Line data Source code
1 : /*--------------------------------------------------------------------------
2 : *
3 : * test_predtest.c
4 : * Test correctness of optimizer's predicate proof logic.
5 : *
6 : * Copyright (c) 2018-2024, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * src/test/modules/test_predtest/test_predtest.c
10 : *
11 : * -------------------------------------------------------------------------
12 : */
13 :
14 : #include "postgres.h"
15 :
16 : #include "access/htup_details.h"
17 : #include "catalog/pg_type.h"
18 : #include "executor/spi.h"
19 : #include "funcapi.h"
20 : #include "nodes/makefuncs.h"
21 : #include "optimizer/optimizer.h"
22 : #include "utils/builtins.h"
23 :
24 2 : PG_MODULE_MAGIC;
25 :
26 : /*
27 : * test_predtest(query text) returns record
28 : */
29 4 : PG_FUNCTION_INFO_V1(test_predtest);
30 :
31 : Datum
32 148 : test_predtest(PG_FUNCTION_ARGS)
33 : {
34 148 : text *txt = PG_GETARG_TEXT_PP(0);
35 148 : char *query_string = text_to_cstring(txt);
36 : SPIPlanPtr spiplan;
37 : int spirc;
38 : TupleDesc tupdesc;
39 : bool s_i_holds,
40 : w_i_holds,
41 : s_r_holds,
42 : w_r_holds;
43 : CachedPlan *cplan;
44 : PlannedStmt *stmt;
45 : Plan *plan;
46 : Expr *clause1;
47 : Expr *clause2;
48 : bool strong_implied_by,
49 : weak_implied_by,
50 : strong_refuted_by,
51 : weak_refuted_by;
52 : Datum values[8];
53 148 : bool nulls[8] = {0};
54 : int i;
55 :
56 : /* We use SPI to parse, plan, and execute the test query */
57 148 : if (SPI_connect() != SPI_OK_CONNECT)
58 0 : elog(ERROR, "SPI_connect failed");
59 :
60 : /*
61 : * First, plan and execute the query, and inspect the results. To the
62 : * extent that the query fully exercises the two expressions, this
63 : * provides an experimental indication of whether implication or
64 : * refutation holds.
65 : */
66 148 : spiplan = SPI_prepare(query_string, 0, NULL);
67 148 : if (spiplan == NULL)
68 0 : elog(ERROR, "SPI_prepare failed for \"%s\"", query_string);
69 :
70 148 : spirc = SPI_execute_plan(spiplan, NULL, NULL, true, 0);
71 148 : if (spirc != SPI_OK_SELECT)
72 0 : elog(ERROR, "failed to execute \"%s\"", query_string);
73 148 : tupdesc = SPI_tuptable->tupdesc;
74 148 : if (tupdesc->natts != 2 ||
75 148 : TupleDescAttr(tupdesc, 0)->atttypid != BOOLOID ||
76 148 : TupleDescAttr(tupdesc, 1)->atttypid != BOOLOID)
77 0 : elog(ERROR, "query must yield two boolean columns");
78 :
79 148 : s_i_holds = w_i_holds = s_r_holds = w_r_holds = true;
80 15100 : for (i = 0; i < SPI_processed; i++)
81 : {
82 14952 : HeapTuple tup = SPI_tuptable->vals[i];
83 : Datum dat;
84 : bool isnull;
85 : char c1,
86 : c2;
87 :
88 : /* Extract column values in a 3-way representation */
89 14952 : dat = SPI_getbinval(tup, tupdesc, 1, &isnull);
90 14952 : if (isnull)
91 2308 : c1 = 'n';
92 12644 : else if (DatumGetBool(dat))
93 6252 : c1 = 't';
94 : else
95 6392 : c1 = 'f';
96 :
97 14952 : dat = SPI_getbinval(tup, tupdesc, 2, &isnull);
98 14952 : if (isnull)
99 2384 : c2 = 'n';
100 12568 : else if (DatumGetBool(dat))
101 5240 : c2 = 't';
102 : else
103 7328 : c2 = 'f';
104 :
105 : /* Check for violations of various proof conditions */
106 :
107 : /* strong implication: truth of c2 implies truth of c1 */
108 14952 : if (c2 == 't' && c1 != 't')
109 2732 : s_i_holds = false;
110 : /* weak implication: non-falsity of c2 implies non-falsity of c1 */
111 14952 : if (c2 != 'f' && c1 == 'f')
112 2840 : w_i_holds = false;
113 : /* strong refutation: truth of c2 implies falsity of c1 */
114 14952 : if (c2 == 't' && c1 != 'f')
115 2904 : s_r_holds = false;
116 : /* weak refutation: truth of c2 implies non-truth of c1 */
117 14952 : if (c2 == 't' && c1 == 't')
118 2508 : w_r_holds = false;
119 : }
120 :
121 : /*
122 : * Strong refutation implies weak refutation, so we should never observe
123 : * s_r_holds = true with w_r_holds = false.
124 : *
125 : * We can't make a comparable assertion for implication since moving from
126 : * strong to weak implication expands the allowed values of "A" from true
127 : * to either true or NULL.
128 : *
129 : * If this fails it constitutes a bug not with the proofs but with either
130 : * this test module or a more core part of expression evaluation since we
131 : * are validating the logical correctness of the observed result rather
132 : * than the proof.
133 : */
134 148 : if (s_r_holds && !w_r_holds)
135 0 : elog(WARNING, "s_r_holds was true; w_r_holds must not be false");
136 :
137 : /*
138 : * Now, dig the clause querytrees out of the plan, and see what predtest.c
139 : * does with them.
140 : */
141 148 : cplan = SPI_plan_get_cached_plan(spiplan);
142 :
143 148 : if (list_length(cplan->stmt_list) != 1)
144 0 : elog(ERROR, "failed to decipher query plan");
145 148 : stmt = linitial_node(PlannedStmt, cplan->stmt_list);
146 148 : if (stmt->commandType != CMD_SELECT)
147 0 : elog(ERROR, "failed to decipher query plan");
148 148 : plan = stmt->planTree;
149 : Assert(list_length(plan->targetlist) >= 2);
150 148 : clause1 = linitial_node(TargetEntry, plan->targetlist)->expr;
151 148 : clause2 = lsecond_node(TargetEntry, plan->targetlist)->expr;
152 :
153 : /*
154 : * Because the clauses are in the SELECT list, preprocess_expression did
155 : * not pass them through canonicalize_qual nor make_ands_implicit.
156 : *
157 : * We can't do canonicalize_qual here, since it's unclear whether the
158 : * expressions ought to be treated as WHERE or CHECK clauses. Fortunately,
159 : * useful test expressions wouldn't be affected by those transformations
160 : * anyway. We should do make_ands_implicit, though.
161 : *
162 : * Another way in which this does not exactly duplicate the normal usage
163 : * of the proof functions is that they are often given qual clauses
164 : * containing RestrictInfo nodes. But since predtest.c just looks through
165 : * those anyway, it seems OK to not worry about that point.
166 : */
167 148 : clause1 = (Expr *) make_ands_implicit(clause1);
168 148 : clause2 = (Expr *) make_ands_implicit(clause2);
169 :
170 148 : strong_implied_by = predicate_implied_by((List *) clause1,
171 : (List *) clause2,
172 : false);
173 :
174 148 : weak_implied_by = predicate_implied_by((List *) clause1,
175 : (List *) clause2,
176 : true);
177 :
178 148 : strong_refuted_by = predicate_refuted_by((List *) clause1,
179 : (List *) clause2,
180 : false);
181 :
182 148 : weak_refuted_by = predicate_refuted_by((List *) clause1,
183 : (List *) clause2,
184 : true);
185 :
186 : /*
187 : * Issue warning if any proof is demonstrably incorrect.
188 : */
189 148 : if (strong_implied_by && !s_i_holds)
190 0 : elog(WARNING, "strong_implied_by result is incorrect");
191 148 : if (weak_implied_by && !w_i_holds)
192 0 : elog(WARNING, "weak_implied_by result is incorrect");
193 148 : if (strong_refuted_by && !s_r_holds)
194 0 : elog(WARNING, "strong_refuted_by result is incorrect");
195 148 : if (weak_refuted_by && !w_r_holds)
196 0 : elog(WARNING, "weak_refuted_by result is incorrect");
197 :
198 : /*
199 : * As with our earlier check of the logical consistency of whether strong
200 : * and weak refutation hold, we ought never prove strong refutation
201 : * without also proving weak refutation.
202 : *
203 : * Also as earlier we cannot make the same guarantee about implication
204 : * proofs.
205 : *
206 : * A warning here suggests a bug in the proof code.
207 : */
208 148 : if (strong_refuted_by && !weak_refuted_by)
209 0 : elog(WARNING, "strong_refuted_by was proven; weak_refuted_by should also be proven");
210 :
211 : /*
212 : * Clean up and return a record of the results.
213 : */
214 148 : if (SPI_finish() != SPI_OK_FINISH)
215 0 : elog(ERROR, "SPI_finish failed");
216 :
217 148 : tupdesc = CreateTemplateTupleDesc(8);
218 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 1,
219 : "strong_implied_by", BOOLOID, -1, 0);
220 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 2,
221 : "weak_implied_by", BOOLOID, -1, 0);
222 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 3,
223 : "strong_refuted_by", BOOLOID, -1, 0);
224 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 4,
225 : "weak_refuted_by", BOOLOID, -1, 0);
226 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 5,
227 : "s_i_holds", BOOLOID, -1, 0);
228 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 6,
229 : "w_i_holds", BOOLOID, -1, 0);
230 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 7,
231 : "s_r_holds", BOOLOID, -1, 0);
232 148 : TupleDescInitEntry(tupdesc, (AttrNumber) 8,
233 : "w_r_holds", BOOLOID, -1, 0);
234 148 : tupdesc = BlessTupleDesc(tupdesc);
235 :
236 148 : values[0] = BoolGetDatum(strong_implied_by);
237 148 : values[1] = BoolGetDatum(weak_implied_by);
238 148 : values[2] = BoolGetDatum(strong_refuted_by);
239 148 : values[3] = BoolGetDatum(weak_refuted_by);
240 148 : values[4] = BoolGetDatum(s_i_holds);
241 148 : values[5] = BoolGetDatum(w_i_holds);
242 148 : values[6] = BoolGetDatum(s_r_holds);
243 148 : values[7] = BoolGetDatum(w_r_holds);
244 :
245 148 : PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
246 : }
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