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Diffstat (limited to 'src/backend/access/nbtree/nbtpage.c')
-rw-r--r--src/backend/access/nbtree/nbtpage.c484
1 files changed, 0 insertions, 484 deletions
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
deleted file mode 100644
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--- a/src/backend/access/nbtree/nbtpage.c
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-/*-------------------------------------------------------------------------
- *
- * nbtpage.c
- * BTree-specific page management code for the Postgres btree access
- * method.
- *
- * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.57 2002/06/20 20:29:25 momjian Exp $
- *
- * NOTES
- * Postgres btree pages look like ordinary relation pages. The opaque
- * data at high addresses includes pointers to left and right siblings
- * and flag data describing page state. The first page in a btree, page
- * zero, is special -- it stores meta-information describing the tree.
- * Pages one and higher store the actual tree data.
- *
- *-------------------------------------------------------------------------
- */
-#include "postgres.h"
-
-#include <time.h>
-
-#include "access/nbtree.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
-
-extern bool FixBTree; /* comments in nbtree.c */
-extern Buffer _bt_fixroot(Relation rel, Buffer oldrootbuf, bool release);
-
-/*
- * We use high-concurrency locking on btrees. There are two cases in
- * which we don't do locking. One is when we're building the btree.
- * Since the creating transaction has not committed, no one can see
- * the index, and there's no reason to share locks. The second case
- * is when we're just starting up the database system. We use some
- * special-purpose initialization code in the relation cache manager
- * (see utils/cache/relcache.c) to allow us to do indexed scans on
- * the system catalogs before we'd normally be able to. This happens
- * before the lock table is fully initialized, so we can't use it.
- * Strictly speaking, this violates 2pl, but we don't do 2pl on the
- * system catalogs anyway, so I declare this to be okay.
- */
-
-#define USELOCKING (!BuildingBtree && !IsInitProcessingMode())
-
-/*
- * _bt_metapinit() -- Initialize the metadata page of a btree.
- */
-void
-_bt_metapinit(Relation rel)
-{
- Buffer buf;
- Page pg;
- BTMetaPageData metad;
- BTPageOpaque op;
-
- /* can't be sharing this with anyone, now... */
- if (USELOCKING)
- LockRelation(rel, AccessExclusiveLock);
-
- if (RelationGetNumberOfBlocks(rel) != 0)
- elog(ERROR, "Cannot initialize non-empty btree %s",
- RelationGetRelationName(rel));
-
- buf = ReadBuffer(rel, P_NEW);
- pg = BufferGetPage(buf);
- _bt_pageinit(pg, BufferGetPageSize(buf));
-
- metad.btm_magic = BTREE_MAGIC;
- metad.btm_version = BTREE_VERSION;
- metad.btm_root = P_NONE;
- metad.btm_level = 0;
- memcpy((char *) BTPageGetMeta(pg), (char *) &metad, sizeof(metad));
-
- op = (BTPageOpaque) PageGetSpecialPointer(pg);
- op->btpo_flags = BTP_META;
-
- WriteBuffer(buf);
-
- /* all done */
- if (USELOCKING)
- UnlockRelation(rel, AccessExclusiveLock);
-}
-
-/*
- * _bt_getroot() -- Get the root page of the btree.
- *
- * Since the root page can move around the btree file, we have to read
- * its location from the metadata page, and then read the root page
- * itself. If no root page exists yet, we have to create one. The
- * standard class of race conditions exists here; I think I covered
- * them all in the Hopi Indian rain dance of lock requests below.
- *
- * The access type parameter (BT_READ or BT_WRITE) controls whether
- * a new root page will be created or not. If access = BT_READ,
- * and no root page exists, we just return InvalidBuffer. For
- * BT_WRITE, we try to create the root page if it doesn't exist.
- * NOTE that the returned root page will have only a read lock set
- * on it even if access = BT_WRITE!
- *
- * On successful return, the root page is pinned and read-locked.
- * The metadata page is not locked or pinned on exit.
- */
-Buffer
-_bt_getroot(Relation rel, int access)
-{
- Buffer metabuf;
- Page metapg;
- BTPageOpaque metaopaque;
- Buffer rootbuf;
- Page rootpage;
- BTPageOpaque rootopaque;
- BlockNumber rootblkno;
- BTMetaPageData *metad;
-
- metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
- metapg = BufferGetPage(metabuf);
- metaopaque = (BTPageOpaque) PageGetSpecialPointer(metapg);
- metad = BTPageGetMeta(metapg);
-
- if (!(metaopaque->btpo_flags & BTP_META) ||
- metad->btm_magic != BTREE_MAGIC)
- elog(ERROR, "Index %s is not a btree",
- RelationGetRelationName(rel));
-
- if (metad->btm_version != BTREE_VERSION)
- elog(ERROR, "Version mismatch on %s: version %d file, version %d code",
- RelationGetRelationName(rel),
- metad->btm_version, BTREE_VERSION);
-
- /* if no root page initialized yet, do it */
- if (metad->btm_root == P_NONE)
- {
- /* If access = BT_READ, caller doesn't want us to create root yet */
- if (access == BT_READ)
- {
- _bt_relbuf(rel, metabuf);
- return InvalidBuffer;
- }
-
- /* trade in our read lock for a write lock */
- LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
- LockBuffer(metabuf, BT_WRITE);
-
- /*
- * Race condition: if someone else initialized the metadata
- * between the time we released the read lock and acquired the
- * write lock, above, we must avoid doing it again.
- */
- if (metad->btm_root == P_NONE)
- {
- /*
- * Get, initialize, write, and leave a lock of the appropriate
- * type on the new root page. Since this is the first page in
- * the tree, it's a leaf as well as the root.
- */
- rootbuf = _bt_getbuf(rel, P_NEW, BT_WRITE);
- rootblkno = BufferGetBlockNumber(rootbuf);
- rootpage = BufferGetPage(rootbuf);
-
- /* NO ELOG(ERROR) till meta is updated */
- START_CRIT_SECTION();
-
- metad->btm_root = rootblkno;
- metad->btm_level = 1;
-
- _bt_pageinit(rootpage, BufferGetPageSize(rootbuf));
- rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
- rootopaque->btpo_flags |= (BTP_LEAF | BTP_ROOT);
-
- /* XLOG stuff */
- {
- xl_btree_newroot xlrec;
- XLogRecPtr recptr;
- XLogRecData rdata;
-
- xlrec.node = rel->rd_node;
- xlrec.level = 1;
- BlockIdSet(&(xlrec.rootblk), rootblkno);
- rdata.buffer = InvalidBuffer;
- rdata.data = (char *) &xlrec;
- rdata.len = SizeOfBtreeNewroot;
- rdata.next = NULL;
-
- recptr = XLogInsert(RM_BTREE_ID,
- XLOG_BTREE_NEWROOT | XLOG_BTREE_LEAF, &rdata);
-
- PageSetLSN(rootpage, recptr);
- PageSetSUI(rootpage, ThisStartUpID);
- PageSetLSN(metapg, recptr);
- PageSetSUI(metapg, ThisStartUpID);
- }
-
- END_CRIT_SECTION();
-
- _bt_wrtnorelbuf(rel, rootbuf);
-
- /* swap write lock for read lock */
- LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
- LockBuffer(rootbuf, BT_READ);
-
- /* okay, metadata is correct, write and release it */
- _bt_wrtbuf(rel, metabuf);
- }
- else
- {
- /*
- * Metadata initialized by someone else. In order to
- * guarantee no deadlocks, we have to release the metadata
- * page and start all over again.
- */
- _bt_relbuf(rel, metabuf);
- return _bt_getroot(rel, access);
- }
- }
- else
- {
- rootblkno = metad->btm_root;
- _bt_relbuf(rel, metabuf); /* done with the meta page */
-
- rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
- }
-
- /*
- * Race condition: If the root page split between the time we looked
- * at the metadata page and got the root buffer, then we got the wrong
- * buffer. Release it and try again.
- */
- rootpage = BufferGetPage(rootbuf);
- rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
-
- if (!P_ISROOT(rootopaque))
- {
- /*
- * It happened, but if root page splitter failed to create new
- * root page then we'll go in loop trying to call _bt_getroot
- * again and again.
- */
- if (FixBTree)
- {
- Buffer newrootbuf;
-
- check_parent:;
- if (BTreeInvalidParent(rootopaque)) /* unupdated! */
- {
- LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
- LockBuffer(rootbuf, BT_WRITE);
-
- /* handle concurrent fix of root page */
- if (BTreeInvalidParent(rootopaque)) /* unupdated! */
- {
- elog(WARNING, "bt_getroot[%s]: fixing root page", RelationGetRelationName(rel));
- newrootbuf = _bt_fixroot(rel, rootbuf, true);
- LockBuffer(newrootbuf, BUFFER_LOCK_UNLOCK);
- LockBuffer(newrootbuf, BT_READ);
- rootbuf = newrootbuf;
- rootpage = BufferGetPage(rootbuf);
- rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
- /* New root might be splitted while changing lock */
- if (P_ISROOT(rootopaque))
- return (rootbuf);
- /* rootbuf is read locked */
- goto check_parent;
- }
- else
- {
- /* someone else already fixed root */
- LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
- LockBuffer(rootbuf, BT_READ);
- }
- }
-
- /*
- * Ok, here we have old root page with btpo_parent pointing to
- * upper level - check parent page because of there is good
- * chance that parent is root page.
- */
- newrootbuf = _bt_getbuf(rel, rootopaque->btpo_parent, BT_READ);
- _bt_relbuf(rel, rootbuf);
- rootbuf = newrootbuf;
- rootpage = BufferGetPage(rootbuf);
- rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
- if (P_ISROOT(rootopaque))
- return (rootbuf);
- /* no luck -:( */
- }
-
- /* try again */
- _bt_relbuf(rel, rootbuf);
- return _bt_getroot(rel, access);
- }
-
- /*
- * By here, we have a correct lock on the root block, its reference
- * count is correct, and we have no lock set on the metadata page.
- * Return the root block.
- */
- return rootbuf;
-}
-
-/*
- * _bt_getbuf() -- Get a buffer by block number for read or write.
- *
- * When this routine returns, the appropriate lock is set on the
- * requested buffer and its reference count has been incremented
- * (ie, the buffer is "locked and pinned").
- */
-Buffer
-_bt_getbuf(Relation rel, BlockNumber blkno, int access)
-{
- Buffer buf;
-
- if (blkno != P_NEW)
- {
- /* Read an existing block of the relation */
- buf = ReadBuffer(rel, blkno);
- LockBuffer(buf, access);
- }
- else
- {
- Page page;
-
- /*
- * Extend the relation by one page.
- *
- * Extend bufmgr code is unclean and so we have to use extra locking
- * here.
- */
- LockPage(rel, 0, ExclusiveLock);
- buf = ReadBuffer(rel, blkno);
- LockBuffer(buf, access);
- UnlockPage(rel, 0, ExclusiveLock);
-
- /* Initialize the new page before returning it */
- page = BufferGetPage(buf);
- _bt_pageinit(page, BufferGetPageSize(buf));
- }
-
- /* ref count and lock type are correct */
- return buf;
-}
-
-/*
- * _bt_relbuf() -- release a locked buffer.
- *
- * Lock and pin (refcount) are both dropped. Note that either read or
- * write lock can be dropped this way, but if we modified the buffer,
- * this is NOT the right way to release a write lock.
- */
-void
-_bt_relbuf(Relation rel, Buffer buf)
-{
- LockBuffer(buf, BUFFER_LOCK_UNLOCK);
- ReleaseBuffer(buf);
-}
-
-/*
- * _bt_wrtbuf() -- write a btree page to disk.
- *
- * This routine releases the lock held on the buffer and our refcount
- * for it. It is an error to call _bt_wrtbuf() without a write lock
- * and a pin on the buffer.
- *
- * NOTE: actually, the buffer manager just marks the shared buffer page
- * dirty here, the real I/O happens later. Since we can't persuade the
- * Unix kernel to schedule disk writes in a particular order, there's not
- * much point in worrying about this. The most we can say is that all the
- * writes will occur before commit.
- */
-void
-_bt_wrtbuf(Relation rel, Buffer buf)
-{
- LockBuffer(buf, BUFFER_LOCK_UNLOCK);
- WriteBuffer(buf);
-}
-
-/*
- * _bt_wrtnorelbuf() -- write a btree page to disk, but do not release
- * our reference or lock.
- *
- * It is an error to call _bt_wrtnorelbuf() without a write lock
- * and a pin on the buffer.
- *
- * See above NOTE.
- */
-void
-_bt_wrtnorelbuf(Relation rel, Buffer buf)
-{
- WriteNoReleaseBuffer(buf);
-}
-
-/*
- * _bt_pageinit() -- Initialize a new page.
- */
-void
-_bt_pageinit(Page page, Size size)
-{
- PageInit(page, size, sizeof(BTPageOpaqueData));
- ((BTPageOpaque) PageGetSpecialPointer(page))->btpo_parent =
- InvalidBlockNumber;
-}
-
-/*
- * _bt_metaproot() -- Change the root page of the btree.
- *
- * Lehman and Yao require that the root page move around in order to
- * guarantee deadlock-free short-term, fine-granularity locking. When
- * we split the root page, we record the new parent in the metadata page
- * for the relation. This routine does the work.
- *
- * No direct preconditions, but if you don't have the write lock on
- * at least the old root page when you call this, you're making a big
- * mistake. On exit, metapage data is correct and we no longer have
- * a pin or lock on the metapage.
- */
-void
-_bt_metaproot(Relation rel, BlockNumber rootbknum, int level)
-{
- Buffer metabuf;
- Page metap;
- BTPageOpaque metaopaque;
- BTMetaPageData *metad;
-
- metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
- metap = BufferGetPage(metabuf);
- metaopaque = (BTPageOpaque) PageGetSpecialPointer(metap);
- Assert(metaopaque->btpo_flags & BTP_META);
- metad = BTPageGetMeta(metap);
- metad->btm_root = rootbknum;
- if (level == 0) /* called from _do_insert */
- metad->btm_level += 1;
- else
- metad->btm_level = level; /* called from btsort */
- _bt_wrtbuf(rel, metabuf);
-}
-
-/*
- * Delete an item from a btree page.
- *
- * This routine assumes that the caller has pinned and locked the buffer,
- * and will write the buffer afterwards.
- */
-void
-_bt_itemdel(Relation rel, Buffer buf, ItemPointer tid)
-{
- Page page = BufferGetPage(buf);
- OffsetNumber offno;
-
- offno = ItemPointerGetOffsetNumber(tid);
-
- START_CRIT_SECTION();
-
- PageIndexTupleDelete(page, offno);
-
- /* XLOG stuff */
- {
- xl_btree_delete xlrec;
- XLogRecPtr recptr;
- XLogRecData rdata[2];
-
- xlrec.target.node = rel->rd_node;
- xlrec.target.tid = *tid;
- rdata[0].buffer = InvalidBuffer;
- rdata[0].data = (char *) &xlrec;
- rdata[0].len = SizeOfBtreeDelete;
- rdata[0].next = &(rdata[1]);
-
- rdata[1].buffer = buf;
- rdata[1].data = NULL;
- rdata[1].len = 0;
- rdata[1].next = NULL;
-
- recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_DELETE, rdata);
-
- PageSetLSN(page, recptr);
- PageSetSUI(page, ThisStartUpID);
- }
-
- END_CRIT_SECTION();
-}
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