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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * partcache.c
4 : : * Support routines for manipulating partition information cached in
5 : : * relcache
6 : : *
7 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
8 : : * Portions Copyright (c) 1994, Regents of the University of California
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/utils/cache/partcache.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : : #include "postgres.h"
16 : :
17 : : #include "access/hash.h"
18 : : #include "access/htup_details.h"
19 : : #include "access/nbtree.h"
20 : : #include "access/relation.h"
21 : : #include "catalog/partition.h"
22 : : #include "catalog/pg_opclass.h"
23 : : #include "catalog/pg_partitioned_table.h"
24 : : #include "miscadmin.h"
25 : : #include "nodes/makefuncs.h"
26 : : #include "nodes/nodeFuncs.h"
27 : : #include "optimizer/optimizer.h"
28 : : #include "partitioning/partbounds.h"
29 : : #include "utils/builtins.h"
30 : : #include "utils/lsyscache.h"
31 : : #include "utils/memutils.h"
32 : : #include "utils/partcache.h"
33 : : #include "utils/rel.h"
34 : : #include "utils/syscache.h"
35 : :
36 : :
37 : : static void RelationBuildPartitionKey(Relation relation);
38 : : static List *generate_partition_qual(Relation rel);
39 : :
40 : : /*
41 : : * RelationGetPartitionKey -- get partition key, if relation is partitioned
42 : : *
43 : : * Note: partition keys are not allowed to change after the partitioned rel
44 : : * is created. RelationClearRelation knows this and preserves rd_partkey
45 : : * across relcache rebuilds, as long as the relation is open. Therefore,
46 : : * even though we hand back a direct pointer into the relcache entry, it's
47 : : * safe for callers to continue to use that pointer as long as they hold
48 : : * the relation open.
49 : : */
50 : : PartitionKey
51 : 17016 : RelationGetPartitionKey(Relation rel)
52 : : {
53 [ + + ]: 17016 : if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
54 : 2 : return NULL;
55 : :
56 [ + + ]: 17014 : if (unlikely(rel->rd_partkey == NULL))
57 : 2776 : RelationBuildPartitionKey(rel);
58 : :
59 : 17014 : return rel->rd_partkey;
60 : 17016 : }
61 : :
62 : : /*
63 : : * RelationBuildPartitionKey
64 : : * Build partition key data of relation, and attach to relcache
65 : : *
66 : : * Partitioning key data is a complex structure; to avoid complicated logic to
67 : : * free individual elements whenever the relcache entry is flushed, we give it
68 : : * its own memory context, a child of CacheMemoryContext, which can easily be
69 : : * deleted on its own. To avoid leaking memory in that context in case of an
70 : : * error partway through this function, the context is initially created as a
71 : : * child of CurTransactionContext and only re-parented to CacheMemoryContext
72 : : * at the end, when no further errors are possible. Also, we don't make this
73 : : * context the current context except in very brief code sections, out of fear
74 : : * that some of our callees allocate memory on their own which would be leaked
75 : : * permanently.
76 : : */
77 : : static void
78 : 2776 : RelationBuildPartitionKey(Relation relation)
79 : : {
80 : 2776 : Form_pg_partitioned_table form;
81 : 2776 : HeapTuple tuple;
82 : 2776 : bool isnull;
83 : 2776 : int i;
84 : 2776 : PartitionKey key;
85 : 2776 : AttrNumber *attrs;
86 : 2776 : oidvector *opclass;
87 : 2776 : oidvector *collation;
88 : 2776 : ListCell *partexprs_item;
89 : 2776 : Datum datum;
90 : 2776 : MemoryContext partkeycxt,
91 : : oldcxt;
92 : 2776 : int16 procnum;
93 : :
94 : 2776 : tuple = SearchSysCache1(PARTRELID,
95 : 2776 : ObjectIdGetDatum(RelationGetRelid(relation)));
96 : :
97 [ + - ]: 2776 : if (!HeapTupleIsValid(tuple))
98 [ # # # # ]: 0 : elog(ERROR, "cache lookup failed for partition key of relation %u",
99 : : RelationGetRelid(relation));
100 : :
101 : 2776 : partkeycxt = AllocSetContextCreate(CurTransactionContext,
102 : : "partition key",
103 : : ALLOCSET_SMALL_SIZES);
104 : 2776 : MemoryContextCopyAndSetIdentifier(partkeycxt,
105 : : RelationGetRelationName(relation));
106 : :
107 : 2776 : key = (PartitionKey) MemoryContextAllocZero(partkeycxt,
108 : : sizeof(PartitionKeyData));
109 : :
110 : : /* Fixed-length attributes */
111 : 2776 : form = (Form_pg_partitioned_table) GETSTRUCT(tuple);
112 : 2776 : key->strategy = form->partstrat;
113 : 2776 : key->partnatts = form->partnatts;
114 : :
115 : : /* Validate partition strategy code */
116 [ + + ]: 2776 : if (key->strategy != PARTITION_STRATEGY_LIST &&
117 [ + + + - ]: 1651 : key->strategy != PARTITION_STRATEGY_RANGE &&
118 : 139 : key->strategy != PARTITION_STRATEGY_HASH)
119 [ # # # # ]: 0 : elog(ERROR, "invalid partition strategy \"%c\"", key->strategy);
120 : :
121 : : /*
122 : : * We can rely on the first variable-length attribute being mapped to the
123 : : * relevant field of the catalog's C struct, because all previous
124 : : * attributes are non-nullable and fixed-length.
125 : : */
126 : 2776 : attrs = form->partattrs.values;
127 : :
128 : : /* But use the hard way to retrieve further variable-length attributes */
129 : : /* Operator class */
130 : 2776 : datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
131 : : Anum_pg_partitioned_table_partclass);
132 : 2776 : opclass = (oidvector *) DatumGetPointer(datum);
133 : :
134 : : /* Collation */
135 : 2776 : datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
136 : : Anum_pg_partitioned_table_partcollation);
137 : 2776 : collation = (oidvector *) DatumGetPointer(datum);
138 : :
139 : : /* Expressions */
140 : 2776 : datum = SysCacheGetAttr(PARTRELID, tuple,
141 : : Anum_pg_partitioned_table_partexprs, &isnull);
142 [ + + ]: 2776 : if (!isnull)
143 : : {
144 : 163 : char *exprString;
145 : 163 : Node *expr;
146 : :
147 : 163 : exprString = TextDatumGetCString(datum);
148 : 163 : expr = stringToNode(exprString);
149 : 163 : pfree(exprString);
150 : :
151 : : /*
152 : : * Run the expressions through const-simplification since the planner
153 : : * will be comparing them to similarly-processed qual clause operands,
154 : : * and may fail to detect valid matches without this step; fix
155 : : * opfuncids while at it. We don't need to bother with
156 : : * canonicalize_qual() though, because partition expressions should be
157 : : * in canonical form already (ie, no need for OR-merging or constant
158 : : * elimination).
159 : : */
160 : 163 : expr = eval_const_expressions(NULL, expr);
161 : 163 : fix_opfuncids(expr);
162 : :
163 : 163 : oldcxt = MemoryContextSwitchTo(partkeycxt);
164 : 163 : key->partexprs = (List *) copyObject(expr);
165 : 163 : MemoryContextSwitchTo(oldcxt);
166 : 163 : }
167 : :
168 : : /* Allocate assorted arrays in the partkeycxt, which we'll fill below */
169 : 2776 : oldcxt = MemoryContextSwitchTo(partkeycxt);
170 : 2776 : key->partattrs = palloc0_array(AttrNumber, key->partnatts);
171 : 2776 : key->partopfamily = palloc0_array(Oid, key->partnatts);
172 : 2776 : key->partopcintype = palloc0_array(Oid, key->partnatts);
173 : 2776 : key->partsupfunc = palloc0_array(FmgrInfo, key->partnatts);
174 : :
175 : 2776 : key->partcollation = palloc0_array(Oid, key->partnatts);
176 : 2776 : key->parttypid = palloc0_array(Oid, key->partnatts);
177 : 2776 : key->parttypmod = palloc0_array(int32, key->partnatts);
178 : 2776 : key->parttyplen = palloc0_array(int16, key->partnatts);
179 : 2776 : key->parttypbyval = palloc0_array(bool, key->partnatts);
180 : 2776 : key->parttypalign = palloc0_array(char, key->partnatts);
181 : 2776 : key->parttypcoll = palloc0_array(Oid, key->partnatts);
182 : 2776 : MemoryContextSwitchTo(oldcxt);
183 : :
184 : : /* determine support function number to search for */
185 : 2776 : procnum = (key->strategy == PARTITION_STRATEGY_HASH) ?
186 : : HASHEXTENDED_PROC : BTORDER_PROC;
187 : :
188 : : /* Copy partattrs and fill other per-attribute info */
189 : 2776 : memcpy(key->partattrs, attrs, key->partnatts * sizeof(int16));
190 : 2776 : partexprs_item = list_head(key->partexprs);
191 [ + + ]: 5896 : for (i = 0; i < key->partnatts; i++)
192 : : {
193 : 3120 : AttrNumber attno = key->partattrs[i];
194 : 3120 : HeapTuple opclasstup;
195 : 3120 : Form_pg_opclass opclassform;
196 : 3120 : Oid funcid;
197 : :
198 : : /* Collect opfamily information */
199 : 3120 : opclasstup = SearchSysCache1(CLAOID,
200 : 3120 : ObjectIdGetDatum(opclass->values[i]));
201 [ + - ]: 3120 : if (!HeapTupleIsValid(opclasstup))
202 [ # # # # ]: 0 : elog(ERROR, "cache lookup failed for opclass %u", opclass->values[i]);
203 : :
204 : 3120 : opclassform = (Form_pg_opclass) GETSTRUCT(opclasstup);
205 : 3120 : key->partopfamily[i] = opclassform->opcfamily;
206 : 3120 : key->partopcintype[i] = opclassform->opcintype;
207 : :
208 : : /* Get a support function for the specified opfamily and datatypes */
209 : 6240 : funcid = get_opfamily_proc(opclassform->opcfamily,
210 : 3120 : opclassform->opcintype,
211 : 3120 : opclassform->opcintype,
212 : 3120 : procnum);
213 [ + - ]: 3120 : if (!OidIsValid(funcid))
214 [ # # # # ]: 0 : ereport(ERROR,
215 : : (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
216 : : errmsg("operator class \"%s\" of access method %s is missing support function %d for type %s",
217 : : NameStr(opclassform->opcname),
218 : : (key->strategy == PARTITION_STRATEGY_HASH) ?
219 : : "hash" : "btree",
220 : : procnum,
221 : : format_type_be(opclassform->opcintype))));
222 : :
223 : 3120 : fmgr_info_cxt(funcid, &key->partsupfunc[i], partkeycxt);
224 : :
225 : : /* Collation */
226 : 3120 : key->partcollation[i] = collation->values[i];
227 : :
228 : : /* Collect type information */
229 [ + + ]: 3120 : if (attno != 0)
230 : : {
231 : 2945 : Form_pg_attribute att = TupleDescAttr(relation->rd_att, attno - 1);
232 : :
233 : 2945 : key->parttypid[i] = att->atttypid;
234 : 2945 : key->parttypmod[i] = att->atttypmod;
235 : 2945 : key->parttypcoll[i] = att->attcollation;
236 : 2945 : }
237 : : else
238 : : {
239 [ + - ]: 175 : if (partexprs_item == NULL)
240 [ # # # # ]: 0 : elog(ERROR, "wrong number of partition key expressions");
241 : :
242 : 175 : key->parttypid[i] = exprType(lfirst(partexprs_item));
243 : 175 : key->parttypmod[i] = exprTypmod(lfirst(partexprs_item));
244 : 175 : key->parttypcoll[i] = exprCollation(lfirst(partexprs_item));
245 : :
246 : 175 : partexprs_item = lnext(key->partexprs, partexprs_item);
247 : : }
248 : 6240 : get_typlenbyvalalign(key->parttypid[i],
249 : 3120 : &key->parttyplen[i],
250 : 3120 : &key->parttypbyval[i],
251 : 3120 : &key->parttypalign[i]);
252 : :
253 : 3120 : ReleaseSysCache(opclasstup);
254 : 3120 : }
255 : :
256 : 2776 : ReleaseSysCache(tuple);
257 : :
258 : : /* Assert that we're not leaking any old data during assignments below */
259 [ + - ]: 2776 : Assert(relation->rd_partkeycxt == NULL);
260 [ + - ]: 2776 : Assert(relation->rd_partkey == NULL);
261 : :
262 : : /*
263 : : * Success --- reparent our context and make the relcache point to the
264 : : * newly constructed key
265 : : */
266 : 2776 : MemoryContextSetParent(partkeycxt, CacheMemoryContext);
267 : 2776 : relation->rd_partkeycxt = partkeycxt;
268 : 2776 : relation->rd_partkey = key;
269 : 2776 : }
270 : :
271 : : /*
272 : : * RelationGetPartitionQual
273 : : *
274 : : * Returns a list of partition quals
275 : : */
276 : : List *
277 : 3110 : RelationGetPartitionQual(Relation rel)
278 : : {
279 : : /* Quick exit */
280 [ + + ]: 3110 : if (!rel->rd_rel->relispartition)
281 : 1975 : return NIL;
282 : :
283 : 1135 : return generate_partition_qual(rel);
284 : 3110 : }
285 : :
286 : : /*
287 : : * get_partition_qual_relid
288 : : *
289 : : * Returns an expression tree describing the passed-in relation's partition
290 : : * constraint.
291 : : *
292 : : * If the relation is not found, or is not a partition, or there is no
293 : : * partition constraint, return NULL. We must guard against the first two
294 : : * cases because this supports a SQL function that could be passed any OID.
295 : : * The last case can happen even if relispartition is true, when a default
296 : : * partition is the only partition.
297 : : */
298 : : Expr *
299 : 48 : get_partition_qual_relid(Oid relid)
300 : : {
301 : 48 : Expr *result = NULL;
302 : :
303 : : /* Do the work only if this relation exists and is a partition. */
304 [ - + ]: 48 : if (get_rel_relispartition(relid))
305 : : {
306 : 48 : Relation rel = relation_open(relid, AccessShareLock);
307 : 48 : List *and_args;
308 : :
309 : 48 : and_args = generate_partition_qual(rel);
310 : :
311 : : /* Convert implicit-AND list format to boolean expression */
312 [ + + ]: 48 : if (and_args == NIL)
313 : 4 : result = NULL;
314 [ + + ]: 44 : else if (list_length(and_args) > 1)
315 : 41 : result = makeBoolExpr(AND_EXPR, and_args, -1);
316 : : else
317 : 3 : result = linitial(and_args);
318 : :
319 : : /* Keep the lock, to allow safe deparsing against the rel by caller. */
320 : 48 : relation_close(rel, NoLock);
321 : 48 : }
322 : :
323 : 96 : return result;
324 : 48 : }
325 : :
326 : : /*
327 : : * generate_partition_qual
328 : : *
329 : : * Generate partition predicate from rel's partition bound expression. The
330 : : * function returns a NIL list if there is no predicate.
331 : : *
332 : : * We cache a copy of the result in the relcache entry, after constructing
333 : : * it using the caller's context. This approach avoids leaking any data
334 : : * into long-lived cache contexts, especially if we fail partway through.
335 : : */
336 : : static List *
337 : 1278 : generate_partition_qual(Relation rel)
338 : : {
339 : 1278 : HeapTuple tuple;
340 : 1278 : MemoryContext oldcxt;
341 : 1278 : Datum boundDatum;
342 : 1278 : bool isnull;
343 : 1278 : List *my_qual = NIL,
344 : 1278 : *result = NIL;
345 : 1278 : Oid parentrelid;
346 : 1278 : Relation parent;
347 : :
348 : : /* Guard against stack overflow due to overly deep partition tree */
349 : 1278 : check_stack_depth();
350 : :
351 : : /* If we already cached the result, just return a copy */
352 [ + + ]: 1278 : if (rel->rd_partcheckvalid)
353 : 784 : return copyObject(rel->rd_partcheck);
354 : :
355 : : /*
356 : : * Grab at least an AccessShareLock on the parent table. Must do this
357 : : * even if the partition has been partially detached, because transactions
358 : : * concurrent with the detach might still be trying to use a partition
359 : : * descriptor that includes it.
360 : : */
361 : 494 : parentrelid = get_partition_parent(RelationGetRelid(rel), true);
362 : 494 : parent = relation_open(parentrelid, AccessShareLock);
363 : :
364 : : /* Get pg_class.relpartbound */
365 : 494 : tuple = SearchSysCache1(RELOID,
366 : 494 : ObjectIdGetDatum(RelationGetRelid(rel)));
367 [ + - ]: 494 : if (!HeapTupleIsValid(tuple))
368 [ # # # # ]: 0 : elog(ERROR, "cache lookup failed for relation %u",
369 : : RelationGetRelid(rel));
370 : :
371 : 494 : boundDatum = SysCacheGetAttr(RELOID, tuple,
372 : : Anum_pg_class_relpartbound,
373 : : &isnull);
374 [ + + ]: 494 : if (!isnull)
375 : : {
376 : 492 : PartitionBoundSpec *bound;
377 : :
378 : 492 : bound = castNode(PartitionBoundSpec,
379 : : stringToNode(TextDatumGetCString(boundDatum)));
380 : :
381 : 492 : my_qual = get_qual_from_partbound(parent, bound);
382 : 492 : }
383 : :
384 : 494 : ReleaseSysCache(tuple);
385 : :
386 : : /* Add the parent's quals to the list (if any) */
387 [ + + ]: 494 : if (parent->rd_rel->relispartition)
388 : 95 : result = list_concat(generate_partition_qual(parent), my_qual);
389 : : else
390 : 399 : result = my_qual;
391 : :
392 : : /*
393 : : * Change Vars to have partition's attnos instead of the parent's. We do
394 : : * this after we concatenate the parent's quals, because we want every Var
395 : : * in it to bear this relation's attnos. It's safe to assume varno = 1
396 : : * here.
397 : : */
398 : 494 : result = map_partition_varattnos(result, 1, rel, parent);
399 : :
400 : : /* Assert that we're not leaking any old data during assignments below */
401 [ + - ]: 494 : Assert(rel->rd_partcheckcxt == NULL);
402 [ + - ]: 494 : Assert(rel->rd_partcheck == NIL);
403 : :
404 : : /*
405 : : * Save a copy in the relcache. The order of these operations is fairly
406 : : * critical to avoid memory leaks and ensure that we don't leave a corrupt
407 : : * relcache entry if we fail partway through copyObject.
408 : : *
409 : : * If, as is definitely possible, the partcheck list is NIL, then we do
410 : : * not need to make a context to hold it.
411 : : */
412 [ + + ]: 494 : if (result != NIL)
413 : : {
414 : 485 : rel->rd_partcheckcxt = AllocSetContextCreate(CacheMemoryContext,
415 : : "partition constraint",
416 : : ALLOCSET_SMALL_SIZES);
417 : 485 : MemoryContextCopyAndSetIdentifier(rel->rd_partcheckcxt,
418 : : RelationGetRelationName(rel));
419 : 485 : oldcxt = MemoryContextSwitchTo(rel->rd_partcheckcxt);
420 : 485 : rel->rd_partcheck = copyObject(result);
421 : 485 : MemoryContextSwitchTo(oldcxt);
422 : 485 : }
423 : : else
424 : 9 : rel->rd_partcheck = NIL;
425 : 494 : rel->rd_partcheckvalid = true;
426 : :
427 : : /* Keep the parent locked until commit */
428 : 494 : relation_close(parent, NoLock);
429 : :
430 : : /* Return the working copy to the caller */
431 : 494 : return result;
432 : 1278 : }
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