1 /*-------------------------------------------------------------------------
4 * Routines copied from PostgreSQL core distribution.
6 * src/backend/optimizer/path/joinrels.c
9 * Portions Copyright (c) 2013-2014, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
10 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
11 * Portions Copyright (c) 1994, Regents of the University of California
13 *-------------------------------------------------------------------------
17 * adjust_rows: tweak estimated row numbers according to the hint.
20 adjust_rows(double rows, RowsHint *hint)
22 double result = 0.0; /* keep compiler quiet */
24 if (hint->value_type == RVT_ABSOLUTE)
26 else if (hint->value_type == RVT_ADD)
27 result = rows + hint->rows;
28 else if (hint->value_type == RVT_SUB)
29 result = rows - hint->rows;
30 else if (hint->value_type == RVT_MULTI)
31 result = rows * hint->rows;
33 Assert(false); /* unrecognized rows value type */
35 hint->base.state = HINT_STATE_USED;
38 (errmsg("Force estimate to be at least one row, to avoid possible divide-by-zero when interpolating costs : %s",
39 hint->base.hint_str)));
40 result = clamp_row_est(result);
41 elog(DEBUG1, "adjusted rows %d to %d", (int) rows, (int) result);
48 * Find or create a join RelOptInfo that represents the join of
49 * the two given rels, and add to it path information for paths
50 * created with the two rels as outer and inner rel.
51 * (The join rel may already contain paths generated from other
52 * pairs of rels that add up to the same set of base rels.)
54 * NB: will return NULL if attempted join is not valid. This can happen
55 * when working with outer joins, or with IN or EXISTS clauses that have been
59 make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
62 SpecialJoinInfo *sjinfo;
64 SpecialJoinInfo sjinfo_data;
68 /* We should never try to join two overlapping sets of rels. */
69 Assert(!bms_overlap(rel1->relids, rel2->relids));
71 /* Construct Relids set that identifies the joinrel. */
72 joinrelids = bms_union(rel1->relids, rel2->relids);
74 /* Check validity and determine join type. */
75 if (!join_is_legal(root, rel1, rel2, joinrelids,
78 /* invalid join path */
83 /* Swap rels if needed to match the join info. */
86 RelOptInfo *trel = rel1;
93 * If it's a plain inner join, then we won't have found anything in
94 * join_info_list. Make up a SpecialJoinInfo so that selectivity
95 * estimation functions will know what's being joined.
99 sjinfo = &sjinfo_data;
100 sjinfo->type = T_SpecialJoinInfo;
101 sjinfo->min_lefthand = rel1->relids;
102 sjinfo->min_righthand = rel2->relids;
103 sjinfo->syn_lefthand = rel1->relids;
104 sjinfo->syn_righthand = rel2->relids;
105 sjinfo->jointype = JOIN_INNER;
106 /* we don't bother trying to make the remaining fields valid */
107 sjinfo->lhs_strict = false;
108 sjinfo->delay_upper_joins = false;
109 sjinfo->semi_can_btree = false;
110 sjinfo->semi_can_hash = false;
111 sjinfo->semi_operators = NIL;
112 sjinfo->semi_rhs_exprs = NIL;
116 * Find or build the join RelOptInfo, and compute the restrictlist that
117 * goes with this particular joining.
119 joinrel = build_join_rel(root, joinrelids, rel1, rel2, sjinfo,
122 /* !!! START: HERE IS THE PART WHICH ADDED FOR PG_HINT_PLAN !!! */
124 RowsHint *rows_hint = NULL;
126 RowsHint *justforme = NULL;
127 RowsHint *domultiply = NULL;
129 /* Search for applicable rows hint for this join node */
130 for (i = 0; i < current_hint->num_hints[HINT_TYPE_ROWS]; i++)
132 rows_hint = current_hint->rows_hints[i];
135 * Skip this rows_hint if it is invalid from the first or it
136 * doesn't target any join rels.
138 if (!rows_hint->joinrelids ||
139 rows_hint->base.state == HINT_STATE_ERROR)
142 if (bms_equal(joinrelids, rows_hint->joinrelids))
145 * This joinrel is just the target of this rows_hint, so tweak
146 * rows estimation according to the hint.
148 justforme = rows_hint;
150 else if (!(bms_is_subset(rows_hint->joinrelids, rel1->relids) ||
151 bms_is_subset(rows_hint->joinrelids, rel2->relids)) &&
152 bms_is_subset(rows_hint->joinrelids, joinrelids) &&
153 rows_hint->value_type == RVT_MULTI)
156 * If the rows_hint's target relids is not a subset of both of
157 * component rels and is a subset of this joinrel, ths hint's
158 * targets spread over both component rels. This menas that
159 * this hint has been never applied so far and this joinrel is
160 * the first (and only) chance to fire in current join tree.
161 * Only the multiplication hint has the cumulative nature so we
162 * apply only RVT_MULTI in this way.
164 domultiply = rows_hint;
171 * If a hint just for me is found, no other adjust method is
172 * useles, but this cannot be more than twice becuase this joinrel
173 * is already adjusted by this hint.
175 if (justforme->base.state == HINT_STATE_NOTUSED)
176 joinrel->rows = adjust_rows(joinrel->rows, justforme);
183 * If we have multiple routes up to this joinrel which are not
184 * applicable this hint, this multiply hint will applied more
185 * than twice. But there's no means to know of that,
186 * re-estimate the row number of this joinrel always just
187 * before applying the hint. This is a bit different from
188 * normal planner behavior but it doesn't harm so much.
190 set_joinrel_size_estimates(root, joinrel, rel1, rel2, sjinfo,
193 joinrel->rows = adjust_rows(joinrel->rows, domultiply);
198 /* !!! END: HERE IS THE PART WHICH ADDED FOR PG_HINT_PLAN !!! */
201 * If we've already proven this join is empty, we needn't consider any
204 if (is_dummy_rel(joinrel))
206 bms_free(joinrelids);
211 * Consider paths using each rel as both outer and inner. Depending on
212 * the join type, a provably empty outer or inner rel might mean the join
213 * is provably empty too; in which case throw away any previously computed
214 * paths and mark the join as dummy. (We do it this way since it's
215 * conceivable that dummy-ness of a multi-element join might only be
216 * noticeable for certain construction paths.)
218 * Also, a provably constant-false join restriction typically means that
219 * we can skip evaluating one or both sides of the join. We do this by
220 * marking the appropriate rel as dummy. For outer joins, a
221 * constant-false restriction that is pushed down still means the whole
222 * join is dummy, while a non-pushed-down one means that no inner rows
223 * will join so we can treat the inner rel as dummy.
225 * We need only consider the jointypes that appear in join_info_list, plus
228 switch (sjinfo->jointype)
231 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
232 restriction_is_constant_false(restrictlist, false))
234 mark_dummy_rel(joinrel);
237 add_paths_to_joinrel(root, joinrel, rel1, rel2,
240 add_paths_to_joinrel(root, joinrel, rel2, rel1,
245 if (is_dummy_rel(rel1) ||
246 restriction_is_constant_false(restrictlist, true))
248 mark_dummy_rel(joinrel);
251 if (restriction_is_constant_false(restrictlist, false) &&
252 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
253 mark_dummy_rel(rel2);
254 add_paths_to_joinrel(root, joinrel, rel1, rel2,
257 add_paths_to_joinrel(root, joinrel, rel2, rel1,
262 if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) ||
263 restriction_is_constant_false(restrictlist, true))
265 mark_dummy_rel(joinrel);
268 add_paths_to_joinrel(root, joinrel, rel1, rel2,
271 add_paths_to_joinrel(root, joinrel, rel2, rel1,
276 * If there are join quals that aren't mergeable or hashable, we
277 * may not be able to build any valid plan. Complain here so that
278 * we can give a somewhat-useful error message. (Since we have no
279 * flexibility of planning for a full join, there's no chance of
280 * succeeding later with another pair of input rels.)
282 if (joinrel->pathlist == NIL)
284 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
285 errmsg("FULL JOIN is only supported with merge-joinable or hash-joinable join conditions")));
290 * We might have a normal semijoin, or a case where we don't have
291 * enough rels to do the semijoin but can unique-ify the RHS and
292 * then do an innerjoin (see comments in join_is_legal). In the
293 * latter case we can't apply JOIN_SEMI joining.
295 if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
296 bms_is_subset(sjinfo->min_righthand, rel2->relids))
298 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
299 restriction_is_constant_false(restrictlist, false))
301 mark_dummy_rel(joinrel);
304 add_paths_to_joinrel(root, joinrel, rel1, rel2,
310 * If we know how to unique-ify the RHS and one input rel is
311 * exactly the RHS (not a superset) we can consider unique-ifying
312 * it and then doing a regular join. (The create_unique_path
313 * check here is probably redundant with what join_is_legal did,
314 * but if so the check is cheap because it's cached. So test
315 * anyway to be sure.)
317 if (bms_equal(sjinfo->syn_righthand, rel2->relids) &&
318 create_unique_path(root, rel2, rel2->cheapest_total_path,
321 if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
322 restriction_is_constant_false(restrictlist, false))
324 mark_dummy_rel(joinrel);
327 add_paths_to_joinrel(root, joinrel, rel1, rel2,
328 JOIN_UNIQUE_INNER, sjinfo,
330 add_paths_to_joinrel(root, joinrel, rel2, rel1,
331 JOIN_UNIQUE_OUTER, sjinfo,
336 if (is_dummy_rel(rel1) ||
337 restriction_is_constant_false(restrictlist, true))
339 mark_dummy_rel(joinrel);
342 if (restriction_is_constant_false(restrictlist, false) &&
343 bms_is_subset(rel2->relids, sjinfo->syn_righthand))
344 mark_dummy_rel(rel2);
345 add_paths_to_joinrel(root, joinrel, rel1, rel2,
350 /* other values not expected here */
351 elog(ERROR, "unrecognized join type: %d", (int) sjinfo->jointype);
355 bms_free(joinrelids);