Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * partcache.c
4 : * Support routines for manipulating partition information cached in
5 : * relcache
6 : *
7 : * Portions Copyright (c) 1996-2025, 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 116284 : RelationGetPartitionKey(Relation rel)
52 : {
53 116284 : if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
54 12 : return NULL;
55 :
56 116272 : if (unlikely(rel->rd_partkey == NULL))
57 18404 : RelationBuildPartitionKey(rel);
58 :
59 116272 : return rel->rd_partkey;
60 : }
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 18404 : RelationBuildPartitionKey(Relation relation)
79 : {
80 : Form_pg_partitioned_table form;
81 : HeapTuple tuple;
82 : bool isnull;
83 : int i;
84 : PartitionKey key;
85 : AttrNumber *attrs;
86 : oidvector *opclass;
87 : oidvector *collation;
88 : ListCell *partexprs_item;
89 : Datum datum;
90 : MemoryContext partkeycxt,
91 : oldcxt;
92 : int16 procnum;
93 :
94 18404 : tuple = SearchSysCache1(PARTRELID,
95 : ObjectIdGetDatum(RelationGetRelid(relation)));
96 :
97 18404 : if (!HeapTupleIsValid(tuple))
98 0 : elog(ERROR, "cache lookup failed for partition key of relation %u",
99 : RelationGetRelid(relation));
100 :
101 18404 : partkeycxt = AllocSetContextCreate(CurTransactionContext,
102 : "partition key",
103 : ALLOCSET_SMALL_SIZES);
104 18404 : MemoryContextCopyAndSetIdentifier(partkeycxt,
105 : RelationGetRelationName(relation));
106 :
107 18404 : key = (PartitionKey) MemoryContextAllocZero(partkeycxt,
108 : sizeof(PartitionKeyData));
109 :
110 : /* Fixed-length attributes */
111 18404 : form = (Form_pg_partitioned_table) GETSTRUCT(tuple);
112 18404 : key->strategy = form->partstrat;
113 18404 : key->partnatts = form->partnatts;
114 :
115 : /* Validate partition strategy code */
116 18404 : if (key->strategy != PARTITION_STRATEGY_LIST &&
117 9632 : key->strategy != PARTITION_STRATEGY_RANGE &&
118 982 : 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 18404 : attrs = form->partattrs.values;
127 :
128 : /* But use the hard way to retrieve further variable-length attributes */
129 : /* Operator class */
130 18404 : datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
131 : Anum_pg_partitioned_table_partclass);
132 18404 : opclass = (oidvector *) DatumGetPointer(datum);
133 :
134 : /* Collation */
135 18404 : datum = SysCacheGetAttrNotNull(PARTRELID, tuple,
136 : Anum_pg_partitioned_table_partcollation);
137 18404 : collation = (oidvector *) DatumGetPointer(datum);
138 :
139 : /* Expressions */
140 18404 : datum = SysCacheGetAttr(PARTRELID, tuple,
141 : Anum_pg_partitioned_table_partexprs, &isnull);
142 18404 : if (!isnull)
143 : {
144 : char *exprString;
145 : Node *expr;
146 :
147 1018 : exprString = TextDatumGetCString(datum);
148 1018 : expr = stringToNode(exprString);
149 1018 : 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 1018 : expr = eval_const_expressions(NULL, expr);
161 1018 : fix_opfuncids(expr);
162 :
163 1018 : oldcxt = MemoryContextSwitchTo(partkeycxt);
164 1018 : key->partexprs = (List *) copyObject(expr);
165 1018 : MemoryContextSwitchTo(oldcxt);
166 : }
167 :
168 : /* Allocate assorted arrays in the partkeycxt, which we'll fill below */
169 18404 : oldcxt = MemoryContextSwitchTo(partkeycxt);
170 18404 : key->partattrs = (AttrNumber *) palloc0(key->partnatts * sizeof(AttrNumber));
171 18404 : key->partopfamily = (Oid *) palloc0(key->partnatts * sizeof(Oid));
172 18404 : key->partopcintype = (Oid *) palloc0(key->partnatts * sizeof(Oid));
173 18404 : key->partsupfunc = (FmgrInfo *) palloc0(key->partnatts * sizeof(FmgrInfo));
174 :
175 18404 : key->partcollation = (Oid *) palloc0(key->partnatts * sizeof(Oid));
176 18404 : key->parttypid = (Oid *) palloc0(key->partnatts * sizeof(Oid));
177 18404 : key->parttypmod = (int32 *) palloc0(key->partnatts * sizeof(int32));
178 18404 : key->parttyplen = (int16 *) palloc0(key->partnatts * sizeof(int16));
179 18404 : key->parttypbyval = (bool *) palloc0(key->partnatts * sizeof(bool));
180 18404 : key->parttypalign = (char *) palloc0(key->partnatts * sizeof(char));
181 18404 : key->parttypcoll = (Oid *) palloc0(key->partnatts * sizeof(Oid));
182 18404 : MemoryContextSwitchTo(oldcxt);
183 :
184 : /* determine support function number to search for */
185 18404 : procnum = (key->strategy == PARTITION_STRATEGY_HASH) ?
186 : HASHEXTENDED_PROC : BTORDER_PROC;
187 :
188 : /* Copy partattrs and fill other per-attribute info */
189 18404 : memcpy(key->partattrs, attrs, key->partnatts * sizeof(int16));
190 18404 : partexprs_item = list_head(key->partexprs);
191 38772 : for (i = 0; i < key->partnatts; i++)
192 : {
193 20368 : AttrNumber attno = key->partattrs[i];
194 : HeapTuple opclasstup;
195 : Form_pg_opclass opclassform;
196 : Oid funcid;
197 :
198 : /* Collect opfamily information */
199 20368 : opclasstup = SearchSysCache1(CLAOID,
200 : ObjectIdGetDatum(opclass->values[i]));
201 20368 : if (!HeapTupleIsValid(opclasstup))
202 0 : elog(ERROR, "cache lookup failed for opclass %u", opclass->values[i]);
203 :
204 20368 : opclassform = (Form_pg_opclass) GETSTRUCT(opclasstup);
205 20368 : key->partopfamily[i] = opclassform->opcfamily;
206 20368 : key->partopcintype[i] = opclassform->opcintype;
207 :
208 : /* Get a support function for the specified opfamily and datatypes */
209 20368 : funcid = get_opfamily_proc(opclassform->opcfamily,
210 : opclassform->opcintype,
211 : opclassform->opcintype,
212 : procnum);
213 20368 : 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 20368 : fmgr_info_cxt(funcid, &key->partsupfunc[i], partkeycxt);
224 :
225 : /* Collation */
226 20368 : key->partcollation[i] = collation->values[i];
227 :
228 : /* Collect type information */
229 20368 : if (attno != 0)
230 : {
231 19278 : Form_pg_attribute att = TupleDescAttr(relation->rd_att, attno - 1);
232 :
233 19278 : key->parttypid[i] = att->atttypid;
234 19278 : key->parttypmod[i] = att->atttypmod;
235 19278 : key->parttypcoll[i] = att->attcollation;
236 : }
237 : else
238 : {
239 1090 : if (partexprs_item == NULL)
240 0 : elog(ERROR, "wrong number of partition key expressions");
241 :
242 1090 : key->parttypid[i] = exprType(lfirst(partexprs_item));
243 1090 : key->parttypmod[i] = exprTypmod(lfirst(partexprs_item));
244 1090 : key->parttypcoll[i] = exprCollation(lfirst(partexprs_item));
245 :
246 1090 : partexprs_item = lnext(key->partexprs, partexprs_item);
247 : }
248 20368 : get_typlenbyvalalign(key->parttypid[i],
249 20368 : &key->parttyplen[i],
250 20368 : &key->parttypbyval[i],
251 20368 : &key->parttypalign[i]);
252 :
253 20368 : ReleaseSysCache(opclasstup);
254 : }
255 :
256 18404 : ReleaseSysCache(tuple);
257 :
258 : /* Assert that we're not leaking any old data during assignments below */
259 : Assert(relation->rd_partkeycxt == NULL);
260 : 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 18404 : MemoryContextSetParent(partkeycxt, CacheMemoryContext);
267 18404 : relation->rd_partkeycxt = partkeycxt;
268 18404 : relation->rd_partkey = key;
269 18404 : }
270 :
271 : /*
272 : * RelationGetPartitionQual
273 : *
274 : * Returns a list of partition quals
275 : */
276 : List *
277 25272 : RelationGetPartitionQual(Relation rel)
278 : {
279 : /* Quick exit */
280 25272 : if (!rel->rd_rel->relispartition)
281 15616 : return NIL;
282 :
283 9656 : return generate_partition_qual(rel);
284 : }
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 *
299 292 : get_partition_qual_relid(Oid relid)
300 : {
301 292 : Expr *result = NULL;
302 :
303 : /* Do the work only if this relation exists and is a partition. */
304 292 : if (get_rel_relispartition(relid))
305 : {
306 292 : Relation rel = relation_open(relid, AccessShareLock);
307 : List *and_args;
308 :
309 292 : and_args = generate_partition_qual(rel);
310 :
311 : /* Convert implicit-AND list format to boolean expression */
312 292 : if (and_args == NIL)
313 18 : result = NULL;
314 274 : else if (list_length(and_args) > 1)
315 262 : result = makeBoolExpr(AND_EXPR, and_args, -1);
316 : else
317 12 : result = linitial(and_args);
318 :
319 : /* Keep the lock, to allow safe deparsing against the rel by caller. */
320 292 : relation_close(rel, NoLock);
321 : }
322 :
323 292 : return result;
324 : }
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 10592 : generate_partition_qual(Relation rel)
338 : {
339 : HeapTuple tuple;
340 : MemoryContext oldcxt;
341 : Datum boundDatum;
342 : bool isnull;
343 10592 : List *my_qual = NIL,
344 10592 : *result = NIL;
345 : Oid parentrelid;
346 : Relation parent;
347 :
348 : /* Guard against stack overflow due to overly deep partition tree */
349 10592 : check_stack_depth();
350 :
351 : /* If we already cached the result, just return a copy */
352 10592 : if (rel->rd_partcheckvalid)
353 6600 : 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 3992 : parentrelid = get_partition_parent(RelationGetRelid(rel), true);
362 3992 : parent = relation_open(parentrelid, AccessShareLock);
363 :
364 : /* Get pg_class.relpartbound */
365 3992 : tuple = SearchSysCache1(RELOID,
366 : ObjectIdGetDatum(RelationGetRelid(rel)));
367 3992 : if (!HeapTupleIsValid(tuple))
368 0 : elog(ERROR, "cache lookup failed for relation %u",
369 : RelationGetRelid(rel));
370 :
371 3992 : boundDatum = SysCacheGetAttr(RELOID, tuple,
372 : Anum_pg_class_relpartbound,
373 : &isnull);
374 3992 : if (!isnull)
375 : {
376 : PartitionBoundSpec *bound;
377 :
378 3980 : bound = castNode(PartitionBoundSpec,
379 : stringToNode(TextDatumGetCString(boundDatum)));
380 :
381 3980 : my_qual = get_qual_from_partbound(parent, bound);
382 : }
383 :
384 3992 : ReleaseSysCache(tuple);
385 :
386 : /* Add the parent's quals to the list (if any) */
387 3992 : if (parent->rd_rel->relispartition)
388 644 : result = list_concat(generate_partition_qual(parent), my_qual);
389 : else
390 3348 : 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 3992 : result = map_partition_varattnos(result, 1, rel, parent);
399 :
400 : /* Assert that we're not leaking any old data during assignments below */
401 : Assert(rel->rd_partcheckcxt == NULL);
402 : 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 3992 : if (result != NIL)
413 : {
414 3932 : rel->rd_partcheckcxt = AllocSetContextCreate(CacheMemoryContext,
415 : "partition constraint",
416 : ALLOCSET_SMALL_SIZES);
417 3932 : MemoryContextCopyAndSetIdentifier(rel->rd_partcheckcxt,
418 : RelationGetRelationName(rel));
419 3932 : oldcxt = MemoryContextSwitchTo(rel->rd_partcheckcxt);
420 3932 : rel->rd_partcheck = copyObject(result);
421 3932 : MemoryContextSwitchTo(oldcxt);
422 : }
423 : else
424 60 : rel->rd_partcheck = NIL;
425 3992 : rel->rd_partcheckvalid = true;
426 :
427 : /* Keep the parent locked until commit */
428 3992 : relation_close(parent, NoLock);
429 :
430 : /* Return the working copy to the caller */
431 3992 : return result;
432 : }
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