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postgresql/src/include/access/gist_private.h

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/*-------------------------------------------------------------------------
*
* gist_private.h
* private declarations for GiST -- declarations related to the
* internal implementation of GiST, not the public API
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/gist_private.h
*
*-------------------------------------------------------------------------
*/
#ifndef GIST_PRIVATE_H
#define GIST_PRIVATE_H
#include "access/amapi.h"
#include "access/gist.h"
#include "access/itup.h"
#include "lib/pairingheap.h"
#include "storage/bufmgr.h"
#include "storage/buffile.h"
#include "utils/hsearch.h"
#include "access/genam.h"
/*
* Maximum number of "halves" a page can be split into in one operation.
* Typically a split produces 2 halves, but can be more if keys have very
* different lengths, or when inserting multiple keys in one operation (as
* when inserting downlinks to an internal node). There is no theoretical
* limit on this, but in practice if you get more than a handful page halves
* in one split, there's something wrong with the opclass implementation.
* GIST_MAX_SPLIT_PAGES is an arbitrary limit on that, used to size some
* local arrays used during split. Note that there is also a limit on the
* number of buffers that can be held locked at a time, MAX_SIMUL_LWLOCKS,
* so if you raise this higher than that limit, you'll just get a different
* error.
*/
#define GIST_MAX_SPLIT_PAGES 75
/* Buffer lock modes */
#define GIST_SHARE BUFFER_LOCK_SHARE
#define GIST_EXCLUSIVE BUFFER_LOCK_EXCLUSIVE
#define GIST_UNLOCK BUFFER_LOCK_UNLOCK
typedef struct
{
BlockNumber prev;
uint32 freespace;
char tupledata[FLEXIBLE_ARRAY_MEMBER];
} GISTNodeBufferPage;
#define BUFFER_PAGE_DATA_OFFSET MAXALIGN(offsetof(GISTNodeBufferPage, tupledata))
/* Returns free space in node buffer page */
#define PAGE_FREE_SPACE(nbp) (nbp->freespace)
/* Checks if node buffer page is empty */
#define PAGE_IS_EMPTY(nbp) (nbp->freespace == BLCKSZ - BUFFER_PAGE_DATA_OFFSET)
/* Checks if node buffers page don't contain sufficient space for index tuple */
#define PAGE_NO_SPACE(nbp, itup) (PAGE_FREE_SPACE(nbp) < \
MAXALIGN(IndexTupleSize(itup)))
/*
* GISTSTATE: information needed for any GiST index operation
*
* This struct retains call info for the index's opclass-specific support
* functions (per index column), plus the index's tuple descriptor.
*
* scanCxt holds the GISTSTATE itself as well as any data that lives for the
* lifetime of the index operation. We pass this to the support functions
* via fn_mcxt, so that they can store scan-lifespan data in it. The
* functions are invoked in tempCxt, which is typically short-lifespan
* (that is, it's reset after each tuple). However, tempCxt can be the same
* as scanCxt if we're not bothering with per-tuple context resets.
*/
typedef struct GISTSTATE
{
MemoryContext scanCxt; /* context for scan-lifespan data */
MemoryContext tempCxt; /* short-term context for calling functions */
TupleDesc leafTupdesc; /* index's tuple descriptor */
TupleDesc nonLeafTupdesc; /* truncated tuple descriptor for non-leaf
* pages */
TupleDesc fetchTupdesc; /* tuple descriptor for tuples returned in an
* index-only scan */
FmgrInfo consistentFn[INDEX_MAX_KEYS];
FmgrInfo unionFn[INDEX_MAX_KEYS];
FmgrInfo compressFn[INDEX_MAX_KEYS];
FmgrInfo decompressFn[INDEX_MAX_KEYS];
FmgrInfo penaltyFn[INDEX_MAX_KEYS];
FmgrInfo picksplitFn[INDEX_MAX_KEYS];
FmgrInfo equalFn[INDEX_MAX_KEYS];
FmgrInfo distanceFn[INDEX_MAX_KEYS];
FmgrInfo fetchFn[INDEX_MAX_KEYS];
/* Collations to pass to the support functions */
Oid supportCollation[INDEX_MAX_KEYS];
} GISTSTATE;
/*
* During a GiST index search, we must maintain a queue of unvisited items,
* which can be either individual heap tuples or whole index pages. If it
* is an ordered search, the unvisited items should be visited in distance
* order. Unvisited items at the same distance should be visited in
* depth-first order, that is heap items first, then lower index pages, then
* upper index pages; this rule avoids doing extra work during a search that
* ends early due to LIMIT.
*
* To perform an ordered search, we use a pairing heap to manage the
* distance-order queue. In a non-ordered search (no order-by operators),
* we use it to return heap tuples before unvisited index pages, to
* ensure depth-first order, but all entries are otherwise considered
* equal.
*/
/* Individual heap tuple to be visited */
typedef struct GISTSearchHeapItem
{
ItemPointerData heapPtr;
bool recheck; /* T if quals must be rechecked */
bool recheckDistances; /* T if distances must be rechecked */
HeapTuple recontup; /* data reconstructed from the index, used in
* index-only scans */
OffsetNumber offnum; /* track offset in page to mark tuple as
* LP_DEAD */
} GISTSearchHeapItem;
/* Unvisited item, either index page or heap tuple */
typedef struct GISTSearchItem
{
pairingheap_node phNode;
BlockNumber blkno; /* index page number, or InvalidBlockNumber */
union
{
GistNSN parentlsn; /* parent page's LSN, if index page */
/* we must store parentlsn to detect whether a split occurred */
GISTSearchHeapItem heap; /* heap info, if heap tuple */
} data;
/* numberOfOrderBys entries */
IndexOrderByDistance distances[FLEXIBLE_ARRAY_MEMBER];
} GISTSearchItem;
#define GISTSearchItemIsHeap(item) ((item).blkno == InvalidBlockNumber)
#define SizeOfGISTSearchItem(n_distances) \
(offsetof(GISTSearchItem, distances) + \
sizeof(IndexOrderByDistance) * (n_distances))
/*
* GISTScanOpaqueData: private state for a scan of a GiST index
*/
typedef struct GISTScanOpaqueData
{
GISTSTATE *giststate; /* index information, see above */
Oid *orderByTypes; /* datatypes of ORDER BY expressions */
pairingheap *queue; /* queue of unvisited items */
MemoryContext queueCxt; /* context holding the queue */
bool qual_ok; /* false if qual can never be satisfied */
bool firstCall; /* true until first gistgettuple call */
/* pre-allocated workspace arrays */
IndexOrderByDistance *distances; /* output area for gistindex_keytest */
/* info about killed items if any (killedItems is NULL if never used) */
OffsetNumber *killedItems; /* offset numbers of killed items */
int numKilled; /* number of currently stored items */
BlockNumber curBlkno; /* current number of block */
GistNSN curPageLSN; /* pos in the WAL stream when page was read */
/* In a non-ordered search, returnable heap items are stored here: */
GISTSearchHeapItem pageData[BLCKSZ / sizeof(IndexTupleData)];
OffsetNumber nPageData; /* number of valid items in array */
OffsetNumber curPageData; /* next item to return */
MemoryContext pageDataCxt; /* context holding the fetched tuples, for
* index-only scans */
} GISTScanOpaqueData;
typedef GISTScanOpaqueData *GISTScanOpaque;
/* despite the name, gistxlogPage is not part of any xlog record */
typedef struct gistxlogPage
{
BlockNumber blkno;
int num; /* number of index tuples following */
} gistxlogPage;
/* SplitedPageLayout - gistSplit function result */
typedef struct SplitedPageLayout
{
gistxlogPage block;
IndexTupleData *list;
int lenlist;
IndexTuple itup; /* union key for page */
Page page; /* to operate */
Buffer buffer; /* to write after all proceed */
struct SplitedPageLayout *next;
} SplitedPageLayout;
/*
* GISTInsertStack used for locking buffers and transfer arguments during
* insertion
*/
typedef struct GISTInsertStack
{
/* current page */
BlockNumber blkno;
Buffer buffer;
Page page;
/*
* log sequence number from page->lsn to recognize page update and compare
* it with page's nsn to recognize page split
*/
GistNSN lsn;
/*
* If set, we split the page while descending the tree to find an
* insertion target. It means that we need to retry from the parent,
* because the downlink of this page might no longer cover the new key.
*/
bool retry_from_parent;
/* offset of the downlink in the parent page, that points to this page */
OffsetNumber downlinkoffnum;
/* pointer to parent */
struct GISTInsertStack *parent;
} GISTInsertStack;
/* Working state and results for multi-column split logic in gistsplit.c */
typedef struct GistSplitVector
{
GIST_SPLITVEC splitVector; /* passed to/from user PickSplit method */
Datum spl_lattr[INDEX_MAX_KEYS]; /* Union of subkeys in
* splitVector.spl_left */
bool spl_lisnull[INDEX_MAX_KEYS];
Datum spl_rattr[INDEX_MAX_KEYS]; /* Union of subkeys in
* splitVector.spl_right */
bool spl_risnull[INDEX_MAX_KEYS];
bool *spl_dontcare; /* flags tuples which could go to either side
* of the split for zero penalty */
} GistSplitVector;
typedef struct
{
Relation r;
Relation heapRel;
Size freespace; /* free space to be left */
bool is_build;
GISTInsertStack *stack;
} GISTInsertState;
/* root page of a gist index */
#define GIST_ROOT_BLKNO 0
/*
* Before PostgreSQL 9.1, we used to rely on so-called "invalid tuples" on
* inner pages to finish crash recovery of incomplete page splits. If a crash
* happened in the middle of a page split, so that the downlink pointers were
* not yet inserted, crash recovery inserted a special downlink pointer. The
* semantics of an invalid tuple was that it if you encounter one in a scan,
* it must always be followed, because we don't know if the tuples on the
* child page match or not.
*
* We no longer create such invalid tuples, we now mark the left-half of such
* an incomplete split with the F_FOLLOW_RIGHT flag instead, and finish the
* split properly the next time we need to insert on that page. To retain
* on-disk compatibility for the sake of pg_upgrade, we still store 0xffff as
* the offset number of all inner tuples. If we encounter any invalid tuples
* with 0xfffe during insertion, we throw an error, though scans still handle
* them. You should only encounter invalid tuples if you pg_upgrade a pre-9.1
* gist index which already has invalid tuples in it because of a crash. That
* should be rare, and you are recommended to REINDEX anyway if you have any
* invalid tuples in an index, so throwing an error is as far as we go with
* supporting that.
*/
#define TUPLE_IS_VALID 0xffff
#define TUPLE_IS_INVALID 0xfffe
#define GistTupleIsInvalid(itup) ( ItemPointerGetOffsetNumber( &((itup)->t_tid) ) == TUPLE_IS_INVALID )
#define GistTupleSetValid(itup) ItemPointerSetOffsetNumber( &((itup)->t_tid), TUPLE_IS_VALID )
/*
* A buffer attached to an internal node, used when building an index in
* buffering mode.
*/
typedef struct
{
BlockNumber nodeBlocknum; /* index block # this buffer is for */
int32 blocksCount; /* current # of blocks occupied by buffer */
BlockNumber pageBlocknum; /* temporary file block # */
GISTNodeBufferPage *pageBuffer; /* in-memory buffer page */
/* is this buffer queued for emptying? */
bool queuedForEmptying;
/* is this a temporary copy, not in the hash table? */
bool isTemp;
int level; /* 0 == leaf */
} GISTNodeBuffer;
/*
* Does specified level have buffers? (Beware of multiple evaluation of
* arguments.)
*/
#define LEVEL_HAS_BUFFERS(nlevel, gfbb) \
((nlevel) != 0 && (nlevel) % (gfbb)->levelStep == 0 && \
(nlevel) != (gfbb)->rootlevel)
/* Is specified buffer at least half-filled (should be queued for emptying)? */
#define BUFFER_HALF_FILLED(nodeBuffer, gfbb) \
((nodeBuffer)->blocksCount > (gfbb)->pagesPerBuffer / 2)
/*
* Is specified buffer full? Our buffers can actually grow indefinitely,
* beyond the "maximum" size, so this just means whether the buffer has grown
* beyond the nominal maximum size.
*/
#define BUFFER_OVERFLOWED(nodeBuffer, gfbb) \
((nodeBuffer)->blocksCount > (gfbb)->pagesPerBuffer)
/*
* Data structure with general information about build buffers.
*/
typedef struct GISTBuildBuffers
{
/* Persistent memory context for the buffers and metadata. */
MemoryContext context;
BufFile *pfile; /* Temporary file to store buffers in */
long nFileBlocks; /* Current size of the temporary file */
/*
* resizable array of free blocks.
*/
long *freeBlocks;
int nFreeBlocks; /* # of currently free blocks in the array */
int freeBlocksLen; /* current allocated length of the array */
/* Hash for buffers by block number */
HTAB *nodeBuffersTab;
/* List of buffers scheduled for emptying */
List *bufferEmptyingQueue;
/*
* Parameters to the buffering build algorithm. levelStep determines which
* levels in the tree have buffers, and pagesPerBuffer determines how
* large each buffer is.
*/
int levelStep;
int pagesPerBuffer;
/* Array of lists of buffers on each level, for final emptying */
List **buffersOnLevels;
int buffersOnLevelsLen;
/*
* Dynamically-sized array of buffers that currently have their last page
* loaded in main memory.
*/
GISTNodeBuffer **loadedBuffers;
int loadedBuffersCount; /* # of entries in loadedBuffers */
int loadedBuffersLen; /* allocated size of loadedBuffers */
/* Level of the current root node (= height of the index tree - 1) */
int rootlevel;
} GISTBuildBuffers;
/* GiSTOptions->buffering_mode values */
typedef enum GistOptBufferingMode
{
GIST_OPTION_BUFFERING_AUTO,
GIST_OPTION_BUFFERING_ON,
GIST_OPTION_BUFFERING_OFF
} GistOptBufferingMode;
/*
* Storage type for GiST's reloptions
*/
typedef struct GiSTOptions
{
int32 vl_len_; /* varlena header (do not touch directly!) */
int fillfactor; /* page fill factor in percent (0..100) */
GistOptBufferingMode buffering_mode; /* buffering build mode */
} GiSTOptions;
/* gist.c */
extern void gistbuildempty(Relation index);
extern bool gistinsert(Relation r, Datum *values, bool *isnull,
ItemPointer ht_ctid, Relation heapRel,
IndexUniqueCheck checkUnique,
bool indexUnchanged,
struct IndexInfo *indexInfo);
extern MemoryContext createTempGistContext(void);
extern GISTSTATE *initGISTstate(Relation index);
extern void freeGISTstate(GISTSTATE *giststate);
extern void gistdoinsert(Relation r,
IndexTuple itup,
Size freespace,
GISTSTATE *giststate,
Relation heapRel,
bool is_build);
/* A List of these is returned from gistplacetopage() in *splitinfo */
typedef struct
{
Buffer buf; /* the split page "half" */
IndexTuple downlink; /* downlink for this half. */
} GISTPageSplitInfo;
extern bool gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
Buffer buffer,
IndexTuple *itup, int ntup,
OffsetNumber oldoffnum, BlockNumber *newblkno,
Buffer leftchildbuf,
List **splitinfo,
bool markfollowright,
Relation heapRel,
bool is_build);
extern SplitedPageLayout *gistSplit(Relation r, Page page, IndexTuple *itup,
int len, GISTSTATE *giststate);
/* gistxlog.c */
extern XLogRecPtr gistXLogPageDelete(Buffer buffer,
FullTransactionId xid, Buffer parentBuffer,
OffsetNumber downlinkOffset);
extern void gistXLogPageReuse(Relation rel, Relation heaprel, BlockNumber blkno,
FullTransactionId deleteXid);
extern XLogRecPtr gistXLogUpdate(Buffer buffer,
OffsetNumber *todelete, int ntodelete,
IndexTuple *itup, int ituplen,
Buffer leftchildbuf);
extern XLogRecPtr gistXLogDelete(Buffer buffer, OffsetNumber *todelete,
int ntodelete, TransactionId snapshotConflictHorizon,
Relation heaprel);
extern XLogRecPtr gistXLogSplit(bool page_is_leaf,
SplitedPageLayout *dist,
BlockNumber origrlink, GistNSN orignsn,
Buffer leftchildbuf, bool markfollowright);
extern XLogRecPtr gistXLogAssignLSN(void);
/* gistget.c */
extern bool gistgettuple(IndexScanDesc scan, ScanDirection dir);
extern int64 gistgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
extern bool gistcanreturn(Relation index, int attno);
/* gistvalidate.c */
extern bool gistvalidate(Oid opclassoid);
extern void gistadjustmembers(Oid opfamilyoid,
Oid opclassoid,
List *operators,
List *functions);
/* gistutil.c */
#define GiSTPageSize \
( BLCKSZ - SizeOfPageHeaderData - MAXALIGN(sizeof(GISTPageOpaqueData)) )
#define GIST_MIN_FILLFACTOR 10
#define GIST_DEFAULT_FILLFACTOR 90
extern bytea *gistoptions(Datum reloptions, bool validate);
extern bool gistproperty(Oid index_oid, int attno,
IndexAMProperty prop, const char *propname,
bool *res, bool *isnull);
extern bool gistfitpage(IndexTuple *itvec, int len);
extern bool gistnospace(Page page, IndexTuple *itvec, int len, OffsetNumber todelete, Size freespace);
extern void gistcheckpage(Relation rel, Buffer buf);
extern Buffer gistNewBuffer(Relation r, Relation heaprel);
extern bool gistPageRecyclable(Page page);
extern void gistfillbuffer(Page page, IndexTuple *itup, int len,
OffsetNumber off);
extern IndexTuple *gistextractpage(Page page, int *len /* out */ );
extern IndexTuple *gistjoinvector(IndexTuple *itvec, int *len,
IndexTuple *additvec, int addlen);
extern IndexTupleData *gistfillitupvec(IndexTuple *vec, int veclen, int *memlen);
extern IndexTuple gistunion(Relation r, IndexTuple *itvec,
int len, GISTSTATE *giststate);
extern IndexTuple gistgetadjusted(Relation r,
IndexTuple oldtup,
IndexTuple addtup,
GISTSTATE *giststate);
extern IndexTuple gistFormTuple(GISTSTATE *giststate,
Relation r, Datum *attdata, bool *isnull, bool isleaf);
extern void gistCompressValues(GISTSTATE *giststate, Relation r,
Datum *attdata, bool *isnull, bool isleaf, Datum *compatt);
extern OffsetNumber gistchoose(Relation r, Page p,
IndexTuple it,
GISTSTATE *giststate);
extern void GISTInitBuffer(Buffer b, uint32 f);
extern void gistinitpage(Page page, uint32 f);
extern void gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e,
Datum k, Relation r, Page pg, OffsetNumber o,
bool l, bool isNull);
extern float gistpenalty(GISTSTATE *giststate, int attno,
GISTENTRY *orig, bool isNullOrig,
GISTENTRY *add, bool isNullAdd);
extern void gistMakeUnionItVec(GISTSTATE *giststate, IndexTuple *itvec, int len,
Datum *attr, bool *isnull);
extern bool gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b);
extern void gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p,
OffsetNumber o, GISTENTRY *attdata, bool *isnull);
extern HeapTuple gistFetchTuple(GISTSTATE *giststate, Relation r,
IndexTuple tuple);
extern void gistMakeUnionKey(GISTSTATE *giststate, int attno,
GISTENTRY *entry1, bool isnull1,
GISTENTRY *entry2, bool isnull2,
Datum *dst, bool *dstisnull);
extern XLogRecPtr gistGetFakeLSN(Relation rel);
/* gistvacuum.c */
extern IndexBulkDeleteResult *gistbulkdelete(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats,
IndexBulkDeleteCallback callback,
void *callback_state);
extern IndexBulkDeleteResult *gistvacuumcleanup(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats);
/* gistsplit.c */
extern void gistSplitByKey(Relation r, Page page, IndexTuple *itup,
int len, GISTSTATE *giststate,
GistSplitVector *v,
int attno);
/* gistbuild.c */
extern IndexBuildResult *gistbuild(Relation heap, Relation index,
struct IndexInfo *indexInfo);
/* gistbuildbuffers.c */
extern GISTBuildBuffers *gistInitBuildBuffers(int pagesPerBuffer, int levelStep,
int maxLevel);
extern GISTNodeBuffer *gistGetNodeBuffer(GISTBuildBuffers *gfbb,
GISTSTATE *giststate,
BlockNumber nodeBlocknum, int level);
extern void gistPushItupToNodeBuffer(GISTBuildBuffers *gfbb,
GISTNodeBuffer *nodeBuffer, IndexTuple itup);
extern bool gistPopItupFromNodeBuffer(GISTBuildBuffers *gfbb,
GISTNodeBuffer *nodeBuffer, IndexTuple *itup);
extern void gistFreeBuildBuffers(GISTBuildBuffers *gfbb);
extern void gistRelocateBuildBuffersOnSplit(GISTBuildBuffers *gfbb,
GISTSTATE *giststate, Relation r,
int level, Buffer buffer,
List *splitinfo);
extern void gistUnloadNodeBuffers(GISTBuildBuffers *gfbb);
#endif /* GIST_PRIVATE_H */
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