diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c index c721054787..0942cba00b 100644 --- a/src/backend/optimizer/plan/subselect.c +++ b/src/backend/optimizer/plan/subselect.c @@ -87,6 +87,8 @@ static bool contain_dml(Node *node); static bool contain_dml_walker(Node *node, void *context); static void inline_cte(PlannerInfo *root, CommonTableExpr *cte); static bool inline_cte_walker(Node *node, inline_cte_walker_context *context); +static bool is_NOTANY_compatible_with_antijoin(Query *outerquery, + SubLink * sublink); static bool simplify_EXISTS_query(PlannerInfo *root, Query *query); static Query *convert_EXISTS_to_ANY(PlannerInfo *root, Query *subselect, Node **testexpr, List **paramIds); @@ -1108,6 +1110,118 @@ inline_cte_walker(Node *node, inline_cte_walker_context *context) } +/* + * is_NOTANY_compatible_with_antijoin + * True if the NOT IN sublink can be safely converted into an ANTI JOIN. + * Per SQL spec, NOT IN is not ordinarily equivalent to an anti-join, + * however, if we can prove that all of the expressions on both sides of + * the would be join condition are all certainly not NULL, then it's safe + * to convert NOT IN to an anti-join. + * + * Note: + * This function is quite locked into the NOT IN syntax. Certain assumptions + * are made about the structure of the join conditions: + * + * 1. We assume that when more than 1 join condition exists that these are + * AND type conditions, i.e not OR conditions. + * + * 2. We assume that each join qual has 2 arguments and the first arguments + * in each join qual is the one that belongs to the outer side of the + * NOT IN clause. + */ +static bool +is_NOTANY_compatible_with_antijoin(Query *outerquery, SubLink *sublink) +{ + ListCell *lc; + List *outerexpr; + List *innerexpr; + Node *testexpr = sublink->testexpr; + Query *subselect = (Query *) sublink->subselect; + + /* + * We must build 2 lists of expressions, one for the outer query side and + * one for the subquery/inner side of the NOT IN clause. It is these lists + * that we pass to to expressions_are_not_nullable to allow it to determine + * if each expression cannot contain NULL values or not. We'll try and be + * as lazy about this as possible and we won't bother generating the 2nd + * list if the first list can't be proved to be free from null-able + * expressions. The order that we checks these lists does not really matter + * as neither one seems to be more likely to allow us to exit from this + * function more quickly. + */ + + /* if it's a single expression */ + if (IsA(testexpr, OpExpr)) + { + OpExpr *opexpr = (OpExpr *) testexpr; + + Assert(list_length(opexpr->args) == 2); + + outerexpr = list_make1(linitial(opexpr->args)); + } + + /* multiple expressions ANDed together */ + else if (IsA(testexpr, BoolExpr)) + { + List *list = ((BoolExpr *) testexpr)->args; + + outerexpr = NIL; + + /* loop through each expression appending to the list each iteration. */ + foreach(lc, list) + { + OpExpr *opexpr = (OpExpr *) lfirst(lc); + + Assert(list_length(opexpr->args) == 2); + + outerexpr = lappend(outerexpr, linitial(opexpr->args)); + } + } + else + elog(ERROR, "unrecognized node type: %d", + (int) nodeTag(testexpr)); + + if (outerexpr == NIL) + elog(ERROR, "unexpected empty clause"); + + /* + * Check the expressions being used in the outer query side of the NOT IN + * clause to ensure NULLs are not possible. + */ + if (!expressions_are_not_nullable(outerquery, outerexpr)) + return false; + + /* + * Now we check to ensure each TargetEntry in the subquery can be proved to + * never be NULL. + */ + + innerexpr = NIL; + + foreach(lc, subselect->targetList) + { + TargetEntry *tle = (TargetEntry *) lfirst(lc); + + /* Resjunk columns can be ignored: they don't produce output values */ + if (tle->resjunk) + continue; + + innerexpr = lappend(innerexpr, tle->expr); + } + + if (innerexpr == NIL) + elog(ERROR, "unexpected empty clause"); + + /* + * Check if all the subquery's targetlist columns can be proved to be not + * null. + */ + if (!expressions_are_not_nullable(subselect, innerexpr)) + return false; + + return true; /* supports ANTI JOIN */ +} + /* * convert_ANY_sublink_to_join: try to convert an ANY SubLink to a join * @@ -1117,11 +1231,14 @@ inline_cte_walker(Node *node, inline_cte_walker_context *context) * If so, form a JoinExpr and return it. Return NULL if the SubLink cannot * be converted to a join. * - * The only non-obvious input parameter is available_rels: this is the set - * of query rels that can safely be referenced in the sublink expression. - * (We must restrict this to avoid changing the semantics when a sublink - * is present in an outer join's ON qual.) The conversion must fail if - * the converted qual would reference any but these parent-query relids. + * If under_not is true, the caller actually found NOT (ANY SubLink), + * so that what we must try to build is an ANTI not SEMI join. + * + * available_rels is the set of query rels that can safely be referenced + * in the sublink expression. (We must restrict this to avoid changing the + * semantics when a sublink is present in an outer join's ON qual.) + * The conversion must fail if the converted qual would reference any but + * these parent-query relids. * * On success, the returned JoinExpr has larg = NULL and rarg = the jointree * item representing the pulled-up subquery. The caller must set larg to @@ -1144,7 +1261,7 @@ inline_cte_walker(Node *node, inline_cte_walker_context *context) */ JoinExpr * convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, - Relids available_rels) + bool under_not, Relids available_rels) { JoinExpr *result; Query *parse = root->parse; @@ -1159,6 +1276,16 @@ convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, Assert(sublink->subLinkType == ANY_SUBLINK); + /* + * Per SQL spec, NOT IN is not ordinarily equivalent to an anti-join, so + * that by default we have to fail when under_not. However, if we can + * prove that all of the expressions on both sides of the, would be, join + * condition are all certainly not NULL, then it's safe to convert NOT IN + * to an anti-join. + */ + if (under_not && !is_NOTANY_compatible_with_antijoin(parse, sublink)) + return NULL; + /* * The sub-select must not refer to any Vars of the parent query. (Vars of * higher levels should be okay, though.) @@ -1228,7 +1355,7 @@ convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, * And finally, build the JoinExpr node. */ result = makeNode(JoinExpr); - result->jointype = JOIN_SEMI; + result->jointype = under_not ? JOIN_ANTI : JOIN_SEMI; result->isNatural = false; result->larg = NULL; /* caller must fill this in */ result->rarg = (Node *) rtr; @@ -1243,9 +1370,7 @@ convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, /* * convert_EXISTS_sublink_to_join: try to convert an EXISTS SubLink to a join * - * The API of this function is identical to convert_ANY_sublink_to_join's, - * except that we also support the case where the caller has found NOT EXISTS, - * so we need an additional input parameter "under_not". + * The API of this function is identical to convert_ANY_sublink_to_join's. */ JoinExpr * convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink, diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c index aebe162713..bab2b37fa7 100644 --- a/src/backend/optimizer/prep/prepjointree.c +++ b/src/backend/optimizer/prep/prepjointree.c @@ -388,7 +388,7 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, /* Is it a convertible ANY or EXISTS clause? */ if (sublink->subLinkType == ANY_SUBLINK) { - if ((j = convert_ANY_sublink_to_join(root, sublink, + if ((j = convert_ANY_sublink_to_join(root, sublink, false, available_rels1)) != NULL) { /* Yes; insert the new join node into the join tree */ @@ -414,7 +414,7 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, return NULL; } if (available_rels2 != NULL && - (j = convert_ANY_sublink_to_join(root, sublink, + (j = convert_ANY_sublink_to_join(root, sublink, false, available_rels2)) != NULL) { /* Yes; insert the new join node into the join tree */ @@ -499,14 +499,68 @@ pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, } if (is_notclause(node)) { - /* If the immediate argument of NOT is EXISTS, try to convert */ + /* If the immediate argument of NOT is ANY or EXISTS, try to convert */ SubLink *sublink = (SubLink *) get_notclausearg((Expr *) node); JoinExpr *j; Relids child_rels; if (sublink && IsA(sublink, SubLink)) { - if (sublink->subLinkType == EXISTS_SUBLINK) + if (sublink->subLinkType == ANY_SUBLINK) + { + if ((j = convert_ANY_sublink_to_join(root, sublink, true, + available_rels1)) != NULL) + { + /* Yes; insert the new join node into the join tree */ + j->larg = *jtlink1; + *jtlink1 = (Node *) j; + /* Recursively process pulled-up jointree nodes */ + j->rarg = pull_up_sublinks_jointree_recurse(root, + j->rarg, + &child_rels); + + /* + * Now recursively process the pulled-up quals. Because + * we are underneath a NOT, we can't pull up sublinks that + * reference the left-hand stuff, but it's still okay to + * pull up sublinks referencing j->rarg. + */ + j->quals = pull_up_sublinks_qual_recurse(root, + j->quals, + &j->rarg, + child_rels, + NULL, NULL); + /* Return NULL representing constant TRUE */ + return NULL; + } + if (available_rels2 != NULL && + (j = convert_ANY_sublink_to_join(root, sublink, true, + available_rels2)) != NULL) + { + /* Yes; insert the new join node into the join tree */ + j->larg = *jtlink2; + *jtlink2 = (Node *) j; + /* Recursively process pulled-up jointree nodes */ + j->rarg = pull_up_sublinks_jointree_recurse(root, + j->rarg, + &child_rels); + + /* + * Now recursively process the pulled-up quals. Because + * we are underneath a NOT, we can't pull up sublinks that + * reference the left-hand stuff, but it's still okay to + * pull up sublinks referencing j->rarg. + */ + j->quals = pull_up_sublinks_qual_recurse(root, + j->quals, + &j->rarg, + child_rels, + NULL, NULL); + /* Return NULL representing constant TRUE */ + return NULL; + } + } + else if (sublink->subLinkType == EXISTS_SUBLINK) { if ((j = convert_EXISTS_sublink_to_join(root, sublink, true, available_rels1)) != NULL) diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index 3737166e8f..239ff93038 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -42,6 +42,7 @@ #include "parser/parse_agg.h" #include "parser/parse_coerce.h" #include "parser/parse_func.h" +#include "parser/parsetree.h" #include "rewrite/rewriteManip.h" #include "tcop/tcopprot.h" #include "utils/acl.h" @@ -113,6 +114,8 @@ static bool contain_context_dependent_node_walker(Node *node, int *flags); static bool contain_leaked_vars_walker(Node *node, void *context); static Relids find_nonnullable_rels_walker(Node *node, bool top_level); static List *find_nonnullable_vars_walker(Node *node, bool top_level); +static void find_innerjoined_rels(Node *jtnode, + Relids *innerjoined_rels, List **usable_quals); static bool is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK); static Node *eval_const_expressions_mutator(Node *node, eval_const_expressions_context *context); @@ -1458,6 +1461,10 @@ contain_leaked_vars_walker(Node *node, void *context) context); } +/***************************************************************************** + * Nullability analysis + *****************************************************************************/ + /* * find_nonnullable_rels * Determine which base rels are forced nonnullable by given clause. @@ -1701,7 +1708,7 @@ find_nonnullable_rels_walker(Node *node, bool top_level) * but here we assume that the input is a Boolean expression, and wish to * see if NULL inputs will provably cause a FALSE-or-NULL result. We expect * the expression to have been AND/OR flattened and converted to implicit-AND - * format. + * format (but the results are still good if it wasn't AND/OR flattened). * * The result is a palloc'd List, but we have not copied the member Var nodes. * Also, we don't bother trying to eliminate duplicate entries. @@ -2002,6 +2009,234 @@ find_forced_null_var(Node *node) return NULL; } +/* + * expressions_are_not_nullable + * Returns TRUE if each Expr in the expression list is certainly not NULL. + * All Exprs must return non-NULL to answer TRUE. + * + * The reason this takes a Query, and not just an individual tlist expression, + * is so that we can make use of the query's WHERE/ON clauses to prove it does + * not return nulls. + * + * In current usage, the passed sub-Query hasn't yet been through any planner + * processing. This means that applying find_nonnullable_vars() to its WHERE + * clauses isn't really ideal: for lack of const-simplification, we might be + * unable to prove not-nullness in some cases where we could have proved it + * afterwards. However, we should not get any false positive results. + * + * Like the other forms of nullability analysis above, we can err on the + * side of conservatism: if we're not sure, it's okay to return FALSE. + */ +bool +expressions_are_not_nullable(Query *query, List *exprlist) +{ + Relids innerjoined_rels = NULL; + bool computed_innerjoined_rels = false; + List *usable_quals = NIL; + List *nonnullable_vars = NIL; + bool computed_nonnullable_vars = false; + ListCell *lc; + + /* + * If the query contains set operations, punt. The set ops themselves + * couldn't introduce nulls that weren't in their inputs, but the tlist + * present in the top-level query is just dummy and won't give us useful + * info. We could get an answer by recursing to examine each leaf query, + * but for the moment it doesn't seem worth the extra complication. + * + * Note that we needn't consider other top-level operators such as + * DISTINCT, GROUP BY, etc, as those will not introduce nulls either. + */ + if (query->setOperations) + return false; + + /* + * Examine each Expr to prove that it can't produce NULL. + */ + foreach(lc, exprlist) + { + Expr *expr = (Expr *) lfirst(lc); + + /* + * For the most part we don't try to deal with anything more complex + * than Consts and Vars; but it seems worthwhile to look through + * binary relabelings, since we know those don't introduce nulls. + */ + while (expr && IsA(expr, RelabelType)) + expr = ((RelabelType *) expr)->arg; + + if (expr == NULL) /* paranoia */ + return false; + + if (IsA(expr, Const)) + { + /* Consts are easy: they're either null or not. */ + if (((Const *) expr)->constisnull) + return false; + } + else if (IsA(expr, Var)) + { + Var *var = (Var *) expr; + + /* Currently, we punt for any nonlocal Vars */ + if (var->varlevelsup != 0) + return false; + + /* + * Since the subquery hasn't yet been through expression + * preprocessing, we must apply flatten_join_alias_vars to the + * given Var, and to any Vars found by find_nonnullable_vars, to + * avoid being fooled by join aliases. If we get something other + * than a plain Var out of the substitution, punt. + */ + var = (Var *) flatten_join_alias_vars(query, (Node *) var); + + if (!IsA(var, Var)) + return false; + Assert(var->varlevelsup == 0); + + /* + * We don't bother to compute innerjoined_rels and usable_quals + * until we've found a Var we must analyze. + */ + if (!computed_innerjoined_rels) + { + find_innerjoined_rels((Node *) query->jointree, + &innerjoined_rels, &usable_quals); + computed_innerjoined_rels = true; + } + + /* + * If Var is from a plain relation, and that relation is not on + * the nullable side of any outer join, and its column is marked + * NOT NULL according to the catalogs, it can't produce NULL. + */ + if (bms_is_member(var->varno, innerjoined_rels)) + { + RangeTblEntry *rte = rt_fetch(var->varno, query->rtable); + + if (rte->rtekind == RTE_RELATION && + get_attnotnull(rte->relid, var->varattno)) + continue; /* cannot produce NULL */ + } + + /* + * Even if that didn't work, we can conclude that the Var is not + * nullable if find_nonnullable_vars can find a "var IS NOT NULL" + * or similarly strict condition among the usable_quals. Compute + * the list of Vars having such quals if we didn't already. + */ + if (!computed_nonnullable_vars) + { + nonnullable_vars = find_nonnullable_vars((Node *) usable_quals); + nonnullable_vars = (List *) + flatten_join_alias_vars(query, + (Node *) nonnullable_vars); + /* We don't bother removing any non-Vars from the result */ + computed_nonnullable_vars = true; + } + + if (!list_member(nonnullable_vars, var)) + return false; /* we failed to prove the Var non-null */ + } + else + { + /* Not a Const or Var; punt */ + return false; + } + } + + return true; /* query cannot emit NULLs */ +} + +/* + * find_innerjoined_rels + * Traverse jointree to locate non-outerjoined-rels and quals above them + * + * We fill innerjoined_rels with the relids of all rels that are not below + * the nullable side of any outer join (which would cause their Vars to be + * possibly NULL regardless of what's in the catalogs). In the same scan, + * we locate all WHERE and JOIN/ON quals that constrain these rels, and add + * them to the usable_quals list (forming a list with implicit-AND semantics). + * + * Top-level caller must initialize innerjoined_rels/usable_quals to NULL/NIL. + */ +static void +find_innerjoined_rels(Node *jtnode, + Relids *innerjoined_rels, List **usable_quals) +{ + if (jtnode == NULL) + return; + if (IsA(jtnode, RangeTblRef)) + { + int varno = ((RangeTblRef *) jtnode)->rtindex; + + *innerjoined_rels = bms_add_member(*innerjoined_rels, varno); + } + else if (IsA(jtnode, FromExpr)) + { + FromExpr *f = (FromExpr *) jtnode; + ListCell *lc; + + /* All elements of the FROM list are allowable */ + foreach(lc, f->fromlist) + find_innerjoined_rels((Node *) lfirst(lc), + innerjoined_rels, usable_quals); + /* ... and its WHERE quals are too */ + if (f->quals) + *usable_quals = lappend(*usable_quals, f->quals); + } + else if (IsA(jtnode, JoinExpr)) + { + JoinExpr *j = (JoinExpr *) jtnode; + + switch (j->jointype) + { + case JOIN_INNER: + /* visit both children */ + find_innerjoined_rels(j->larg, + innerjoined_rels, usable_quals); + find_innerjoined_rels(j->rarg, + innerjoined_rels, usable_quals); + /* and grab the ON quals too */ + if (j->quals) + *usable_quals = lappend(*usable_quals, j->quals); + break; + + case JOIN_LEFT: + case JOIN_SEMI: + case JOIN_ANTI: + + /* + * Only the left input is possibly non-nullable; furthermore, + * the quals of this join don't constrain the left input. + * Note: we probably can't see SEMI or ANTI joins at this + * point, but if we do, we can treat them like LEFT joins. + */ + find_innerjoined_rels(j->larg, + innerjoined_rels, usable_quals); + break; + + case JOIN_RIGHT: + /* Reverse of the above case */ + find_innerjoined_rels(j->rarg, + innerjoined_rels, usable_quals); + break; + + case JOIN_FULL: + /* Neither side is non-nullable, so stop descending */ + break; + + default: + elog(ERROR, "unrecognized join type: %d", + (int) j->jointype); + } + } + else + elog(ERROR, "unrecognized node type: %d", + (int) nodeTag(jtnode)); +} + /* * Can we treat a ScalarArrayOpExpr as strict? * diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c index e88c45d268..1201fdeb5a 100644 --- a/src/backend/utils/cache/lsyscache.c +++ b/src/backend/utils/cache/lsyscache.c @@ -878,6 +878,34 @@ get_atttypetypmodcoll(Oid relid, AttrNumber attnum, ReleaseSysCache(tp); } +/* + * get_attnotnull + * + * Given the relation id and the attribute number, + * return the "attnotnull" field from the attribute relation. + */ +bool +get_attnotnull(Oid relid, AttrNumber attnum) +{ + HeapTuple tp; + + /* XXX worth special casing system columns? */ + tp = SearchSysCache2(ATTNUM, + ObjectIdGetDatum(relid), + Int16GetDatum(attnum)); + if (HeapTupleIsValid(tp)) + { + Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp); + bool result; + + result = att_tup->attnotnull; + ReleaseSysCache(tp); + return result; + } + else + return false; +} + /* ---------- COLLATION CACHE ---------- */ /* diff --git a/src/include/optimizer/clauses.h b/src/include/optimizer/clauses.h index 5e10fb1d50..dcfed985b5 100644 --- a/src/include/optimizer/clauses.h +++ b/src/include/optimizer/clauses.h @@ -44,6 +44,7 @@ extern Relids find_nonnullable_rels(Node *clause); extern List *find_nonnullable_vars(Node *clause); extern List *find_forced_null_vars(Node *clause); extern Var *find_forced_null_var(Node *clause); +extern bool expressions_are_not_nullable(Query *query, List *exprlist); extern bool is_pseudo_constant_clause(Node *clause); extern bool is_pseudo_constant_clause_relids(Node *clause, Relids relids); diff --git a/src/include/optimizer/subselect.h b/src/include/optimizer/subselect.h index 2d2c3bcbc0..efc5bf75cc 100644 --- a/src/include/optimizer/subselect.h +++ b/src/include/optimizer/subselect.h @@ -19,6 +19,7 @@ extern void SS_process_ctes(PlannerInfo *root); extern JoinExpr *convert_ANY_sublink_to_join(PlannerInfo *root, SubLink *sublink, + bool under_not, Relids available_rels); extern JoinExpr *convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink, diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h index 16b0b1d2dc..71370d8877 100644 --- a/src/include/utils/lsyscache.h +++ b/src/include/utils/lsyscache.h @@ -89,6 +89,7 @@ extern AttrNumber get_attnum(Oid relid, const char *attname); extern Oid get_atttype(Oid relid, AttrNumber attnum); extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum, Oid *typid, int32 *typmod, Oid *collid); +extern bool get_attnotnull(Oid relid, AttrNumber attnum); extern char *get_collation_name(Oid colloid); extern char *get_constraint_name(Oid conoid); extern char *get_language_name(Oid langoid, bool missing_ok); diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out index cc3f5f3737..f2d5d6679f 100644 --- a/src/test/regress/expected/subselect.out +++ b/src/test/regress/expected/subselect.out @@ -1310,3 +1310,367 @@ select * from x for update; Output: subselect_tbl.f1, subselect_tbl.f2, subselect_tbl.f3 (2 rows) +-- +-- Check NOT IN performs an ANTI JOIN when NULLs are not possible +-- on either side of the, would be, join condition. +-- +BEGIN; +CREATE TEMP TABLE a (id INT PRIMARY KEY); +CREATE TEMP TABLE b (x INT NOT NULL, y INT); +CREATE TEMP TABLE c (z INT NOT NULL); +INSERT INTO b VALUES(1,1),(2,2),(3,NULL); +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a +LEFT OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT z FROM c); + QUERY PLAN +------------------------------------ + Hash Right Join + Hash Cond: (b.x = a.id) + Filter: (NOT (hashed SubPlan 1)) + -> Seq Scan on b + -> Hash + -> Seq Scan on a + SubPlan 1 + -> Seq Scan on c +(8 rows) + +-- ANTI JOIN, b.x is from an outer join but b.x > 100 +-- forces the join not to produce NULL on the righthand +-- side. +EXPLAIN (COSTS OFF) +SELECT * FROM a +LEFT OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT z FROM c) + AND b.x > 100; + QUERY PLAN +--------------------------------- + Hash Join + Hash Cond: (b.x = a.id) + -> Hash Anti Join + Hash Cond: (b.x = c.z) + -> Seq Scan on b + Filter: (x > 100) + -> Hash + -> Seq Scan on c + -> Hash + -> Seq Scan on a +(10 rows) + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a +FULL OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT y FROM c); + QUERY PLAN +----------------------------- + Hash Full Join + Hash Cond: (b.x = a.id) + Filter: (NOT (SubPlan 1)) + -> Seq Scan on b + -> Hash + -> Seq Scan on a + SubPlan 1 + -> Seq Scan on c +(8 rows) + +-- No ANTI JOIN. y can have NULLs +EXPLAIN (COSTS OFF) +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + QUERY PLAN +------------------------------------ + Seq Scan on b + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on c +(4 rows) + +-- c is an empty relation so should cause no filtering on b +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + x | y +---+--- + 1 | 1 + 2 | 2 + 3 | +(3 rows) + +INSERT INTO c VALUES(1); +-- Records where y is NULL should be filtered out. +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + x | y +---+--- + 2 | 2 +(1 row) + +-- No ANTI JOIN, y can be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on b +(4 rows) + +-- No ANTI JOIN, x is NOT NULL, but we don't know if + 1 will change that. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT x+1 FROM b); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on b +(4 rows) + +-- ANTI JOIN 1 is a Const that is not null. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT 1 FROM b); + QUERY PLAN +--------------------------- + Nested Loop Anti Join + Join Filter: (a.id = 1) + -> Seq Scan on a + -> Materialize + -> Seq Scan on b +(5 rows) + +-- No ANTI JOIN, results contain a NULL Const +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT NULL::int FROM b); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on b +(4 rows) + +-- ANTI JOIN y = 1 means y can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE y = 1); + QUERY PLAN +------------------------------- + Hash Anti Join + Hash Cond: (a.id = b.y) + -> Seq Scan on a + -> Hash + -> Seq Scan on b + Filter: (y = 1) +(6 rows) + +-- No ANTI JOIN, OR condition does not ensure y = 1 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE y = 1 OR x = 1); + QUERY PLAN +---------------------------------------- + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on b + Filter: ((y = 1) OR (x = 1)) +(5 rows) + +-- No ANTI JOIN, OR condition does not ensure y = 1 or y = 2 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR x = 1) AND (y = 2 OR x = 2)); + QUERY PLAN +------------------------------------------------------------------- + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Seq Scan on b + Filter: (((y = 1) OR (x = 1)) AND ((y = 2) OR (x = 2))) +(5 rows) + +-- ANTI JOIN y must be 2, so can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR x = 1) AND y = 2); + QUERY PLAN +---------------------------------------------------------- + Hash Anti Join + Hash Cond: (a.id = b.y) + -> Seq Scan on a + -> Hash + -> Seq Scan on b + Filter: ((y = 2) AND ((y = 1) OR (x = 1))) +(6 rows) + +-- ANTI JOIN y can be 1 or 2, but can't be null. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR y = 2)); + QUERY PLAN +-------------------------------------------- + Hash Anti Join + Hash Cond: (a.id = b.y) + -> Seq Scan on a + -> Hash + -> Seq Scan on b + Filter: ((y = 1) OR (y = 2)) +(6 rows) + +-- No ANTI JOIN c.z is from a left outer join so it can have nulls. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Merge Left Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +-- ANTI JOIN, c.z is not from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b RIGHT JOIN c ON b.x = c.z); + QUERY PLAN +----------------------------------------- + Merge Anti Join + Merge Cond: (a.id = c.z) + -> Index Only Scan using a_pkey on a + -> Merge Left Join + Merge Cond: (c.z = b.x) + -> Sort + Sort Key: c.z + -> Seq Scan on c + -> Sort + Sort Key: b.x + -> Seq Scan on b +(11 rows) + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.x FROM b RIGHT JOIN c ON b.x = c.z); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Merge Right Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +-- No ANTI JOIN, c.z is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b FULL JOIN c ON b.x = c.z); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Merge Full Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.x FROM b FULL JOIN c ON b.x = c.z); + QUERY PLAN +------------------------------------ + Seq Scan on a + Filter: (NOT (hashed SubPlan 1)) + SubPlan 1 + -> Merge Full Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +-- ANTI JOIN, c.z is from an inner join and has a NOT NULL constraint. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b INNER JOIN c ON b.x = c.z); + QUERY PLAN +----------------------------------------- + Merge Anti Join + Merge Cond: (a.id = c.z) + -> Index Only Scan using a_pkey on a + -> Merge Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +-- ANTI JOIN, c.z must be 1 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z WHERE c.z = 1); + QUERY PLAN +------------------------------------------- + Hash Anti Join + Hash Cond: (a.id = c.z) + -> Seq Scan on a + -> Hash + -> Nested Loop + -> Seq Scan on c + Filter: (z = 1) + -> Materialize + -> Seq Scan on b + Filter: (x = 1) +(10 rows) + +-- ANTI JOIN, c.z can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z WHERE c.z IS NOT NULL); + QUERY PLAN +--------------------------------------------- + Merge Anti Join + Merge Cond: (a.id = c.z) + -> Index Only Scan using a_pkey on a + -> Merge Join + Merge Cond: (b.x = c.z) + -> Sort + Sort Key: b.x + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c + Filter: (z IS NOT NULL) +(12 rows) + +-- ANTI JOIN, b.y cannot be NULL due to the join condition b.y = c.z +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.y FROM b INNER JOIN c ON b.y = c.z); + QUERY PLAN +----------------------------------------- + Merge Anti Join + Merge Cond: (a.id = b.y) + -> Index Only Scan using a_pkey on a + -> Merge Join + Merge Cond: (b.y = c.z) + -> Sort + Sort Key: b.y + -> Seq Scan on b + -> Sort + Sort Key: c.z + -> Seq Scan on c +(11 rows) + +ROLLBACK; diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql index 8bca1f5d55..d6fff1f2ae 100644 --- a/src/test/regress/sql/subselect.sql +++ b/src/test/regress/sql/subselect.sql @@ -683,3 +683,123 @@ select * from (with x as (select 2 as y) select * from x) ss; explain (verbose, costs off) with x as (select * from subselect_tbl) select * from x for update; + +-- +-- Check NOT IN performs an ANTI JOIN when NULLs are not possible +-- on either side of the, would be, join condition. +-- + +BEGIN; + +CREATE TEMP TABLE a (id INT PRIMARY KEY); +CREATE TEMP TABLE b (x INT NOT NULL, y INT); +CREATE TEMP TABLE c (z INT NOT NULL); + +INSERT INTO b VALUES(1,1),(2,2),(3,NULL); + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a +LEFT OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT z FROM c); + +-- ANTI JOIN, b.x is from an outer join but b.x > 100 +-- forces the join not to produce NULL on the righthand +-- side. +EXPLAIN (COSTS OFF) +SELECT * FROM a +LEFT OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT z FROM c) + AND b.x > 100; + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a +FULL OUTER JOIN b ON a.id = b.x +WHERE b.x NOT IN(SELECT y FROM c); + +-- No ANTI JOIN. y can have NULLs +EXPLAIN (COSTS OFF) +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + +-- c is an empty relation so should cause no filtering on b +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + +INSERT INTO c VALUES(1); + +-- Records where y is NULL should be filtered out. +SELECT * FROM b WHERE y NOT IN (SELECT z FROM c); + +-- No ANTI JOIN, y can be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b); + +-- No ANTI JOIN, x is NOT NULL, but we don't know if + 1 will change that. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT x+1 FROM b); + +-- ANTI JOIN 1 is a Const that is not null. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT 1 FROM b); + +-- No ANTI JOIN, results contain a NULL Const +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT NULL::int FROM b); + +-- ANTI JOIN y = 1 means y can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE y = 1); + +-- No ANTI JOIN, OR condition does not ensure y = 1 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE y = 1 OR x = 1); + +-- No ANTI JOIN, OR condition does not ensure y = 1 or y = 2 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR x = 1) AND (y = 2 OR x = 2)); + +-- ANTI JOIN y must be 2, so can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR x = 1) AND y = 2); + +-- ANTI JOIN y can be 1 or 2, but can't be null. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT y FROM b WHERE (y = 1 OR y = 2)); + +-- No ANTI JOIN c.z is from a left outer join so it can have nulls. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z); + +-- ANTI JOIN, c.z is not from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b RIGHT JOIN c ON b.x = c.z); + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.x FROM b RIGHT JOIN c ON b.x = c.z); + +-- No ANTI JOIN, c.z is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b FULL JOIN c ON b.x = c.z); + +-- No ANTI JOIN, b.x is from an outer join +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.x FROM b FULL JOIN c ON b.x = c.z); + +-- ANTI JOIN, c.z is from an inner join and has a NOT NULL constraint. +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b INNER JOIN c ON b.x = c.z); + +-- ANTI JOIN, c.z must be 1 +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z WHERE c.z = 1); + +-- ANTI JOIN, c.z can't be NULL +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT c.z FROM b LEFT JOIN c ON b.x = c.z WHERE c.z IS NOT NULL); + +-- ANTI JOIN, b.y cannot be NULL due to the join condition b.y = c.z +EXPLAIN (COSTS OFF) +SELECT * FROM a WHERE id NOT IN (SELECT b.y FROM b INNER JOIN c ON b.y = c.z); + +ROLLBACK;