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799bc58dc7
now knows what to do upon hitting a dead page (in theory anyway, it's untested...). Add a post-VACUUM-cleanup entry point for index AMs, to provide a place for dead-page scavenging to happen. Also, fix oversight that broke btpo_prev links in temporary indexes. initdb forced due to additions in pg_am.
509 lines
18 KiB
C
509 lines
18 KiB
C
/*-------------------------------------------------------------------------
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*
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* nbtree.h
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* header file for postgres btree access method implementation.
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*
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*
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* Portions Copyright (c) 1996-2002, 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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* $Id: nbtree.h,v 1.65 2003/02/22 00:45:05 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef NBTREE_H
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#define NBTREE_H
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#include "access/itup.h"
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#include "access/relscan.h"
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#include "access/sdir.h"
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#include "access/xlogutils.h"
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/*
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* BTPageOpaqueData -- At the end of every page, we store a pointer
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* to both siblings in the tree. This is used to do forward/backward
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* index scans. The next-page link is also critical for recovery when
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* a search has navigated to the wrong page due to concurrent page splits
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* or deletions; see src/backend/access/nbtree/README for more info.
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*
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* In addition, we store the page's btree level (counting upwards from
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* zero at a leaf page) as well as some flag bits indicating the page type
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* and status. If the page is deleted, we replace the level with the
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* next-transaction-ID value indicating when it is safe to reclaim the page.
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*
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* NOTE: the BTP_LEAF flag bit is redundant since level==0 could be tested
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* instead.
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*/
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typedef struct BTPageOpaqueData
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{
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BlockNumber btpo_prev; /* left sibling, or P_NONE if leftmost */
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BlockNumber btpo_next; /* right sibling, or P_NONE if rightmost */
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union
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{
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uint32 level; /* tree level --- zero for leaf pages */
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TransactionId xact; /* next transaction ID, if deleted */
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} btpo;
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uint16 btpo_flags; /* flag bits, see below */
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} BTPageOpaqueData;
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typedef BTPageOpaqueData *BTPageOpaque;
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/* Bits defined in btpo_flags */
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#define BTP_LEAF (1 << 0) /* leaf page, i.e. not internal page */
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#define BTP_ROOT (1 << 1) /* root page (has no parent) */
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#define BTP_DELETED (1 << 2) /* page has been deleted from tree */
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#define BTP_META (1 << 3) /* meta-page */
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#define BTP_HALF_DEAD (1 << 4) /* empty, but still in tree */
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/*
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* The Meta page is always the first page in the btree index.
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* Its primary purpose is to point to the location of the btree root page.
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* We also point to the "fast" root, which is the current effective root;
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* see README for discussion.
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*/
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typedef struct BTMetaPageData
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{
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uint32 btm_magic; /* should contain BTREE_MAGIC */
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uint32 btm_version; /* should contain BTREE_VERSION */
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BlockNumber btm_root; /* current root location */
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uint32 btm_level; /* tree level of the root page */
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BlockNumber btm_fastroot; /* current "fast" root location */
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uint32 btm_fastlevel; /* tree level of the "fast" root page */
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} BTMetaPageData;
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#define BTPageGetMeta(p) \
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((BTMetaPageData *) PageGetContents(p))
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#define BTREE_METAPAGE 0 /* first page is meta */
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#define BTREE_MAGIC 0x053162 /* magic number of btree pages */
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#define BTREE_VERSION 2 /* current version number */
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/*
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* We actually need to be able to fit three items on every page,
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* so restrict any one item to 1/3 the per-page available space.
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*/
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#define BTMaxItemSize(page) \
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((PageGetPageSize(page) - \
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sizeof(PageHeaderData) - \
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MAXALIGN(sizeof(BTPageOpaqueData))) / 3 - sizeof(ItemIdData))
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/*
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* BTItems are what we store in the btree. Each item is an index tuple,
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* including key and pointer values. (In some cases either the key or the
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* pointer may go unused, see backend/access/nbtree/README for details.)
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*
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* Old comments:
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* In addition, we must guarantee that all tuples in the index are unique,
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* in order to satisfy some assumptions in Lehman and Yao. The way that we
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* do this is by generating a new OID for every insertion that we do in the
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* tree. This adds eight bytes to the size of btree index tuples. Note
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* that we do not use the OID as part of a composite key; the OID only
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* serves as a unique identifier for a given index tuple (logical position
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* within a page).
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*
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* New comments:
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* actually, we must guarantee that all tuples in A LEVEL
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* are unique, not in ALL INDEX. So, we can use bti_itup->t_tid
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* as unique identifier for a given index tuple (logical position
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* within a level). - vadim 04/09/97
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*/
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typedef struct BTItemData
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{
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IndexTupleData bti_itup;
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} BTItemData;
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typedef BTItemData *BTItem;
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/*
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* For XLOG: size without alignment. Sizeof works as long as
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* IndexTupleData has exactly 8 bytes.
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*/
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#define SizeOfBTItem sizeof(BTItemData)
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/* Test whether items are the "same" per the above notes */
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#define BTTidSame(i1, i2) \
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( (i1).ip_blkid.bi_hi == (i2).ip_blkid.bi_hi && \
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(i1).ip_blkid.bi_lo == (i2).ip_blkid.bi_lo && \
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(i1).ip_posid == (i2).ip_posid )
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#define BTItemSame(i1, i2) \
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BTTidSame((i1)->bti_itup.t_tid, (i2)->bti_itup.t_tid)
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/*
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* In general, the btree code tries to localize its knowledge about
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* page layout to a couple of routines. However, we need a special
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* value to indicate "no page number" in those places where we expect
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* page numbers. We can use zero for this because we never need to
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* make a pointer to the metadata page.
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*/
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#define P_NONE 0
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/*
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* Macros to test whether a page is leftmost or rightmost on its tree level,
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* as well as other state info kept in the opaque data.
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*/
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#define P_LEFTMOST(opaque) ((opaque)->btpo_prev == P_NONE)
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#define P_RIGHTMOST(opaque) ((opaque)->btpo_next == P_NONE)
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#define P_ISLEAF(opaque) ((opaque)->btpo_flags & BTP_LEAF)
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#define P_ISROOT(opaque) ((opaque)->btpo_flags & BTP_ROOT)
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#define P_ISDELETED(opaque) ((opaque)->btpo_flags & BTP_DELETED)
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#define P_IGNORE(opaque) ((opaque)->btpo_flags & (BTP_DELETED|BTP_HALF_DEAD))
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/*
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* Lehman and Yao's algorithm requires a ``high key'' on every non-rightmost
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* page. The high key is not a data key, but gives info about what range of
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* keys is supposed to be on this page. The high key on a page is required
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* to be greater than or equal to any data key that appears on the page.
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* If we find ourselves trying to insert a key > high key, we know we need
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* to move right (this should only happen if the page was split since we
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* examined the parent page).
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*
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* Our insertion algorithm guarantees that we can use the initial least key
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* on our right sibling as the high key. Once a page is created, its high
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* key changes only if the page is split.
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*
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* On a non-rightmost page, the high key lives in item 1 and data items
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* start in item 2. Rightmost pages have no high key, so we store data
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* items beginning in item 1.
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*/
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#define P_HIKEY ((OffsetNumber) 1)
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#define P_FIRSTKEY ((OffsetNumber) 2)
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#define P_FIRSTDATAKEY(opaque) (P_RIGHTMOST(opaque) ? P_HIKEY : P_FIRSTKEY)
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/*
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* XLOG records for btree operations
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*
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* XLOG allows to store some information in high 4 bits of log
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* record xl_info field
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*/
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#define XLOG_BTREE_INSERT_LEAF 0x00 /* add btitem without split */
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#define XLOG_BTREE_INSERT_UPPER 0x10 /* same, on a non-leaf page */
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#define XLOG_BTREE_INSERT_META 0x20 /* same, plus update metapage */
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#define XLOG_BTREE_SPLIT_L 0x30 /* add btitem with split */
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#define XLOG_BTREE_SPLIT_R 0x40 /* as above, new item on right */
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#define XLOG_BTREE_SPLIT_L_ROOT 0x50 /* add btitem with split of root */
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#define XLOG_BTREE_SPLIT_R_ROOT 0x60 /* as above, new item on right */
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#define XLOG_BTREE_DELETE 0x70 /* delete leaf btitem */
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#define XLOG_BTREE_DELETE_PAGE 0x80 /* delete an entire page */
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#define XLOG_BTREE_DELETE_PAGE_META 0x90 /* same, plus update metapage */
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#define XLOG_BTREE_NEWROOT 0xA0 /* new root page */
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#define XLOG_BTREE_NEWMETA 0xB0 /* update metadata page */
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#define XLOG_BTREE_NEWPAGE 0xC0 /* new index page during build */
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/*
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* All that we need to find changed index tuple
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*/
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typedef struct xl_btreetid
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{
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RelFileNode node;
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ItemPointerData tid; /* changed tuple id */
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} xl_btreetid;
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/*
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* All that we need to regenerate the meta-data page
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*/
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typedef struct xl_btree_metadata
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{
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BlockNumber root;
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uint32 level;
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BlockNumber fastroot;
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uint32 fastlevel;
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} xl_btree_metadata;
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/*
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* This is what we need to know about simple (without split) insert.
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*
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* This data record is used for INSERT_LEAF, INSERT_UPPER, INSERT_META.
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* Note that INSERT_META implies it's not a leaf page.
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*/
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typedef struct xl_btree_insert
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{
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xl_btreetid target; /* inserted tuple id */
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/* xl_btree_metadata FOLLOWS IF XLOG_BTREE_INSERT_META */
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/* BTITEM FOLLOWS AT END OF STRUCT */
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} xl_btree_insert;
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#define SizeOfBtreeInsert (offsetof(xl_btreetid, tid) + SizeOfIptrData)
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/*
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* On insert with split we save items of both left and right siblings
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* and restore content of both pages from log record. This way takes less
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* xlog space than the normal approach, because if we did it standardly,
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* XLogInsert would almost always think the right page is new and store its
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* whole page image.
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*
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* Note: the four XLOG_BTREE_SPLIT xl_info codes all use this data record.
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* The _L and _R variants indicate whether the inserted btitem went into the
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* left or right split page (and thus, whether otherblk is the right or left
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* page of the split pair). The _ROOT variants indicate that we are splitting
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* the root page, and thus that a newroot record rather than an insert or
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* split record should follow. Note that a split record never carries a
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* metapage update --- we'll do that in the parent-level update.
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*/
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typedef struct xl_btree_split
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{
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xl_btreetid target; /* inserted tuple id */
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BlockNumber otherblk; /* second block participated in split: */
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/* first one is stored in target' tid */
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BlockNumber leftblk; /* prev/left block */
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BlockNumber rightblk; /* next/right block */
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uint32 level; /* tree level of page being split */
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uint16 leftlen; /* len of left page items below */
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/* LEFT AND RIGHT PAGES TUPLES FOLLOW AT THE END */
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} xl_btree_split;
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#define SizeOfBtreeSplit (offsetof(xl_btree_split, leftlen) + sizeof(uint16))
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/*
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* This is what we need to know about delete of an individual leaf btitem
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*/
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typedef struct xl_btree_delete
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{
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xl_btreetid target; /* deleted tuple id */
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} xl_btree_delete;
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#define SizeOfBtreeDelete (offsetof(xl_btreetid, tid) + SizeOfIptrData)
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/*
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* This is what we need to know about deletion of a btree page. The target
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* identifies the tuple removed from the parent page (note that we remove
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* this tuple's downlink and the *following* tuple's key). Note we do not
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* store any content for the deleted page --- it is just rewritten as empty
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* during recovery.
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*/
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typedef struct xl_btree_delete_page
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{
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xl_btreetid target; /* deleted tuple id in parent page */
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BlockNumber deadblk; /* child block being deleted */
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BlockNumber leftblk; /* child block's left sibling, if any */
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BlockNumber rightblk; /* child block's right sibling */
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/* xl_btree_metadata FOLLOWS IF XLOG_BTREE_DELETE_PAGE_META */
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} xl_btree_delete_page;
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#define SizeOfBtreeDeletePage (offsetof(xl_btree_delete_page, rightblk) + sizeof(BlockNumber))
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/*
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* New root log record. There are zero btitems if this is to establish an
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* empty root, or two if it is the result of splitting an old root.
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*
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* Note that although this implies rewriting the metadata page, we don't need
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* an xl_btree_metadata record --- the rootblk and level are sufficient.
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*/
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typedef struct xl_btree_newroot
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{
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RelFileNode node;
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BlockNumber rootblk; /* location of new root */
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uint32 level; /* its tree level */
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/* 0 or 2 BTITEMS FOLLOW AT END OF STRUCT */
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} xl_btree_newroot;
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#define SizeOfBtreeNewroot (offsetof(xl_btree_newroot, level) + sizeof(uint32))
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/*
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* New metapage log record. This is not issued during routine operations;
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* it's only used when initializing an empty index and at completion of
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* index build.
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*/
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typedef struct xl_btree_newmeta
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{
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RelFileNode node;
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xl_btree_metadata meta;
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} xl_btree_newmeta;
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#define SizeOfBtreeNewmeta (sizeof(xl_btree_newmeta))
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/*
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* New index page log record. This is only used while building a new index.
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*/
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typedef struct xl_btree_newpage
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{
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RelFileNode node;
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BlockNumber blkno; /* location of new page */
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/* entire page contents follow at end of record */
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} xl_btree_newpage;
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#define SizeOfBtreeNewpage (offsetof(xl_btree_newpage, blkno) + sizeof(BlockNumber))
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/*
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* Operator strategy numbers -- ordering of these is <, <=, =, >=, >
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*/
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#define BTLessStrategyNumber 1
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#define BTLessEqualStrategyNumber 2
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#define BTEqualStrategyNumber 3
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#define BTGreaterEqualStrategyNumber 4
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#define BTGreaterStrategyNumber 5
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#define BTMaxStrategyNumber 5
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/*
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* When a new operator class is declared, we require that the user
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* supply us with an amproc procedure for determining whether, for
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* two keys a and b, a < b, a = b, or a > b. This routine must
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* return < 0, 0, > 0, respectively, in these three cases. Since we
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* only have one such proc in amproc, it's number 1.
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*/
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#define BTORDER_PROC 1
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/*
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* We need to be able to tell the difference between read and write
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* requests for pages, in order to do locking correctly.
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*/
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#define BT_READ BUFFER_LOCK_SHARE
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#define BT_WRITE BUFFER_LOCK_EXCLUSIVE
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/*
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* BTStackData -- As we descend a tree, we push the (location, downlink)
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* pairs from internal pages onto a private stack. If we split a
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* leaf, we use this stack to walk back up the tree and insert data
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* into parent pages (and possibly to split them, too). Lehman and
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* Yao's update algorithm guarantees that under no circumstances can
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* our private stack give us an irredeemably bad picture up the tree.
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* Again, see the paper for details.
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*/
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typedef struct BTStackData
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{
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BlockNumber bts_blkno;
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OffsetNumber bts_offset;
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BTItemData bts_btitem;
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struct BTStackData *bts_parent;
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} BTStackData;
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typedef BTStackData *BTStack;
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/*
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* BTScanOpaqueData is used to remember which buffers we're currently
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* examining in the scan. We keep these buffers pinned (but not locked,
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* see nbtree.c) and recorded in the opaque entry of the scan to avoid
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* doing a ReadBuffer() for every tuple in the index.
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*
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* And it's used to remember actual scankey info (we need it
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* if some scankeys evaled at runtime).
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*
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* curHeapIptr & mrkHeapIptr are heap iptr-s from current/marked
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* index tuples: we don't adjust scans on insertions (and, if LLL
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* is ON, don't hold locks on index pages between passes) - we
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* use these pointers to restore index scan positions...
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* - vadim 07/29/98
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*/
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typedef struct BTScanOpaqueData
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{
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Buffer btso_curbuf;
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Buffer btso_mrkbuf;
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ItemPointerData curHeapIptr;
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ItemPointerData mrkHeapIptr;
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/* these fields are set by _bt_orderkeys(), which see for more info: */
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bool qual_ok; /* false if qual can never be satisfied */
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int numberOfKeys; /* number of scan keys */
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int numberOfRequiredKeys; /* number of keys that must be
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* matched to continue the scan */
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ScanKey keyData; /* array of scan keys */
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} BTScanOpaqueData;
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typedef BTScanOpaqueData *BTScanOpaque;
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/*
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* prototypes for functions in nbtree.c (external entry points for btree)
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*/
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extern void AtEOXact_nbtree(void);
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extern Datum btbuild(PG_FUNCTION_ARGS);
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extern Datum btinsert(PG_FUNCTION_ARGS);
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extern Datum btgettuple(PG_FUNCTION_ARGS);
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extern Datum btbeginscan(PG_FUNCTION_ARGS);
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extern Datum btrescan(PG_FUNCTION_ARGS);
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extern void btmovescan(IndexScanDesc scan, Datum v);
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extern Datum btendscan(PG_FUNCTION_ARGS);
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extern Datum btmarkpos(PG_FUNCTION_ARGS);
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extern Datum btrestrpos(PG_FUNCTION_ARGS);
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extern Datum btbulkdelete(PG_FUNCTION_ARGS);
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extern Datum btvacuumcleanup(PG_FUNCTION_ARGS);
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/*
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* prototypes for functions in nbtinsert.c
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*/
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extern InsertIndexResult _bt_doinsert(Relation rel, BTItem btitem,
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bool index_is_unique, Relation heapRel);
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extern void _bt_insert_parent(Relation rel, Buffer buf, Buffer rbuf,
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BTStack stack, bool is_root, bool is_only);
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/*
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* prototypes for functions in nbtpage.c
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*/
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extern void _bt_metapinit(Relation rel);
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extern Buffer _bt_getroot(Relation rel, int access);
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extern Buffer _bt_gettrueroot(Relation rel);
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extern Buffer _bt_getbuf(Relation rel, BlockNumber blkno, int access);
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extern void _bt_relbuf(Relation rel, Buffer buf);
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extern void _bt_wrtbuf(Relation rel, Buffer buf);
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extern void _bt_wrtnorelbuf(Relation rel, Buffer buf);
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extern void _bt_pageinit(Page page, Size size);
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extern void _bt_metaproot(Relation rel, BlockNumber rootbknum, uint32 level);
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extern void _bt_itemdel(Relation rel, Buffer buf, ItemPointer tid);
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/*
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* prototypes for functions in nbtsearch.c
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*/
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extern BTStack _bt_search(Relation rel, int keysz, ScanKey scankey,
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Buffer *bufP, int access);
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extern Buffer _bt_moveright(Relation rel, Buffer buf, int keysz,
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ScanKey scankey, int access);
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extern OffsetNumber _bt_binsrch(Relation rel, Buffer buf, int keysz,
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ScanKey scankey);
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extern int32 _bt_compare(Relation rel, int keysz, ScanKey scankey,
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Page page, OffsetNumber offnum);
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extern bool _bt_next(IndexScanDesc scan, ScanDirection dir);
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extern bool _bt_first(IndexScanDesc scan, ScanDirection dir);
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extern bool _bt_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir);
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extern Buffer _bt_get_endpoint(Relation rel, uint32 level, bool rightmost);
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/*
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* prototypes for functions in nbtstrat.c
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*/
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extern StrategyNumber _bt_getstrat(Relation rel, AttrNumber attno,
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RegProcedure proc);
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/*
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* prototypes for functions in nbtutils.c
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*/
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extern ScanKey _bt_mkscankey(Relation rel, IndexTuple itup);
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extern ScanKey _bt_mkscankey_nodata(Relation rel);
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extern void _bt_freeskey(ScanKey skey);
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extern void _bt_freestack(BTStack stack);
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extern void _bt_orderkeys(IndexScanDesc scan);
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extern bool _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
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ScanDirection dir, bool *continuescan);
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extern BTItem _bt_formitem(IndexTuple itup);
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/*
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* prototypes for functions in nbtsort.c
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*/
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typedef struct BTSpool BTSpool; /* opaque type known only within nbtsort.c */
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extern BTSpool *_bt_spoolinit(Relation index, bool isunique);
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extern void _bt_spooldestroy(BTSpool *btspool);
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extern void _bt_spool(BTItem btitem, BTSpool *btspool);
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extern void _bt_leafbuild(BTSpool *btspool, BTSpool *spool2);
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/*
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* prototypes for functions in nbtxlog.c
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*/
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extern void btree_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void btree_undo(XLogRecPtr lsn, XLogRecord *record);
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extern void btree_desc(char *buf, uint8 xl_info, char *rec);
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extern void btree_xlog_startup(void);
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extern void btree_xlog_cleanup(void);
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#endif /* NBTREE_H */
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