1/*-------------------------------------------------------------------------
2 *
3 * nbtree.h
4 * header file for postgres btree access method implementation.
5 *
6 *
7 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 * src/include/access/nbtree.h
11 *
12 *-------------------------------------------------------------------------
13 */
14#ifndef NBTREE_H
15#define NBTREE_H
16
17#include "access/amapi.h"
18#include "access/itup.h"
19#include "access/sdir.h"
20#include "access/xlogreader.h"
21#include "catalog/pg_index.h"
22#include "lib/stringinfo.h"
23#include "storage/bufmgr.h"
24#include "storage/shm_toc.h"
25
26/* There's room for a 16-bit vacuum cycle ID in BTPageOpaqueData */
27typedef uint16 BTCycleId;
28
29/*
30 * BTPageOpaqueData -- At the end of every page, we store a pointer
31 * to both siblings in the tree. This is used to do forward/backward
32 * index scans. The next-page link is also critical for recovery when
33 * a search has navigated to the wrong page due to concurrent page splits
34 * or deletions; see src/backend/access/nbtree/README for more info.
35 *
36 * In addition, we store the page's btree level (counting upwards from
37 * zero at a leaf page) as well as some flag bits indicating the page type
38 * and status. If the page is deleted, we replace the level with the
39 * next-transaction-ID value indicating when it is safe to reclaim the page.
40 *
41 * We also store a "vacuum cycle ID". When a page is split while VACUUM is
42 * processing the index, a nonzero value associated with the VACUUM run is
43 * stored into both halves of the split page. (If VACUUM is not running,
44 * both pages receive zero cycleids.) This allows VACUUM to detect whether
45 * a page was split since it started, with a small probability of false match
46 * if the page was last split some exact multiple of MAX_BT_CYCLE_ID VACUUMs
47 * ago. Also, during a split, the BTP_SPLIT_END flag is cleared in the left
48 * (original) page, and set in the right page, but only if the next page
49 * to its right has a different cycleid.
50 *
51 * NOTE: the BTP_LEAF flag bit is redundant since level==0 could be tested
52 * instead.
53 */
54
55typedef struct BTPageOpaqueData
56{
57 BlockNumber btpo_prev; /* left sibling, or P_NONE if leftmost */
58 BlockNumber btpo_next; /* right sibling, or P_NONE if rightmost */
59 union
60 {
61 uint32 level; /* tree level --- zero for leaf pages */
62 TransactionId xact; /* next transaction ID, if deleted */
63 } btpo;
64 uint16 btpo_flags; /* flag bits, see below */
65 BTCycleId btpo_cycleid; /* vacuum cycle ID of latest split */
66} BTPageOpaqueData;
67
68typedef BTPageOpaqueData *BTPageOpaque;
69
70/* Bits defined in btpo_flags */
71#define BTP_LEAF (1 << 0) /* leaf page, i.e. not internal page */
72#define BTP_ROOT (1 << 1) /* root page (has no parent) */
73#define BTP_DELETED (1 << 2) /* page has been deleted from tree */
74#define BTP_META (1 << 3) /* meta-page */
75#define BTP_HALF_DEAD (1 << 4) /* empty, but still in tree */
76#define BTP_SPLIT_END (1 << 5) /* rightmost page of split group */
77#define BTP_HAS_GARBAGE (1 << 6) /* page has LP_DEAD tuples */
78#define BTP_INCOMPLETE_SPLIT (1 << 7) /* right sibling's downlink is missing */
79
80/*
81 * The max allowed value of a cycle ID is a bit less than 64K. This is
82 * for convenience of pg_filedump and similar utilities: we want to use
83 * the last 2 bytes of special space as an index type indicator, and
84 * restricting cycle ID lets btree use that space for vacuum cycle IDs
85 * while still allowing index type to be identified.
86 */
87#define MAX_BT_CYCLE_ID 0xFF7F
88
89
90/*
91 * The Meta page is always the first page in the btree index.
92 * Its primary purpose is to point to the location of the btree root page.
93 * We also point to the "fast" root, which is the current effective root;
94 * see README for discussion.
95 */
96
97typedef struct BTMetaPageData
98{
99 uint32 btm_magic; /* should contain BTREE_MAGIC */
100 uint32 btm_version; /* nbtree version (always <= BTREE_VERSION) */
101 BlockNumber btm_root; /* current root location */
102 uint32 btm_level; /* tree level of the root page */
103 BlockNumber btm_fastroot; /* current "fast" root location */
104 uint32 btm_fastlevel; /* tree level of the "fast" root page */
105 /* remaining fields only valid when btm_version >= BTREE_NOVAC_VERSION */
106 TransactionId btm_oldest_btpo_xact; /* oldest btpo_xact among all deleted
107 * pages */
108 float8 btm_last_cleanup_num_heap_tuples; /* number of heap tuples
109 * during last cleanup */
110} BTMetaPageData;
111
112#define BTPageGetMeta(p) \
113 ((BTMetaPageData *) PageGetContents(p))
114
115/*
116 * The current Btree version is 4. That's what you'll get when you create
117 * a new index.
118 *
119 * Btree version 3 was used in PostgreSQL v11. It is mostly the same as
120 * version 4, but heap TIDs were not part of the keyspace. Index tuples
121 * with duplicate keys could be stored in any order. We continue to
122 * support reading and writing Btree versions 2 and 3, so that they don't
123 * need to be immediately re-indexed at pg_upgrade. In order to get the
124 * new heapkeyspace semantics, however, a REINDEX is needed.
125 *
126 * Btree version 2 is mostly the same as version 3. There are two new
127 * fields in the metapage that were introduced in version 3. A version 2
128 * metapage will be automatically upgraded to version 3 on the first
129 * insert to it. INCLUDE indexes cannot use version 2.
130 */
131#define BTREE_METAPAGE 0 /* first page is meta */
132#define BTREE_MAGIC 0x053162 /* magic number in metapage */
133#define BTREE_VERSION 4 /* current version number */
134#define BTREE_MIN_VERSION 2 /* minimal supported version number */
135#define BTREE_NOVAC_VERSION 3 /* minimal version with all meta fields */
136
137/*
138 * Maximum size of a btree index entry, including its tuple header.
139 *
140 * We actually need to be able to fit three items on every page,
141 * so restrict any one item to 1/3 the per-page available space.
142 *
143 * There are rare cases where _bt_truncate() will need to enlarge
144 * a heap index tuple to make space for a tiebreaker heap TID
145 * attribute, which we account for here.
146 */
147#define BTMaxItemSize(page) \
148 MAXALIGN_DOWN((PageGetPageSize(page) - \
149 MAXALIGN(SizeOfPageHeaderData + \
150 3*sizeof(ItemIdData) + \
151 3*sizeof(ItemPointerData)) - \
152 MAXALIGN(sizeof(BTPageOpaqueData))) / 3)
153#define BTMaxItemSizeNoHeapTid(page) \
154 MAXALIGN_DOWN((PageGetPageSize(page) - \
155 MAXALIGN(SizeOfPageHeaderData + 3*sizeof(ItemIdData)) - \
156 MAXALIGN(sizeof(BTPageOpaqueData))) / 3)
157
158/*
159 * The leaf-page fillfactor defaults to 90% but is user-adjustable.
160 * For pages above the leaf level, we use a fixed 70% fillfactor.
161 * The fillfactor is applied during index build and when splitting
162 * a rightmost page; when splitting non-rightmost pages we try to
163 * divide the data equally. When splitting a page that's entirely
164 * filled with a single value (duplicates), the effective leaf-page
165 * fillfactor is 96%, regardless of whether the page is a rightmost
166 * page.
167 */
168#define BTREE_MIN_FILLFACTOR 10
169#define BTREE_DEFAULT_FILLFACTOR 90
170#define BTREE_NONLEAF_FILLFACTOR 70
171#define BTREE_SINGLEVAL_FILLFACTOR 96
172
173/*
174 * In general, the btree code tries to localize its knowledge about
175 * page layout to a couple of routines. However, we need a special
176 * value to indicate "no page number" in those places where we expect
177 * page numbers. We can use zero for this because we never need to
178 * make a pointer to the metadata page.
179 */
180
181#define P_NONE 0
182
183/*
184 * Macros to test whether a page is leftmost or rightmost on its tree level,
185 * as well as other state info kept in the opaque data.
186 */
187#define P_LEFTMOST(opaque) ((opaque)->btpo_prev == P_NONE)
188#define P_RIGHTMOST(opaque) ((opaque)->btpo_next == P_NONE)
189#define P_ISLEAF(opaque) (((opaque)->btpo_flags & BTP_LEAF) != 0)
190#define P_ISROOT(opaque) (((opaque)->btpo_flags & BTP_ROOT) != 0)
191#define P_ISDELETED(opaque) (((opaque)->btpo_flags & BTP_DELETED) != 0)
192#define P_ISMETA(opaque) (((opaque)->btpo_flags & BTP_META) != 0)
193#define P_ISHALFDEAD(opaque) (((opaque)->btpo_flags & BTP_HALF_DEAD) != 0)
194#define P_IGNORE(opaque) (((opaque)->btpo_flags & (BTP_DELETED|BTP_HALF_DEAD)) != 0)
195#define P_HAS_GARBAGE(opaque) (((opaque)->btpo_flags & BTP_HAS_GARBAGE) != 0)
196#define P_INCOMPLETE_SPLIT(opaque) (((opaque)->btpo_flags & BTP_INCOMPLETE_SPLIT) != 0)
197
198/*
199 * Lehman and Yao's algorithm requires a ``high key'' on every non-rightmost
200 * page. The high key is not a tuple that is used to visit the heap. It is
201 * a pivot tuple (see "Notes on B-Tree tuple format" below for definition).
202 * The high key on a page is required to be greater than or equal to any
203 * other key that appears on the page. If we find ourselves trying to
204 * insert a key that is strictly > high key, we know we need to move right
205 * (this should only happen if the page was split since we examined the
206 * parent page).
207 *
208 * Our insertion algorithm guarantees that we can use the initial least key
209 * on our right sibling as the high key. Once a page is created, its high
210 * key changes only if the page is split.
211 *
212 * On a non-rightmost page, the high key lives in item 1 and data items
213 * start in item 2. Rightmost pages have no high key, so we store data
214 * items beginning in item 1.
215 */
216
217#define P_HIKEY ((OffsetNumber) 1)
218#define P_FIRSTKEY ((OffsetNumber) 2)
219#define P_FIRSTDATAKEY(opaque) (P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY)
220
221/*
222 * Notes on B-Tree tuple format, and key and non-key attributes:
223 *
224 * INCLUDE B-Tree indexes have non-key attributes. These are extra
225 * attributes that may be returned by index-only scans, but do not influence
226 * the order of items in the index (formally, non-key attributes are not
227 * considered to be part of the key space). Non-key attributes are only
228 * present in leaf index tuples whose item pointers actually point to heap
229 * tuples (non-pivot tuples). _bt_check_natts() enforces the rules
230 * described here.
231 *
232 * Non-pivot tuple format:
233 *
234 * t_tid | t_info | key values | INCLUDE columns, if any
235 *
236 * t_tid points to the heap TID, which is a tiebreaker key column as of
237 * BTREE_VERSION 4. Currently, the INDEX_ALT_TID_MASK status bit is never
238 * set for non-pivot tuples.
239 *
240 * All other types of index tuples ("pivot" tuples) only have key columns,
241 * since pivot tuples only exist to represent how the key space is
242 * separated. In general, any B-Tree index that has more than one level
243 * (i.e. any index that does not just consist of a metapage and a single
244 * leaf root page) must have some number of pivot tuples, since pivot
245 * tuples are used for traversing the tree. Suffix truncation can omit
246 * trailing key columns when a new pivot is formed, which makes minus
247 * infinity their logical value. Since BTREE_VERSION 4 indexes treat heap
248 * TID as a trailing key column that ensures that all index tuples are
249 * physically unique, it is necessary to represent heap TID as a trailing
250 * key column in pivot tuples, though very often this can be truncated
251 * away, just like any other key column. (Actually, the heap TID is
252 * omitted rather than truncated, since its representation is different to
253 * the non-pivot representation.)
254 *
255 * Pivot tuple format:
256 *
257 * t_tid | t_info | key values | [heap TID]
258 *
259 * We store the number of columns present inside pivot tuples by abusing
260 * their t_tid offset field, since pivot tuples never need to store a real
261 * offset (downlinks only need to store a block number in t_tid). The
262 * offset field only stores the number of columns/attributes when the
263 * INDEX_ALT_TID_MASK bit is set, which doesn't count the trailing heap
264 * TID column sometimes stored in pivot tuples -- that's represented by
265 * the presence of BT_HEAP_TID_ATTR. The INDEX_ALT_TID_MASK bit in t_info
266 * is always set on BTREE_VERSION 4. BT_HEAP_TID_ATTR can only be set on
267 * BTREE_VERSION 4.
268 *
269 * In version 3 indexes, the INDEX_ALT_TID_MASK flag might not be set in
270 * pivot tuples. In that case, the number of key columns is implicitly
271 * the same as the number of key columns in the index. It is not usually
272 * set on version 2 indexes, which predate the introduction of INCLUDE
273 * indexes. (Only explicitly truncated pivot tuples explicitly represent
274 * the number of key columns on versions 2 and 3, whereas all pivot tuples
275 * are formed using truncation on version 4. A version 2 index will have
276 * it set for an internal page negative infinity item iff internal page
277 * split occurred after upgrade to Postgres 11+.)
278 *
279 * The 12 least significant offset bits from t_tid are used to represent
280 * the number of columns in INDEX_ALT_TID_MASK tuples, leaving 4 status
281 * bits (BT_RESERVED_OFFSET_MASK bits), 3 of which that are reserved for
282 * future use. BT_N_KEYS_OFFSET_MASK should be large enough to store any
283 * number of columns/attributes <= INDEX_MAX_KEYS.
284 *
285 * Note well: The macros that deal with the number of attributes in tuples
286 * assume that a tuple with INDEX_ALT_TID_MASK set must be a pivot tuple,
287 * and that a tuple without INDEX_ALT_TID_MASK set must be a non-pivot
288 * tuple (or must have the same number of attributes as the index has
289 * generally in the case of !heapkeyspace indexes). They will need to be
290 * updated if non-pivot tuples ever get taught to use INDEX_ALT_TID_MASK
291 * for something else.
292 */
293#define INDEX_ALT_TID_MASK INDEX_AM_RESERVED_BIT
294
295/* Item pointer offset bits */
296#define BT_RESERVED_OFFSET_MASK 0xF000
297#define BT_N_KEYS_OFFSET_MASK 0x0FFF
298#define BT_HEAP_TID_ATTR 0x1000
299
300/* Get/set downlink block number */
301#define BTreeInnerTupleGetDownLink(itup) \
302 ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid))
303#define BTreeInnerTupleSetDownLink(itup, blkno) \
304 ItemPointerSetBlockNumber(&((itup)->t_tid), (blkno))
305
306/*
307 * Get/set leaf page highkey's link. During the second phase of deletion, the
308 * target leaf page's high key may point to an ancestor page (at all other
309 * times, the leaf level high key's link is not used). See the nbtree README
310 * for full details.
311 */
312#define BTreeTupleGetTopParent(itup) \
313 ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid))
314#define BTreeTupleSetTopParent(itup, blkno) \
315 do { \
316 ItemPointerSetBlockNumber(&((itup)->t_tid), (blkno)); \
317 BTreeTupleSetNAtts((itup), 0); \
318 } while(0)
319
320/*
321 * Get/set number of attributes within B-tree index tuple.
322 *
323 * Note that this does not include an implicit tiebreaker heap TID
324 * attribute, if any. Note also that the number of key attributes must be
325 * explicitly represented in all heapkeyspace pivot tuples.
326 */
327#define BTreeTupleGetNAtts(itup, rel) \
328 ( \
329 (itup)->t_info & INDEX_ALT_TID_MASK ? \
330 ( \
331 ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_N_KEYS_OFFSET_MASK \
332 ) \
333 : \
334 IndexRelationGetNumberOfAttributes(rel) \
335 )
336#define BTreeTupleSetNAtts(itup, n) \
337 do { \
338 (itup)->t_info |= INDEX_ALT_TID_MASK; \
339 ItemPointerSetOffsetNumber(&(itup)->t_tid, (n) & BT_N_KEYS_OFFSET_MASK); \
340 } while(0)
341
342/*
343 * Get tiebreaker heap TID attribute, if any. Macro works with both pivot
344 * and non-pivot tuples, despite differences in how heap TID is represented.
345 */
346#define BTreeTupleGetHeapTID(itup) \
347 ( \
348 (itup)->t_info & INDEX_ALT_TID_MASK && \
349 (ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_HEAP_TID_ATTR) != 0 ? \
350 ( \
351 (ItemPointer) (((char *) (itup) + IndexTupleSize(itup)) - \
352 sizeof(ItemPointerData)) \
353 ) \
354 : (itup)->t_info & INDEX_ALT_TID_MASK ? NULL : (ItemPointer) &((itup)->t_tid) \
355 )
356/*
357 * Set the heap TID attribute for a tuple that uses the INDEX_ALT_TID_MASK
358 * representation (currently limited to pivot tuples)
359 */
360#define BTreeTupleSetAltHeapTID(itup) \
361 do { \
362 Assert((itup)->t_info & INDEX_ALT_TID_MASK); \
363 ItemPointerSetOffsetNumber(&(itup)->t_tid, \
364 ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) | BT_HEAP_TID_ATTR); \
365 } while(0)
366
367/*
368 * Operator strategy numbers for B-tree have been moved to access/stratnum.h,
369 * because many places need to use them in ScanKeyInit() calls.
370 *
371 * The strategy numbers are chosen so that we can commute them by
372 * subtraction, thus:
373 */
374#define BTCommuteStrategyNumber(strat) (BTMaxStrategyNumber + 1 - (strat))
375
376/*
377 * When a new operator class is declared, we require that the user
378 * supply us with an amproc procedure (BTORDER_PROC) for determining
379 * whether, for two keys a and b, a < b, a = b, or a > b. This routine
380 * must return < 0, 0, > 0, respectively, in these three cases.
381 *
382 * To facilitate accelerated sorting, an operator class may choose to
383 * offer a second procedure (BTSORTSUPPORT_PROC). For full details, see
384 * src/include/utils/sortsupport.h.
385 *
386 * To support window frames defined by "RANGE offset PRECEDING/FOLLOWING",
387 * an operator class may choose to offer a third amproc procedure
388 * (BTINRANGE_PROC), independently of whether it offers sortsupport.
389 * For full details, see doc/src/sgml/btree.sgml.
390 */
391
392#define BTORDER_PROC 1
393#define BTSORTSUPPORT_PROC 2
394#define BTINRANGE_PROC 3
395#define BTNProcs 3
396
397/*
398 * We need to be able to tell the difference between read and write
399 * requests for pages, in order to do locking correctly.
400 */
401
402#define BT_READ BUFFER_LOCK_SHARE
403#define BT_WRITE BUFFER_LOCK_EXCLUSIVE
404
405/*
406 * BTStackData -- As we descend a tree, we push the (location, downlink)
407 * pairs from internal pages onto a private stack. If we split a
408 * leaf, we use this stack to walk back up the tree and insert data
409 * into parent pages (and possibly to split them, too). Lehman and
410 * Yao's update algorithm guarantees that under no circumstances can
411 * our private stack give us an irredeemably bad picture up the tree.
412 * Again, see the paper for details.
413 */
414
415typedef struct BTStackData
416{
417 BlockNumber bts_blkno;
418 OffsetNumber bts_offset;
419 BlockNumber bts_btentry;
420 struct BTStackData *bts_parent;
421} BTStackData;
422
423typedef BTStackData *BTStack;
424
425/*
426 * BTScanInsertData is the btree-private state needed to find an initial
427 * position for an indexscan, or to insert new tuples -- an "insertion
428 * scankey" (not to be confused with a search scankey). It's used to descend
429 * a B-Tree using _bt_search.
430 *
431 * heapkeyspace indicates if we expect all keys in the index to be physically
432 * unique because heap TID is used as a tiebreaker attribute, and if index may
433 * have truncated key attributes in pivot tuples. This is actually a property
434 * of the index relation itself (not an indexscan). heapkeyspace indexes are
435 * indexes whose version is >= version 4. It's convenient to keep this close
436 * by, rather than accessing the metapage repeatedly.
437 *
438 * anynullkeys indicates if any of the keys had NULL value when scankey was
439 * built from index tuple (note that already-truncated tuple key attributes
440 * set NULL as a placeholder key value, which also affects value of
441 * anynullkeys). This is a convenience for unique index non-pivot tuple
442 * insertion, which usually temporarily unsets scantid, but shouldn't iff
443 * anynullkeys is true. Value generally matches non-pivot tuple's HasNulls
444 * bit, but may not when inserting into an INCLUDE index (tuple header value
445 * is affected by the NULL-ness of both key and non-key attributes).
446 *
447 * When nextkey is false (the usual case), _bt_search and _bt_binsrch will
448 * locate the first item >= scankey. When nextkey is true, they will locate
449 * the first item > scan key.
450 *
451 * pivotsearch is set to true by callers that want to re-find a leaf page
452 * using a scankey built from a leaf page's high key. Most callers set this
453 * to false.
454 *
455 * scantid is the heap TID that is used as a final tiebreaker attribute. It
456 * is set to NULL when index scan doesn't need to find a position for a
457 * specific physical tuple. Must be set when inserting new tuples into
458 * heapkeyspace indexes, since every tuple in the tree unambiguously belongs
459 * in one exact position (it's never set with !heapkeyspace indexes, though).
460 * Despite the representational difference, nbtree search code considers
461 * scantid to be just another insertion scankey attribute.
462 *
463 * scankeys is an array of scan key entries for attributes that are compared
464 * before scantid (user-visible attributes). keysz is the size of the array.
465 * During insertion, there must be a scan key for every attribute, but when
466 * starting a regular index scan some can be omitted. The array is used as a
467 * flexible array member, though it's sized in a way that makes it possible to
468 * use stack allocations. See nbtree/README for full details.
469 */
470typedef struct BTScanInsertData
471{
472 bool heapkeyspace;
473 bool anynullkeys;
474 bool nextkey;
475 bool pivotsearch;
476 ItemPointer scantid; /* tiebreaker for scankeys */
477 int keysz; /* Size of scankeys array */
478 ScanKeyData scankeys[INDEX_MAX_KEYS]; /* Must appear last */
479} BTScanInsertData;
480
481typedef BTScanInsertData *BTScanInsert;
482
483/*
484 * BTInsertStateData is a working area used during insertion.
485 *
486 * This is filled in after descending the tree to the first leaf page the new
487 * tuple might belong on. Tracks the current position while performing
488 * uniqueness check, before we have determined which exact page to insert
489 * to.
490 *
491 * (This should be private to nbtinsert.c, but it's also used by
492 * _bt_binsrch_insert)
493 */
494typedef struct BTInsertStateData
495{
496 IndexTuple itup; /* Item we're inserting */
497 Size itemsz; /* Size of itup -- should be MAXALIGN()'d */
498 BTScanInsert itup_key; /* Insertion scankey */
499
500 /* Buffer containing leaf page we're likely to insert itup on */
501 Buffer buf;
502
503 /*
504 * Cache of bounds within the current buffer. Only used for insertions
505 * where _bt_check_unique is called. See _bt_binsrch_insert and
506 * _bt_findinsertloc for details.
507 */
508 bool bounds_valid;
509 OffsetNumber low;
510 OffsetNumber stricthigh;
511} BTInsertStateData;
512
513typedef BTInsertStateData *BTInsertState;
514
515/*
516 * BTScanOpaqueData is the btree-private state needed for an indexscan.
517 * This consists of preprocessed scan keys (see _bt_preprocess_keys() for
518 * details of the preprocessing), information about the current location
519 * of the scan, and information about the marked location, if any. (We use
520 * BTScanPosData to represent the data needed for each of current and marked
521 * locations.) In addition we can remember some known-killed index entries
522 * that must be marked before we can move off the current page.
523 *
524 * Index scans work a page at a time: we pin and read-lock the page, identify
525 * all the matching items on the page and save them in BTScanPosData, then
526 * release the read-lock while returning the items to the caller for
527 * processing. This approach minimizes lock/unlock traffic. Note that we
528 * keep the pin on the index page until the caller is done with all the items
529 * (this is needed for VACUUM synchronization, see nbtree/README). When we
530 * are ready to step to the next page, if the caller has told us any of the
531 * items were killed, we re-lock the page to mark them killed, then unlock.
532 * Finally we drop the pin and step to the next page in the appropriate
533 * direction.
534 *
535 * If we are doing an index-only scan, we save the entire IndexTuple for each
536 * matched item, otherwise only its heap TID and offset. The IndexTuples go
537 * into a separate workspace array; each BTScanPosItem stores its tuple's
538 * offset within that array.
539 */
540
541typedef struct BTScanPosItem /* what we remember about each match */
542{
543 ItemPointerData heapTid; /* TID of referenced heap item */
544 OffsetNumber indexOffset; /* index item's location within page */
545 LocationIndex tupleOffset; /* IndexTuple's offset in workspace, if any */
546} BTScanPosItem;
547
548typedef struct BTScanPosData
549{
550 Buffer buf; /* if valid, the buffer is pinned */
551
552 XLogRecPtr lsn; /* pos in the WAL stream when page was read */
553 BlockNumber currPage; /* page referenced by items array */
554 BlockNumber nextPage; /* page's right link when we scanned it */
555
556 /*
557 * moreLeft and moreRight track whether we think there may be matching
558 * index entries to the left and right of the current page, respectively.
559 * We can clear the appropriate one of these flags when _bt_checkkeys()
560 * returns continuescan = false.
561 */
562 bool moreLeft;
563 bool moreRight;
564
565 /*
566 * If we are doing an index-only scan, nextTupleOffset is the first free
567 * location in the associated tuple storage workspace.
568 */
569 int nextTupleOffset;
570
571 /*
572 * The items array is always ordered in index order (ie, increasing
573 * indexoffset). When scanning backwards it is convenient to fill the
574 * array back-to-front, so we start at the last slot and fill downwards.
575 * Hence we need both a first-valid-entry and a last-valid-entry counter.
576 * itemIndex is a cursor showing which entry was last returned to caller.
577 */
578 int firstItem; /* first valid index in items[] */
579 int lastItem; /* last valid index in items[] */
580 int itemIndex; /* current index in items[] */
581
582 BTScanPosItem items[MaxIndexTuplesPerPage]; /* MUST BE LAST */
583} BTScanPosData;
584
585typedef BTScanPosData *BTScanPos;
586
587#define BTScanPosIsPinned(scanpos) \
588( \
589 AssertMacro(BlockNumberIsValid((scanpos).currPage) || \
590 !BufferIsValid((scanpos).buf)), \
591 BufferIsValid((scanpos).buf) \
592)
593#define BTScanPosUnpin(scanpos) \
594 do { \
595 ReleaseBuffer((scanpos).buf); \
596 (scanpos).buf = InvalidBuffer; \
597 } while (0)
598#define BTScanPosUnpinIfPinned(scanpos) \
599 do { \
600 if (BTScanPosIsPinned(scanpos)) \
601 BTScanPosUnpin(scanpos); \
602 } while (0)
603
604#define BTScanPosIsValid(scanpos) \
605( \
606 AssertMacro(BlockNumberIsValid((scanpos).currPage) || \
607 !BufferIsValid((scanpos).buf)), \
608 BlockNumberIsValid((scanpos).currPage) \
609)
610#define BTScanPosInvalidate(scanpos) \
611 do { \
612 (scanpos).currPage = InvalidBlockNumber; \
613 (scanpos).nextPage = InvalidBlockNumber; \
614 (scanpos).buf = InvalidBuffer; \
615 (scanpos).lsn = InvalidXLogRecPtr; \
616 (scanpos).nextTupleOffset = 0; \
617 } while (0);
618
619/* We need one of these for each equality-type SK_SEARCHARRAY scan key */
620typedef struct BTArrayKeyInfo
621{
622 int scan_key; /* index of associated key in arrayKeyData */
623 int cur_elem; /* index of current element in elem_values */
624 int mark_elem; /* index of marked element in elem_values */
625 int num_elems; /* number of elems in current array value */
626 Datum *elem_values; /* array of num_elems Datums */
627} BTArrayKeyInfo;
628
629typedef struct BTScanOpaqueData
630{
631 /* these fields are set by _bt_preprocess_keys(): */
632 bool qual_ok; /* false if qual can never be satisfied */
633 int numberOfKeys; /* number of preprocessed scan keys */
634 ScanKey keyData; /* array of preprocessed scan keys */
635
636 /* workspace for SK_SEARCHARRAY support */
637 ScanKey arrayKeyData; /* modified copy of scan->keyData */
638 int numArrayKeys; /* number of equality-type array keys (-1 if
639 * there are any unsatisfiable array keys) */
640 int arrayKeyCount; /* count indicating number of array scan keys
641 * processed */
642 BTArrayKeyInfo *arrayKeys; /* info about each equality-type array key */
643 MemoryContext arrayContext; /* scan-lifespan context for array data */
644
645 /* info about killed items if any (killedItems is NULL if never used) */
646 int *killedItems; /* currPos.items indexes of killed items */
647 int numKilled; /* number of currently stored items */
648
649 /*
650 * If we are doing an index-only scan, these are the tuple storage
651 * workspaces for the currPos and markPos respectively. Each is of size
652 * BLCKSZ, so it can hold as much as a full page's worth of tuples.
653 */
654 char *currTuples; /* tuple storage for currPos */
655 char *markTuples; /* tuple storage for markPos */
656
657 /*
658 * If the marked position is on the same page as current position, we
659 * don't use markPos, but just keep the marked itemIndex in markItemIndex
660 * (all the rest of currPos is valid for the mark position). Hence, to
661 * determine if there is a mark, first look at markItemIndex, then at
662 * markPos.
663 */
664 int markItemIndex; /* itemIndex, or -1 if not valid */
665
666 /* keep these last in struct for efficiency */
667 BTScanPosData currPos; /* current position data */
668 BTScanPosData markPos; /* marked position, if any */
669} BTScanOpaqueData;
670
671typedef BTScanOpaqueData *BTScanOpaque;
672
673/*
674 * We use some private sk_flags bits in preprocessed scan keys. We're allowed
675 * to use bits 16-31 (see skey.h). The uppermost bits are copied from the
676 * index's indoption[] array entry for the index attribute.
677 */
678#define SK_BT_REQFWD 0x00010000 /* required to continue forward scan */
679#define SK_BT_REQBKWD 0x00020000 /* required to continue backward scan */
680#define SK_BT_INDOPTION_SHIFT 24 /* must clear the above bits */
681#define SK_BT_DESC (INDOPTION_DESC << SK_BT_INDOPTION_SHIFT)
682#define SK_BT_NULLS_FIRST (INDOPTION_NULLS_FIRST << SK_BT_INDOPTION_SHIFT)
683
684/*
685 * Constant definition for progress reporting. Phase numbers must match
686 * btbuildphasename.
687 */
688/* PROGRESS_CREATEIDX_SUBPHASE_INITIALIZE is 1 (see progress.h) */
689#define PROGRESS_BTREE_PHASE_INDEXBUILD_TABLESCAN 2
690#define PROGRESS_BTREE_PHASE_PERFORMSORT_1 3
691#define PROGRESS_BTREE_PHASE_PERFORMSORT_2 4
692#define PROGRESS_BTREE_PHASE_LEAF_LOAD 5
693
694/*
695 * external entry points for btree, in nbtree.c
696 */
697extern void btbuildempty(Relation index);
698extern bool btinsert(Relation rel, Datum *values, bool *isnull,
699 ItemPointer ht_ctid, Relation heapRel,
700 IndexUniqueCheck checkUnique,
701 struct IndexInfo *indexInfo);
702extern IndexScanDesc btbeginscan(Relation rel, int nkeys, int norderbys);
703extern Size btestimateparallelscan(void);
704extern void btinitparallelscan(void *target);
705extern bool btgettuple(IndexScanDesc scan, ScanDirection dir);
706extern int64 btgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
707extern void btrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
708 ScanKey orderbys, int norderbys);
709extern void btparallelrescan(IndexScanDesc scan);
710extern void btendscan(IndexScanDesc scan);
711extern void btmarkpos(IndexScanDesc scan);
712extern void btrestrpos(IndexScanDesc scan);
713extern IndexBulkDeleteResult *btbulkdelete(IndexVacuumInfo *info,
714 IndexBulkDeleteResult *stats,
715 IndexBulkDeleteCallback callback,
716 void *callback_state);
717extern IndexBulkDeleteResult *btvacuumcleanup(IndexVacuumInfo *info,
718 IndexBulkDeleteResult *stats);
719extern bool btcanreturn(Relation index, int attno);
720
721/*
722 * prototypes for internal functions in nbtree.c
723 */
724extern bool _bt_parallel_seize(IndexScanDesc scan, BlockNumber *pageno);
725extern void _bt_parallel_release(IndexScanDesc scan, BlockNumber scan_page);
726extern void _bt_parallel_done(IndexScanDesc scan);
727extern void _bt_parallel_advance_array_keys(IndexScanDesc scan);
728
729/*
730 * prototypes for functions in nbtinsert.c
731 */
732extern bool _bt_doinsert(Relation rel, IndexTuple itup,
733 IndexUniqueCheck checkUnique, Relation heapRel);
734extern Buffer _bt_getstackbuf(Relation rel, BTStack stack);
735extern void _bt_finish_split(Relation rel, Buffer bbuf, BTStack stack);
736
737/*
738 * prototypes for functions in nbtsplitloc.c
739 */
740extern OffsetNumber _bt_findsplitloc(Relation rel, Page page,
741 OffsetNumber newitemoff, Size newitemsz, IndexTuple newitem,
742 bool *newitemonleft);
743
744/*
745 * prototypes for functions in nbtpage.c
746 */
747extern void _bt_initmetapage(Page page, BlockNumber rootbknum, uint32 level);
748extern void _bt_update_meta_cleanup_info(Relation rel,
749 TransactionId oldestBtpoXact, float8 numHeapTuples);
750extern void _bt_upgrademetapage(Page page);
751extern Buffer _bt_getroot(Relation rel, int access);
752extern Buffer _bt_gettrueroot(Relation rel);
753extern int _bt_getrootheight(Relation rel);
754extern bool _bt_heapkeyspace(Relation rel);
755extern void _bt_checkpage(Relation rel, Buffer buf);
756extern Buffer _bt_getbuf(Relation rel, BlockNumber blkno, int access);
757extern Buffer _bt_relandgetbuf(Relation rel, Buffer obuf,
758 BlockNumber blkno, int access);
759extern void _bt_relbuf(Relation rel, Buffer buf);
760extern void _bt_pageinit(Page page, Size size);
761extern bool _bt_page_recyclable(Page page);
762extern void _bt_delitems_delete(Relation rel, Buffer buf,
763 OffsetNumber *itemnos, int nitems, Relation heapRel);
764extern void _bt_delitems_vacuum(Relation rel, Buffer buf,
765 OffsetNumber *itemnos, int nitems,
766 BlockNumber lastBlockVacuumed);
767extern int _bt_pagedel(Relation rel, Buffer buf);
768
769/*
770 * prototypes for functions in nbtsearch.c
771 */
772extern BTStack _bt_search(Relation rel, BTScanInsert key, Buffer *bufP,
773 int access, Snapshot snapshot);
774extern Buffer _bt_moveright(Relation rel, BTScanInsert key, Buffer buf,
775 bool forupdate, BTStack stack, int access, Snapshot snapshot);
776extern OffsetNumber _bt_binsrch_insert(Relation rel, BTInsertState insertstate);
777extern int32 _bt_compare(Relation rel, BTScanInsert key, Page page, OffsetNumber offnum);
778extern bool _bt_first(IndexScanDesc scan, ScanDirection dir);
779extern bool _bt_next(IndexScanDesc scan, ScanDirection dir);
780extern Buffer _bt_get_endpoint(Relation rel, uint32 level, bool rightmost,
781 Snapshot snapshot);
782
783/*
784 * prototypes for functions in nbtutils.c
785 */
786extern BTScanInsert _bt_mkscankey(Relation rel, IndexTuple itup);
787extern void _bt_freestack(BTStack stack);
788extern void _bt_preprocess_array_keys(IndexScanDesc scan);
789extern void _bt_start_array_keys(IndexScanDesc scan, ScanDirection dir);
790extern bool _bt_advance_array_keys(IndexScanDesc scan, ScanDirection dir);
791extern void _bt_mark_array_keys(IndexScanDesc scan);
792extern void _bt_restore_array_keys(IndexScanDesc scan);
793extern void _bt_preprocess_keys(IndexScanDesc scan);
794extern bool _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
795 int tupnatts, ScanDirection dir, bool *continuescan);
796extern void _bt_killitems(IndexScanDesc scan);
797extern BTCycleId _bt_vacuum_cycleid(Relation rel);
798extern BTCycleId _bt_start_vacuum(Relation rel);
799extern void _bt_end_vacuum(Relation rel);
800extern void _bt_end_vacuum_callback(int code, Datum arg);
801extern Size BTreeShmemSize(void);
802extern void BTreeShmemInit(void);
803extern bytea *btoptions(Datum reloptions, bool validate);
804extern bool btproperty(Oid index_oid, int attno,
805 IndexAMProperty prop, const char *propname,
806 bool *res, bool *isnull);
807extern char *btbuildphasename(int64 phasenum);
808extern IndexTuple _bt_truncate(Relation rel, IndexTuple lastleft,
809 IndexTuple firstright, BTScanInsert itup_key);
810extern int _bt_keep_natts_fast(Relation rel, IndexTuple lastleft,
811 IndexTuple firstright);
812extern bool _bt_check_natts(Relation rel, bool heapkeyspace, Page page,
813 OffsetNumber offnum);
814extern void _bt_check_third_page(Relation rel, Relation heap,
815 bool needheaptidspace, Page page, IndexTuple newtup);
816
817/*
818 * prototypes for functions in nbtvalidate.c
819 */
820extern bool btvalidate(Oid opclassoid);
821
822/*
823 * prototypes for functions in nbtsort.c
824 */
825extern IndexBuildResult *btbuild(Relation heap, Relation index,
826 struct IndexInfo *indexInfo);
827extern void _bt_parallel_build_main(dsm_segment *seg, shm_toc *toc);
828
829#endif /* NBTREE_H */
830