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partcache.c
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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) 1996-2023, 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_inherits.h"
23 #include "catalog/pg_opclass.h"
25 #include "miscadmin.h"
26 #include "nodes/makefuncs.h"
27 #include "nodes/nodeFuncs.h"
28 #include "optimizer/optimizer.h"
30 #include "rewrite/rewriteHandler.h"
31 #include "utils/builtins.h"
32 #include "utils/datum.h"
33 #include "utils/lsyscache.h"
34 #include "utils/memutils.h"
35 #include "utils/partcache.h"
36 #include "utils/rel.h"
37 #include "utils/syscache.h"
38 
39 
40 static void RelationBuildPartitionKey(Relation relation);
42 
43 /*
44  * RelationGetPartitionKey -- get partition key, if relation is partitioned
45  *
46  * Note: partition keys are not allowed to change after the partitioned rel
47  * is created. RelationClearRelation knows this and preserves rd_partkey
48  * across relcache rebuilds, as long as the relation is open. Therefore,
49  * even though we hand back a direct pointer into the relcache entry, it's
50  * safe for callers to continue to use that pointer as long as they hold
51  * the relation open.
52  */
55 {
56  if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
57  return NULL;
58 
59  if (unlikely(rel->rd_partkey == NULL))
61 
62  return rel->rd_partkey;
63 }
64 
65 /*
66  * RelationBuildPartitionKey
67  * Build partition key data of relation, and attach to relcache
68  *
69  * Partitioning key data is a complex structure; to avoid complicated logic to
70  * free individual elements whenever the relcache entry is flushed, we give it
71  * its own memory context, a child of CacheMemoryContext, which can easily be
72  * deleted on its own. To avoid leaking memory in that context in case of an
73  * error partway through this function, the context is initially created as a
74  * child of CurTransactionContext and only re-parented to CacheMemoryContext
75  * at the end, when no further errors are possible. Also, we don't make this
76  * context the current context except in very brief code sections, out of fear
77  * that some of our callees allocate memory on their own which would be leaked
78  * permanently.
79  */
80 static void
82 {
84  HeapTuple tuple;
85  bool isnull;
86  int i;
88  AttrNumber *attrs;
89  oidvector *opclass;
90  oidvector *collation;
91  ListCell *partexprs_item;
92  Datum datum;
93  MemoryContext partkeycxt,
94  oldcxt;
95  int16 procnum;
96 
97  tuple = SearchSysCache1(PARTRELID,
99 
100  if (!HeapTupleIsValid(tuple))
101  elog(ERROR, "cache lookup failed for partition key of relation %u",
102  RelationGetRelid(relation));
103 
105  "partition key",
108  RelationGetRelationName(relation));
109 
110  key = (PartitionKey) MemoryContextAllocZero(partkeycxt,
111  sizeof(PartitionKeyData));
112 
113  /* Fixed-length attributes */
114  form = (Form_pg_partitioned_table) GETSTRUCT(tuple);
115  key->strategy = form->partstrat;
116  key->partnatts = form->partnatts;
117 
118  /* Validate partition strategy code */
119  if (key->strategy != PARTITION_STRATEGY_LIST &&
120  key->strategy != PARTITION_STRATEGY_RANGE &&
121  key->strategy != PARTITION_STRATEGY_HASH)
122  elog(ERROR, "invalid partition strategy \"%c\"", key->strategy);
123 
124  /*
125  * We can rely on the first variable-length attribute being mapped to the
126  * relevant field of the catalog's C struct, because all previous
127  * attributes are non-nullable and fixed-length.
128  */
129  attrs = form->partattrs.values;
130 
131  /* But use the hard way to retrieve further variable-length attributes */
132  /* Operator class */
133  datum = SysCacheGetAttr(PARTRELID, tuple,
134  Anum_pg_partitioned_table_partclass, &isnull);
135  Assert(!isnull);
136  opclass = (oidvector *) DatumGetPointer(datum);
137 
138  /* Collation */
139  datum = SysCacheGetAttr(PARTRELID, tuple,
140  Anum_pg_partitioned_table_partcollation, &isnull);
141  Assert(!isnull);
142  collation = (oidvector *) DatumGetPointer(datum);
143 
144  /* Expressions */
145  datum = SysCacheGetAttr(PARTRELID, tuple,
146  Anum_pg_partitioned_table_partexprs, &isnull);
147  if (!isnull)
148  {
149  char *exprString;
150  Node *expr;
151 
152  exprString = TextDatumGetCString(datum);
153  expr = stringToNode(exprString);
154  pfree(exprString);
155 
156  /*
157  * Run the expressions through const-simplification since the planner
158  * will be comparing them to similarly-processed qual clause operands,
159  * and may fail to detect valid matches without this step; fix
160  * opfuncids while at it. We don't need to bother with
161  * canonicalize_qual() though, because partition expressions should be
162  * in canonical form already (ie, no need for OR-merging or constant
163  * elimination).
164  */
165  expr = eval_const_expressions(NULL, expr);
166  fix_opfuncids(expr);
167 
168  oldcxt = MemoryContextSwitchTo(partkeycxt);
169  key->partexprs = (List *) copyObject(expr);
170  MemoryContextSwitchTo(oldcxt);
171  }
172 
173  /* Allocate assorted arrays in the partkeycxt, which we'll fill below */
174  oldcxt = MemoryContextSwitchTo(partkeycxt);
175  key->partattrs = (AttrNumber *) palloc0(key->partnatts * sizeof(AttrNumber));
176  key->partopfamily = (Oid *) palloc0(key->partnatts * sizeof(Oid));
177  key->partopcintype = (Oid *) palloc0(key->partnatts * sizeof(Oid));
178  key->partsupfunc = (FmgrInfo *) palloc0(key->partnatts * sizeof(FmgrInfo));
179 
180  key->partcollation = (Oid *) palloc0(key->partnatts * sizeof(Oid));
181  key->parttypid = (Oid *) palloc0(key->partnatts * sizeof(Oid));
182  key->parttypmod = (int32 *) palloc0(key->partnatts * sizeof(int32));
183  key->parttyplen = (int16 *) palloc0(key->partnatts * sizeof(int16));
184  key->parttypbyval = (bool *) palloc0(key->partnatts * sizeof(bool));
185  key->parttypalign = (char *) palloc0(key->partnatts * sizeof(char));
186  key->parttypcoll = (Oid *) palloc0(key->partnatts * sizeof(Oid));
187  MemoryContextSwitchTo(oldcxt);
188 
189  /* determine support function number to search for */
190  procnum = (key->strategy == PARTITION_STRATEGY_HASH) ?
192 
193  /* Copy partattrs and fill other per-attribute info */
194  memcpy(key->partattrs, attrs, key->partnatts * sizeof(int16));
195  partexprs_item = list_head(key->partexprs);
196  for (i = 0; i < key->partnatts; i++)
197  {
198  AttrNumber attno = key->partattrs[i];
199  HeapTuple opclasstup;
200  Form_pg_opclass opclassform;
201  Oid funcid;
202 
203  /* Collect opfamily information */
204  opclasstup = SearchSysCache1(CLAOID,
205  ObjectIdGetDatum(opclass->values[i]));
206  if (!HeapTupleIsValid(opclasstup))
207  elog(ERROR, "cache lookup failed for opclass %u", opclass->values[i]);
208 
209  opclassform = (Form_pg_opclass) GETSTRUCT(opclasstup);
210  key->partopfamily[i] = opclassform->opcfamily;
211  key->partopcintype[i] = opclassform->opcintype;
212 
213  /* Get a support function for the specified opfamily and datatypes */
214  funcid = get_opfamily_proc(opclassform->opcfamily,
215  opclassform->opcintype,
216  opclassform->opcintype,
217  procnum);
218  if (!OidIsValid(funcid))
219  ereport(ERROR,
220  (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
221  errmsg("operator class \"%s\" of access method %s is missing support function %d for type %s",
222  NameStr(opclassform->opcname),
223  (key->strategy == PARTITION_STRATEGY_HASH) ?
224  "hash" : "btree",
225  procnum,
226  format_type_be(opclassform->opcintype))));
227 
228  fmgr_info_cxt(funcid, &key->partsupfunc[i], partkeycxt);
229 
230  /* Collation */
231  key->partcollation[i] = collation->values[i];
232 
233  /* Collect type information */
234  if (attno != 0)
235  {
236  Form_pg_attribute att = TupleDescAttr(relation->rd_att, attno - 1);
237 
238  key->parttypid[i] = att->atttypid;
239  key->parttypmod[i] = att->atttypmod;
240  key->parttypcoll[i] = att->attcollation;
241  }
242  else
243  {
244  if (partexprs_item == NULL)
245  elog(ERROR, "wrong number of partition key expressions");
246 
247  key->parttypid[i] = exprType(lfirst(partexprs_item));
248  key->parttypmod[i] = exprTypmod(lfirst(partexprs_item));
249  key->parttypcoll[i] = exprCollation(lfirst(partexprs_item));
250 
251  partexprs_item = lnext(key->partexprs, partexprs_item);
252  }
253  get_typlenbyvalalign(key->parttypid[i],
254  &key->parttyplen[i],
255  &key->parttypbyval[i],
256  &key->parttypalign[i]);
257 
258  ReleaseSysCache(opclasstup);
259  }
260 
261  ReleaseSysCache(tuple);
262 
263  /* Assert that we're not leaking any old data during assignments below */
264  Assert(relation->rd_partkeycxt == NULL);
265  Assert(relation->rd_partkey == NULL);
266 
267  /*
268  * Success --- reparent our context and make the relcache point to the
269  * newly constructed key
270  */
272  relation->rd_partkeycxt = partkeycxt;
273  relation->rd_partkey = key;
274 }
275 
276 /*
277  * RelationGetPartitionQual
278  *
279  * Returns a list of partition quals
280  */
281 List *
283 {
284  /* Quick exit */
285  if (!rel->rd_rel->relispartition)
286  return NIL;
287 
288  return generate_partition_qual(rel);
289 }
290 
291 /*
292  * get_partition_qual_relid
293  *
294  * Returns an expression tree describing the passed-in relation's partition
295  * constraint.
296  *
297  * If the relation is not found, or is not a partition, or there is no
298  * partition constraint, return NULL. We must guard against the first two
299  * cases because this supports a SQL function that could be passed any OID.
300  * The last case can happen even if relispartition is true, when a default
301  * partition is the only partition.
302  */
303 Expr *
305 {
306  Expr *result = NULL;
307 
308  /* Do the work only if this relation exists and is a partition. */
309  if (get_rel_relispartition(relid))
310  {
311  Relation rel = relation_open(relid, AccessShareLock);
312  List *and_args;
313 
314  and_args = generate_partition_qual(rel);
315 
316  /* Convert implicit-AND list format to boolean expression */
317  if (and_args == NIL)
318  result = NULL;
319  else if (list_length(and_args) > 1)
320  result = makeBoolExpr(AND_EXPR, and_args, -1);
321  else
322  result = linitial(and_args);
323 
324  /* Keep the lock, to allow safe deparsing against the rel by caller. */
325  relation_close(rel, NoLock);
326  }
327 
328  return result;
329 }
330 
331 /*
332  * generate_partition_qual
333  *
334  * Generate partition predicate from rel's partition bound expression. The
335  * function returns a NIL list if there is no predicate.
336  *
337  * We cache a copy of the result in the relcache entry, after constructing
338  * it using the caller's context. This approach avoids leaking any data
339  * into long-lived cache contexts, especially if we fail partway through.
340  */
341 static List *
343 {
344  HeapTuple tuple;
345  MemoryContext oldcxt;
346  Datum boundDatum;
347  bool isnull;
348  List *my_qual = NIL,
349  *result = NIL;
350  Oid parentrelid;
351  Relation parent;
352 
353  /* Guard against stack overflow due to overly deep partition tree */
355 
356  /* If we already cached the result, just return a copy */
357  if (rel->rd_partcheckvalid)
358  return copyObject(rel->rd_partcheck);
359 
360  /*
361  * Grab at least an AccessShareLock on the parent table. Must do this
362  * even if the partition has been partially detached, because transactions
363  * concurrent with the detach might still be trying to use a partition
364  * descriptor that includes it.
365  */
366  parentrelid = get_partition_parent(RelationGetRelid(rel), true);
367  parent = relation_open(parentrelid, AccessShareLock);
368 
369  /* Get pg_class.relpartbound */
370  tuple = SearchSysCache1(RELOID, RelationGetRelid(rel));
371  if (!HeapTupleIsValid(tuple))
372  elog(ERROR, "cache lookup failed for relation %u",
373  RelationGetRelid(rel));
374 
375  boundDatum = SysCacheGetAttr(RELOID, tuple,
376  Anum_pg_class_relpartbound,
377  &isnull);
378  if (!isnull)
379  {
380  PartitionBoundSpec *bound;
381 
383  stringToNode(TextDatumGetCString(boundDatum)));
384 
385  my_qual = get_qual_from_partbound(parent, bound);
386  }
387 
388  ReleaseSysCache(tuple);
389 
390  /* Add the parent's quals to the list (if any) */
391  if (parent->rd_rel->relispartition)
392  result = list_concat(generate_partition_qual(parent), my_qual);
393  else
394  result = my_qual;
395 
396  /*
397  * Change Vars to have partition's attnos instead of the parent's. We do
398  * this after we concatenate the parent's quals, because we want every Var
399  * in it to bear this relation's attnos. It's safe to assume varno = 1
400  * here.
401  */
402  result = map_partition_varattnos(result, 1, rel, parent);
403 
404  /* Assert that we're not leaking any old data during assignments below */
405  Assert(rel->rd_partcheckcxt == NULL);
406  Assert(rel->rd_partcheck == NIL);
407 
408  /*
409  * Save a copy in the relcache. The order of these operations is fairly
410  * critical to avoid memory leaks and ensure that we don't leave a corrupt
411  * relcache entry if we fail partway through copyObject.
412  *
413  * If, as is definitely possible, the partcheck list is NIL, then we do
414  * not need to make a context to hold it.
415  */
416  if (result != NIL)
417  {
419  "partition constraint",
423  oldcxt = MemoryContextSwitchTo(rel->rd_partcheckcxt);
424  rel->rd_partcheck = copyObject(result);
425  MemoryContextSwitchTo(oldcxt);
426  }
427  else
428  rel->rd_partcheck = NIL;
429  rel->rd_partcheckvalid = true;
430 
431  /* Keep the parent locked until commit */
432  relation_close(parent, NoLock);
433 
434  /* Return the working copy to the caller */
435  return result;
436 }
int16 AttrNumber
Definition: attnum.h:21
#define TextDatumGetCString(d)
Definition: builtins.h:95
#define NameStr(name)
Definition: c.h:730
signed short int16
Definition: c.h:477
signed int int32
Definition: c.h:478
#define unlikely(x)
Definition: c.h:295
#define OidIsValid(objectId)
Definition: c.h:759
Node * eval_const_expressions(PlannerInfo *root, Node *node)
Definition: clauses.c:2134
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Definition: elog.c:858
int errmsg(const char *fmt,...)
Definition: elog.c:1069
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Definition: elog.h:39
#define ereport(elevel,...)
Definition: elog.h:149
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Definition: fmgr.c:137
char * format_type_be(Oid type_oid)
Definition: format_type.c:339
#define HASHEXTENDED_PROC
Definition: hash.h:356
#define HeapTupleIsValid(tuple)
Definition: htup.h:78
#define GETSTRUCT(TUP)
Definition: htup_details.h:653
int i
Definition: isn.c:73
Assert(fmt[strlen(fmt) - 1] !='\n')
List * list_concat(List *list1, const List *list2)
Definition: list.c:560
#define NoLock
Definition: lockdefs.h:34
#define AccessShareLock
Definition: lockdefs.h:36
bool get_rel_relispartition(Oid relid)
Definition: lsyscache.c:2009
void get_typlenbyvalalign(Oid typid, int16 *typlen, bool *typbyval, char *typalign)
Definition: lsyscache.c:2229
Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype, int16 procnum)
Definition: lsyscache.c:795
Expr * makeBoolExpr(BoolExprType boolop, List *args, int location)
Definition: makefuncs.c:371
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Definition: mcxt.c:530
void pfree(void *pointer)
Definition: mcxt.c:1436
void * palloc0(Size size)
Definition: mcxt.c:1241
void * MemoryContextAllocZero(MemoryContext context, Size size)
Definition: mcxt.c:1048
MemoryContext CurTransactionContext
Definition: mcxt.c:147
MemoryContext CacheMemoryContext
Definition: mcxt.c:144
#define AllocSetContextCreate
Definition: memutils.h:129
#define ALLOCSET_SMALL_SIZES
Definition: memutils.h:163
#define MemoryContextCopyAndSetIdentifier(cxt, id)
Definition: memutils.h:101
#define BTORDER_PROC
Definition: nbtree.h:708
Oid exprType(const Node *expr)
Definition: nodeFuncs.c:43
int32 exprTypmod(const Node *expr)
Definition: nodeFuncs.c:266
Oid exprCollation(const Node *expr)
Definition: nodeFuncs.c:764
void fix_opfuncids(Node *node)
Definition: nodeFuncs.c:1641
#define copyObject(obj)
Definition: nodes.h:244
#define castNode(_type_, nodeptr)
Definition: nodes.h:197
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:138
@ PARTITION_STRATEGY_HASH
Definition: parsenodes.h:869
@ PARTITION_STRATEGY_LIST
Definition: parsenodes.h:867
@ PARTITION_STRATEGY_RANGE
Definition: parsenodes.h:868
List * get_qual_from_partbound(Relation parent, PartitionBoundSpec *spec)
Definition: partbounds.c:250
Expr * get_partition_qual_relid(Oid relid)
Definition: partcache.c:304
static List * generate_partition_qual(Relation rel)
Definition: partcache.c:342
static void RelationBuildPartitionKey(Relation relation)
Definition: partcache.c:81
List * RelationGetPartitionQual(Relation rel)
Definition: partcache.c:282
PartitionKey RelationGetPartitionKey(Relation rel)
Definition: partcache.c:54
struct PartitionKeyData * PartitionKey
Definition: partdefs.h:18
List * map_partition_varattnos(List *expr, int fromrel_varno, Relation to_rel, Relation from_rel)
Definition: partition.c:221
Oid get_partition_parent(Oid relid, bool even_if_detached)
Definition: partition.c:54
FormData_pg_attribute * Form_pg_attribute
Definition: pg_attribute.h:207
#define lfirst(lc)
Definition: pg_list.h:172
static int list_length(const List *l)
Definition: pg_list.h:152
#define NIL
Definition: pg_list.h:68
static ListCell * list_head(const List *l)
Definition: pg_list.h:128
#define linitial(l)
Definition: pg_list.h:178
static ListCell * lnext(const List *l, const ListCell *c)
Definition: pg_list.h:343
FormData_pg_opclass * Form_pg_opclass
Definition: pg_opclass.h:83
FormData_pg_partitioned_table * Form_pg_partitioned_table
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Definition: postgres.c:3461
uintptr_t Datum
Definition: postgres.h:64
static Datum ObjectIdGetDatum(Oid X)
Definition: postgres.h:252
static Pointer DatumGetPointer(Datum X)
Definition: postgres.h:312
unsigned int Oid
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@ AND_EXPR
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void * stringToNode(const char *str)
Definition: read.c:90
#define RelationGetRelid(relation)
Definition: rel.h:503
#define RelationGetRelationName(relation)
Definition: rel.h:537
void relation_close(Relation relation, LOCKMODE lockmode)
Definition: relation.c:206
Relation relation_open(Oid relationId, LOCKMODE lockmode)
Definition: relation.c:48
Definition: fmgr.h:57
Definition: pg_list.h:54
Definition: nodes.h:129
List * rd_partcheck
Definition: rel.h:146
bool rd_partcheckvalid
Definition: rel.h:147
MemoryContext rd_partkeycxt
Definition: rel.h:126
MemoryContext rd_partcheckcxt
Definition: rel.h:148
TupleDesc rd_att
Definition: rel.h:111
PartitionKey rd_partkey
Definition: rel.h:125
Form_pg_class rd_rel
Definition: rel.h:110
Definition: c.h:710
Oid values[FLEXIBLE_ARRAY_MEMBER]
Definition: c.h:717
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Definition: syscache.c:865
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Definition: syscache.c:817
Datum SysCacheGetAttr(int cacheId, HeapTuple tup, AttrNumber attributeNumber, bool *isNull)
Definition: syscache.c:1078
@ RELOID
Definition: syscache.h:89
@ CLAOID
Definition: syscache.h:48
@ PARTRELID
Definition: syscache.h:77
#define TupleDescAttr(tupdesc, i)
Definition: tupdesc.h:92