Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeMemoize.c
4 : * Routines to handle caching of results from parameterized nodes
5 : *
6 : * Portions Copyright (c) 2021-2025, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/executor/nodeMemoize.c
12 : *
13 : * Memoize nodes are intended to sit above parameterized nodes in the plan
14 : * tree in order to cache results from them. The intention here is that a
15 : * repeat scan with a parameter value that has already been seen by the node
16 : * can fetch tuples from the cache rather than having to re-scan the inner
17 : * node all over again. The query planner may choose to make use of one of
18 : * these when it thinks rescans for previously seen values are likely enough
19 : * to warrant adding the additional node.
20 : *
21 : * The method of cache we use is a hash table. When the cache fills, we never
22 : * spill tuples to disk, instead, we choose to evict the least recently used
23 : * cache entry from the cache. We remember the least recently used entry by
24 : * always pushing new entries and entries we look for onto the tail of a
25 : * doubly linked list. This means that older items always bubble to the top
26 : * of this LRU list.
27 : *
28 : * Sometimes our callers won't run their scans to completion. For example a
29 : * semi-join only needs to run until it finds a matching tuple, and once it
30 : * does, the join operator skips to the next outer tuple and does not execute
31 : * the inner side again on that scan. Because of this, we must keep track of
32 : * when a cache entry is complete, and by default, we know it is when we run
33 : * out of tuples to read during the scan. However, there are cases where we
34 : * can mark the cache entry as complete without exhausting the scan of all
35 : * tuples. One case is unique joins, where the join operator knows that there
36 : * will only be at most one match for any given outer tuple. In order to
37 : * support such cases we allow the "singlerow" option to be set for the cache.
38 : * This option marks the cache entry as complete after we read the first tuple
39 : * from the subnode.
40 : *
41 : * It's possible when we're filling the cache for a given set of parameters
42 : * that we're unable to free enough memory to store any more tuples. If this
43 : * happens then we'll have already evicted all other cache entries. When
44 : * caching another tuple would cause us to exceed our memory budget, we must
45 : * free the entry that we're currently populating and move the state machine
46 : * into MEMO_CACHE_BYPASS_MODE. This means that we'll not attempt to cache
47 : * any further tuples for this particular scan. We don't have the memory for
48 : * it. The state machine will be reset again on the next rescan. If the
49 : * memory requirements to cache the next parameter's tuples are less
50 : * demanding, then that may allow us to start putting useful entries back into
51 : * the cache again.
52 : *
53 : *
54 : * INTERFACE ROUTINES
55 : * ExecMemoize - lookup cache, exec subplan when not found
56 : * ExecInitMemoize - initialize node and subnodes
57 : * ExecEndMemoize - shutdown node and subnodes
58 : * ExecReScanMemoize - rescan the memoize node
59 : *
60 : * ExecMemoizeEstimate estimates DSM space needed for parallel plan
61 : * ExecMemoizeInitializeDSM initialize DSM for parallel plan
62 : * ExecMemoizeInitializeWorker attach to DSM info in parallel worker
63 : * ExecMemoizeRetrieveInstrumentation get instrumentation from worker
64 : *-------------------------------------------------------------------------
65 : */
66 :
67 : #include "postgres.h"
68 :
69 : #include "access/htup_details.h"
70 : #include "common/hashfn.h"
71 : #include "executor/executor.h"
72 : #include "executor/nodeMemoize.h"
73 : #include "lib/ilist.h"
74 : #include "miscadmin.h"
75 : #include "utils/datum.h"
76 : #include "utils/lsyscache.h"
77 :
78 : /* States of the ExecMemoize state machine */
79 : #define MEMO_CACHE_LOOKUP 1 /* Attempt to perform a cache lookup */
80 : #define MEMO_CACHE_FETCH_NEXT_TUPLE 2 /* Get another tuple from the cache */
81 : #define MEMO_FILLING_CACHE 3 /* Read outer node to fill cache */
82 : #define MEMO_CACHE_BYPASS_MODE 4 /* Bypass mode. Just read from our
83 : * subplan without caching anything */
84 : #define MEMO_END_OF_SCAN 5 /* Ready for rescan */
85 :
86 :
87 : /* Helper macros for memory accounting */
88 : #define EMPTY_ENTRY_MEMORY_BYTES(e) (sizeof(MemoizeEntry) + \
89 : sizeof(MemoizeKey) + \
90 : (e)->key->params->t_len);
91 : #define CACHE_TUPLE_BYTES(t) (sizeof(MemoizeTuple) + \
92 : (t)->mintuple->t_len)
93 :
94 : /* MemoizeTuple Stores an individually cached tuple */
95 : typedef struct MemoizeTuple
96 : {
97 : MinimalTuple mintuple; /* Cached tuple */
98 : struct MemoizeTuple *next; /* The next tuple with the same parameter
99 : * values or NULL if it's the last one */
100 : } MemoizeTuple;
101 :
102 : /*
103 : * MemoizeKey
104 : * The hash table key for cached entries plus the LRU list link
105 : */
106 : typedef struct MemoizeKey
107 : {
108 : MinimalTuple params;
109 : dlist_node lru_node; /* Pointer to next/prev key in LRU list */
110 : } MemoizeKey;
111 :
112 : /*
113 : * MemoizeEntry
114 : * The data struct that the cache hash table stores
115 : */
116 : typedef struct MemoizeEntry
117 : {
118 : MemoizeKey *key; /* Hash key for hash table lookups */
119 : MemoizeTuple *tuplehead; /* Pointer to the first tuple or NULL if no
120 : * tuples are cached for this entry */
121 : uint32 hash; /* Hash value (cached) */
122 : char status; /* Hash status */
123 : bool complete; /* Did we read the outer plan to completion? */
124 : } MemoizeEntry;
125 :
126 :
127 : #define SH_PREFIX memoize
128 : #define SH_ELEMENT_TYPE MemoizeEntry
129 : #define SH_KEY_TYPE MemoizeKey *
130 : #define SH_SCOPE static inline
131 : #define SH_DECLARE
132 : #include "lib/simplehash.h"
133 :
134 : static uint32 MemoizeHash_hash(struct memoize_hash *tb,
135 : const MemoizeKey *key);
136 : static bool MemoizeHash_equal(struct memoize_hash *tb,
137 : const MemoizeKey *key1,
138 : const MemoizeKey *key2);
139 :
140 : #define SH_PREFIX memoize
141 : #define SH_ELEMENT_TYPE MemoizeEntry
142 : #define SH_KEY_TYPE MemoizeKey *
143 : #define SH_KEY key
144 : #define SH_HASH_KEY(tb, key) MemoizeHash_hash(tb, key)
145 : #define SH_EQUAL(tb, a, b) MemoizeHash_equal(tb, a, b)
146 : #define SH_SCOPE static inline
147 : #define SH_STORE_HASH
148 : #define SH_GET_HASH(tb, a) a->hash
149 : #define SH_DEFINE
150 : #include "lib/simplehash.h"
151 :
152 : /*
153 : * MemoizeHash_hash
154 : * Hash function for simplehash hashtable. 'key' is unused here as we
155 : * require that all table lookups first populate the MemoizeState's
156 : * probeslot with the key values to be looked up.
157 : */
158 : static uint32
159 814936 : MemoizeHash_hash(struct memoize_hash *tb, const MemoizeKey *key)
160 : {
161 814936 : MemoizeState *mstate = (MemoizeState *) tb->private_data;
162 814936 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
163 : MemoryContext oldcontext;
164 814936 : TupleTableSlot *pslot = mstate->probeslot;
165 814936 : uint32 hashkey = 0;
166 814936 : int numkeys = mstate->nkeys;
167 :
168 814936 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
169 :
170 814936 : if (mstate->binary_mode)
171 : {
172 223606 : for (int i = 0; i < numkeys; i++)
173 : {
174 : /* combine successive hashkeys by rotating */
175 120748 : hashkey = pg_rotate_left32(hashkey, 1);
176 :
177 120748 : if (!pslot->tts_isnull[i]) /* treat nulls as having hash key 0 */
178 : {
179 : CompactAttribute *attr;
180 : uint32 hkey;
181 :
182 120748 : attr = TupleDescCompactAttr(pslot->tts_tupleDescriptor, i);
183 :
184 120748 : hkey = datum_image_hash(pslot->tts_values[i], attr->attbyval, attr->attlen);
185 :
186 120748 : hashkey ^= hkey;
187 : }
188 : }
189 : }
190 : else
191 : {
192 712078 : FmgrInfo *hashfunctions = mstate->hashfunctions;
193 712078 : Oid *collations = mstate->collations;
194 :
195 1424646 : for (int i = 0; i < numkeys; i++)
196 : {
197 : /* combine successive hashkeys by rotating */
198 712568 : hashkey = pg_rotate_left32(hashkey, 1);
199 :
200 712568 : if (!pslot->tts_isnull[i]) /* treat nulls as having hash key 0 */
201 : {
202 : uint32 hkey;
203 :
204 711742 : hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
205 711742 : collations[i], pslot->tts_values[i]));
206 711742 : hashkey ^= hkey;
207 : }
208 : }
209 : }
210 :
211 814936 : MemoryContextSwitchTo(oldcontext);
212 814936 : return murmurhash32(hashkey);
213 : }
214 :
215 : /*
216 : * MemoizeHash_equal
217 : * Equality function for confirming hash value matches during a hash
218 : * table lookup. 'key2' is never used. Instead the MemoizeState's
219 : * probeslot is always populated with details of what's being looked up.
220 : */
221 : static bool
222 719994 : MemoizeHash_equal(struct memoize_hash *tb, const MemoizeKey *key1,
223 : const MemoizeKey *key2)
224 : {
225 719994 : MemoizeState *mstate = (MemoizeState *) tb->private_data;
226 719994 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
227 719994 : TupleTableSlot *tslot = mstate->tableslot;
228 719994 : TupleTableSlot *pslot = mstate->probeslot;
229 :
230 : /* probeslot should have already been prepared by prepare_probe_slot() */
231 719994 : ExecStoreMinimalTuple(key1->params, tslot, false);
232 :
233 719994 : if (mstate->binary_mode)
234 : {
235 : MemoryContext oldcontext;
236 102010 : int numkeys = mstate->nkeys;
237 102010 : bool match = true;
238 :
239 102010 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
240 :
241 102010 : slot_getallattrs(tslot);
242 102010 : slot_getallattrs(pslot);
243 :
244 221574 : for (int i = 0; i < numkeys; i++)
245 : {
246 : CompactAttribute *attr;
247 :
248 119564 : if (tslot->tts_isnull[i] != pslot->tts_isnull[i])
249 : {
250 0 : match = false;
251 0 : break;
252 : }
253 :
254 : /* both NULL? they're equal */
255 119564 : if (tslot->tts_isnull[i])
256 0 : continue;
257 :
258 : /* perform binary comparison on the two datums */
259 119564 : attr = TupleDescCompactAttr(tslot->tts_tupleDescriptor, i);
260 119564 : if (!datum_image_eq(tslot->tts_values[i], pslot->tts_values[i],
261 119564 : attr->attbyval, attr->attlen))
262 : {
263 0 : match = false;
264 0 : break;
265 : }
266 : }
267 :
268 102010 : MemoryContextSwitchTo(oldcontext);
269 102010 : return match;
270 : }
271 : else
272 : {
273 617984 : econtext->ecxt_innertuple = tslot;
274 617984 : econtext->ecxt_outertuple = pslot;
275 617984 : return ExecQual(mstate->cache_eq_expr, econtext);
276 : }
277 : }
278 :
279 : /*
280 : * Initialize the hash table to empty. The MemoizeState's hashtable field
281 : * must point to NULL.
282 : */
283 : static void
284 1624 : build_hash_table(MemoizeState *mstate, uint32 size)
285 : {
286 : Assert(mstate->hashtable == NULL);
287 :
288 : /* Make a guess at a good size when we're not given a valid size. */
289 1624 : if (size == 0)
290 0 : size = 1024;
291 :
292 : /* memoize_create will convert the size to a power of 2 */
293 1624 : mstate->hashtable = memoize_create(mstate->tableContext, size, mstate);
294 1624 : }
295 :
296 : /*
297 : * prepare_probe_slot
298 : * Populate mstate's probeslot with the values from the tuple stored
299 : * in 'key'. If 'key' is NULL, then perform the population by evaluating
300 : * mstate's param_exprs.
301 : */
302 : static inline void
303 814936 : prepare_probe_slot(MemoizeState *mstate, MemoizeKey *key)
304 : {
305 814936 : TupleTableSlot *pslot = mstate->probeslot;
306 814936 : TupleTableSlot *tslot = mstate->tableslot;
307 814936 : int numKeys = mstate->nkeys;
308 :
309 814936 : ExecClearTuple(pslot);
310 :
311 814936 : if (key == NULL)
312 : {
313 812536 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
314 : MemoryContext oldcontext;
315 :
316 812536 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
317 :
318 : /* Set the probeslot's values based on the current parameter values */
319 1643452 : for (int i = 0; i < numKeys; i++)
320 830916 : pslot->tts_values[i] = ExecEvalExpr(mstate->param_exprs[i],
321 : econtext,
322 830916 : &pslot->tts_isnull[i]);
323 :
324 812536 : MemoryContextSwitchTo(oldcontext);
325 : }
326 : else
327 : {
328 : /* Process the key's MinimalTuple and store the values in probeslot */
329 2400 : ExecStoreMinimalTuple(key->params, tslot, false);
330 2400 : slot_getallattrs(tslot);
331 2400 : memcpy(pslot->tts_values, tslot->tts_values, sizeof(Datum) * numKeys);
332 2400 : memcpy(pslot->tts_isnull, tslot->tts_isnull, sizeof(bool) * numKeys);
333 : }
334 :
335 814936 : ExecStoreVirtualTuple(pslot);
336 814936 : }
337 :
338 : /*
339 : * entry_purge_tuples
340 : * Remove all tuples from the cache entry pointed to by 'entry'. This
341 : * leaves an empty cache entry. Also, update the memory accounting to
342 : * reflect the removal of the tuples.
343 : */
344 : static inline void
345 2388 : entry_purge_tuples(MemoizeState *mstate, MemoizeEntry *entry)
346 : {
347 2388 : MemoizeTuple *tuple = entry->tuplehead;
348 2388 : uint64 freed_mem = 0;
349 :
350 4776 : while (tuple != NULL)
351 : {
352 2388 : MemoizeTuple *next = tuple->next;
353 :
354 2388 : freed_mem += CACHE_TUPLE_BYTES(tuple);
355 :
356 : /* Free memory used for this tuple */
357 2388 : pfree(tuple->mintuple);
358 2388 : pfree(tuple);
359 :
360 2388 : tuple = next;
361 : }
362 :
363 2388 : entry->complete = false;
364 2388 : entry->tuplehead = NULL;
365 :
366 : /* Update the memory accounting */
367 2388 : mstate->mem_used -= freed_mem;
368 2388 : }
369 :
370 : /*
371 : * remove_cache_entry
372 : * Remove 'entry' from the cache and free memory used by it.
373 : */
374 : static void
375 2388 : remove_cache_entry(MemoizeState *mstate, MemoizeEntry *entry)
376 : {
377 2388 : MemoizeKey *key = entry->key;
378 :
379 2388 : dlist_delete(&entry->key->lru_node);
380 :
381 : /* Remove all of the tuples from this entry */
382 2388 : entry_purge_tuples(mstate, entry);
383 :
384 : /*
385 : * Update memory accounting. entry_purge_tuples should have already
386 : * subtracted the memory used for each cached tuple. Here we just update
387 : * the amount used by the entry itself.
388 : */
389 2388 : mstate->mem_used -= EMPTY_ENTRY_MEMORY_BYTES(entry);
390 :
391 : /* Remove the entry from the cache */
392 2388 : memoize_delete_item(mstate->hashtable, entry);
393 :
394 2388 : pfree(key->params);
395 2388 : pfree(key);
396 2388 : }
397 :
398 : /*
399 : * cache_purge_all
400 : * Remove all items from the cache
401 : */
402 : static void
403 18 : cache_purge_all(MemoizeState *mstate)
404 : {
405 18 : uint64 evictions = 0;
406 :
407 18 : if (mstate->hashtable != NULL)
408 12 : evictions = mstate->hashtable->members;
409 :
410 : /*
411 : * Likely the most efficient way to remove all items is to just reset the
412 : * memory context for the cache and then rebuild a fresh hash table. This
413 : * saves having to remove each item one by one and pfree each cached tuple
414 : */
415 18 : MemoryContextReset(mstate->tableContext);
416 :
417 : /* NULLify so we recreate the table on the next call */
418 18 : mstate->hashtable = NULL;
419 :
420 : /* reset the LRU list */
421 18 : dlist_init(&mstate->lru_list);
422 18 : mstate->last_tuple = NULL;
423 18 : mstate->entry = NULL;
424 :
425 18 : mstate->mem_used = 0;
426 :
427 : /* XXX should we add something new to track these purges? */
428 18 : mstate->stats.cache_evictions += evictions; /* Update Stats */
429 18 : }
430 :
431 : /*
432 : * cache_reduce_memory
433 : * Evict older and less recently used items from the cache in order to
434 : * reduce the memory consumption back to something below the
435 : * MemoizeState's mem_limit.
436 : *
437 : * 'specialkey', if not NULL, causes the function to return false if the entry
438 : * which the key belongs to is removed from the cache.
439 : */
440 : static bool
441 2388 : cache_reduce_memory(MemoizeState *mstate, MemoizeKey *specialkey)
442 : {
443 2388 : bool specialkey_intact = true; /* for now */
444 : dlist_mutable_iter iter;
445 2388 : uint64 evictions = 0;
446 :
447 : /* Update peak memory usage */
448 2388 : if (mstate->mem_used > mstate->stats.mem_peak)
449 6 : mstate->stats.mem_peak = mstate->mem_used;
450 :
451 : /* We expect only to be called when we've gone over budget on memory */
452 : Assert(mstate->mem_used > mstate->mem_limit);
453 :
454 : /* Start the eviction process starting at the head of the LRU list. */
455 2388 : dlist_foreach_modify(iter, &mstate->lru_list)
456 : {
457 2388 : MemoizeKey *key = dlist_container(MemoizeKey, lru_node, iter.cur);
458 : MemoizeEntry *entry;
459 :
460 : /*
461 : * Populate the hash probe slot in preparation for looking up this LRU
462 : * entry.
463 : */
464 2388 : prepare_probe_slot(mstate, key);
465 :
466 : /*
467 : * Ideally the LRU list pointers would be stored in the entry itself
468 : * rather than in the key. Unfortunately, we can't do that as the
469 : * simplehash.h code may resize the table and allocate new memory for
470 : * entries which would result in those pointers pointing to the old
471 : * buckets. However, it's fine to use the key to store this as that's
472 : * only referenced by a pointer in the entry, which of course follows
473 : * the entry whenever the hash table is resized. Since we only have a
474 : * pointer to the key here, we must perform a hash table lookup to
475 : * find the entry that the key belongs to.
476 : */
477 2388 : entry = memoize_lookup(mstate->hashtable, NULL);
478 :
479 : /*
480 : * Sanity check that we found the entry belonging to the LRU list
481 : * item. A misbehaving hash or equality function could cause the
482 : * entry not to be found or the wrong entry to be found.
483 : */
484 2388 : if (unlikely(entry == NULL || entry->key != key))
485 0 : elog(ERROR, "could not find memoization table entry");
486 :
487 : /*
488 : * If we're being called to free memory while the cache is being
489 : * populated with new tuples, then we'd better take some care as we
490 : * could end up freeing the entry which 'specialkey' belongs to.
491 : * Generally callers will pass 'specialkey' as the key for the cache
492 : * entry which is currently being populated, so we must set
493 : * 'specialkey_intact' to false to inform the caller the specialkey
494 : * entry has been removed.
495 : */
496 2388 : if (key == specialkey)
497 0 : specialkey_intact = false;
498 :
499 : /*
500 : * Finally remove the entry. This will remove from the LRU list too.
501 : */
502 2388 : remove_cache_entry(mstate, entry);
503 :
504 2388 : evictions++;
505 :
506 : /* Exit if we've freed enough memory */
507 2388 : if (mstate->mem_used <= mstate->mem_limit)
508 2388 : break;
509 : }
510 :
511 2388 : mstate->stats.cache_evictions += evictions; /* Update Stats */
512 :
513 2388 : return specialkey_intact;
514 : }
515 :
516 : /*
517 : * cache_lookup
518 : * Perform a lookup to see if we've already cached tuples based on the
519 : * scan's current parameters. If we find an existing entry we move it to
520 : * the end of the LRU list, set *found to true then return it. If we
521 : * don't find an entry then we create a new one and add it to the end of
522 : * the LRU list. We also update cache memory accounting and remove older
523 : * entries if we go over the memory budget. If we managed to free enough
524 : * memory we return the new entry, else we return NULL.
525 : *
526 : * Callers can assume we'll never return NULL when *found is true.
527 : */
528 : static MemoizeEntry *
529 812536 : cache_lookup(MemoizeState *mstate, bool *found)
530 : {
531 : MemoizeKey *key;
532 : MemoizeEntry *entry;
533 : MemoryContext oldcontext;
534 :
535 : /* prepare the probe slot with the current scan parameters */
536 812536 : prepare_probe_slot(mstate, NULL);
537 :
538 : /*
539 : * Add the new entry to the cache. No need to pass a valid key since the
540 : * hash function uses mstate's probeslot, which we populated above.
541 : */
542 812536 : entry = memoize_insert(mstate->hashtable, NULL, found);
543 :
544 812536 : if (*found)
545 : {
546 : /*
547 : * Move existing entry to the tail of the LRU list to mark it as the
548 : * most recently used item.
549 : */
550 717594 : dlist_move_tail(&mstate->lru_list, &entry->key->lru_node);
551 :
552 717594 : return entry;
553 : }
554 :
555 94942 : oldcontext = MemoryContextSwitchTo(mstate->tableContext);
556 :
557 : /* Allocate a new key */
558 94942 : entry->key = key = (MemoizeKey *) palloc(sizeof(MemoizeKey));
559 94942 : key->params = ExecCopySlotMinimalTuple(mstate->probeslot);
560 :
561 : /* Update the total cache memory utilization */
562 94942 : mstate->mem_used += EMPTY_ENTRY_MEMORY_BYTES(entry);
563 :
564 : /* Initialize this entry */
565 94942 : entry->complete = false;
566 94942 : entry->tuplehead = NULL;
567 :
568 : /*
569 : * Since this is the most recently used entry, push this entry onto the
570 : * end of the LRU list.
571 : */
572 94942 : dlist_push_tail(&mstate->lru_list, &entry->key->lru_node);
573 :
574 94942 : mstate->last_tuple = NULL;
575 :
576 94942 : MemoryContextSwitchTo(oldcontext);
577 :
578 : /*
579 : * If we've gone over our memory budget, then we'll free up some space in
580 : * the cache.
581 : */
582 94942 : if (mstate->mem_used > mstate->mem_limit)
583 : {
584 : /*
585 : * Try to free up some memory. It's highly unlikely that we'll fail
586 : * to do so here since the entry we've just added is yet to contain
587 : * any tuples and we're able to remove any other entry to reduce the
588 : * memory consumption.
589 : */
590 2388 : if (unlikely(!cache_reduce_memory(mstate, key)))
591 0 : return NULL;
592 :
593 : /*
594 : * The process of removing entries from the cache may have caused the
595 : * code in simplehash.h to shuffle elements to earlier buckets in the
596 : * hash table. If it has, we'll need to find the entry again by
597 : * performing a lookup. Fortunately, we can detect if this has
598 : * happened by seeing if the entry is still in use and that the key
599 : * pointer matches our expected key.
600 : */
601 2388 : if (entry->status != memoize_SH_IN_USE || entry->key != key)
602 : {
603 : /*
604 : * We need to repopulate the probeslot as lookups performed during
605 : * the cache evictions above will have stored some other key.
606 : */
607 12 : prepare_probe_slot(mstate, key);
608 :
609 : /* Re-find the newly added entry */
610 12 : entry = memoize_lookup(mstate->hashtable, NULL);
611 : Assert(entry != NULL);
612 : }
613 : }
614 :
615 94942 : return entry;
616 : }
617 :
618 : /*
619 : * cache_store_tuple
620 : * Add the tuple stored in 'slot' to the mstate's current cache entry.
621 : * The cache entry must have already been made with cache_lookup().
622 : * mstate's last_tuple field must point to the tail of mstate->entry's
623 : * list of tuples.
624 : */
625 : static bool
626 88726 : cache_store_tuple(MemoizeState *mstate, TupleTableSlot *slot)
627 : {
628 : MemoizeTuple *tuple;
629 88726 : MemoizeEntry *entry = mstate->entry;
630 : MemoryContext oldcontext;
631 :
632 : Assert(slot != NULL);
633 : Assert(entry != NULL);
634 :
635 88726 : oldcontext = MemoryContextSwitchTo(mstate->tableContext);
636 :
637 88726 : tuple = (MemoizeTuple *) palloc(sizeof(MemoizeTuple));
638 88726 : tuple->mintuple = ExecCopySlotMinimalTuple(slot);
639 88726 : tuple->next = NULL;
640 :
641 : /* Account for the memory we just consumed */
642 88726 : mstate->mem_used += CACHE_TUPLE_BYTES(tuple);
643 :
644 88726 : if (entry->tuplehead == NULL)
645 : {
646 : /*
647 : * This is the first tuple for this entry, so just point the list head
648 : * to it.
649 : */
650 88268 : entry->tuplehead = tuple;
651 : }
652 : else
653 : {
654 : /* push this tuple onto the tail of the list */
655 458 : mstate->last_tuple->next = tuple;
656 : }
657 :
658 88726 : mstate->last_tuple = tuple;
659 88726 : MemoryContextSwitchTo(oldcontext);
660 :
661 : /*
662 : * If we've gone over our memory budget then free up some space in the
663 : * cache.
664 : */
665 88726 : if (mstate->mem_used > mstate->mem_limit)
666 : {
667 0 : MemoizeKey *key = entry->key;
668 :
669 0 : if (!cache_reduce_memory(mstate, key))
670 0 : return false;
671 :
672 : /*
673 : * The process of removing entries from the cache may have caused the
674 : * code in simplehash.h to shuffle elements to earlier buckets in the
675 : * hash table. If it has, we'll need to find the entry again by
676 : * performing a lookup. Fortunately, we can detect if this has
677 : * happened by seeing if the entry is still in use and that the key
678 : * pointer matches our expected key.
679 : */
680 0 : if (entry->status != memoize_SH_IN_USE || entry->key != key)
681 : {
682 : /*
683 : * We need to repopulate the probeslot as lookups performed during
684 : * the cache evictions above will have stored some other key.
685 : */
686 0 : prepare_probe_slot(mstate, key);
687 :
688 : /* Re-find the entry */
689 0 : mstate->entry = entry = memoize_lookup(mstate->hashtable, NULL);
690 : Assert(entry != NULL);
691 : }
692 : }
693 :
694 88726 : return true;
695 : }
696 :
697 : static TupleTableSlot *
698 971310 : ExecMemoize(PlanState *pstate)
699 : {
700 971310 : MemoizeState *node = castNode(MemoizeState, pstate);
701 971310 : ExprContext *econtext = node->ss.ps.ps_ExprContext;
702 : PlanState *outerNode;
703 : TupleTableSlot *slot;
704 :
705 971310 : CHECK_FOR_INTERRUPTS();
706 :
707 : /*
708 : * Reset per-tuple memory context to free any expression evaluation
709 : * storage allocated in the previous tuple cycle.
710 : */
711 971310 : ResetExprContext(econtext);
712 :
713 971310 : switch (node->mstatus)
714 : {
715 812536 : case MEMO_CACHE_LOOKUP:
716 : {
717 : MemoizeEntry *entry;
718 : TupleTableSlot *outerslot;
719 : bool found;
720 :
721 : Assert(node->entry == NULL);
722 :
723 : /* first call? we'll need a hash table. */
724 812536 : if (unlikely(node->hashtable == NULL))
725 1624 : build_hash_table(node, ((Memoize *) pstate->plan)->est_entries);
726 :
727 : /*
728 : * We're only ever in this state for the first call of the
729 : * scan. Here we have a look to see if we've already seen the
730 : * current parameters before and if we have already cached a
731 : * complete set of records that the outer plan will return for
732 : * these parameters.
733 : *
734 : * When we find a valid cache entry, we'll return the first
735 : * tuple from it. If not found, we'll create a cache entry and
736 : * then try to fetch a tuple from the outer scan. If we find
737 : * one there, we'll try to cache it.
738 : */
739 :
740 : /* see if we've got anything cached for the current parameters */
741 812536 : entry = cache_lookup(node, &found);
742 :
743 812536 : if (found && entry->complete)
744 : {
745 717594 : node->stats.cache_hits += 1; /* stats update */
746 :
747 : /*
748 : * Set last_tuple and entry so that the state
749 : * MEMO_CACHE_FETCH_NEXT_TUPLE can easily find the next
750 : * tuple for these parameters.
751 : */
752 717594 : node->last_tuple = entry->tuplehead;
753 717594 : node->entry = entry;
754 :
755 : /* Fetch the first cached tuple, if there is one */
756 717594 : if (entry->tuplehead)
757 : {
758 427784 : node->mstatus = MEMO_CACHE_FETCH_NEXT_TUPLE;
759 :
760 427784 : slot = node->ss.ps.ps_ResultTupleSlot;
761 427784 : ExecStoreMinimalTuple(entry->tuplehead->mintuple,
762 : slot, false);
763 :
764 427784 : return slot;
765 : }
766 :
767 : /* The cache entry is void of any tuples. */
768 289810 : node->mstatus = MEMO_END_OF_SCAN;
769 289810 : return NULL;
770 : }
771 :
772 : /* Handle cache miss */
773 94942 : node->stats.cache_misses += 1; /* stats update */
774 :
775 94942 : if (found)
776 : {
777 : /*
778 : * A cache entry was found, but the scan for that entry
779 : * did not run to completion. We'll just remove all
780 : * tuples and start again. It might be tempting to
781 : * continue where we left off, but there's no guarantee
782 : * the outer node will produce the tuples in the same
783 : * order as it did last time.
784 : */
785 0 : entry_purge_tuples(node, entry);
786 : }
787 :
788 : /* Scan the outer node for a tuple to cache */
789 94942 : outerNode = outerPlanState(node);
790 94942 : outerslot = ExecProcNode(outerNode);
791 94942 : if (TupIsNull(outerslot))
792 : {
793 : /*
794 : * cache_lookup may have returned NULL due to failure to
795 : * free enough cache space, so ensure we don't do anything
796 : * here that assumes it worked. There's no need to go into
797 : * bypass mode here as we're setting mstatus to end of
798 : * scan.
799 : */
800 6674 : if (likely(entry))
801 6674 : entry->complete = true;
802 :
803 6674 : node->mstatus = MEMO_END_OF_SCAN;
804 6674 : return NULL;
805 : }
806 :
807 88268 : node->entry = entry;
808 :
809 : /*
810 : * If we failed to create the entry or failed to store the
811 : * tuple in the entry, then go into bypass mode.
812 : */
813 88268 : if (unlikely(entry == NULL ||
814 : !cache_store_tuple(node, outerslot)))
815 : {
816 0 : node->stats.cache_overflows += 1; /* stats update */
817 :
818 0 : node->mstatus = MEMO_CACHE_BYPASS_MODE;
819 :
820 : /*
821 : * No need to clear out last_tuple as we'll stay in bypass
822 : * mode until the end of the scan.
823 : */
824 : }
825 : else
826 : {
827 : /*
828 : * If we only expect a single row from this scan then we
829 : * can mark that we're not expecting more. This allows
830 : * cache lookups to work even when the scan has not been
831 : * executed to completion.
832 : */
833 88268 : entry->complete = node->singlerow;
834 88268 : node->mstatus = MEMO_FILLING_CACHE;
835 : }
836 :
837 88268 : slot = node->ss.ps.ps_ResultTupleSlot;
838 88268 : ExecCopySlot(slot, outerslot);
839 88268 : return slot;
840 : }
841 :
842 90276 : case MEMO_CACHE_FETCH_NEXT_TUPLE:
843 : {
844 : /* We shouldn't be in this state if these are not set */
845 : Assert(node->entry != NULL);
846 : Assert(node->last_tuple != NULL);
847 :
848 : /* Skip to the next tuple to output */
849 90276 : node->last_tuple = node->last_tuple->next;
850 :
851 : /* No more tuples in the cache */
852 90276 : if (node->last_tuple == NULL)
853 : {
854 85080 : node->mstatus = MEMO_END_OF_SCAN;
855 85080 : return NULL;
856 : }
857 :
858 5196 : slot = node->ss.ps.ps_ResultTupleSlot;
859 5196 : ExecStoreMinimalTuple(node->last_tuple->mintuple, slot,
860 : false);
861 :
862 5196 : return slot;
863 : }
864 :
865 68498 : case MEMO_FILLING_CACHE:
866 : {
867 : TupleTableSlot *outerslot;
868 68498 : MemoizeEntry *entry = node->entry;
869 :
870 : /* entry should already have been set by MEMO_CACHE_LOOKUP */
871 : Assert(entry != NULL);
872 :
873 : /*
874 : * When in the MEMO_FILLING_CACHE state, we've just had a
875 : * cache miss and are populating the cache with the current
876 : * scan tuples.
877 : */
878 68498 : outerNode = outerPlanState(node);
879 68498 : outerslot = ExecProcNode(outerNode);
880 68498 : if (TupIsNull(outerslot))
881 : {
882 : /* No more tuples. Mark it as complete */
883 68040 : entry->complete = true;
884 68040 : node->mstatus = MEMO_END_OF_SCAN;
885 68040 : return NULL;
886 : }
887 :
888 : /*
889 : * Validate if the planner properly set the singlerow flag. It
890 : * should only set that if each cache entry can, at most,
891 : * return 1 row.
892 : */
893 458 : if (unlikely(entry->complete))
894 0 : elog(ERROR, "cache entry already complete");
895 :
896 : /* Record the tuple in the current cache entry */
897 458 : if (unlikely(!cache_store_tuple(node, outerslot)))
898 : {
899 : /* Couldn't store it? Handle overflow */
900 0 : node->stats.cache_overflows += 1; /* stats update */
901 :
902 0 : node->mstatus = MEMO_CACHE_BYPASS_MODE;
903 :
904 : /*
905 : * No need to clear out entry or last_tuple as we'll stay
906 : * in bypass mode until the end of the scan.
907 : */
908 : }
909 :
910 458 : slot = node->ss.ps.ps_ResultTupleSlot;
911 458 : ExecCopySlot(slot, outerslot);
912 458 : return slot;
913 : }
914 :
915 0 : case MEMO_CACHE_BYPASS_MODE:
916 : {
917 : TupleTableSlot *outerslot;
918 :
919 : /*
920 : * When in bypass mode we just continue to read tuples without
921 : * caching. We need to wait until the next rescan before we
922 : * can come out of this mode.
923 : */
924 0 : outerNode = outerPlanState(node);
925 0 : outerslot = ExecProcNode(outerNode);
926 0 : if (TupIsNull(outerslot))
927 : {
928 0 : node->mstatus = MEMO_END_OF_SCAN;
929 0 : return NULL;
930 : }
931 :
932 0 : slot = node->ss.ps.ps_ResultTupleSlot;
933 0 : ExecCopySlot(slot, outerslot);
934 0 : return slot;
935 : }
936 :
937 0 : case MEMO_END_OF_SCAN:
938 :
939 : /*
940 : * We've already returned NULL for this scan, but just in case
941 : * something calls us again by mistake.
942 : */
943 0 : return NULL;
944 :
945 0 : default:
946 0 : elog(ERROR, "unrecognized memoize state: %d",
947 : (int) node->mstatus);
948 : return NULL;
949 : } /* switch */
950 : }
951 :
952 : MemoizeState *
953 2000 : ExecInitMemoize(Memoize *node, EState *estate, int eflags)
954 : {
955 2000 : MemoizeState *mstate = makeNode(MemoizeState);
956 : Plan *outerNode;
957 : int i;
958 : int nkeys;
959 : Oid *eqfuncoids;
960 :
961 : /* check for unsupported flags */
962 : Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
963 :
964 2000 : mstate->ss.ps.plan = (Plan *) node;
965 2000 : mstate->ss.ps.state = estate;
966 2000 : mstate->ss.ps.ExecProcNode = ExecMemoize;
967 :
968 : /*
969 : * Miscellaneous initialization
970 : *
971 : * create expression context for node
972 : */
973 2000 : ExecAssignExprContext(estate, &mstate->ss.ps);
974 :
975 2000 : outerNode = outerPlan(node);
976 2000 : outerPlanState(mstate) = ExecInitNode(outerNode, estate, eflags);
977 :
978 : /*
979 : * Initialize return slot and type. No need to initialize projection info
980 : * because this node doesn't do projections.
981 : */
982 2000 : ExecInitResultTupleSlotTL(&mstate->ss.ps, &TTSOpsMinimalTuple);
983 2000 : mstate->ss.ps.ps_ProjInfo = NULL;
984 :
985 : /*
986 : * Initialize scan slot and type.
987 : */
988 2000 : ExecCreateScanSlotFromOuterPlan(estate, &mstate->ss, &TTSOpsMinimalTuple);
989 :
990 : /*
991 : * Set the state machine to lookup the cache. We won't find anything
992 : * until we cache something, but this saves a special case to create the
993 : * first entry.
994 : */
995 2000 : mstate->mstatus = MEMO_CACHE_LOOKUP;
996 :
997 2000 : mstate->nkeys = nkeys = node->numKeys;
998 2000 : mstate->hashkeydesc = ExecTypeFromExprList(node->param_exprs);
999 2000 : mstate->tableslot = MakeSingleTupleTableSlot(mstate->hashkeydesc,
1000 : &TTSOpsMinimalTuple);
1001 2000 : mstate->probeslot = MakeSingleTupleTableSlot(mstate->hashkeydesc,
1002 : &TTSOpsVirtual);
1003 :
1004 2000 : mstate->param_exprs = (ExprState **) palloc(nkeys * sizeof(ExprState *));
1005 2000 : mstate->collations = node->collations; /* Just point directly to the plan
1006 : * data */
1007 2000 : mstate->hashfunctions = (FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
1008 :
1009 2000 : eqfuncoids = palloc(nkeys * sizeof(Oid));
1010 :
1011 4062 : for (i = 0; i < nkeys; i++)
1012 : {
1013 2062 : Oid hashop = node->hashOperators[i];
1014 : Oid left_hashfn;
1015 : Oid right_hashfn;
1016 2062 : Expr *param_expr = (Expr *) list_nth(node->param_exprs, i);
1017 :
1018 2062 : if (!get_op_hash_functions(hashop, &left_hashfn, &right_hashfn))
1019 0 : elog(ERROR, "could not find hash function for hash operator %u",
1020 : hashop);
1021 :
1022 2062 : fmgr_info(left_hashfn, &mstate->hashfunctions[i]);
1023 :
1024 2062 : mstate->param_exprs[i] = ExecInitExpr(param_expr, (PlanState *) mstate);
1025 2062 : eqfuncoids[i] = get_opcode(hashop);
1026 : }
1027 :
1028 4000 : mstate->cache_eq_expr = ExecBuildParamSetEqual(mstate->hashkeydesc,
1029 : &TTSOpsMinimalTuple,
1030 : &TTSOpsVirtual,
1031 : eqfuncoids,
1032 2000 : node->collations,
1033 2000 : node->param_exprs,
1034 : (PlanState *) mstate);
1035 :
1036 2000 : pfree(eqfuncoids);
1037 2000 : mstate->mem_used = 0;
1038 :
1039 : /* Limit the total memory consumed by the cache to this */
1040 2000 : mstate->mem_limit = get_hash_memory_limit();
1041 :
1042 : /* A memory context dedicated for the cache */
1043 2000 : mstate->tableContext = AllocSetContextCreate(CurrentMemoryContext,
1044 : "MemoizeHashTable",
1045 : ALLOCSET_DEFAULT_SIZES);
1046 :
1047 2000 : dlist_init(&mstate->lru_list);
1048 2000 : mstate->last_tuple = NULL;
1049 2000 : mstate->entry = NULL;
1050 :
1051 : /*
1052 : * Mark if we can assume the cache entry is completed after we get the
1053 : * first record for it. Some callers might not call us again after
1054 : * getting the first match. e.g. A join operator performing a unique join
1055 : * is able to skip to the next outer tuple after getting the first
1056 : * matching inner tuple. In this case, the cache entry is complete after
1057 : * getting the first tuple. This allows us to mark it as so.
1058 : */
1059 2000 : mstate->singlerow = node->singlerow;
1060 2000 : mstate->keyparamids = node->keyparamids;
1061 :
1062 : /*
1063 : * Record if the cache keys should be compared bit by bit, or logically
1064 : * using the type's hash equality operator
1065 : */
1066 2000 : mstate->binary_mode = node->binary_mode;
1067 :
1068 : /* Zero the statistics counters */
1069 2000 : memset(&mstate->stats, 0, sizeof(MemoizeInstrumentation));
1070 :
1071 : /*
1072 : * Because it may require a large allocation, we delay building of the
1073 : * hash table until executor run.
1074 : */
1075 2000 : mstate->hashtable = NULL;
1076 :
1077 2000 : return mstate;
1078 : }
1079 :
1080 : void
1081 2000 : ExecEndMemoize(MemoizeState *node)
1082 : {
1083 : #ifdef USE_ASSERT_CHECKING
1084 : /* Validate the memory accounting code is correct in assert builds. */
1085 : if (node->hashtable != NULL)
1086 : {
1087 : int count;
1088 : uint64 mem = 0;
1089 : memoize_iterator i;
1090 : MemoizeEntry *entry;
1091 :
1092 : memoize_start_iterate(node->hashtable, &i);
1093 :
1094 : count = 0;
1095 : while ((entry = memoize_iterate(node->hashtable, &i)) != NULL)
1096 : {
1097 : MemoizeTuple *tuple = entry->tuplehead;
1098 :
1099 : mem += EMPTY_ENTRY_MEMORY_BYTES(entry);
1100 : while (tuple != NULL)
1101 : {
1102 : mem += CACHE_TUPLE_BYTES(tuple);
1103 : tuple = tuple->next;
1104 : }
1105 : count++;
1106 : }
1107 :
1108 : Assert(count == node->hashtable->members);
1109 : Assert(mem == node->mem_used);
1110 : }
1111 : #endif
1112 :
1113 : /*
1114 : * When ending a parallel worker, copy the statistics gathered by the
1115 : * worker back into shared memory so that it can be picked up by the main
1116 : * process to report in EXPLAIN ANALYZE.
1117 : */
1118 2000 : if (node->shared_info != NULL && IsParallelWorker())
1119 : {
1120 : MemoizeInstrumentation *si;
1121 :
1122 : /* Make mem_peak available for EXPLAIN */
1123 0 : if (node->stats.mem_peak == 0)
1124 0 : node->stats.mem_peak = node->mem_used;
1125 :
1126 : Assert(ParallelWorkerNumber <= node->shared_info->num_workers);
1127 0 : si = &node->shared_info->sinstrument[ParallelWorkerNumber];
1128 0 : memcpy(si, &node->stats, sizeof(MemoizeInstrumentation));
1129 : }
1130 :
1131 : /* Remove the cache context */
1132 2000 : MemoryContextDelete(node->tableContext);
1133 :
1134 : /*
1135 : * shut down the subplan
1136 : */
1137 2000 : ExecEndNode(outerPlanState(node));
1138 2000 : }
1139 :
1140 : void
1141 812536 : ExecReScanMemoize(MemoizeState *node)
1142 : {
1143 812536 : PlanState *outerPlan = outerPlanState(node);
1144 :
1145 : /* Mark that we must lookup the cache for a new set of parameters */
1146 812536 : node->mstatus = MEMO_CACHE_LOOKUP;
1147 :
1148 : /* nullify pointers used for the last scan */
1149 812536 : node->entry = NULL;
1150 812536 : node->last_tuple = NULL;
1151 :
1152 : /*
1153 : * if chgParam of subnode is not null then plan will be re-scanned by
1154 : * first ExecProcNode.
1155 : */
1156 812536 : if (outerPlan->chgParam == NULL)
1157 0 : ExecReScan(outerPlan);
1158 :
1159 : /*
1160 : * Purge the entire cache if a parameter changed that is not part of the
1161 : * cache key.
1162 : */
1163 812536 : if (bms_nonempty_difference(outerPlan->chgParam, node->keyparamids))
1164 18 : cache_purge_all(node);
1165 812536 : }
1166 :
1167 : /*
1168 : * ExecEstimateCacheEntryOverheadBytes
1169 : * For use in the query planner to help it estimate the amount of memory
1170 : * required to store a single entry in the cache.
1171 : */
1172 : double
1173 285996 : ExecEstimateCacheEntryOverheadBytes(double ntuples)
1174 : {
1175 285996 : return sizeof(MemoizeEntry) + sizeof(MemoizeKey) + sizeof(MemoizeTuple) *
1176 : ntuples;
1177 : }
1178 :
1179 : /* ----------------------------------------------------------------
1180 : * Parallel Query Support
1181 : * ----------------------------------------------------------------
1182 : */
1183 :
1184 : /* ----------------------------------------------------------------
1185 : * ExecMemoizeEstimate
1186 : *
1187 : * Estimate space required to propagate memoize statistics.
1188 : * ----------------------------------------------------------------
1189 : */
1190 : void
1191 6 : ExecMemoizeEstimate(MemoizeState *node, ParallelContext *pcxt)
1192 : {
1193 : Size size;
1194 :
1195 : /* don't need this if not instrumenting or no workers */
1196 6 : if (!node->ss.ps.instrument || pcxt->nworkers == 0)
1197 6 : return;
1198 :
1199 0 : size = mul_size(pcxt->nworkers, sizeof(MemoizeInstrumentation));
1200 0 : size = add_size(size, offsetof(SharedMemoizeInfo, sinstrument));
1201 0 : shm_toc_estimate_chunk(&pcxt->estimator, size);
1202 0 : shm_toc_estimate_keys(&pcxt->estimator, 1);
1203 : }
1204 :
1205 : /* ----------------------------------------------------------------
1206 : * ExecMemoizeInitializeDSM
1207 : *
1208 : * Initialize DSM space for memoize statistics.
1209 : * ----------------------------------------------------------------
1210 : */
1211 : void
1212 6 : ExecMemoizeInitializeDSM(MemoizeState *node, ParallelContext *pcxt)
1213 : {
1214 : Size size;
1215 :
1216 : /* don't need this if not instrumenting or no workers */
1217 6 : if (!node->ss.ps.instrument || pcxt->nworkers == 0)
1218 6 : return;
1219 :
1220 0 : size = offsetof(SharedMemoizeInfo, sinstrument)
1221 0 : + pcxt->nworkers * sizeof(MemoizeInstrumentation);
1222 0 : node->shared_info = shm_toc_allocate(pcxt->toc, size);
1223 : /* ensure any unfilled slots will contain zeroes */
1224 0 : memset(node->shared_info, 0, size);
1225 0 : node->shared_info->num_workers = pcxt->nworkers;
1226 0 : shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id,
1227 0 : node->shared_info);
1228 : }
1229 :
1230 : /* ----------------------------------------------------------------
1231 : * ExecMemoizeInitializeWorker
1232 : *
1233 : * Attach worker to DSM space for memoize statistics.
1234 : * ----------------------------------------------------------------
1235 : */
1236 : void
1237 12 : ExecMemoizeInitializeWorker(MemoizeState *node, ParallelWorkerContext *pwcxt)
1238 : {
1239 12 : node->shared_info =
1240 12 : shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, true);
1241 12 : }
1242 :
1243 : /* ----------------------------------------------------------------
1244 : * ExecMemoizeRetrieveInstrumentation
1245 : *
1246 : * Transfer memoize statistics from DSM to private memory.
1247 : * ----------------------------------------------------------------
1248 : */
1249 : void
1250 0 : ExecMemoizeRetrieveInstrumentation(MemoizeState *node)
1251 : {
1252 : Size size;
1253 : SharedMemoizeInfo *si;
1254 :
1255 0 : if (node->shared_info == NULL)
1256 0 : return;
1257 :
1258 0 : size = offsetof(SharedMemoizeInfo, sinstrument)
1259 0 : + node->shared_info->num_workers * sizeof(MemoizeInstrumentation);
1260 0 : si = palloc(size);
1261 0 : memcpy(si, node->shared_info, size);
1262 0 : node->shared_info = si;
1263 : }
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