfamily 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 IsBooleanOpfamily() recognizes the
* index's operator family. 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 opfamily operators.
* Return 'true' if we can do something with it anyway.
*/
static bool
match_special_index_operator(Expr *clause, Oid opfamily, Oid idxcollation,
bool indexkey_on_left)
{
bool isIndexable = false;
Node *rightop;
Oid expr_op;
Oid expr_coll;
Const *patt;
Const *prefix = NULL;
Const *rest = NULL;
Pattern_Prefix_Status pstatus = Pattern_Prefix_None;
/*
* 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;
expr_coll = ((OpExpr *) clause)->inputcollid;
/* 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 */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll,
&prefix, &rest);
isIndexable = (pstatus != Pattern_Prefix_None);
break;
case OID_BYTEA_LIKE_OP:
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll,
&prefix, &rest);
isIndexable = (pstatus != 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 */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC, expr_coll,
&prefix, &rest);
isIndexable = (pstatus != 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 */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex, expr_coll,
&prefix, &rest);
isIndexable = (pstatus != 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 */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC, expr_coll,
&prefix, &rest);
isIndexable = (pstatus != 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 opfamily supports the operators we will
* want to apply. (A hash index, for example, will not support ">=".)
* Currently, only btree supports the operators we need.
*
* Note: actually, in the Pattern_Prefix_Exact case, we only need "=" so a
* hash index would work. Currently it doesn't seem worth checking for
* that, however.
*
* We insist on the opfamily being the specific one we expect, else we'd
* do the wrong thing if someone were to make a reverse-sort opfamily with
* the same operators.
*
* The non-pattern opclasses will not sort the way we need in most non-C
* locales. We can use such an index anyway for an exact match (simple
* equality), but not for prefix-match cases. Note that here we are
* looking at the index's collation, not the expression's collation --
* this test is *not* dependent on the LIKE/regex operator's collation.
*/
switch (expr_op)
{
case OID_TEXT_LIKE_OP:
case OID_TEXT_ICLIKE_OP:
case OID_TEXT_REGEXEQ_OP:
case OID_TEXT_ICREGEXEQ_OP:
isIndexable =
(opfamily == TEXT_PATTERN_BTREE_FAM_OID) ||
(opfamily == TEXT_BTREE_FAM_OID &&
(pstatus == Pattern_Prefix_Exact ||
lc_collate_is_c(idxcollation)));
break;
case OID_BPCHAR_LIKE_OP:
case OID_BPCHAR_ICLIKE_OP:
case OID_BPCHAR_REGEXEQ_OP:
case OID_BPCHAR_ICREGEXEQ_OP:
isIndexable =
(opfamily == BPCHAR_PATTERN_BTREE_FAM_OID) ||
(opfamily == BPCHAR_BTREE_FAM_OID &&
(pstatus == Pattern_Prefix_Exact ||
lc_collate_is_c(idxcollation)));
break;
case OID_NAME_LIKE_OP:
case OID_NAME_ICLIKE_OP:
case OID_NAME_REGEXEQ_OP:
case OID_NAME_ICREGEXEQ_OP:
/* name uses locale-insensitive sorting */
isIndexable = (opfamily == NAME_BTREE_FAM_OID);
break;
case OID_BYTEA_LIKE_OP:
isIndexable = (opfamily == BYTEA_BTREE_FAM_OID);
break;
case OID_INET_SUB_OP:
case OID_INET_SUBEQ_OP:
isIndexable = (opfamily == NETWORK_BTREE_FAM_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
* opfamily) 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 *lc;
int indexcol;
if (clausegroups == NIL)
return NIL;
/* clausegroups must correspond to index columns */
Assert(list_length(clausegroups) <= index->ncolumns);
indexcol = 0;
foreach(lc, clausegroups)
{
List *clausegroup = (List *) lfirst(lc);
Oid curFamily = index->opfamily[indexcol];
Oid curCollation = index->indexcollations[indexcol];
ListCell *lc2;
foreach(lc2, clausegroup)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc2);
Expr *clause = rinfo->clause;
/* First check for boolean cases */
if (IsBooleanOpfamily(curFamily))
{
Expr *boolqual;
boolqual = expand_boolean_index_clause((Node *) clause,
indexcol,
index);
if (boolqual)
{
resultquals = lappend(resultquals,
make_simple_restrictinfo(boolqual));
continue;
}
}
/*
* Else it must be an opclause (usual case), ScalarArrayOp,
* RowCompare, or NullTest
*/
if (is_opclause(clause))
{
resultquals = list_concat(resultquals,
expand_indexqual_opclause(rinfo,
curFamily,
curCollation));
}
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 if (IsA(clause, NullTest))
{
Assert(index->amsearchnulls);
resultquals = lappend(resultquals,
make_simple_restrictinfo(clause));
}
else
elog(ERROR, "unsupported indexqual type: %d",
(int) nodeTag(clause));
}
indexcol++;
}
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),
InvalidOid, InvalidOid);
}
/* 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),
InvalidOid, InvalidOid);
}
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),
InvalidOid, InvalidOid);
}
if (btest->booltesttype == IS_FALSE)
{
/* convert to indexkey = FALSE */
return make_opclause(BooleanEqualOperator, BOOLOID, false,
(Expr *) arg,
(Expr *) makeBoolConst(false, false),
InvalidOid, InvalidOid);
}
/* 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.
*
* In the base case this is just list_make1(), but we have to be prepared to
* expand special cases that were accepted by match_special_index_operator().
*/
static List *
expand_indexqual_opclause(RestrictInfo *rinfo, Oid opfamily, Oid idxcollation)
{
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;
Oid expr_coll = ((OpExpr *) clause)->inputcollid;
Const *patt = (Const *) rightop;
Const *prefix = NULL;
Const *rest = NULL;
Pattern_Prefix_Status pstatus;
/*
* LIKE and regex operators are not members of any btree index opfamily,
* but they can be members of opfamilies for more exotic index types such
* as GIN. Therefore, we should only do expansion if the operator is
* actually not in the opfamily. But checking that requires a syscache
* lookup, so it's best to first see if the operator is one we are
* interested in.
*/
switch (expr_op)
{
case OID_TEXT_LIKE_OP:
case OID_BPCHAR_LIKE_OP:
case OID_NAME_LIKE_OP:
case OID_BYTEA_LIKE_OP:
if (!op_in_opfamily(expr_op, opfamily))
{
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like, expr_coll,
&prefix, &rest);
return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus);
}
break;
case OID_TEXT_ICLIKE_OP:
case OID_BPCHAR_ICLIKE_OP:
case OID_NAME_ICLIKE_OP:
if (!op_in_opfamily(expr_op, opfamily))
{
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Like_IC, expr_coll,
&prefix, &rest);
return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus);
}
break;
case OID_TEXT_REGEXEQ_OP:
case OID_BPCHAR_REGEXEQ_OP:
case OID_NAME_REGEXEQ_OP:
if (!op_in_opfamily(expr_op, opfamily))
{
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex, expr_coll,
&prefix, &rest);
return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus);
}
break;
case OID_TEXT_ICREGEXEQ_OP:
case OID_BPCHAR_ICREGEXEQ_OP:
case OID_NAME_ICREGEXEQ_OP:
if (!op_in_opfamily(expr_op, opfamily))
{
/* the right-hand const is type text for all of these */
pstatus = pattern_fixed_prefix(patt, Pattern_Type_Regex_IC, expr_coll,
&prefix, &rest);
return prefix_quals(leftop, opfamily, idxcollation, prefix, pstatus);
}
break;
case OID_INET_SUB_OP:
case OID_INET_SUBEQ_OP:
if (!op_in_opfamily(expr_op, opfamily))
{
return network_prefix_quals(leftop, expr_op, opfamily,
patt->constvalue);
}
break;
}
/* Default case: just make a list of the unmodified indexqual */
return list_make1(rinfo);
}
/*
* 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 opfamilies.
* 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_lefttype;
Oid op_righttype;
int matching_cols;
Oid expr_op;
List *opfamilies;
List *lefttypes;
List *righttypes;
List *new_ops;
ListCell *largs_cell;
ListCell *rargs_cell;
ListCell *opnos_cell;
ListCell *collids_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_opfamily_properties(expr_op, index->opfamily[indexcol], false,
&op_strategy,
&op_lefttype,
&op_righttype);
/* Build lists of the opfamilies and operator datatypes in case needed */
opfamilies = list_make1_oid(index->opfamily[indexcol]);
lefttypes = list_make1_oid(op_lefttype);
righttypes = list_make1_oid(op_righttype);
/*
* 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));
collids_cell = lnext(list_head(clause->inputcollids));
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_opfamily_strategy(expr_op, index->opfamily[i])
!= op_strategy)
break;
/* Does collation match? */
if (!IndexCollMatchesExprColl(index->indexcollations[i],
lfirst_oid(collids_cell)))
break;
/* Add opfamily and datatypes to lists */
get_op_opfamily_properties(expr_op, index->opfamily[i], false,
&op_strategy,
&op_lefttype,
&op_righttype);
opfamilies = lappend_oid(opfamilies, index->opfamily[i]);
lefttypes = lappend_oid(lefttypes, op_lefttype);
righttypes = lappend_oid(righttypes, op_righttype);
/* This column matches, keep scanning */
matching_cols++;
largs_cell = lnext(largs_cell);
rargs_cell = lnext(rargs_cell);
opnos_cell = lnext(opnos_cell);
collids_cell = lnext(collids_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 *opfamilies_cell;
ListCell *lefttypes_cell;
ListCell *righttypes_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;
lefttypes_cell = list_head(lefttypes);
righttypes_cell = list_head(righttypes);
foreach(opfamilies_cell, opfamilies)
{
Oid opfam = lfirst_oid(opfamilies_cell);
Oid lefttype = lfirst_oid(lefttypes_cell);
Oid righttype = lfirst_oid(righttypes_cell);
expr_op = get_opfamily_member(opfam, lefttype, righttype,
op_strategy);
if (!OidIsValid(expr_op)) /* should not happen */
elog(ERROR, "could not find member %d(%u,%u) of opfamily %u",
op_strategy, lefttype, righttype, opfam);
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(%u,%u) of opfamily %u",
op_strategy, lefttype, righttype, opfam);
}
new_ops = lappend_oid(new_ops, expr_op);
lefttypes_cell = lnext(lefttypes_cell);
righttypes_cell = lnext(righttypes_cell);
}
}
/* 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->opfamilies = list_truncate(list_copy(clause->opfamilies),
matching_cols);
rc->inputcollids = list_truncate(list_copy(clause->inputcollids),
matching_cols);
rc->largs = list_truncate((List *) copyObject(clause->largs),
matching_cols);
rc->rargs = list_truncate((List *) copyObject(clause->rargs),
matching_cols);
return make_simple_restrictinfo((Expr *) rc);
}
else
{
Expr *opexpr;
opexpr = make_opclause(linitial_oid(new_ops), BOOLOID, false,
copyObject(linitial(clause->largs)),
copyObject(linitial(clause->rargs)),
InvalidOid,
linitial_oid(clause->inputcollids));
return make_simple_restrictinfo(opexpr);
}
}
/*
* Given a fixed prefix that all the "leftop" values must have,
* generate suitable indexqual condition(s). opfamily is the index
* operator family; we use it to deduce the appropriate comparison
* operators and operand datatypes. collation is the input collation to use.
*/
static List *
prefix_quals(Node *leftop, Oid opfamily, Oid collation,
Const *prefix_const, Pattern_Prefix_Status pstatus)
{
List *result;
Oid datatype;
Oid oproid;
Expr *expr;
FmgrInfo ltproc;
Const *greaterstr;
Assert(pstatus != Pattern_Prefix_None);
switch (opfamily)
{
case TEXT_BTREE_FAM_OID:
case TEXT_PATTERN_BTREE_FAM_OID:
datatype = TEXTOID;
break;
case BPCHAR_BTREE_FAM_OID:
case BPCHAR_PATTERN_BTREE_FAM_OID:
datatype = BPCHAROID;
break;
case NAME_BTREE_FAM_OID:
datatype = NAMEOID;
break;
case BYTEA_BTREE_FAM_OID:
datatype = BYTEAOID;
break;
default:
/* shouldn't get here */
elog(ERROR, "unexpected opfamily: %u", opfamily);
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 = TextDatumGetCString(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_opfamily_member(opfamily, datatype, datatype,
BTEqualStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no = operator for opfamily %u", opfamily);
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) prefix_const,
InvalidOid, collation);
result = list_make1(make_simple_restrictinfo(expr));
return result;
}
/*
* Otherwise, we have a nonempty required prefix of the values.
*
* We can always say "x >= prefix".
*/
oproid = get_opfamily_member(opfamily, datatype, datatype,
BTGreaterEqualStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no >= operator for opfamily %u", opfamily);
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) prefix_const,
InvalidOid, collation);
result = list_make1(make_simple_restrictinfo(expr));
/*-------
* If we can create a string larger than the prefix, we can say
* "x < greaterstr". NB: we rely on make_greater_string() to generate
* a guaranteed-greater string, not just a probably-greater string.
* In general this is only guaranteed in C locale, so we'd better be
* using a C-locale index collation.
*-------
*/
oproid = get_opfamily_member(opfamily, datatype, datatype,
BTLessStrategyNumber);
if (oproid == InvalidOid)
elog(ERROR, "no < operator for opfamily %u", opfamily);
fmgr_info(get_opcode(oproid), &ltproc);
greaterstr = make_greater_string(prefix_const, &ltproc, collation);
if (greaterstr)
{
expr = make_opclause(oproid, BOOLOID, false,
(Expr *) leftop, (Expr *) greaterstr,
InvalidOid, collation);
result = lappend(result, make_simple_restrictinfo(expr));
}
return result;
}
/*
* Given a leftop and a rightop, and a inet-family sup/sub operator,
* generate suitable indexqual condition(s). expr_op is the original
* operator, and opfamily is the index opfamily.
*/
static List *
network_prefix_quals(Node *leftop, Oid expr_op, Oid opfamily, 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_opfamily_member(opfamily, datatype, datatype,
BTGreaterEqualStrategyNumber);
if (opr1oid == InvalidOid)
elog(ERROR, "no >= operator for opfamily %u", opfamily);
}
else
{
opr1oid = get_opfamily_member(opfamily, datatype, datatype,
BTGreaterStrategyNumber);
if (opr1oid == InvalidOid)
elog(ERROR, "no > operator for opfamily %u", opfamily);
}
opr1right = network_scan_first(rightop);
expr = make_opclause(opr1oid, BOOLOID, false,
(Expr *) leftop,
(Expr *) makeConst(datatype, -1,
InvalidOid, /* not collatable */
-1, opr1right,
false, false),
InvalidOid, InvalidOid);
result = list_make1(make_simple_restrictinfo(expr));
/* create clause "key <= network_scan_last( rightop )" */
opr2oid = get_opfamily_member(opfamily, datatype, datatype,
BTLessEqualStrategyNumber);
if (opr2oid == InvalidOid)
elog(ERROR, "no <= operator for opfamily %u", opfamily);
opr2right = network_scan_last(rightop);
expr = make_opclause(opr2oid, BOOLOID, false,
(Expr *) leftop,
(Expr *) makeConst(datatype, -1,
InvalidOid, /* not collatable */
-1, opr2right,
false, false),
InvalidOid, InvalidOid);
result = lappend(result, make_simple_restrictinfo(expr));
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 CStringGetTextDatum() 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 CStringGetTextDatum(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);
Oid collation;
int constlen;
/*
* We only need to support a few datatypes here, so hard-wire properties
* instead of incurring the expense of catalog lookups.
*/
switch (datatype)
{
case TEXTOID:
case VARCHAROID:
case BPCHAROID:
collation = DEFAULT_COLLATION_OID;
constlen = -1;
break;
case NAMEOID:
collation = InvalidOid;
constlen = NAMEDATALEN;
break;
case BYTEAOID:
collation = InvalidOid;
constlen = -1;
break;
default:
elog(ERROR, "unexpected datatype in string_to_const: %u",
datatype);
return NULL;
}
return makeConst(datatype, -1, collation, constlen,
conval, false, false);
}