diff options
Diffstat (limited to 'src/backend/optimizer/plan/initsplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/initsplan.c | 61 |
1 files changed, 34 insertions, 27 deletions
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c index 6b6f3971719..207981b527f 100644 --- a/src/backend/optimizer/plan/initsplan.c +++ b/src/backend/optimizer/plan/initsplan.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.45 2000/02/15 20:49:18 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.46 2000/04/12 17:15:21 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -30,7 +30,7 @@ static void add_restrict_and_join_to_rel(Query *root, Node *clause); static void add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo, - Relids join_relids); + Relids join_relids); static void add_vars_to_targetlist(Query *root, List *vars); static void check_mergejoinable(RestrictInfo *restrictinfo); static void check_hashjoinable(RestrictInfo *restrictinfo); @@ -83,7 +83,7 @@ add_vars_to_targetlist(Query *root, List *vars) * * If we have a range variable in the FROM clause that does not appear * in the target list nor qualifications, we must add it to the base - * relation list so that it will be joined. For instance, "select f.x + * relation list so that it will be joined. For instance, "select f.x * from foo f, foo f2" is a join of f and f2. Note that if we have * "select foo.x from foo f", it also gets turned into a join (between * foo as foo and foo as f). @@ -106,13 +106,15 @@ add_missing_rels_to_query(Query *root) { RelOptInfo *rel = get_base_rel(root, varno); - /* If the rel isn't otherwise referenced, give it a dummy + /* + * If the rel isn't otherwise referenced, give it a dummy * targetlist consisting of its own OID. */ if (rel->targetlist == NIL) { Var *var = makeVar(varno, ObjectIdAttributeNumber, OIDOID, -1, 0); + add_var_to_tlist(rel, var); } } @@ -142,14 +144,14 @@ add_restrict_and_join_to_rels(Query *root, List *clauses) List *clause; foreach(clause, clauses) - add_restrict_and_join_to_rel(root, (Node*) lfirst(clause)); + add_restrict_and_join_to_rel(root, (Node *) lfirst(clause)); } /* * add_restrict_and_join_to_rel * Add clause information to either the 'RestrictInfo' or 'JoinInfo' field * (depending on whether the clause is a join) of each base relation - * mentioned in the clause. A RestrictInfo node is created and added to + * mentioned in the clause. A RestrictInfo node is created and added to * the appropriate list for each rel. Also, if the clause uses a * mergejoinable operator, enter the left- and right-side expressions * into the query's lists of equijoined vars. @@ -175,6 +177,7 @@ add_restrict_and_join_to_rel(Query *root, Node *clause) if (length(relids) == 1) { + /* * There is only one relation participating in 'clause', so * 'clause' must be a restriction clause for that relation. @@ -183,21 +186,24 @@ add_restrict_and_join_to_rel(Query *root, Node *clause) rel->baserestrictinfo = lcons(restrictinfo, rel->baserestrictinfo); + /* * Check for a "mergejoinable" clause even though it's not a join - * clause. This is so that we can recognize that "a.x = a.y" makes - * x and y eligible to be considered equal, even when they belong - * to the same rel. Without this, we would not recognize that - * "a.x = a.y AND a.x = b.z AND a.y = c.q" allows us to consider - * z and q equal after their rels are joined. + * clause. This is so that we can recognize that "a.x = a.y" + * makes x and y eligible to be considered equal, even when they + * belong to the same rel. Without this, we would not recognize + * that "a.x = a.y AND a.x = b.z AND a.y = c.q" allows us to + * consider z and q equal after their rels are joined. */ check_mergejoinable(restrictinfo); } else { + /* * 'clause' is a join clause, since there is more than one atom in - * the relid list. Set additional RestrictInfo fields for joining. + * the relid list. Set additional RestrictInfo fields for + * joining. * * We need the merge info whether or not mergejoin is enabled (for * constructing equijoined-var lists), but we don't bother setting @@ -206,16 +212,19 @@ add_restrict_and_join_to_rel(Query *root, Node *clause) check_mergejoinable(restrictinfo); if (enable_hashjoin) check_hashjoinable(restrictinfo); + /* - * Add clause to the join lists of all the relevant - * relations. (If, perchance, 'clause' contains NO vars, then - * nothing will happen...) + * Add clause to the join lists of all the relevant relations. + * (If, perchance, 'clause' contains NO vars, then nothing will + * happen...) */ add_join_info_to_rels(root, restrictinfo, relids); + /* - * Add vars used in the join clause to targetlists of member relations, - * so that they will be emitted by the plan nodes that scan those - * relations (else they won't be available at the join node!). + * Add vars used in the join clause to targetlists of member + * relations, so that they will be emitted by the plan nodes that + * scan those relations (else they won't be available at the join + * node!). */ add_vars_to_targetlist(root, vars); } @@ -267,7 +276,7 @@ add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo, joininfo = find_joininfo_node(get_base_rel(root, cur_relid), unjoined_relids); joininfo->jinfo_restrictinfo = lcons(restrictinfo, - joininfo->jinfo_restrictinfo); + joininfo->jinfo_restrictinfo); } } @@ -296,16 +305,16 @@ check_mergejoinable(RestrictInfo *restrictinfo) leftOp, rightOp; - if (! is_opclause((Node *) clause)) + if (!is_opclause((Node *) clause)) return; left = get_leftop(clause); right = get_rightop(clause); /* caution: is_opclause accepts more than I do, so check it */ - if (! right) + if (!right) return; /* unary opclauses need not apply */ - if (!IsA(left, Var) || !IsA(right, Var)) + if (!IsA(left, Var) ||!IsA(right, Var)) return; opno = ((Oper *) clause->oper)->opno; @@ -339,16 +348,16 @@ check_hashjoinable(RestrictInfo *restrictinfo) *right; Oid opno; - if (! is_opclause((Node *) clause)) + if (!is_opclause((Node *) clause)) return; left = get_leftop(clause); right = get_rightop(clause); /* caution: is_opclause accepts more than I do, so check it */ - if (! right) + if (!right) return; /* unary opclauses need not apply */ - if (!IsA(left, Var) || !IsA(right, Var)) + if (!IsA(left, Var) ||!IsA(right, Var)) return; opno = ((Oper *) clause->oper)->opno; @@ -356,7 +365,5 @@ check_hashjoinable(RestrictInfo *restrictinfo) if (op_hashjoinable(opno, left->vartype, right->vartype)) - { restrictinfo->hashjoinoperator = opno; - } } |