Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * nodeMemoize.c
4 : * Routines to handle caching of results from parameterized nodes
5 : *
6 : * Portions Copyright (c) 2021-2024, 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 "common/hashfn.h"
70 : #include "executor/executor.h"
71 : #include "executor/nodeMemoize.h"
72 : #include "lib/ilist.h"
73 : #include "miscadmin.h"
74 : #include "utils/datum.h"
75 : #include "utils/lsyscache.h"
76 :
77 : /* States of the ExecMemoize state machine */
78 : #define MEMO_CACHE_LOOKUP 1 /* Attempt to perform a cache lookup */
79 : #define MEMO_CACHE_FETCH_NEXT_TUPLE 2 /* Get another tuple from the cache */
80 : #define MEMO_FILLING_CACHE 3 /* Read outer node to fill cache */
81 : #define MEMO_CACHE_BYPASS_MODE 4 /* Bypass mode. Just read from our
82 : * subplan without caching anything */
83 : #define MEMO_END_OF_SCAN 5 /* Ready for rescan */
84 :
85 :
86 : /* Helper macros for memory accounting */
87 : #define EMPTY_ENTRY_MEMORY_BYTES(e) (sizeof(MemoizeEntry) + \
88 : sizeof(MemoizeKey) + \
89 : (e)->key->params->t_len);
90 : #define CACHE_TUPLE_BYTES(t) (sizeof(MemoizeTuple) + \
91 : (t)->mintuple->t_len)
92 :
93 : /* MemoizeTuple Stores an individually cached tuple */
94 : typedef struct MemoizeTuple
95 : {
96 : MinimalTuple mintuple; /* Cached tuple */
97 : struct MemoizeTuple *next; /* The next tuple with the same parameter
98 : * values or NULL if it's the last one */
99 : } MemoizeTuple;
100 :
101 : /*
102 : * MemoizeKey
103 : * The hash table key for cached entries plus the LRU list link
104 : */
105 : typedef struct MemoizeKey
106 : {
107 : MinimalTuple params;
108 : dlist_node lru_node; /* Pointer to next/prev key in LRU list */
109 : } MemoizeKey;
110 :
111 : /*
112 : * MemoizeEntry
113 : * The data struct that the cache hash table stores
114 : */
115 : typedef struct MemoizeEntry
116 : {
117 : MemoizeKey *key; /* Hash key for hash table lookups */
118 : MemoizeTuple *tuplehead; /* Pointer to the first tuple or NULL if no
119 : * tuples are cached for this entry */
120 : uint32 hash; /* Hash value (cached) */
121 : char status; /* Hash status */
122 : bool complete; /* Did we read the outer plan to completion? */
123 : } MemoizeEntry;
124 :
125 :
126 : #define SH_PREFIX memoize
127 : #define SH_ELEMENT_TYPE MemoizeEntry
128 : #define SH_KEY_TYPE MemoizeKey *
129 : #define SH_SCOPE static inline
130 : #define SH_DECLARE
131 : #include "lib/simplehash.h"
132 :
133 : static uint32 MemoizeHash_hash(struct memoize_hash *tb,
134 : const MemoizeKey *key);
135 : static bool MemoizeHash_equal(struct memoize_hash *tb,
136 : const MemoizeKey *key1,
137 : const MemoizeKey *key2);
138 :
139 : #define SH_PREFIX memoize
140 : #define SH_ELEMENT_TYPE MemoizeEntry
141 : #define SH_KEY_TYPE MemoizeKey *
142 : #define SH_KEY key
143 : #define SH_HASH_KEY(tb, key) MemoizeHash_hash(tb, key)
144 : #define SH_EQUAL(tb, a, b) MemoizeHash_equal(tb, a, b)
145 : #define SH_SCOPE static inline
146 : #define SH_STORE_HASH
147 : #define SH_GET_HASH(tb, a) a->hash
148 : #define SH_DEFINE
149 : #include "lib/simplehash.h"
150 :
151 : /*
152 : * MemoizeHash_hash
153 : * Hash function for simplehash hashtable. 'key' is unused here as we
154 : * require that all table lookups first populate the MemoizeState's
155 : * probeslot with the key values to be looked up.
156 : */
157 : static uint32
158 477738 : MemoizeHash_hash(struct memoize_hash *tb, const MemoizeKey *key)
159 : {
160 477738 : MemoizeState *mstate = (MemoizeState *) tb->private_data;
161 477738 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
162 : MemoryContext oldcontext;
163 477738 : TupleTableSlot *pslot = mstate->probeslot;
164 477738 : uint32 hashkey = 0;
165 477738 : int numkeys = mstate->nkeys;
166 :
167 477738 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
168 :
169 477738 : if (mstate->binary_mode)
170 : {
171 159586 : for (int i = 0; i < numkeys; i++)
172 : {
173 : /* combine successive hashkeys by rotating */
174 82074 : hashkey = pg_rotate_left32(hashkey, 1);
175 :
176 82074 : if (!pslot->tts_isnull[i]) /* treat nulls as having hash key 0 */
177 : {
178 : FormData_pg_attribute *attr;
179 : uint32 hkey;
180 :
181 82074 : attr = &pslot->tts_tupleDescriptor->attrs[i];
182 :
183 82074 : hkey = datum_image_hash(pslot->tts_values[i], attr->attbyval, attr->attlen);
184 :
185 82074 : hashkey ^= hkey;
186 : }
187 : }
188 : }
189 : else
190 : {
191 400226 : FmgrInfo *hashfunctions = mstate->hashfunctions;
192 400226 : Oid *collations = mstate->collations;
193 :
194 800692 : for (int i = 0; i < numkeys; i++)
195 : {
196 : /* combine successive hashkeys by rotating */
197 400466 : hashkey = pg_rotate_left32(hashkey, 1);
198 :
199 400466 : if (!pslot->tts_isnull[i]) /* treat nulls as having hash key 0 */
200 : {
201 : uint32 hkey;
202 :
203 399946 : hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
204 399946 : collations[i], pslot->tts_values[i]));
205 399946 : hashkey ^= hkey;
206 : }
207 : }
208 : }
209 :
210 477738 : MemoryContextSwitchTo(oldcontext);
211 477738 : return murmurhash32(hashkey);
212 : }
213 :
214 : /*
215 : * MemoizeHash_equal
216 : * Equality function for confirming hash value matches during a hash
217 : * table lookup. 'key2' is never used. Instead the MemoizeState's
218 : * probeslot is always populated with details of what's being looked up.
219 : */
220 : static bool
221 399332 : MemoizeHash_equal(struct memoize_hash *tb, const MemoizeKey *key1,
222 : const MemoizeKey *key2)
223 : {
224 399332 : MemoizeState *mstate = (MemoizeState *) tb->private_data;
225 399332 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
226 399332 : TupleTableSlot *tslot = mstate->tableslot;
227 399332 : TupleTableSlot *pslot = mstate->probeslot;
228 :
229 : /* probeslot should have already been prepared by prepare_probe_slot() */
230 399332 : ExecStoreMinimalTuple(key1->params, tslot, false);
231 :
232 399332 : if (mstate->binary_mode)
233 : {
234 : MemoryContext oldcontext;
235 76982 : int numkeys = mstate->nkeys;
236 76982 : bool match = true;
237 :
238 76982 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
239 :
240 76982 : slot_getallattrs(tslot);
241 76982 : slot_getallattrs(pslot);
242 :
243 158466 : for (int i = 0; i < numkeys; i++)
244 : {
245 : FormData_pg_attribute *attr;
246 :
247 81484 : if (tslot->tts_isnull[i] != pslot->tts_isnull[i])
248 : {
249 0 : match = false;
250 0 : break;
251 : }
252 :
253 : /* both NULL? they're equal */
254 81484 : if (tslot->tts_isnull[i])
255 0 : continue;
256 :
257 : /* perform binary comparison on the two datums */
258 81484 : attr = &tslot->tts_tupleDescriptor->attrs[i];
259 81484 : if (!datum_image_eq(tslot->tts_values[i], pslot->tts_values[i],
260 81484 : attr->attbyval, attr->attlen))
261 : {
262 0 : match = false;
263 0 : break;
264 : }
265 : }
266 :
267 76982 : MemoryContextSwitchTo(oldcontext);
268 76982 : return match;
269 : }
270 : else
271 : {
272 322350 : econtext->ecxt_innertuple = tslot;
273 322350 : econtext->ecxt_outertuple = pslot;
274 322350 : return ExecQual(mstate->cache_eq_expr, econtext);
275 : }
276 : }
277 :
278 : /*
279 : * Initialize the hash table to empty. The MemoizeState's hashtable field
280 : * must point to NULL.
281 : */
282 : static void
283 1078 : build_hash_table(MemoizeState *mstate, uint32 size)
284 : {
285 : Assert(mstate->hashtable == NULL);
286 :
287 : /* Make a guess at a good size when we're not given a valid size. */
288 1078 : if (size == 0)
289 0 : size = 1024;
290 :
291 : /* memoize_create will convert the size to a power of 2 */
292 1078 : mstate->hashtable = memoize_create(mstate->tableContext, size, mstate);
293 1078 : }
294 :
295 : /*
296 : * prepare_probe_slot
297 : * Populate mstate's probeslot with the values from the tuple stored
298 : * in 'key'. If 'key' is NULL, then perform the population by evaluating
299 : * mstate's param_exprs.
300 : */
301 : static inline void
302 477738 : prepare_probe_slot(MemoizeState *mstate, MemoizeKey *key)
303 : {
304 477738 : TupleTableSlot *pslot = mstate->probeslot;
305 477738 : TupleTableSlot *tslot = mstate->tableslot;
306 477738 : int numKeys = mstate->nkeys;
307 :
308 477738 : ExecClearTuple(pslot);
309 :
310 477738 : if (key == NULL)
311 : {
312 475338 : ExprContext *econtext = mstate->ss.ps.ps_ExprContext;
313 : MemoryContext oldcontext;
314 :
315 475338 : oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
316 :
317 : /* Set the probeslot's values based on the current parameter values */
318 955478 : for (int i = 0; i < numKeys; i++)
319 480140 : pslot->tts_values[i] = ExecEvalExpr(mstate->param_exprs[i],
320 : econtext,
321 480140 : &pslot->tts_isnull[i]);
322 :
323 475338 : MemoryContextSwitchTo(oldcontext);
324 : }
325 : else
326 : {
327 : /* Process the key's MinimalTuple and store the values in probeslot */
328 2400 : ExecStoreMinimalTuple(key->params, tslot, false);
329 2400 : slot_getallattrs(tslot);
330 2400 : memcpy(pslot->tts_values, tslot->tts_values, sizeof(Datum) * numKeys);
331 2400 : memcpy(pslot->tts_isnull, tslot->tts_isnull, sizeof(bool) * numKeys);
332 : }
333 :
334 477738 : ExecStoreVirtualTuple(pslot);
335 477738 : }
336 :
337 : /*
338 : * entry_purge_tuples
339 : * Remove all tuples from the cache entry pointed to by 'entry'. This
340 : * leaves an empty cache entry. Also, update the memory accounting to
341 : * reflect the removal of the tuples.
342 : */
343 : static inline void
344 2388 : entry_purge_tuples(MemoizeState *mstate, MemoizeEntry *entry)
345 : {
346 2388 : MemoizeTuple *tuple = entry->tuplehead;
347 2388 : uint64 freed_mem = 0;
348 :
349 4776 : while (tuple != NULL)
350 : {
351 2388 : MemoizeTuple *next = tuple->next;
352 :
353 2388 : freed_mem += CACHE_TUPLE_BYTES(tuple);
354 :
355 : /* Free memory used for this tuple */
356 2388 : pfree(tuple->mintuple);
357 2388 : pfree(tuple);
358 :
359 2388 : tuple = next;
360 : }
361 :
362 2388 : entry->complete = false;
363 2388 : entry->tuplehead = NULL;
364 :
365 : /* Update the memory accounting */
366 2388 : mstate->mem_used -= freed_mem;
367 2388 : }
368 :
369 : /*
370 : * remove_cache_entry
371 : * Remove 'entry' from the cache and free memory used by it.
372 : */
373 : static void
374 2388 : remove_cache_entry(MemoizeState *mstate, MemoizeEntry *entry)
375 : {
376 2388 : MemoizeKey *key = entry->key;
377 :
378 2388 : dlist_delete(&entry->key->lru_node);
379 :
380 : /* Remove all of the tuples from this entry */
381 2388 : entry_purge_tuples(mstate, entry);
382 :
383 : /*
384 : * Update memory accounting. entry_purge_tuples should have already
385 : * subtracted the memory used for each cached tuple. Here we just update
386 : * the amount used by the entry itself.
387 : */
388 2388 : mstate->mem_used -= EMPTY_ENTRY_MEMORY_BYTES(entry);
389 :
390 : /* Remove the entry from the cache */
391 2388 : memoize_delete_item(mstate->hashtable, entry);
392 :
393 2388 : pfree(key->params);
394 2388 : pfree(key);
395 2388 : }
396 :
397 : /*
398 : * cache_purge_all
399 : * Remove all items from the cache
400 : */
401 : static void
402 18 : cache_purge_all(MemoizeState *mstate)
403 : {
404 18 : uint64 evictions = 0;
405 :
406 18 : if (mstate->hashtable != NULL)
407 12 : evictions = mstate->hashtable->members;
408 :
409 : /*
410 : * Likely the most efficient way to remove all items is to just reset the
411 : * memory context for the cache and then rebuild a fresh hash table. This
412 : * saves having to remove each item one by one and pfree each cached tuple
413 : */
414 18 : MemoryContextReset(mstate->tableContext);
415 :
416 : /* NULLify so we recreate the table on the next call */
417 18 : mstate->hashtable = NULL;
418 :
419 : /* reset the LRU list */
420 18 : dlist_init(&mstate->lru_list);
421 18 : mstate->last_tuple = NULL;
422 18 : mstate->entry = NULL;
423 :
424 18 : mstate->mem_used = 0;
425 :
426 : /* XXX should we add something new to track these purges? */
427 18 : mstate->stats.cache_evictions += evictions; /* Update Stats */
428 18 : }
429 :
430 : /*
431 : * cache_reduce_memory
432 : * Evict older and less recently used items from the cache in order to
433 : * reduce the memory consumption back to something below the
434 : * MemoizeState's mem_limit.
435 : *
436 : * 'specialkey', if not NULL, causes the function to return false if the entry
437 : * which the key belongs to is removed from the cache.
438 : */
439 : static bool
440 2388 : cache_reduce_memory(MemoizeState *mstate, MemoizeKey *specialkey)
441 : {
442 2388 : bool specialkey_intact = true; /* for now */
443 : dlist_mutable_iter iter;
444 2388 : uint64 evictions = 0;
445 :
446 : /* Update peak memory usage */
447 2388 : if (mstate->mem_used > mstate->stats.mem_peak)
448 6 : mstate->stats.mem_peak = mstate->mem_used;
449 :
450 : /* We expect only to be called when we've gone over budget on memory */
451 : Assert(mstate->mem_used > mstate->mem_limit);
452 :
453 : /* Start the eviction process starting at the head of the LRU list. */
454 2388 : dlist_foreach_modify(iter, &mstate->lru_list)
455 : {
456 2388 : MemoizeKey *key = dlist_container(MemoizeKey, lru_node, iter.cur);
457 : MemoizeEntry *entry;
458 :
459 : /*
460 : * Populate the hash probe slot in preparation for looking up this LRU
461 : * entry.
462 : */
463 2388 : prepare_probe_slot(mstate, key);
464 :
465 : /*
466 : * Ideally the LRU list pointers would be stored in the entry itself
467 : * rather than in the key. Unfortunately, we can't do that as the
468 : * simplehash.h code may resize the table and allocate new memory for
469 : * entries which would result in those pointers pointing to the old
470 : * buckets. However, it's fine to use the key to store this as that's
471 : * only referenced by a pointer in the entry, which of course follows
472 : * the entry whenever the hash table is resized. Since we only have a
473 : * pointer to the key here, we must perform a hash table lookup to
474 : * find the entry that the key belongs to.
475 : */
476 2388 : entry = memoize_lookup(mstate->hashtable, NULL);
477 :
478 : /*
479 : * Sanity check that we found the entry belonging to the LRU list
480 : * item. A misbehaving hash or equality function could cause the
481 : * entry not to be found or the wrong entry to be found.
482 : */
483 2388 : if (unlikely(entry == NULL || entry->key != key))
484 0 : elog(ERROR, "could not find memoization table entry");
485 :
486 : /*
487 : * If we're being called to free memory while the cache is being
488 : * populated with new tuples, then we'd better take some care as we
489 : * could end up freeing the entry which 'specialkey' belongs to.
490 : * Generally callers will pass 'specialkey' as the key for the cache
491 : * entry which is currently being populated, so we must set
492 : * 'specialkey_intact' to false to inform the caller the specialkey
493 : * entry has been removed.
494 : */
495 2388 : if (key == specialkey)
496 0 : specialkey_intact = false;
497 :
498 : /*
499 : * Finally remove the entry. This will remove from the LRU list too.
500 : */
501 2388 : remove_cache_entry(mstate, entry);
502 :
503 2388 : evictions++;
504 :
505 : /* Exit if we've freed enough memory */
506 2388 : if (mstate->mem_used <= mstate->mem_limit)
507 2388 : break;
508 : }
509 :
510 2388 : mstate->stats.cache_evictions += evictions; /* Update Stats */
511 :
512 2388 : return specialkey_intact;
513 : }
514 :
515 : /*
516 : * cache_lookup
517 : * Perform a lookup to see if we've already cached tuples based on the
518 : * scan's current parameters. If we find an existing entry we move it to
519 : * the end of the LRU list, set *found to true then return it. If we
520 : * don't find an entry then we create a new one and add it to the end of
521 : * the LRU list. We also update cache memory accounting and remove older
522 : * entries if we go over the memory budget. If we managed to free enough
523 : * memory we return the new entry, else we return NULL.
524 : *
525 : * Callers can assume we'll never return NULL when *found is true.
526 : */
527 : static MemoizeEntry *
528 475338 : cache_lookup(MemoizeState *mstate, bool *found)
529 : {
530 : MemoizeKey *key;
531 : MemoizeEntry *entry;
532 : MemoryContext oldcontext;
533 :
534 : /* prepare the probe slot with the current scan parameters */
535 475338 : prepare_probe_slot(mstate, NULL);
536 :
537 : /*
538 : * Add the new entry to the cache. No need to pass a valid key since the
539 : * hash function uses mstate's probeslot, which we populated above.
540 : */
541 475338 : entry = memoize_insert(mstate->hashtable, NULL, found);
542 :
543 475338 : if (*found)
544 : {
545 : /*
546 : * Move existing entry to the tail of the LRU list to mark it as the
547 : * most recently used item.
548 : */
549 396932 : dlist_move_tail(&mstate->lru_list, &entry->key->lru_node);
550 :
551 396932 : return entry;
552 : }
553 :
554 78406 : oldcontext = MemoryContextSwitchTo(mstate->tableContext);
555 :
556 : /* Allocate a new key */
557 78406 : entry->key = key = (MemoizeKey *) palloc(sizeof(MemoizeKey));
558 78406 : key->params = ExecCopySlotMinimalTuple(mstate->probeslot);
559 :
560 : /* Update the total cache memory utilization */
561 78406 : mstate->mem_used += EMPTY_ENTRY_MEMORY_BYTES(entry);
562 :
563 : /* Initialize this entry */
564 78406 : entry->complete = false;
565 78406 : entry->tuplehead = NULL;
566 :
567 : /*
568 : * Since this is the most recently used entry, push this entry onto the
569 : * end of the LRU list.
570 : */
571 78406 : dlist_push_tail(&mstate->lru_list, &entry->key->lru_node);
572 :
573 78406 : mstate->last_tuple = NULL;
574 :
575 78406 : MemoryContextSwitchTo(oldcontext);
576 :
577 : /*
578 : * If we've gone over our memory budget, then we'll free up some space in
579 : * the cache.
580 : */
581 78406 : if (mstate->mem_used > mstate->mem_limit)
582 : {
583 : /*
584 : * Try to free up some memory. It's highly unlikely that we'll fail
585 : * to do so here since the entry we've just added is yet to contain
586 : * any tuples and we're able to remove any other entry to reduce the
587 : * memory consumption.
588 : */
589 2388 : if (unlikely(!cache_reduce_memory(mstate, key)))
590 0 : return NULL;
591 :
592 : /*
593 : * The process of removing entries from the cache may have caused the
594 : * code in simplehash.h to shuffle elements to earlier buckets in the
595 : * hash table. If it has, we'll need to find the entry again by
596 : * performing a lookup. Fortunately, we can detect if this has
597 : * happened by seeing if the entry is still in use and that the key
598 : * pointer matches our expected key.
599 : */
600 2388 : if (entry->status != memoize_SH_IN_USE || entry->key != key)
601 : {
602 : /*
603 : * We need to repopulate the probeslot as lookups performed during
604 : * the cache evictions above will have stored some other key.
605 : */
606 12 : prepare_probe_slot(mstate, key);
607 :
608 : /* Re-find the newly added entry */
609 12 : entry = memoize_lookup(mstate->hashtable, NULL);
610 : Assert(entry != NULL);
611 : }
612 : }
613 :
614 78406 : return entry;
615 : }
616 :
617 : /*
618 : * cache_store_tuple
619 : * Add the tuple stored in 'slot' to the mstate's current cache entry.
620 : * The cache entry must have already been made with cache_lookup().
621 : * mstate's last_tuple field must point to the tail of mstate->entry's
622 : * list of tuples.
623 : */
624 : static bool
625 71802 : cache_store_tuple(MemoizeState *mstate, TupleTableSlot *slot)
626 : {
627 : MemoizeTuple *tuple;
628 71802 : MemoizeEntry *entry = mstate->entry;
629 : MemoryContext oldcontext;
630 :
631 : Assert(slot != NULL);
632 : Assert(entry != NULL);
633 :
634 71802 : oldcontext = MemoryContextSwitchTo(mstate->tableContext);
635 :
636 71802 : tuple = (MemoizeTuple *) palloc(sizeof(MemoizeTuple));
637 71802 : tuple->mintuple = ExecCopySlotMinimalTuple(slot);
638 71802 : tuple->next = NULL;
639 :
640 : /* Account for the memory we just consumed */
641 71802 : mstate->mem_used += CACHE_TUPLE_BYTES(tuple);
642 :
643 71802 : if (entry->tuplehead == NULL)
644 : {
645 : /*
646 : * This is the first tuple for this entry, so just point the list head
647 : * to it.
648 : */
649 71344 : entry->tuplehead = tuple;
650 : }
651 : else
652 : {
653 : /* push this tuple onto the tail of the list */
654 458 : mstate->last_tuple->next = tuple;
655 : }
656 :
657 71802 : mstate->last_tuple = tuple;
658 71802 : MemoryContextSwitchTo(oldcontext);
659 :
660 : /*
661 : * If we've gone over our memory budget then free up some space in the
662 : * cache.
663 : */
664 71802 : if (mstate->mem_used > mstate->mem_limit)
665 : {
666 0 : MemoizeKey *key = entry->key;
667 :
668 0 : if (!cache_reduce_memory(mstate, key))
669 0 : return false;
670 :
671 : /*
672 : * The process of removing entries from the cache may have caused the
673 : * code in simplehash.h to shuffle elements to earlier buckets in the
674 : * hash table. If it has, we'll need to find the entry again by
675 : * performing a lookup. Fortunately, we can detect if this has
676 : * happened by seeing if the entry is still in use and that the key
677 : * pointer matches our expected key.
678 : */
679 0 : if (entry->status != memoize_SH_IN_USE || entry->key != key)
680 : {
681 : /*
682 : * We need to repopulate the probeslot as lookups performed during
683 : * the cache evictions above will have stored some other key.
684 : */
685 0 : prepare_probe_slot(mstate, key);
686 :
687 : /* Re-find the entry */
688 0 : mstate->entry = entry = memoize_lookup(mstate->hashtable, NULL);
689 : Assert(entry != NULL);
690 : }
691 : }
692 :
693 71802 : return true;
694 : }
695 :
696 : static TupleTableSlot *
697 609476 : ExecMemoize(PlanState *pstate)
698 : {
699 609476 : MemoizeState *node = castNode(MemoizeState, pstate);
700 609476 : ExprContext *econtext = node->ss.ps.ps_ExprContext;
701 : PlanState *outerNode;
702 : TupleTableSlot *slot;
703 :
704 609476 : CHECK_FOR_INTERRUPTS();
705 :
706 : /*
707 : * Reset per-tuple memory context to free any expression evaluation
708 : * storage allocated in the previous tuple cycle.
709 : */
710 609476 : ResetExprContext(econtext);
711 :
712 609476 : switch (node->mstatus)
713 : {
714 475338 : case MEMO_CACHE_LOOKUP:
715 : {
716 : MemoizeEntry *entry;
717 : TupleTableSlot *outerslot;
718 : bool found;
719 :
720 : Assert(node->entry == NULL);
721 :
722 : /* first call? we'll need a hash table. */
723 475338 : if (unlikely(node->hashtable == NULL))
724 1078 : build_hash_table(node, ((Memoize *) pstate->plan)->est_entries);
725 :
726 : /*
727 : * We're only ever in this state for the first call of the
728 : * scan. Here we have a look to see if we've already seen the
729 : * current parameters before and if we have already cached a
730 : * complete set of records that the outer plan will return for
731 : * these parameters.
732 : *
733 : * When we find a valid cache entry, we'll return the first
734 : * tuple from it. If not found, we'll create a cache entry and
735 : * then try to fetch a tuple from the outer scan. If we find
736 : * one there, we'll try to cache it.
737 : */
738 :
739 : /* see if we've got anything cached for the current parameters */
740 475338 : entry = cache_lookup(node, &found);
741 :
742 475338 : if (found && entry->complete)
743 : {
744 396932 : node->stats.cache_hits += 1; /* stats update */
745 :
746 : /*
747 : * Set last_tuple and entry so that the state
748 : * MEMO_CACHE_FETCH_NEXT_TUPLE can easily find the next
749 : * tuple for these parameters.
750 : */
751 396932 : node->last_tuple = entry->tuplehead;
752 396932 : node->entry = entry;
753 :
754 : /* Fetch the first cached tuple, if there is one */
755 396932 : if (entry->tuplehead)
756 : {
757 117504 : node->mstatus = MEMO_CACHE_FETCH_NEXT_TUPLE;
758 :
759 117504 : slot = node->ss.ps.ps_ResultTupleSlot;
760 117504 : ExecStoreMinimalTuple(entry->tuplehead->mintuple,
761 : slot, false);
762 :
763 117504 : return slot;
764 : }
765 :
766 : /* The cache entry is void of any tuples. */
767 279428 : node->mstatus = MEMO_END_OF_SCAN;
768 279428 : return NULL;
769 : }
770 :
771 : /* Handle cache miss */
772 78406 : node->stats.cache_misses += 1; /* stats update */
773 :
774 78406 : if (found)
775 : {
776 : /*
777 : * A cache entry was found, but the scan for that entry
778 : * did not run to completion. We'll just remove all
779 : * tuples and start again. It might be tempting to
780 : * continue where we left off, but there's no guarantee
781 : * the outer node will produce the tuples in the same
782 : * order as it did last time.
783 : */
784 0 : entry_purge_tuples(node, entry);
785 : }
786 :
787 : /* Scan the outer node for a tuple to cache */
788 78406 : outerNode = outerPlanState(node);
789 78406 : outerslot = ExecProcNode(outerNode);
790 78406 : if (TupIsNull(outerslot))
791 : {
792 : /*
793 : * cache_lookup may have returned NULL due to failure to
794 : * free enough cache space, so ensure we don't do anything
795 : * here that assumes it worked. There's no need to go into
796 : * bypass mode here as we're setting mstatus to end of
797 : * scan.
798 : */
799 7062 : if (likely(entry))
800 7062 : entry->complete = true;
801 :
802 7062 : node->mstatus = MEMO_END_OF_SCAN;
803 7062 : return NULL;
804 : }
805 :
806 71344 : node->entry = entry;
807 :
808 : /*
809 : * If we failed to create the entry or failed to store the
810 : * tuple in the entry, then go into bypass mode.
811 : */
812 71344 : if (unlikely(entry == NULL ||
813 : !cache_store_tuple(node, outerslot)))
814 : {
815 0 : node->stats.cache_overflows += 1; /* stats update */
816 :
817 0 : node->mstatus = MEMO_CACHE_BYPASS_MODE;
818 :
819 : /*
820 : * No need to clear out last_tuple as we'll stay in bypass
821 : * mode until the end of the scan.
822 : */
823 : }
824 : else
825 : {
826 : /*
827 : * If we only expect a single row from this scan then we
828 : * can mark that we're not expecting more. This allows
829 : * cache lookups to work even when the scan has not been
830 : * executed to completion.
831 : */
832 71344 : entry->complete = node->singlerow;
833 71344 : node->mstatus = MEMO_FILLING_CACHE;
834 : }
835 :
836 71344 : slot = node->ss.ps.ps_ResultTupleSlot;
837 71344 : ExecCopySlot(slot, outerslot);
838 71344 : return slot;
839 : }
840 :
841 66540 : case MEMO_CACHE_FETCH_NEXT_TUPLE:
842 : {
843 : /* We shouldn't be in this state if these are not set */
844 : Assert(node->entry != NULL);
845 : Assert(node->last_tuple != NULL);
846 :
847 : /* Skip to the next tuple to output */
848 66540 : node->last_tuple = node->last_tuple->next;
849 :
850 : /* No more tuples in the cache */
851 66540 : if (node->last_tuple == NULL)
852 : {
853 61344 : node->mstatus = MEMO_END_OF_SCAN;
854 61344 : return NULL;
855 : }
856 :
857 5196 : slot = node->ss.ps.ps_ResultTupleSlot;
858 5196 : ExecStoreMinimalTuple(node->last_tuple->mintuple, slot,
859 : false);
860 :
861 5196 : return slot;
862 : }
863 :
864 67598 : case MEMO_FILLING_CACHE:
865 : {
866 : TupleTableSlot *outerslot;
867 67598 : MemoizeEntry *entry = node->entry;
868 :
869 : /* entry should already have been set by MEMO_CACHE_LOOKUP */
870 : Assert(entry != NULL);
871 :
872 : /*
873 : * When in the MEMO_FILLING_CACHE state, we've just had a
874 : * cache miss and are populating the cache with the current
875 : * scan tuples.
876 : */
877 67598 : outerNode = outerPlanState(node);
878 67598 : outerslot = ExecProcNode(outerNode);
879 67598 : if (TupIsNull(outerslot))
880 : {
881 : /* No more tuples. Mark it as complete */
882 67140 : entry->complete = true;
883 67140 : node->mstatus = MEMO_END_OF_SCAN;
884 67140 : return NULL;
885 : }
886 :
887 : /*
888 : * Validate if the planner properly set the singlerow flag. It
889 : * should only set that if each cache entry can, at most,
890 : * return 1 row.
891 : */
892 458 : if (unlikely(entry->complete))
893 0 : elog(ERROR, "cache entry already complete");
894 :
895 : /* Record the tuple in the current cache entry */
896 458 : if (unlikely(!cache_store_tuple(node, outerslot)))
897 : {
898 : /* Couldn't store it? Handle overflow */
899 0 : node->stats.cache_overflows += 1; /* stats update */
900 :
901 0 : node->mstatus = MEMO_CACHE_BYPASS_MODE;
902 :
903 : /*
904 : * No need to clear out entry or last_tuple as we'll stay
905 : * in bypass mode until the end of the scan.
906 : */
907 : }
908 :
909 458 : slot = node->ss.ps.ps_ResultTupleSlot;
910 458 : ExecCopySlot(slot, outerslot);
911 458 : return slot;
912 : }
913 :
914 0 : case MEMO_CACHE_BYPASS_MODE:
915 : {
916 : TupleTableSlot *outerslot;
917 :
918 : /*
919 : * When in bypass mode we just continue to read tuples without
920 : * caching. We need to wait until the next rescan before we
921 : * can come out of this mode.
922 : */
923 0 : outerNode = outerPlanState(node);
924 0 : outerslot = ExecProcNode(outerNode);
925 0 : if (TupIsNull(outerslot))
926 : {
927 0 : node->mstatus = MEMO_END_OF_SCAN;
928 0 : return NULL;
929 : }
930 :
931 0 : slot = node->ss.ps.ps_ResultTupleSlot;
932 0 : ExecCopySlot(slot, outerslot);
933 0 : return slot;
934 : }
935 :
936 0 : case MEMO_END_OF_SCAN:
937 :
938 : /*
939 : * We've already returned NULL for this scan, but just in case
940 : * something calls us again by mistake.
941 : */
942 0 : return NULL;
943 :
944 0 : default:
945 0 : elog(ERROR, "unrecognized memoize state: %d",
946 : (int) node->mstatus);
947 : return NULL;
948 : } /* switch */
949 : }
950 :
951 : MemoizeState *
952 1358 : ExecInitMemoize(Memoize *node, EState *estate, int eflags)
953 : {
954 1358 : MemoizeState *mstate = makeNode(MemoizeState);
955 : Plan *outerNode;
956 : int i;
957 : int nkeys;
958 : Oid *eqfuncoids;
959 :
960 : /* check for unsupported flags */
961 : Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
962 :
963 1358 : mstate->ss.ps.plan = (Plan *) node;
964 1358 : mstate->ss.ps.state = estate;
965 1358 : mstate->ss.ps.ExecProcNode = ExecMemoize;
966 :
967 : /*
968 : * Miscellaneous initialization
969 : *
970 : * create expression context for node
971 : */
972 1358 : ExecAssignExprContext(estate, &mstate->ss.ps);
973 :
974 1358 : outerNode = outerPlan(node);
975 1358 : outerPlanState(mstate) = ExecInitNode(outerNode, estate, eflags);
976 :
977 : /*
978 : * Initialize return slot and type. No need to initialize projection info
979 : * because this node doesn't do projections.
980 : */
981 1358 : ExecInitResultTupleSlotTL(&mstate->ss.ps, &TTSOpsMinimalTuple);
982 1358 : mstate->ss.ps.ps_ProjInfo = NULL;
983 :
984 : /*
985 : * Initialize scan slot and type.
986 : */
987 1358 : ExecCreateScanSlotFromOuterPlan(estate, &mstate->ss, &TTSOpsMinimalTuple);
988 :
989 : /*
990 : * Set the state machine to lookup the cache. We won't find anything
991 : * until we cache something, but this saves a special case to create the
992 : * first entry.
993 : */
994 1358 : mstate->mstatus = MEMO_CACHE_LOOKUP;
995 :
996 1358 : mstate->nkeys = nkeys = node->numKeys;
997 1358 : mstate->hashkeydesc = ExecTypeFromExprList(node->param_exprs);
998 1358 : mstate->tableslot = MakeSingleTupleTableSlot(mstate->hashkeydesc,
999 : &TTSOpsMinimalTuple);
1000 1358 : mstate->probeslot = MakeSingleTupleTableSlot(mstate->hashkeydesc,
1001 : &TTSOpsVirtual);
1002 :
1003 1358 : mstate->param_exprs = (ExprState **) palloc(nkeys * sizeof(ExprState *));
1004 1358 : mstate->collations = node->collations; /* Just point directly to the plan
1005 : * data */
1006 1358 : mstate->hashfunctions = (FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
1007 :
1008 1358 : eqfuncoids = palloc(nkeys * sizeof(Oid));
1009 :
1010 2746 : for (i = 0; i < nkeys; i++)
1011 : {
1012 1388 : Oid hashop = node->hashOperators[i];
1013 : Oid left_hashfn;
1014 : Oid right_hashfn;
1015 1388 : Expr *param_expr = (Expr *) list_nth(node->param_exprs, i);
1016 :
1017 1388 : if (!get_op_hash_functions(hashop, &left_hashfn, &right_hashfn))
1018 0 : elog(ERROR, "could not find hash function for hash operator %u",
1019 : hashop);
1020 :
1021 1388 : fmgr_info(left_hashfn, &mstate->hashfunctions[i]);
1022 :
1023 1388 : mstate->param_exprs[i] = ExecInitExpr(param_expr, (PlanState *) mstate);
1024 1388 : eqfuncoids[i] = get_opcode(hashop);
1025 : }
1026 :
1027 2716 : mstate->cache_eq_expr = ExecBuildParamSetEqual(mstate->hashkeydesc,
1028 : &TTSOpsMinimalTuple,
1029 : &TTSOpsVirtual,
1030 : eqfuncoids,
1031 1358 : node->collations,
1032 1358 : node->param_exprs,
1033 : (PlanState *) mstate);
1034 :
1035 1358 : pfree(eqfuncoids);
1036 1358 : mstate->mem_used = 0;
1037 :
1038 : /* Limit the total memory consumed by the cache to this */
1039 1358 : mstate->mem_limit = get_hash_memory_limit();
1040 :
1041 : /* A memory context dedicated for the cache */
1042 1358 : mstate->tableContext = AllocSetContextCreate(CurrentMemoryContext,
1043 : "MemoizeHashTable",
1044 : ALLOCSET_DEFAULT_SIZES);
1045 :
1046 1358 : dlist_init(&mstate->lru_list);
1047 1358 : mstate->last_tuple = NULL;
1048 1358 : mstate->entry = NULL;
1049 :
1050 : /*
1051 : * Mark if we can assume the cache entry is completed after we get the
1052 : * first record for it. Some callers might not call us again after
1053 : * getting the first match. e.g. A join operator performing a unique join
1054 : * is able to skip to the next outer tuple after getting the first
1055 : * matching inner tuple. In this case, the cache entry is complete after
1056 : * getting the first tuple. This allows us to mark it as so.
1057 : */
1058 1358 : mstate->singlerow = node->singlerow;
1059 1358 : mstate->keyparamids = node->keyparamids;
1060 :
1061 : /*
1062 : * Record if the cache keys should be compared bit by bit, or logically
1063 : * using the type's hash equality operator
1064 : */
1065 1358 : mstate->binary_mode = node->binary_mode;
1066 :
1067 : /* Zero the statistics counters */
1068 1358 : memset(&mstate->stats, 0, sizeof(MemoizeInstrumentation));
1069 :
1070 : /*
1071 : * Because it may require a large allocation, we delay building of the
1072 : * hash table until executor run.
1073 : */
1074 1358 : mstate->hashtable = NULL;
1075 :
1076 1358 : return mstate;
1077 : }
1078 :
1079 : void
1080 1358 : ExecEndMemoize(MemoizeState *node)
1081 : {
1082 : #ifdef USE_ASSERT_CHECKING
1083 : /* Validate the memory accounting code is correct in assert builds. */
1084 : if (node->hashtable != NULL)
1085 : {
1086 : int count;
1087 : uint64 mem = 0;
1088 : memoize_iterator i;
1089 : MemoizeEntry *entry;
1090 :
1091 : memoize_start_iterate(node->hashtable, &i);
1092 :
1093 : count = 0;
1094 : while ((entry = memoize_iterate(node->hashtable, &i)) != NULL)
1095 : {
1096 : MemoizeTuple *tuple = entry->tuplehead;
1097 :
1098 : mem += EMPTY_ENTRY_MEMORY_BYTES(entry);
1099 : while (tuple != NULL)
1100 : {
1101 : mem += CACHE_TUPLE_BYTES(tuple);
1102 : tuple = tuple->next;
1103 : }
1104 : count++;
1105 : }
1106 :
1107 : Assert(count == node->hashtable->members);
1108 : Assert(mem == node->mem_used);
1109 : }
1110 : #endif
1111 :
1112 : /*
1113 : * When ending a parallel worker, copy the statistics gathered by the
1114 : * worker back into shared memory so that it can be picked up by the main
1115 : * process to report in EXPLAIN ANALYZE.
1116 : */
1117 1358 : if (node->shared_info != NULL && IsParallelWorker())
1118 : {
1119 : MemoizeInstrumentation *si;
1120 :
1121 : /* Make mem_peak available for EXPLAIN */
1122 0 : if (node->stats.mem_peak == 0)
1123 0 : node->stats.mem_peak = node->mem_used;
1124 :
1125 : Assert(ParallelWorkerNumber <= node->shared_info->num_workers);
1126 0 : si = &node->shared_info->sinstrument[ParallelWorkerNumber];
1127 0 : memcpy(si, &node->stats, sizeof(MemoizeInstrumentation));
1128 : }
1129 :
1130 : /* Remove the cache context */
1131 1358 : MemoryContextDelete(node->tableContext);
1132 :
1133 : /*
1134 : * shut down the subplan
1135 : */
1136 1358 : ExecEndNode(outerPlanState(node));
1137 1358 : }
1138 :
1139 : void
1140 475338 : ExecReScanMemoize(MemoizeState *node)
1141 : {
1142 475338 : PlanState *outerPlan = outerPlanState(node);
1143 :
1144 : /* Mark that we must lookup the cache for a new set of parameters */
1145 475338 : node->mstatus = MEMO_CACHE_LOOKUP;
1146 :
1147 : /* nullify pointers used for the last scan */
1148 475338 : node->entry = NULL;
1149 475338 : node->last_tuple = NULL;
1150 :
1151 : /*
1152 : * if chgParam of subnode is not null then plan will be re-scanned by
1153 : * first ExecProcNode.
1154 : */
1155 475338 : if (outerPlan->chgParam == NULL)
1156 0 : ExecReScan(outerPlan);
1157 :
1158 : /*
1159 : * Purge the entire cache if a parameter changed that is not part of the
1160 : * cache key.
1161 : */
1162 475338 : if (bms_nonempty_difference(outerPlan->chgParam, node->keyparamids))
1163 18 : cache_purge_all(node);
1164 475338 : }
1165 :
1166 : /*
1167 : * ExecEstimateCacheEntryOverheadBytes
1168 : * For use in the query planner to help it estimate the amount of memory
1169 : * required to store a single entry in the cache.
1170 : */
1171 : double
1172 226778 : ExecEstimateCacheEntryOverheadBytes(double ntuples)
1173 : {
1174 226778 : return sizeof(MemoizeEntry) + sizeof(MemoizeKey) + sizeof(MemoizeTuple) *
1175 : ntuples;
1176 : }
1177 :
1178 : /* ----------------------------------------------------------------
1179 : * Parallel Query Support
1180 : * ----------------------------------------------------------------
1181 : */
1182 :
1183 : /* ----------------------------------------------------------------
1184 : * ExecMemoizeEstimate
1185 : *
1186 : * Estimate space required to propagate memoize statistics.
1187 : * ----------------------------------------------------------------
1188 : */
1189 : void
1190 6 : ExecMemoizeEstimate(MemoizeState *node, ParallelContext *pcxt)
1191 : {
1192 : Size size;
1193 :
1194 : /* don't need this if not instrumenting or no workers */
1195 6 : if (!node->ss.ps.instrument || pcxt->nworkers == 0)
1196 6 : return;
1197 :
1198 0 : size = mul_size(pcxt->nworkers, sizeof(MemoizeInstrumentation));
1199 0 : size = add_size(size, offsetof(SharedMemoizeInfo, sinstrument));
1200 0 : shm_toc_estimate_chunk(&pcxt->estimator, size);
1201 0 : shm_toc_estimate_keys(&pcxt->estimator, 1);
1202 : }
1203 :
1204 : /* ----------------------------------------------------------------
1205 : * ExecMemoizeInitializeDSM
1206 : *
1207 : * Initialize DSM space for memoize statistics.
1208 : * ----------------------------------------------------------------
1209 : */
1210 : void
1211 6 : ExecMemoizeInitializeDSM(MemoizeState *node, ParallelContext *pcxt)
1212 : {
1213 : Size size;
1214 :
1215 : /* don't need this if not instrumenting or no workers */
1216 6 : if (!node->ss.ps.instrument || pcxt->nworkers == 0)
1217 6 : return;
1218 :
1219 0 : size = offsetof(SharedMemoizeInfo, sinstrument)
1220 0 : + pcxt->nworkers * sizeof(MemoizeInstrumentation);
1221 0 : node->shared_info = shm_toc_allocate(pcxt->toc, size);
1222 : /* ensure any unfilled slots will contain zeroes */
1223 0 : memset(node->shared_info, 0, size);
1224 0 : node->shared_info->num_workers = pcxt->nworkers;
1225 0 : shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id,
1226 0 : node->shared_info);
1227 : }
1228 :
1229 : /* ----------------------------------------------------------------
1230 : * ExecMemoizeInitializeWorker
1231 : *
1232 : * Attach worker to DSM space for memoize statistics.
1233 : * ----------------------------------------------------------------
1234 : */
1235 : void
1236 12 : ExecMemoizeInitializeWorker(MemoizeState *node, ParallelWorkerContext *pwcxt)
1237 : {
1238 12 : node->shared_info =
1239 12 : shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, true);
1240 12 : }
1241 :
1242 : /* ----------------------------------------------------------------
1243 : * ExecMemoizeRetrieveInstrumentation
1244 : *
1245 : * Transfer memoize statistics from DSM to private memory.
1246 : * ----------------------------------------------------------------
1247 : */
1248 : void
1249 0 : ExecMemoizeRetrieveInstrumentation(MemoizeState *node)
1250 : {
1251 : Size size;
1252 : SharedMemoizeInfo *si;
1253 :
1254 0 : if (node->shared_info == NULL)
1255 0 : return;
1256 :
1257 0 : size = offsetof(SharedMemoizeInfo, sinstrument)
1258 0 : + node->shared_info->num_workers * sizeof(MemoizeInstrumentation);
1259 0 : si = palloc(size);
1260 0 : memcpy(si, node->shared_info, size);
1261 0 : node->shared_info = si;
1262 : }
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