/* ------------------------------------------------------------------------- * * restrictinfo.cpp * RestrictInfo node manipulation routines. * * Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd. * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/gausskernel/optimizer/util/restrictinfo.cpp * * ------------------------------------------------------------------------- */ #include "postgres.h" #include "knl/knl_variable.h" #include "optimizer/clauses.h" #include "optimizer/predtest.h" #include "optimizer/restrictinfo.h" #include "optimizer/var.h" static RestrictInfo* make_restrictinfo_internal(Expr* clause, Expr* orclause, bool is_pushed_down, bool outerjoin_delayed, bool pseudoconstant, Index security_level, Relids required_relids, Relids outer_relids, Relids nullable_relids); static Expr* make_sub_restrictinfos(Expr* clause, bool is_pushed_down, bool outerjoin_delayed, bool pseudoconstant, Index sucurity_level, Relids required_relids, Relids outer_relids, Relids nullable_relids); /* * * Build a RestrictInfo node containing the given subexpression. * * The is_pushed_down, outerjoin_delayed, and pseudoconstant flags for the * RestrictInfo must be supplied by the caller, as well as the correct values * for security_level, outer_relids, and nullable_relids. * required_relids can be NULL, in which case it defaults to the actual * clause contents (i.e., clause_relids). * * We initialize fields that depend only on the given subexpression, leaving * others that depend on context (or may never be needed at all) to be filled * later. */ RestrictInfo* make_restrictinfo(Expr* clause, bool is_pushed_down, bool outerjoin_delayed, bool pseudoconstant, Index security_level, Relids required_relids, Relids outer_relids, Relids nullable_relids) { /* * If it's an OR clause, build a modified copy with RestrictInfos inserted * above each subclause of the top-level AND/OR structure. */ if (or_clause((Node*)clause)) return (RestrictInfo*)make_sub_restrictinfos(clause, is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, required_relids, outer_relids, nullable_relids); /* Shouldn't be an AND clause, else AND/OR flattening messed up */ AssertEreport(!and_clause((Node*)clause), MOD_OPT, ""); return make_restrictinfo_internal(clause, NULL, is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, required_relids, outer_relids, nullable_relids); } /* * make_restrictinfo_from_bitmapqual * * Given the bitmapqual Path structure for a bitmap indexscan, generate * RestrictInfo node(s) equivalent to the condition represented by the * indexclauses of the Path structure. * * The result is a List (effectively, implicit-AND representation) of * RestrictInfos. * * The caller must pass is_pushed_down, but we assume outerjoin_delayed * and pseudoconstant are false while outer_relids and nullable_relids * are NULL (no other kind of qual should ever get into a bitmapqual). * * If include_predicates is true, we add any partial index predicates to * the explicit index quals. When this is not true, we return a condition * that might be weaker than the actual scan represents. * * To do this through the normal make_restrictinfo() API, callers would have * to strip off the RestrictInfo nodes present in the indexclauses lists, and * then make_restrictinfo() would have to build new ones. It's better to have * a specialized routine to allow sharing of RestrictInfos. * * The qual manipulations here are much the same as in create_bitmap_subplan; * keep the two routines in sync! */ List* make_restrictinfo_from_bitmapqual(Path* bitmapqual, bool is_pushed_down, bool include_predicates) { List* result = NIL; ListCell* l = NULL; if (IsA(bitmapqual, BitmapAndPath)) { BitmapAndPath* apath = (BitmapAndPath*)bitmapqual; /* * There may well be redundant quals among the subplans, since a * top-level WHERE qual might have gotten used to form several * different index quals. We don't try exceedingly hard to eliminate * redundancies, but we do eliminate obvious duplicates by using * list_concat_unique. */ result = NIL; foreach (l, apath->bitmapquals) { List* sublist = NIL; sublist = make_restrictinfo_from_bitmapqual((Path*)lfirst(l), is_pushed_down, include_predicates); result = list_concat_unique(result, sublist); } } else if (IsA(bitmapqual, BitmapOrPath)) { BitmapOrPath* opath = (BitmapOrPath*)bitmapqual; List* withris = NIL; List* withoutris = NIL; /* * Here, we only detect qual-free subplans. A qual-free subplan would * cause us to generate "... OR true ..." which we may as well reduce * to just "true". We do not try to eliminate redundant subclauses * because (a) it's not as likely as in the AND case, and (b) we might * well be working with hundreds or even thousands of OR conditions, * perhaps from a long IN list. The performance of list_append_unique * would be unacceptable. */ foreach (l, opath->bitmapquals) { List* sublist = NIL; sublist = make_restrictinfo_from_bitmapqual((Path*)lfirst(l), is_pushed_down, include_predicates); if (sublist == NIL) { /* * If we find a qual-less subscan, it represents a constant * TRUE, and hence the OR result is also constant TRUE, so we * can stop here. */ return NIL; } /* * If the sublist contains multiple RestrictInfos, we create an * AND subclause. If there's just one, we have to check if it's * an OR clause, and if so flatten it to preserve AND/OR flatness * of our output. * * We construct lists with and without sub-RestrictInfos, so as * not to have to regenerate duplicate RestrictInfos below. */ if (list_length(sublist) > 1) { withris = lappend(withris, make_andclause(sublist)); sublist = get_actual_clauses(sublist); withoutris = lappend(withoutris, make_andclause(sublist)); } else { RestrictInfo* subri = (RestrictInfo*)linitial(sublist); AssertEreport(IsA(subri, RestrictInfo), MOD_OPT, ""); if (restriction_is_or_clause(subri)) { BoolExpr* subor = (BoolExpr*)subri->orclause; AssertEreport(or_clause((Node*)subor), MOD_OPT, ""); withris = list_concat(withris, list_copy(subor->args)); subor = (BoolExpr*)subri->clause; AssertEreport(or_clause((Node*)subor), MOD_OPT, ""); withoutris = list_concat(withoutris, list_copy(subor->args)); } else { withris = lappend(withris, subri); withoutris = lappend(withoutris, subri->clause); } } } /* * Avoid generating one-element ORs, which could happen due to * redundancy elimination or ScalarArrayOpExpr quals. */ if (list_length(withris) <= 1) result = withris; else { /* Here's the magic part not available to outside callers */ result = list_make1(make_restrictinfo_internal( make_orclause(withoutris), make_orclause(withris), is_pushed_down, false, false, 0, NULL, NULL, NULL)); } } else if (IsA(bitmapqual, IndexPath)) { IndexPath* ipath = (IndexPath*)bitmapqual; result = list_copy(ipath->indexclauses); if (include_predicates && ipath->indexinfo->indpred != NIL) { foreach (l, ipath->indexinfo->indpred) { Expr* pred = (Expr*)lfirst(l); /* * We know that the index predicate must have been implied by * the query condition as a whole, but it may or may not be * implied by the conditions that got pushed into the * bitmapqual. Avoid generating redundant conditions. */ if (!predicate_implied_by(list_make1(pred), result)) result = lappend(result, make_restrictinfo(pred, is_pushed_down, false, false, 0, NULL, NULL, NULL)); } } } else { ereport(ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", nodeTag(bitmapqual)))); result = NIL; /* keep compiler quiet */ } return result; } /* * make_restrictinfos_from_actual_clauses * * Given a list of implicitly-ANDed restriction clauses, produce a list * of RestrictInfo nodes. This is used to reconstitute the RestrictInfo * representation after doing transformations of a list of clauses. * * We assume that the clauses are relation-level restrictions and therefore * we don't have to worry about is_pushed_down, outerjoin_delayed, * outer_relids, and nullable_relids (these can be assumed true, false, * NULL, and NULL, respectively). * We do take care to recognize pseudoconstant clauses properly. */ List* make_restrictinfos_from_actual_clauses(PlannerInfo* root, List* clause_list) { List* result = NIL; ListCell* l = NULL; foreach (l, clause_list) { Expr* clause = (Expr*)lfirst(l); bool pseudoconstant = false; RestrictInfo* rinfo = NULL; /* * It's pseudoconstant if it contains no Vars and no volatile * functions. We probably can't see any sublinks here, so * contain_var_clause() would likely be enough, but for safety use * contain_vars_of_level() instead. */ pseudoconstant = !contain_vars_of_level((Node*)clause, 0) && !contain_volatile_functions((Node*)clause); if (pseudoconstant) { /* tell createplan.c to check for gating quals */ root->hasPseudoConstantQuals = true; } rinfo = make_restrictinfo(clause, true, false, pseudoconstant, 0, NULL, NULL, NULL); result = lappend(result, rinfo); } return result; } /* * make_restrictinfo_internal * * Common code for the main entry points and the recursive cases. */ static RestrictInfo* make_restrictinfo_internal(Expr* clause, Expr* orclause, bool is_pushed_down, bool outerjoin_delayed, bool pseudoconstant, Index security_level, Relids required_relids, Relids outer_relids, Relids nullable_relids) { RestrictInfo* restrictinfo = makeNode(RestrictInfo); errno_t rc = EOK; /* Initialize rc to keep compiler slient */ restrictinfo->clause = clause; restrictinfo->orclause = orclause; restrictinfo->is_pushed_down = is_pushed_down; restrictinfo->outerjoin_delayed = outerjoin_delayed; restrictinfo->pseudoconstant = pseudoconstant; restrictinfo->can_join = false; /* may get set below */ restrictinfo->security_level = security_level; restrictinfo->outer_relids = outer_relids; restrictinfo->nullable_relids = nullable_relids; /* * If it's potentially delayable by lower-level security quals, figure out * whether it's leakproof. We can skip testing this for level-zero quals, * since they would never get delayed on security grounds anyway. */ if (security_level > 0) restrictinfo->leakproof = (contain_leaky_functions((Node*)clause) == false); else restrictinfo->leakproof = false; /* really, "don't know" */ /* * If it's a binary opclause, set up left/right relids info. In any case * set up the total clause relids info. */ if (is_opclause(clause) && list_length(((OpExpr*)clause)->args) == 2) { restrictinfo->left_relids = pull_varnos(get_leftop(clause)); restrictinfo->right_relids = pull_varnos(get_rightop(clause)); restrictinfo->clause_relids = bms_union(restrictinfo->left_relids, restrictinfo->right_relids); /* * Does it look like a normal join clause, i.e., a binary operator * relating expressions that come from distinct relations? If so we * might be able to use it in a join algorithm. Note that this is a * purely syntactic test that is made regardless of context. */ if (!bms_is_empty(restrictinfo->left_relids) && !bms_is_empty(restrictinfo->right_relids) && !bms_overlap(restrictinfo->left_relids, restrictinfo->right_relids)) { restrictinfo->can_join = true; /* pseudoconstant should certainly not be true */ AssertEreport(!restrictinfo->pseudoconstant, MOD_OPT, ""); } } else { /* Not a binary opclause, so mark left/right relid sets as empty */ restrictinfo->left_relids = NULL; restrictinfo->right_relids = NULL; /* and get the total relid set the hard way */ restrictinfo->clause_relids = pull_varnos((Node*)clause); } /* required_relids defaults to clause_relids */ if (required_relids != NULL) restrictinfo->required_relids = required_relids; else restrictinfo->required_relids = restrictinfo->clause_relids; /* * Fill in all the cacheable fields with "not yet set" markers. None of * these will be computed until/unless needed. Note in particular that we * don't mark a binary opclause as mergejoinable or hashjoinable here; * that happens only if it appears in the right context (top level of a * joinclause list). */ restrictinfo->parent_ec = NULL; restrictinfo->eval_cost.startup = -1; restrictinfo->norm_selec = -1; restrictinfo->outer_selec = -1; restrictinfo->mergeopfamilies = NIL; restrictinfo->left_ec = NULL; restrictinfo->right_ec = NULL; restrictinfo->left_em = NULL; restrictinfo->right_em = NULL; restrictinfo->scansel_cache = NIL; restrictinfo->outer_is_left = false; restrictinfo->hashjoinoperator = InvalidOid; rc = memset_s(&restrictinfo->left_bucketsize, sizeof(BucketSize), 0, sizeof(BucketSize)); securec_check(rc, "\0", "\0"); rc = memset_s(&restrictinfo->right_bucketsize, sizeof(BucketSize), 0, sizeof(BucketSize)); securec_check(rc, "\0", "\0"); return restrictinfo; } /* * Recursively insert sub-RestrictInfo nodes into a boolean expression. * * We put RestrictInfos above simple (non-AND/OR) clauses and above * sub-OR clauses, but not above sub-AND clauses, because there's no need. * This may seem odd but it is closely related to the fact that we use * implicit-AND lists at top level of RestrictInfo lists. Only ORs and * simple clauses are valid RestrictInfos. * * The same is_pushed_down, outerjoin_delayed, and pseudoconstant flag * values can be applied to all RestrictInfo nodes in the result. Likewise * for security_level, outer_relids and nullable_relids. * * The given required_relids are attached to our top-level output, * but any OR-clause constituents are allowed to default to just the * contained rels. */ static Expr* make_sub_restrictinfos(Expr* clause, bool is_pushed_down, bool outerjoin_delayed, bool pseudoconstant, Index security_level, Relids required_relids, Relids outer_relids, Relids nullable_relids) { if (or_clause((Node*)clause)) { List* orlist = NIL; ListCell* temp = NULL; foreach (temp, ((BoolExpr*)clause)->args) orlist = lappend(orlist, make_sub_restrictinfos((Expr*)lfirst(temp), is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, NULL, outer_relids, nullable_relids)); return (Expr*)make_restrictinfo_internal(clause, make_orclause(orlist), is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, required_relids, outer_relids, nullable_relids); } else if (and_clause((Node*)clause)) { List* andlist = NIL; ListCell* temp = NULL; foreach (temp, ((BoolExpr*)clause)->args) andlist = lappend(andlist, make_sub_restrictinfos((Expr*)lfirst(temp), is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, required_relids, outer_relids, nullable_relids)); return make_andclause(andlist); } else return (Expr*)make_restrictinfo_internal(clause, NULL, is_pushed_down, outerjoin_delayed, pseudoconstant, security_level, required_relids, outer_relids, nullable_relids); } /* * restriction_is_or_clause * * Returns t iff the restrictinfo node contains an 'or' clause. */ bool restriction_is_or_clause(RestrictInfo* restrictinfo) { if (restrictinfo->orclause != NULL) return true; else return false; } /* * restriction_is_securely_promotable * * Returns true if it's okay to evaluate this clause "early", that is before * other restriction clauses attached to the specified relation. */ bool restriction_is_securely_promotable(RestrictInfo* restrictinfo, RelOptInfo* rel) { /* * It's okay if there are no baserestrictinfo clauses for the rel that * would need to go before this one, *or* if this one is leakproof. */ if ((restrictinfo->security_level <= rel->baserestrict_min_security) || restrictinfo->leakproof) return true; else return false; } /* * get_actual_clauses * * Returns a list containing the bare clauses from 'restrictinfo_list'. * * This is only to be used in cases where none of the RestrictInfos can * be pseudoconstant clauses (for instance, it's OK on indexqual lists). */ List* get_actual_clauses(List* restrictinfo_list) { List* result = NIL; ListCell* l = NULL; foreach (l, restrictinfo_list) { RestrictInfo* rinfo = (RestrictInfo*)lfirst(l); AssertEreport(IsA(rinfo, RestrictInfo), MOD_OPT, ""); AssertEreport(!rinfo->pseudoconstant, MOD_OPT, ""); result = lappend(result, rinfo->clause); } return result; } /* * get_all_actual_clauses * * Returns a list containing the bare clauses from 'restrictinfo_list'. * * This loses the distinction between regular and pseudoconstant clauses, * so be careful what you use it for. */ List* get_all_actual_clauses(List* restrictinfo_list) { List* result = NIL; ListCell* l = NULL; foreach (l, restrictinfo_list) { RestrictInfo* rinfo = (RestrictInfo*)lfirst(l); AssertEreport(IsA(rinfo, RestrictInfo), MOD_OPT, ""); result = lappend(result, rinfo->clause); } return result; } /* * extract_actual_clauses * * Extract bare clauses from 'restrictinfo_list', returning either the * regular ones or the pseudoconstant ones per 'pseudoconstant'. */ List* extract_actual_clauses(List* restrictinfo_list, bool pseudoconstant) { List* result = NIL; ListCell* l = NULL; foreach (l, restrictinfo_list) { RestrictInfo* rinfo = (RestrictInfo*)lfirst(l); AssertEreport(IsA(rinfo, RestrictInfo), MOD_OPT, ""); /* we consider the qual is real if pseudoconstant is true and clause_relids is non-null. */ if ((rinfo->pseudoconstant == pseudoconstant) && (!pseudoconstant || bms_is_empty(rinfo->clause_relids))) { result = lappend(result, rinfo->clause); } } return result; } /* * extract_actual_join_clauses * * Extract bare clauses from 'restrictinfo_list', separating those that * syntactically match the join level from those that were pushed down. * Pseudoconstant clauses are excluded from the results. * * This is only used at outer joins, since for plain joins we don't care * about pushed-down-ness. */ void extract_actual_join_clauses(List* restrictinfo_list, List** joinquals, List** otherquals) { ListCell* l = NULL; *joinquals = NIL; *otherquals = NIL; foreach (l, restrictinfo_list) { RestrictInfo* rinfo = (RestrictInfo*)lfirst(l); AssertEreport(IsA(rinfo, RestrictInfo), MOD_OPT, ""); if (rinfo->is_pushed_down) { if (!rinfo->pseudoconstant) *otherquals = lappend(*otherquals, rinfo->clause); } else { /* joinquals shouldn't have been marked pseudoconstant */ AssertEreport(!rinfo->pseudoconstant, MOD_OPT, ""); *joinquals = lappend(*joinquals, rinfo->clause); } } } /* * join_clause_is_movable_to * Test whether a join clause is a safe candidate for parameterization * of a scan on the specified base relation. * * A movable join clause is one that can safely be evaluated at a rel below * its normal semantic level (ie, its required_relids), if the values of * variables that it would need from other rels are provided. * * We insist that the clause actually reference the target relation; this * prevents undesirable movement of degenerate join clauses, and ensures * that there is a unique place that a clause can be moved down to. * * We cannot move an outer-join clause into the non-nullable side of its * outer join, as that would change the results (rows would be suppressed * rather than being null-extended). * * Also there must not be an outer join below the clause that would null the * Vars coming from the target relation. Otherwise the clause might give * results different from what it would give at its normal semantic level. */ bool join_clause_is_movable_to(RestrictInfo* rinfo, Index baserelid) { /* Clause must physically reference target rel */ if (!bms_is_member(baserelid, rinfo->clause_relids)) return false; /* Cannot move an outer-join clause into the join's outer side */ if (bms_is_member(baserelid, rinfo->outer_relids)) return false; /* Target rel must not be nullable below the clause */ if (bms_is_member(baserelid, rinfo->nullable_relids)) return false; return true; } /* * join_clause_is_movable_into * Test whether a join clause is movable and can be evaluated within * the current join context. * * currentrelids: the relids of the proposed evaluation location * current_and_outer: the union of currentrelids and the required_outer * relids (parameterization's outer relations) * * The API would be a bit clearer if we passed the current relids and the * outer relids separately and did bms_union internally; but since most * callers need to apply this function to multiple clauses, we make the * caller perform the union. * * Obviously, the clause must only refer to Vars available from the current * relation plus the outer rels. We also check that it does reference at * least one current Var, ensuring that the clause will be pushed down to * a unique place in a parameterized join tree. And we check that we're * not pushing the clause into its outer-join outer side, nor down into * a lower outer join's inner side. * * The check about pushing a clause down into a lower outer join's inner side * is only approximate; it sometimes returns "false" when actually it would * be safe to use the clause here because we're still above the outer join * in question. This is okay as long as the answers at different join levels * are consistent: it just means we might sometimes fail to push a clause as * far down as it could safely be pushed. It's unclear whether it would be * worthwhile to do this more precisely. (But if it's ever fixed to be * exactly accurate, there's an Assert in get_joinrel_parampathinfo() that * should be re-enabled.) * * Note: if this returns true, it means that the clause could be moved to * this join relation, but that doesn't mean that this is the lowest join * it could be moved to. Caller may need to make additional calls to verify * that this doesn't succeed on either of the inputs of a proposed join. * * Note: get_joinrel_parampathinfo depends on the fact that if * current_and_outer is NULL, this function will always return false * (since one or the other of the first two tests must fail). */ bool join_clause_is_movable_into(RestrictInfo* rinfo, Relids currentrelids, Relids current_and_outer) { /* Clause must be evaluatable given available context */ if (!bms_is_subset(rinfo->clause_relids, current_and_outer)) return false; /* Clause must physically reference at least one target rel */ if (!bms_overlap(currentrelids, rinfo->clause_relids)) return false; /* Cannot move an outer-join clause into the join's outer side */ if (bms_overlap(currentrelids, rinfo->outer_relids)) return false; /* * Target rel(s) must not be nullable below the clause. This is * approximate, in the safe direction, because the current join might be * above the join where the nulling would happen, in which case the clause * would work correctly here. But we don't have enough info to be sure. */ if (bms_overlap(currentrelids, rinfo->nullable_relids)) return false; return true; }