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cleanup stage to finish incomplete inserts or splits anymore. There was two reasons for the cleanup step: 1. When a new tuple was inserted to a leaf page, the downlink in the parent needed to be updated to contain (ie. to be consistent with) the new key. Updating the parent in turn might require recursively updating the parent of the parent. We now handle that by updating the parent while traversing down the tree, so that when we insert the leaf tuple, all the parents are already consistent with the new key, and the tree is consistent at every step. 2. When a page is split, we need to insert the downlink for the new right page(s), and update the downlink for the original page to not include keys that moved to the right page(s). We now handle that by setting a new flag, F_FOLLOW_RIGHT, on the non-rightmost pages in the split. When that flag is set, scans always follow the rightlink, regardless of the NSN mechanism used to detect concurrent page splits. That way the tree is consistent right after split, even though the downlink is still missing. This is very similar to the way B-tree splits are handled. When the downlink is inserted in the parent, the flag is cleared. To keep the insertion algorithm simple, when an insertion sees an incomplete split, indicated by the F_FOLLOW_RIGHT flag, it finishes the split before doing anything else. These changes allow removing the whole "invalid tuple" mechanism, but I retained the scan code to still follow invalid tuples correctly. While we don't create any such tuples anymore, we want to handle them gracefully in case you pg_upgrade a GiST index that has them. If we encounter any on an insert, though, we just throw an error saying that you need to REINDEX. The issue that got me into doing this is that if you did a checkpoint while an insert or split was in progress, and the checkpoint finishes quickly so that there is no WAL record related to the insert between RedoRecPtr and the checkpoint record, recovery from that checkpoint would not know to finish the incomplete insert. IOW, we have the same issue we solved with the rm_safe_restartpoint mechanism during normal operation too. It's highly unlikely to happen in practice, and this fix is far too large to backpatch, so we're just going to live with in previous versions, but this refactoring fixes it going forward. With this patch, you don't get the annoying 'index "FOO" needs VACUUM or REINDEX to finish crash recovery' notices anymore if you crash at an unfortunate moment.
385 lines
13 KiB
C
385 lines
13 KiB
C
/*-------------------------------------------------------------------------
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*
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* gist_private.h
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* private declarations for GiST -- declarations related to the
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* internal implementation of GiST, not the public API
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*
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/gist_private.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef GIST_PRIVATE_H
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#define GIST_PRIVATE_H
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#include "access/gist.h"
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#include "access/itup.h"
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#include "storage/bufmgr.h"
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#include "utils/rbtree.h"
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/* Buffer lock modes */
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#define GIST_SHARE BUFFER_LOCK_SHARE
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#define GIST_EXCLUSIVE BUFFER_LOCK_EXCLUSIVE
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#define GIST_UNLOCK BUFFER_LOCK_UNLOCK
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/*
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* GISTSTATE: information needed for any GiST index operation
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*
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* This struct retains call info for the index's opclass-specific support
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* functions (per index column), plus the index's tuple descriptor.
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*/
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typedef struct GISTSTATE
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{
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FmgrInfo consistentFn[INDEX_MAX_KEYS];
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FmgrInfo unionFn[INDEX_MAX_KEYS];
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FmgrInfo compressFn[INDEX_MAX_KEYS];
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FmgrInfo decompressFn[INDEX_MAX_KEYS];
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FmgrInfo penaltyFn[INDEX_MAX_KEYS];
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FmgrInfo picksplitFn[INDEX_MAX_KEYS];
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FmgrInfo equalFn[INDEX_MAX_KEYS];
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FmgrInfo distanceFn[INDEX_MAX_KEYS];
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TupleDesc tupdesc;
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} GISTSTATE;
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/*
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* During a GiST index search, we must maintain a queue of unvisited items,
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* which can be either individual heap tuples or whole index pages. If it
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* is an ordered search, the unvisited items should be visited in distance
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* order. Unvisited items at the same distance should be visited in
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* depth-first order, that is heap items first, then lower index pages, then
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* upper index pages; this rule avoids doing extra work during a search that
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* ends early due to LIMIT.
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*
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* To perform an ordered search, we use an RBTree to manage the distance-order
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* queue. Each GISTSearchTreeItem stores all unvisited items of the same
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* distance; they are GISTSearchItems chained together via their next fields.
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*
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* In a non-ordered search (no order-by operators), the RBTree degenerates
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* to a single item, which we use as a queue of unvisited index pages only.
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* In this case matched heap items from the current index leaf page are
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* remembered in GISTScanOpaqueData.pageData[] and returned directly from
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* there, instead of building a separate GISTSearchItem for each one.
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*/
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/* Individual heap tuple to be visited */
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typedef struct GISTSearchHeapItem
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{
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ItemPointerData heapPtr;
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bool recheck; /* T if quals must be rechecked */
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} GISTSearchHeapItem;
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/* Unvisited item, either index page or heap tuple */
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typedef struct GISTSearchItem
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{
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struct GISTSearchItem *next; /* list link */
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BlockNumber blkno; /* index page number, or InvalidBlockNumber */
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union
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{
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GistNSN parentlsn; /* parent page's LSN, if index page */
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/* we must store parentlsn to detect whether a split occurred */
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GISTSearchHeapItem heap; /* heap info, if heap tuple */
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} data;
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} GISTSearchItem;
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#define GISTSearchItemIsHeap(item) ((item).blkno == InvalidBlockNumber)
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/*
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* Within a GISTSearchTreeItem's chain, heap items always appear before
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* index-page items, since we want to visit heap items first. lastHeap points
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* to the last heap item in the chain, or is NULL if there are none.
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*/
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typedef struct GISTSearchTreeItem
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{
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RBNode rbnode; /* this is an RBTree item */
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GISTSearchItem *head; /* first chain member */
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GISTSearchItem *lastHeap; /* last heap-tuple member, if any */
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double distances[1]; /* array with numberOfOrderBys entries */
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} GISTSearchTreeItem;
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#define GSTIHDRSZ offsetof(GISTSearchTreeItem, distances)
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/*
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* GISTScanOpaqueData: private state for a scan of a GiST index
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*/
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typedef struct GISTScanOpaqueData
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{
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GISTSTATE *giststate; /* index information, see above */
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RBTree *queue; /* queue of unvisited items */
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MemoryContext queueCxt; /* context holding the queue */
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MemoryContext tempCxt; /* workspace context for calling functions */
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bool qual_ok; /* false if qual can never be satisfied */
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bool firstCall; /* true until first gistgettuple call */
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GISTSearchTreeItem *curTreeItem; /* current queue item, if any */
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/* pre-allocated workspace arrays */
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GISTSearchTreeItem *tmpTreeItem; /* workspace to pass to rb_insert */
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double *distances; /* output area for gistindex_keytest */
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/* In a non-ordered search, returnable heap items are stored here: */
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GISTSearchHeapItem pageData[BLCKSZ / sizeof(IndexTupleData)];
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OffsetNumber nPageData; /* number of valid items in array */
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OffsetNumber curPageData; /* next item to return */
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} GISTScanOpaqueData;
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typedef GISTScanOpaqueData *GISTScanOpaque;
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/* XLog stuff */
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#define XLOG_GIST_PAGE_UPDATE 0x00
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/* #define XLOG_GIST_NEW_ROOT 0x20 */ /* not used anymore */
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#define XLOG_GIST_PAGE_SPLIT 0x30
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/* #define XLOG_GIST_INSERT_COMPLETE 0x40 */ /* not used anymore */
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#define XLOG_GIST_CREATE_INDEX 0x50
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#define XLOG_GIST_PAGE_DELETE 0x60
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typedef struct gistxlogPageUpdate
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{
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RelFileNode node;
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BlockNumber blkno;
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/*
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* If this operation completes a page split, by inserting a downlink for
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* the split page, leftchild points to the left half of the split.
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*/
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BlockNumber leftchild;
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/* number of deleted offsets */
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uint16 ntodelete;
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/*
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* follow: 1. todelete OffsetNumbers 2. tuples to insert
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*/
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} gistxlogPageUpdate;
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typedef struct gistxlogPageSplit
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{
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RelFileNode node;
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BlockNumber origblkno; /* splitted page */
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BlockNumber origrlink; /* rightlink of the page before split */
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GistNSN orignsn; /* NSN of the page before split */
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bool origleaf; /* was splitted page a leaf page? */
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BlockNumber leftchild; /* like in gistxlogPageUpdate */
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uint16 npage; /* # of pages in the split */
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/*
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* follow: 1. gistxlogPage and array of IndexTupleData per page
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*/
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} gistxlogPageSplit;
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typedef struct gistxlogPage
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{
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BlockNumber blkno;
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int num; /* number of index tuples following */
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} gistxlogPage;
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typedef struct gistxlogPageDelete
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{
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RelFileNode node;
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BlockNumber blkno;
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} gistxlogPageDelete;
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/* SplitedPageLayout - gistSplit function result */
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typedef struct SplitedPageLayout
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{
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gistxlogPage block;
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IndexTupleData *list;
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int lenlist;
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IndexTuple itup; /* union key for page */
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Page page; /* to operate */
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Buffer buffer; /* to write after all proceed */
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struct SplitedPageLayout *next;
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} SplitedPageLayout;
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/*
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* GISTInsertStack used for locking buffers and transfer arguments during
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* insertion
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*/
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typedef struct GISTInsertStack
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{
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/* current page */
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BlockNumber blkno;
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Buffer buffer;
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Page page;
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/*
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* log sequence number from page->lsn to recognize page update and
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* compare it with page's nsn to recognize page split
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*/
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GistNSN lsn;
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/* child's offset */
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OffsetNumber childoffnum;
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/* pointer to parent */
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struct GISTInsertStack *parent;
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/* for gistFindPath */
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struct GISTInsertStack *next;
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} GISTInsertStack;
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typedef struct GistSplitVector
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{
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GIST_SPLITVEC splitVector; /* to/from PickSplit method */
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Datum spl_lattr[INDEX_MAX_KEYS]; /* Union of subkeys in
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* spl_left */
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bool spl_lisnull[INDEX_MAX_KEYS];
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Datum spl_rattr[INDEX_MAX_KEYS]; /* Union of subkeys in
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* spl_right */
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bool spl_risnull[INDEX_MAX_KEYS];
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bool *spl_equiv; /* equivalent tuples which can be freely
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* distributed between left and right pages */
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} GistSplitVector;
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typedef struct
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{
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Relation r;
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Size freespace; /* free space to be left */
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GISTInsertStack *stack;
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} GISTInsertState;
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/* root page of a gist index */
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#define GIST_ROOT_BLKNO 0
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/*
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* Before PostgreSQL 9.1, we used rely on so-called "invalid tuples" on inner
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* pages to finish crash recovery of incomplete page splits. If a crash
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* happened in the middle of a page split, so that the downlink pointers were
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* not yet inserted, crash recovery inserted a special downlink pointer. The
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* semantics of an invalid tuple was that it if you encounter one in a scan,
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* it must always be followed, because we don't know if the tuples on the
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* child page match or not.
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*
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* We no longer create such invalid tuples, we now mark the left-half of such
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* an incomplete split with the F_FOLLOW_RIGHT flag instead, and finish the
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* split properly the next time we need to insert on that page. To retain
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* on-disk compatibility for the sake of pg_upgrade, we still store 0xffff as
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* the offset number of all inner tuples. If we encounter any invalid tuples
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* with 0xfffe during insertion, we throw an error, though scans still handle
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* them. You should only encounter invalid tuples if you pg_upgrade a pre-9.1
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* gist index which already has invalid tuples in it because of a crash. That
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* should be rare, and you are recommended to REINDEX anyway if you have any
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* invalid tuples in an index, so throwing an error is as far as we go with
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* supporting that.
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*/
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#define TUPLE_IS_VALID 0xffff
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#define TUPLE_IS_INVALID 0xfffe
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#define GistTupleIsInvalid(itup) ( ItemPointerGetOffsetNumber( &((itup)->t_tid) ) == TUPLE_IS_INVALID )
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#define GistTupleSetValid(itup) ItemPointerSetOffsetNumber( &((itup)->t_tid), TUPLE_IS_VALID )
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/* gist.c */
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extern Datum gistbuild(PG_FUNCTION_ARGS);
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extern Datum gistinsert(PG_FUNCTION_ARGS);
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extern MemoryContext createTempGistContext(void);
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extern void initGISTstate(GISTSTATE *giststate, Relation index);
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extern void freeGISTstate(GISTSTATE *giststate);
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extern SplitedPageLayout *gistSplit(Relation r, Page page, IndexTuple *itup,
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int len, GISTSTATE *giststate);
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extern GISTInsertStack *gistFindPath(Relation r, BlockNumber child);
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/* gistxlog.c */
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extern void gist_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void gist_desc(StringInfo buf, uint8 xl_info, char *rec);
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extern void gist_xlog_startup(void);
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extern void gist_xlog_cleanup(void);
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extern XLogRecPtr gistXLogUpdate(RelFileNode node, Buffer buffer,
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OffsetNumber *todelete, int ntodelete,
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IndexTuple *itup, int ntup,
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Buffer leftchild);
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extern XLogRecPtr gistXLogSplit(RelFileNode node,
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BlockNumber blkno, bool page_is_leaf,
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SplitedPageLayout *dist,
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BlockNumber origrlink, GistNSN oldnsn,
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Buffer leftchild);
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/* gistget.c */
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extern Datum gistgettuple(PG_FUNCTION_ARGS);
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extern Datum gistgetbitmap(PG_FUNCTION_ARGS);
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/* gistutil.c */
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#define GiSTPageSize \
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( BLCKSZ - SizeOfPageHeaderData - MAXALIGN(sizeof(GISTPageOpaqueData)) )
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#define GIST_MIN_FILLFACTOR 10
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#define GIST_DEFAULT_FILLFACTOR 90
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extern Datum gistoptions(PG_FUNCTION_ARGS);
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extern bool gistfitpage(IndexTuple *itvec, int len);
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extern bool gistnospace(Page page, IndexTuple *itvec, int len, OffsetNumber todelete, Size freespace);
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extern void gistcheckpage(Relation rel, Buffer buf);
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extern Buffer gistNewBuffer(Relation r);
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extern void gistfillbuffer(Page page, IndexTuple *itup, int len,
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OffsetNumber off);
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extern IndexTuple *gistextractpage(Page page, int *len /* out */ );
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extern IndexTuple *gistjoinvector(
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IndexTuple *itvec, int *len,
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IndexTuple *additvec, int addlen);
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extern IndexTupleData *gistfillitupvec(IndexTuple *vec, int veclen, int *memlen);
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extern IndexTuple gistunion(Relation r, IndexTuple *itvec,
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int len, GISTSTATE *giststate);
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extern IndexTuple gistgetadjusted(Relation r,
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IndexTuple oldtup,
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IndexTuple addtup,
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GISTSTATE *giststate);
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extern IndexTuple gistFormTuple(GISTSTATE *giststate,
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Relation r, Datum *attdata, bool *isnull, bool newValues);
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extern OffsetNumber gistchoose(Relation r, Page p,
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IndexTuple it,
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GISTSTATE *giststate);
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extern void gistcentryinit(GISTSTATE *giststate, int nkey,
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GISTENTRY *e, Datum k,
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Relation r, Page pg,
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OffsetNumber o, bool l, bool isNull);
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extern void GISTInitBuffer(Buffer b, uint32 f);
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extern void gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e,
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Datum k, Relation r, Page pg, OffsetNumber o,
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bool l, bool isNull);
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extern float gistpenalty(GISTSTATE *giststate, int attno,
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GISTENTRY *key1, bool isNull1,
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GISTENTRY *key2, bool isNull2);
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extern void gistMakeUnionItVec(GISTSTATE *giststate, IndexTuple *itvec, int len, int startkey,
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Datum *attr, bool *isnull);
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extern bool gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b);
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extern void gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p,
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OffsetNumber o, GISTENTRY *attdata, bool *isnull);
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extern void gistMakeUnionKey(GISTSTATE *giststate, int attno,
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GISTENTRY *entry1, bool isnull1,
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GISTENTRY *entry2, bool isnull2,
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Datum *dst, bool *dstisnull);
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extern XLogRecPtr GetXLogRecPtrForTemp(void);
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/* gistvacuum.c */
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extern Datum gistbulkdelete(PG_FUNCTION_ARGS);
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extern Datum gistvacuumcleanup(PG_FUNCTION_ARGS);
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/* gistsplit.c */
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extern void gistSplitByKey(Relation r, Page page, IndexTuple *itup,
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int len, GISTSTATE *giststate,
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GistSplitVector *v, GistEntryVector *entryvec,
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int attno);
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#endif /* GIST_PRIVATE_H */
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