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killed items; just skip to the next item immediately. Only check for key equality when we reach a non-killed item or the end of the index page. This saves key comparisons when there are lots of killed items, as for example in a heavily-updated table that's not been vacuumed lately. Seems to be a win for pgbench anyway.
1605 lines
48 KiB
C
1605 lines
48 KiB
C
/*-------------------------------------------------------------------------
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*
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* btinsert.c
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* Item insertion in Lehman and Yao btrees for Postgres.
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*
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* Portions Copyright (c) 1996-2003, 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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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.105 2003/09/02 22:10:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "access/nbtree.h"
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#include "miscadmin.h"
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typedef struct
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{
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/* context data for _bt_checksplitloc */
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Size newitemsz; /* size of new item to be inserted */
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bool is_leaf; /* T if splitting a leaf page */
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bool is_rightmost; /* T if splitting a rightmost page */
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bool have_split; /* found a valid split? */
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/* these fields valid only if have_split is true */
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bool newitemonleft; /* new item on left or right of best split */
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OffsetNumber firstright; /* best split point */
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int best_delta; /* best size delta so far */
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} FindSplitData;
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static Buffer _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf);
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static TransactionId _bt_check_unique(Relation rel, BTItem btitem,
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Relation heapRel, Buffer buf,
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ScanKey itup_scankey);
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static InsertIndexResult _bt_insertonpg(Relation rel, Buffer buf,
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BTStack stack,
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int keysz, ScanKey scankey,
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BTItem btitem,
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OffsetNumber afteritem,
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bool split_only_page);
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static Buffer _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
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OffsetNumber newitemoff, Size newitemsz,
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BTItem newitem, bool newitemonleft,
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OffsetNumber *itup_off, BlockNumber *itup_blkno);
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static OffsetNumber _bt_findsplitloc(Relation rel, Page page,
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OffsetNumber newitemoff,
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Size newitemsz,
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bool *newitemonleft);
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static void _bt_checksplitloc(FindSplitData *state, OffsetNumber firstright,
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int leftfree, int rightfree,
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bool newitemonleft, Size firstrightitemsz);
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static void _bt_pgaddtup(Relation rel, Page page,
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Size itemsize, BTItem btitem,
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OffsetNumber itup_off, const char *where);
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static bool _bt_isequal(TupleDesc itupdesc, Page page, OffsetNumber offnum,
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int keysz, ScanKey scankey);
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/*
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* _bt_doinsert() -- Handle insertion of a single btitem in the tree.
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*
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* This routine is called by the public interface routines, btbuild
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* and btinsert. By here, btitem is filled in, including the TID.
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*/
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InsertIndexResult
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_bt_doinsert(Relation rel, BTItem btitem,
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bool index_is_unique, Relation heapRel)
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{
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IndexTuple itup = &(btitem->bti_itup);
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int natts = rel->rd_rel->relnatts;
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ScanKey itup_scankey;
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BTStack stack;
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Buffer buf;
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InsertIndexResult res;
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/* we need a scan key to do our search, so build one */
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itup_scankey = _bt_mkscankey(rel, itup);
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top:
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/* find the page containing this key */
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stack = _bt_search(rel, natts, itup_scankey, &buf, BT_WRITE);
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/* trade in our read lock for a write lock */
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LockBuffer(buf, BUFFER_LOCK_UNLOCK);
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LockBuffer(buf, BT_WRITE);
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/*
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* If the page was split between the time that we surrendered our read
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* lock and acquired our write lock, then this page may no longer be
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* the right place for the key we want to insert. In this case, we
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* need to move right in the tree. See Lehman and Yao for an
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* excruciatingly precise description.
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*/
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buf = _bt_moveright(rel, buf, natts, itup_scankey, BT_WRITE);
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/*
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* If we're not allowing duplicates, make sure the key isn't already
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* in the index.
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*
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* NOTE: obviously, _bt_check_unique can only detect keys that are
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* already in the index; so it cannot defend against concurrent
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* insertions of the same key. We protect against that by means of
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* holding a write lock on the target page. Any other would-be
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* inserter of the same key must acquire a write lock on the same
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* target page, so only one would-be inserter can be making the check
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* at one time. Furthermore, once we are past the check we hold write
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* locks continuously until we have performed our insertion, so no
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* later inserter can fail to see our insertion. (This requires some
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* care in _bt_insertonpg.)
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*
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* If we must wait for another xact, we release the lock while waiting,
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* and then must start over completely.
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*/
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if (index_is_unique)
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{
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TransactionId xwait;
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xwait = _bt_check_unique(rel, btitem, heapRel, buf, itup_scankey);
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if (TransactionIdIsValid(xwait))
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{
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/* Have to wait for the other guy ... */
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_bt_relbuf(rel, buf);
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XactLockTableWait(xwait);
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/* start over... */
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_bt_freestack(stack);
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goto top;
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}
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}
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/* do the insertion */
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res = _bt_insertonpg(rel, buf, stack, natts, itup_scankey, btitem,
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0, false);
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/* be tidy */
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_bt_freestack(stack);
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_bt_freeskey(itup_scankey);
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return res;
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}
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/*
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* _bt_check_unique() -- Check for violation of unique index constraint
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*
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* Returns InvalidTransactionId if there is no conflict, else an xact ID
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* we must wait for to see if it commits a conflicting tuple. If an actual
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* conflict is detected, no return --- just ereport().
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*/
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static TransactionId
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_bt_check_unique(Relation rel, BTItem btitem, Relation heapRel,
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Buffer buf, ScanKey itup_scankey)
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{
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TupleDesc itupdesc = RelationGetDescr(rel);
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int natts = rel->rd_rel->relnatts;
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OffsetNumber offset,
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maxoff;
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Page page;
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BTPageOpaque opaque;
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Buffer nbuf = InvalidBuffer;
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page = BufferGetPage(buf);
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opaque = (BTPageOpaque) PageGetSpecialPointer(page);
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maxoff = PageGetMaxOffsetNumber(page);
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/*
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* Find first item >= proposed new item. Note we could also get a
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* pointer to end-of-page here.
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*/
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offset = _bt_binsrch(rel, buf, natts, itup_scankey);
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/*
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* Scan over all equal tuples, looking for live conflicts.
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*/
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for (;;)
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{
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HeapTupleData htup;
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Buffer hbuffer;
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ItemId curitemid;
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BTItem cbti;
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BlockNumber nblkno;
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/*
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* make sure the offset points to an actual item before trying to
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* examine it...
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*/
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if (offset <= maxoff)
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{
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curitemid = PageGetItemId(page, offset);
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/*
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* We can skip items that are marked killed.
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*
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* Formerly, we applied _bt_isequal() before checking the kill
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* flag, so as to fall out of the item loop as soon as possible.
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* However, in the presence of heavy update activity an index
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* may contain many killed items with the same key; running
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* _bt_isequal() on each killed item gets expensive. Furthermore
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* it is likely that the non-killed version of each key appears
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* first, so that we didn't actually get to exit any sooner anyway.
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* So now we just advance over killed items as quickly as we can.
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* We only apply _bt_isequal() when we get to a non-killed item or
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* the end of the page.
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*/
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if (!ItemIdDeleted(curitemid))
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{
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/*
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* _bt_compare returns 0 for (1,NULL) and (1,NULL) - this's
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* how we handling NULLs - and so we must not use _bt_compare
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* in real comparison, but only for ordering/finding items on
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* pages. - vadim 03/24/97
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*/
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if (!_bt_isequal(itupdesc, page, offset, natts, itup_scankey))
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break; /* we're past all the equal tuples */
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/* okay, we gotta fetch the heap tuple ... */
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cbti = (BTItem) PageGetItem(page, curitemid);
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htup.t_self = cbti->bti_itup.t_tid;
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if (heap_fetch(heapRel, SnapshotDirty, &htup, &hbuffer,
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true, NULL))
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{
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/* it is a duplicate */
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TransactionId xwait =
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(TransactionIdIsValid(SnapshotDirty->xmin)) ?
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SnapshotDirty->xmin : SnapshotDirty->xmax;
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ReleaseBuffer(hbuffer);
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/*
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* If this tuple is being updated by other transaction
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* then we have to wait for its commit/abort.
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*/
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if (TransactionIdIsValid(xwait))
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{
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if (nbuf != InvalidBuffer)
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_bt_relbuf(rel, nbuf);
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/* Tell _bt_doinsert to wait... */
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return xwait;
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}
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/*
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* Otherwise we have a definite conflict.
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*/
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ereport(ERROR,
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(errcode(ERRCODE_UNIQUE_VIOLATION),
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errmsg("duplicate key violates UNIQUE constraint \"%s\"",
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RelationGetRelationName(rel))));
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}
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else if (htup.t_data != NULL)
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{
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/*
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* Hmm, if we can't see the tuple, maybe it can be
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* marked killed. This logic should match
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* index_getnext and btgettuple.
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*/
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uint16 sv_infomask;
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LockBuffer(hbuffer, BUFFER_LOCK_SHARE);
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sv_infomask = htup.t_data->t_infomask;
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if (HeapTupleSatisfiesVacuum(htup.t_data,
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RecentGlobalXmin) ==
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HEAPTUPLE_DEAD)
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{
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curitemid->lp_flags |= LP_DELETE;
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SetBufferCommitInfoNeedsSave(buf);
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}
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if (sv_infomask != htup.t_data->t_infomask)
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SetBufferCommitInfoNeedsSave(hbuffer);
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LockBuffer(hbuffer, BUFFER_LOCK_UNLOCK);
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ReleaseBuffer(hbuffer);
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}
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}
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}
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/*
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* Advance to next tuple to continue checking.
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*/
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if (offset < maxoff)
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offset = OffsetNumberNext(offset);
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else
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{
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/* If scankey == hikey we gotta check the next page too */
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if (P_RIGHTMOST(opaque))
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break;
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if (!_bt_isequal(itupdesc, page, P_HIKEY,
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natts, itup_scankey))
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break;
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/* Advance to next non-dead page --- there must be one */
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for (;;)
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{
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nblkno = opaque->btpo_next;
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if (nbuf != InvalidBuffer)
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_bt_relbuf(rel, nbuf);
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nbuf = _bt_getbuf(rel, nblkno, BT_READ);
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page = BufferGetPage(nbuf);
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opaque = (BTPageOpaque) PageGetSpecialPointer(page);
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if (!P_IGNORE(opaque))
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break;
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if (P_RIGHTMOST(opaque))
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elog(ERROR, "fell off the end of \"%s\"",
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RelationGetRelationName(rel));
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}
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maxoff = PageGetMaxOffsetNumber(page);
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offset = P_FIRSTDATAKEY(opaque);
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}
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}
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if (nbuf != InvalidBuffer)
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_bt_relbuf(rel, nbuf);
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return InvalidTransactionId;
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}
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/*----------
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* _bt_insertonpg() -- Insert a tuple on a particular page in the index.
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*
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* This recursive procedure does the following things:
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*
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* + finds the right place to insert the tuple.
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* + if necessary, splits the target page (making sure that the
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* split is equitable as far as post-insert free space goes).
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* + inserts the tuple.
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* + if the page was split, pops the parent stack, and finds the
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* right place to insert the new child pointer (by walking
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* right using information stored in the parent stack).
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* + invokes itself with the appropriate tuple for the right
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* child page on the parent.
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* + updates the metapage if a true root or fast root is split.
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*
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* On entry, we must have the right buffer on which to do the
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* insertion, and the buffer must be pinned and locked. On return,
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* we will have dropped both the pin and the write lock on the buffer.
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*
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* If 'afteritem' is >0 then the new tuple must be inserted after the
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* existing item of that number, noplace else. If 'afteritem' is 0
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* then the procedure finds the exact spot to insert it by searching.
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* (keysz and scankey parameters are used ONLY if afteritem == 0.)
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*
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* NOTE: if the new key is equal to one or more existing keys, we can
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* legitimately place it anywhere in the series of equal keys --- in fact,
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* if the new key is equal to the page's "high key" we can place it on
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* the next page. If it is equal to the high key, and there's not room
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* to insert the new tuple on the current page without splitting, then
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* we can move right hoping to find more free space and avoid a split.
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* (We should not move right indefinitely, however, since that leads to
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* O(N^2) insertion behavior in the presence of many equal keys.)
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* Once we have chosen the page to put the key on, we'll insert it before
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* any existing equal keys because of the way _bt_binsrch() works.
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*
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* The locking interactions in this code are critical. You should
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* grok Lehman and Yao's paper before making any changes. In addition,
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* you need to understand how we disambiguate duplicate keys in this
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* implementation, in order to be able to find our location using
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* L&Y "move right" operations. Since we may insert duplicate user
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* keys, and since these dups may propagate up the tree, we use the
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* 'afteritem' parameter to position ourselves correctly for the
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* insertion on internal pages.
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*----------
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*/
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static InsertIndexResult
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_bt_insertonpg(Relation rel,
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Buffer buf,
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BTStack stack,
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int keysz,
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ScanKey scankey,
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BTItem btitem,
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OffsetNumber afteritem,
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bool split_only_page)
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{
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InsertIndexResult res;
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Page page;
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BTPageOpaque lpageop;
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OffsetNumber itup_off;
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BlockNumber itup_blkno;
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OffsetNumber newitemoff;
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OffsetNumber firstright = InvalidOffsetNumber;
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Size itemsz;
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page = BufferGetPage(buf);
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lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
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itemsz = IndexTupleDSize(btitem->bti_itup)
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+ (sizeof(BTItemData) - sizeof(IndexTupleData));
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itemsz = MAXALIGN(itemsz); /* be safe, PageAddItem will do this but
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* we need to be consistent */
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/*
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* Check whether the item can fit on a btree page at all. (Eventually,
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* we ought to try to apply TOAST methods if not.) We actually need to
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* be able to fit three items on every page, so restrict any one item
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* to 1/3 the per-page available space. Note that at this point,
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* itemsz doesn't include the ItemId.
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*/
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if (itemsz > BTMaxItemSize(page))
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("index tuple size %lu exceeds btree maximum, %lu",
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(unsigned long) itemsz,
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(unsigned long) BTMaxItemSize(page))));
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/*
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* Determine exactly where new item will go.
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*/
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if (afteritem > 0)
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newitemoff = afteritem + 1;
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else
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{
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/*----------
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* If we will need to split the page to put the item here,
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* check whether we can put the tuple somewhere to the right,
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* instead. Keep scanning right until we
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* (a) find a page with enough free space,
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* (b) reach the last page where the tuple can legally go, or
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* (c) get tired of searching.
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* (c) is not flippant; it is important because if there are many
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* pages' worth of equal keys, it's better to split one of the early
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* pages than to scan all the way to the end of the run of equal keys
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* on every insert. We implement "get tired" as a random choice,
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* since stopping after scanning a fixed number of pages wouldn't work
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* well (we'd never reach the right-hand side of previously split
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* pages). Currently the probability of moving right is set at 0.99,
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* which may seem too high to change the behavior much, but it does an
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* excellent job of preventing O(N^2) behavior with many equal keys.
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*----------
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*/
|
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bool movedright = false;
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|
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while (PageGetFreeSpace(page) < itemsz &&
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!P_RIGHTMOST(lpageop) &&
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_bt_compare(rel, keysz, scankey, page, P_HIKEY) == 0 &&
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random() > (MAX_RANDOM_VALUE / 100))
|
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{
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/*
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* step right to next non-dead page
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*
|
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* must write-lock that page before releasing write lock on
|
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* current page; else someone else's _bt_check_unique scan
|
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* could fail to see our insertion. write locks on
|
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* intermediate dead pages won't do because we don't know when
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* they will get de-linked from the tree.
|
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*/
|
|
Buffer rbuf = InvalidBuffer;
|
|
|
|
for (;;)
|
|
{
|
|
BlockNumber rblkno = lpageop->btpo_next;
|
|
|
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if (rbuf != InvalidBuffer)
|
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_bt_relbuf(rel, rbuf);
|
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rbuf = _bt_getbuf(rel, rblkno, BT_WRITE);
|
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page = BufferGetPage(rbuf);
|
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lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
|
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if (!P_IGNORE(lpageop))
|
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break;
|
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if (P_RIGHTMOST(lpageop))
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elog(ERROR, "fell off the end of \"%s\"",
|
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RelationGetRelationName(rel));
|
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}
|
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_bt_relbuf(rel, buf);
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buf = rbuf;
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movedright = true;
|
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}
|
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|
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/*
|
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* Now we are on the right page, so find the insert position. If
|
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* we moved right at all, we know we should insert at the start of
|
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* the page, else must find the position by searching.
|
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*/
|
|
if (movedright)
|
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newitemoff = P_FIRSTDATAKEY(lpageop);
|
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else
|
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newitemoff = _bt_binsrch(rel, buf, keysz, scankey);
|
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}
|
|
|
|
/*
|
|
* Do we need to split the page to fit the item on it?
|
|
*
|
|
* Note: PageGetFreeSpace() subtracts sizeof(ItemIdData) from its result,
|
|
* so this comparison is correct even though we appear to be
|
|
* accounting only for the item and not for its line pointer.
|
|
*/
|
|
if (PageGetFreeSpace(page) < itemsz)
|
|
{
|
|
bool is_root = P_ISROOT(lpageop);
|
|
bool is_only = P_LEFTMOST(lpageop) && P_RIGHTMOST(lpageop);
|
|
bool newitemonleft;
|
|
Buffer rbuf;
|
|
|
|
/* Choose the split point */
|
|
firstright = _bt_findsplitloc(rel, page,
|
|
newitemoff, itemsz,
|
|
&newitemonleft);
|
|
|
|
/* split the buffer into left and right halves */
|
|
rbuf = _bt_split(rel, buf, firstright,
|
|
newitemoff, itemsz, btitem, newitemonleft,
|
|
&itup_off, &itup_blkno);
|
|
|
|
/*----------
|
|
* By here,
|
|
*
|
|
* + our target page has been split;
|
|
* + the original tuple has been inserted;
|
|
* + we have write locks on both the old (left half)
|
|
* and new (right half) buffers, after the split; and
|
|
* + we know the key we want to insert into the parent
|
|
* (it's the "high key" on the left child page).
|
|
*
|
|
* We're ready to do the parent insertion. We need to hold onto the
|
|
* locks for the child pages until we locate the parent, but we can
|
|
* release them before doing the actual insertion (see Lehman and Yao
|
|
* for the reasoning).
|
|
*----------
|
|
*/
|
|
_bt_insert_parent(rel, buf, rbuf, stack, is_root, is_only);
|
|
}
|
|
else
|
|
{
|
|
Buffer metabuf = InvalidBuffer;
|
|
Page metapg = NULL;
|
|
BTMetaPageData *metad = NULL;
|
|
|
|
itup_off = newitemoff;
|
|
itup_blkno = BufferGetBlockNumber(buf);
|
|
|
|
/*
|
|
* If we are doing this insert because we split a page that was
|
|
* the only one on its tree level, but was not the root, it may
|
|
* have been the "fast root". We need to ensure that the fast
|
|
* root link points at or above the current page. We can safely
|
|
* acquire a lock on the metapage here --- see comments for
|
|
* _bt_newroot().
|
|
*/
|
|
if (split_only_page)
|
|
{
|
|
metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
|
|
metapg = BufferGetPage(metabuf);
|
|
metad = BTPageGetMeta(metapg);
|
|
|
|
if (metad->btm_fastlevel >= lpageop->btpo.level)
|
|
{
|
|
/* no update wanted */
|
|
_bt_relbuf(rel, metabuf);
|
|
metabuf = InvalidBuffer;
|
|
}
|
|
}
|
|
|
|
/* Do the update. No ereport(ERROR) until changes are logged */
|
|
START_CRIT_SECTION();
|
|
|
|
_bt_pgaddtup(rel, page, itemsz, btitem, newitemoff, "page");
|
|
|
|
if (BufferIsValid(metabuf))
|
|
{
|
|
metad->btm_fastroot = itup_blkno;
|
|
metad->btm_fastlevel = lpageop->btpo.level;
|
|
}
|
|
|
|
/* XLOG stuff */
|
|
if (!rel->rd_istemp)
|
|
{
|
|
xl_btree_insert xlrec;
|
|
xl_btree_metadata xlmeta;
|
|
uint8 xlinfo;
|
|
XLogRecPtr recptr;
|
|
XLogRecData rdata[3];
|
|
XLogRecData *nextrdata;
|
|
BTItemData truncitem;
|
|
|
|
xlrec.target.node = rel->rd_node;
|
|
ItemPointerSet(&(xlrec.target.tid), itup_blkno, itup_off);
|
|
|
|
rdata[0].buffer = InvalidBuffer;
|
|
rdata[0].data = (char *) &xlrec;
|
|
rdata[0].len = SizeOfBtreeInsert;
|
|
rdata[0].next = nextrdata = &(rdata[1]);
|
|
|
|
if (BufferIsValid(metabuf))
|
|
{
|
|
xlmeta.root = metad->btm_root;
|
|
xlmeta.level = metad->btm_level;
|
|
xlmeta.fastroot = metad->btm_fastroot;
|
|
xlmeta.fastlevel = metad->btm_fastlevel;
|
|
|
|
nextrdata->buffer = InvalidBuffer;
|
|
nextrdata->data = (char *) &xlmeta;
|
|
nextrdata->len = sizeof(xl_btree_metadata);
|
|
nextrdata->next = nextrdata + 1;
|
|
nextrdata++;
|
|
xlinfo = XLOG_BTREE_INSERT_META;
|
|
}
|
|
else if (P_ISLEAF(lpageop))
|
|
xlinfo = XLOG_BTREE_INSERT_LEAF;
|
|
else
|
|
xlinfo = XLOG_BTREE_INSERT_UPPER;
|
|
|
|
/* Read comments in _bt_pgaddtup */
|
|
if (!P_ISLEAF(lpageop) && newitemoff == P_FIRSTDATAKEY(lpageop))
|
|
{
|
|
truncitem = *btitem;
|
|
truncitem.bti_itup.t_info = sizeof(BTItemData);
|
|
nextrdata->data = (char *) &truncitem;
|
|
nextrdata->len = sizeof(BTItemData);
|
|
}
|
|
else
|
|
{
|
|
nextrdata->data = (char *) btitem;
|
|
nextrdata->len = IndexTupleDSize(btitem->bti_itup) +
|
|
(sizeof(BTItemData) - sizeof(IndexTupleData));
|
|
}
|
|
nextrdata->buffer = buf;
|
|
nextrdata->next = NULL;
|
|
|
|
recptr = XLogInsert(RM_BTREE_ID, xlinfo, rdata);
|
|
|
|
if (BufferIsValid(metabuf))
|
|
{
|
|
PageSetLSN(metapg, recptr);
|
|
PageSetSUI(metapg, ThisStartUpID);
|
|
}
|
|
|
|
PageSetLSN(page, recptr);
|
|
PageSetSUI(page, ThisStartUpID);
|
|
}
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/* Write out the updated page and release pin/lock */
|
|
if (BufferIsValid(metabuf))
|
|
_bt_wrtbuf(rel, metabuf);
|
|
|
|
_bt_wrtbuf(rel, buf);
|
|
}
|
|
|
|
/* by here, the new tuple is inserted at itup_blkno/itup_off */
|
|
res = (InsertIndexResult) palloc(sizeof(InsertIndexResultData));
|
|
ItemPointerSet(&(res->pointerData), itup_blkno, itup_off);
|
|
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* _bt_split() -- split a page in the btree.
|
|
*
|
|
* On entry, buf is the page to split, and is write-locked and pinned.
|
|
* firstright is the item index of the first item to be moved to the
|
|
* new right page. newitemoff etc. tell us about the new item that
|
|
* must be inserted along with the data from the old page.
|
|
*
|
|
* Returns the new right sibling of buf, pinned and write-locked.
|
|
* The pin and lock on buf are maintained. *itup_off and *itup_blkno
|
|
* are set to the exact location where newitem was inserted.
|
|
*/
|
|
static Buffer
|
|
_bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
|
|
OffsetNumber newitemoff, Size newitemsz, BTItem newitem,
|
|
bool newitemonleft,
|
|
OffsetNumber *itup_off, BlockNumber *itup_blkno)
|
|
{
|
|
Buffer rbuf;
|
|
Page origpage;
|
|
Page leftpage,
|
|
rightpage;
|
|
BTPageOpaque ropaque,
|
|
lopaque,
|
|
oopaque;
|
|
Buffer sbuf = InvalidBuffer;
|
|
Page spage = NULL;
|
|
BTPageOpaque sopaque = NULL;
|
|
Size itemsz;
|
|
ItemId itemid;
|
|
BTItem item;
|
|
OffsetNumber leftoff,
|
|
rightoff;
|
|
OffsetNumber maxoff;
|
|
OffsetNumber i;
|
|
|
|
rbuf = _bt_getbuf(rel, P_NEW, BT_WRITE);
|
|
origpage = BufferGetPage(buf);
|
|
leftpage = PageGetTempPage(origpage, sizeof(BTPageOpaqueData));
|
|
rightpage = BufferGetPage(rbuf);
|
|
|
|
_bt_pageinit(leftpage, BufferGetPageSize(buf));
|
|
_bt_pageinit(rightpage, BufferGetPageSize(rbuf));
|
|
|
|
/* init btree private data */
|
|
oopaque = (BTPageOpaque) PageGetSpecialPointer(origpage);
|
|
lopaque = (BTPageOpaque) PageGetSpecialPointer(leftpage);
|
|
ropaque = (BTPageOpaque) PageGetSpecialPointer(rightpage);
|
|
|
|
/* if we're splitting this page, it won't be the root when we're done */
|
|
lopaque->btpo_flags = oopaque->btpo_flags;
|
|
lopaque->btpo_flags &= ~BTP_ROOT;
|
|
ropaque->btpo_flags = lopaque->btpo_flags;
|
|
lopaque->btpo_prev = oopaque->btpo_prev;
|
|
lopaque->btpo_next = BufferGetBlockNumber(rbuf);
|
|
ropaque->btpo_prev = BufferGetBlockNumber(buf);
|
|
ropaque->btpo_next = oopaque->btpo_next;
|
|
lopaque->btpo.level = ropaque->btpo.level = oopaque->btpo.level;
|
|
|
|
/*
|
|
* If the page we're splitting is not the rightmost page at its level
|
|
* in the tree, then the first entry on the page is the high key for
|
|
* the page. We need to copy that to the right half. Otherwise
|
|
* (meaning the rightmost page case), all the items on the right half
|
|
* will be user data.
|
|
*/
|
|
rightoff = P_HIKEY;
|
|
|
|
if (!P_RIGHTMOST(oopaque))
|
|
{
|
|
itemid = PageGetItemId(origpage, P_HIKEY);
|
|
itemsz = ItemIdGetLength(itemid);
|
|
item = (BTItem) PageGetItem(origpage, itemid);
|
|
if (PageAddItem(rightpage, (Item) item, itemsz, rightoff,
|
|
LP_USED) == InvalidOffsetNumber)
|
|
elog(PANIC, "failed to add hikey to the right sibling");
|
|
rightoff = OffsetNumberNext(rightoff);
|
|
}
|
|
|
|
/*
|
|
* The "high key" for the new left page will be the first key that's
|
|
* going to go into the new right page. This might be either the
|
|
* existing data item at position firstright, or the incoming tuple.
|
|
*/
|
|
leftoff = P_HIKEY;
|
|
if (!newitemonleft && newitemoff == firstright)
|
|
{
|
|
/* incoming tuple will become first on right page */
|
|
itemsz = newitemsz;
|
|
item = newitem;
|
|
}
|
|
else
|
|
{
|
|
/* existing item at firstright will become first on right page */
|
|
itemid = PageGetItemId(origpage, firstright);
|
|
itemsz = ItemIdGetLength(itemid);
|
|
item = (BTItem) PageGetItem(origpage, itemid);
|
|
}
|
|
if (PageAddItem(leftpage, (Item) item, itemsz, leftoff,
|
|
LP_USED) == InvalidOffsetNumber)
|
|
elog(PANIC, "failed to add hikey to the left sibling");
|
|
leftoff = OffsetNumberNext(leftoff);
|
|
|
|
/*
|
|
* Now transfer all the data items to the appropriate page
|
|
*/
|
|
maxoff = PageGetMaxOffsetNumber(origpage);
|
|
|
|
for (i = P_FIRSTDATAKEY(oopaque); i <= maxoff; i = OffsetNumberNext(i))
|
|
{
|
|
itemid = PageGetItemId(origpage, i);
|
|
itemsz = ItemIdGetLength(itemid);
|
|
item = (BTItem) PageGetItem(origpage, itemid);
|
|
|
|
/* does new item belong before this one? */
|
|
if (i == newitemoff)
|
|
{
|
|
if (newitemonleft)
|
|
{
|
|
_bt_pgaddtup(rel, leftpage, newitemsz, newitem, leftoff,
|
|
"left sibling");
|
|
*itup_off = leftoff;
|
|
*itup_blkno = BufferGetBlockNumber(buf);
|
|
leftoff = OffsetNumberNext(leftoff);
|
|
}
|
|
else
|
|
{
|
|
_bt_pgaddtup(rel, rightpage, newitemsz, newitem, rightoff,
|
|
"right sibling");
|
|
*itup_off = rightoff;
|
|
*itup_blkno = BufferGetBlockNumber(rbuf);
|
|
rightoff = OffsetNumberNext(rightoff);
|
|
}
|
|
}
|
|
|
|
/* decide which page to put it on */
|
|
if (i < firstright)
|
|
{
|
|
_bt_pgaddtup(rel, leftpage, itemsz, item, leftoff,
|
|
"left sibling");
|
|
leftoff = OffsetNumberNext(leftoff);
|
|
}
|
|
else
|
|
{
|
|
_bt_pgaddtup(rel, rightpage, itemsz, item, rightoff,
|
|
"right sibling");
|
|
rightoff = OffsetNumberNext(rightoff);
|
|
}
|
|
}
|
|
|
|
/* cope with possibility that newitem goes at the end */
|
|
if (i <= newitemoff)
|
|
{
|
|
if (newitemonleft)
|
|
{
|
|
_bt_pgaddtup(rel, leftpage, newitemsz, newitem, leftoff,
|
|
"left sibling");
|
|
*itup_off = leftoff;
|
|
*itup_blkno = BufferGetBlockNumber(buf);
|
|
leftoff = OffsetNumberNext(leftoff);
|
|
}
|
|
else
|
|
{
|
|
_bt_pgaddtup(rel, rightpage, newitemsz, newitem, rightoff,
|
|
"right sibling");
|
|
*itup_off = rightoff;
|
|
*itup_blkno = BufferGetBlockNumber(rbuf);
|
|
rightoff = OffsetNumberNext(rightoff);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We have to grab the right sibling (if any) and fix the prev pointer
|
|
* there. We are guaranteed that this is deadlock-free since no other
|
|
* writer will be holding a lock on that page and trying to move left,
|
|
* and all readers release locks on a page before trying to fetch its
|
|
* neighbors.
|
|
*/
|
|
|
|
if (!P_RIGHTMOST(ropaque))
|
|
{
|
|
sbuf = _bt_getbuf(rel, ropaque->btpo_next, BT_WRITE);
|
|
spage = BufferGetPage(sbuf);
|
|
sopaque = (BTPageOpaque) PageGetSpecialPointer(spage);
|
|
if (sopaque->btpo_prev != ropaque->btpo_prev)
|
|
elog(PANIC, "right sibling's left-link doesn't match");
|
|
}
|
|
|
|
/*
|
|
* Right sibling is locked, new siblings are prepared, but original
|
|
* page is not updated yet. Log changes before continuing.
|
|
*
|
|
* NO EREPORT(ERROR) till right sibling is updated.
|
|
*/
|
|
START_CRIT_SECTION();
|
|
|
|
if (!P_RIGHTMOST(ropaque))
|
|
sopaque->btpo_prev = BufferGetBlockNumber(rbuf);
|
|
|
|
/* XLOG stuff */
|
|
if (!rel->rd_istemp)
|
|
{
|
|
xl_btree_split xlrec;
|
|
uint8 xlinfo;
|
|
XLogRecPtr recptr;
|
|
XLogRecData rdata[4];
|
|
|
|
xlrec.target.node = rel->rd_node;
|
|
ItemPointerSet(&(xlrec.target.tid), *itup_blkno, *itup_off);
|
|
if (newitemonleft)
|
|
xlrec.otherblk = BufferGetBlockNumber(rbuf);
|
|
else
|
|
xlrec.otherblk = BufferGetBlockNumber(buf);
|
|
xlrec.leftblk = lopaque->btpo_prev;
|
|
xlrec.rightblk = ropaque->btpo_next;
|
|
xlrec.level = lopaque->btpo.level;
|
|
|
|
/*
|
|
* Direct access to page is not good but faster - we should
|
|
* implement some new func in page API. Note we only store the
|
|
* tuples themselves, knowing that the item pointers are in the
|
|
* same order and can be reconstructed by scanning the tuples.
|
|
*/
|
|
xlrec.leftlen = ((PageHeader) leftpage)->pd_special -
|
|
((PageHeader) leftpage)->pd_upper;
|
|
|
|
rdata[0].buffer = InvalidBuffer;
|
|
rdata[0].data = (char *) &xlrec;
|
|
rdata[0].len = SizeOfBtreeSplit;
|
|
rdata[0].next = &(rdata[1]);
|
|
|
|
rdata[1].buffer = InvalidBuffer;
|
|
rdata[1].data = (char *) leftpage + ((PageHeader) leftpage)->pd_upper;
|
|
rdata[1].len = xlrec.leftlen;
|
|
rdata[1].next = &(rdata[2]);
|
|
|
|
rdata[2].buffer = InvalidBuffer;
|
|
rdata[2].data = (char *) rightpage + ((PageHeader) rightpage)->pd_upper;
|
|
rdata[2].len = ((PageHeader) rightpage)->pd_special -
|
|
((PageHeader) rightpage)->pd_upper;
|
|
rdata[2].next = NULL;
|
|
|
|
if (!P_RIGHTMOST(ropaque))
|
|
{
|
|
rdata[2].next = &(rdata[3]);
|
|
rdata[3].buffer = sbuf;
|
|
rdata[3].data = NULL;
|
|
rdata[3].len = 0;
|
|
rdata[3].next = NULL;
|
|
}
|
|
|
|
if (P_ISROOT(oopaque))
|
|
xlinfo = newitemonleft ? XLOG_BTREE_SPLIT_L_ROOT : XLOG_BTREE_SPLIT_R_ROOT;
|
|
else
|
|
xlinfo = newitemonleft ? XLOG_BTREE_SPLIT_L : XLOG_BTREE_SPLIT_R;
|
|
|
|
recptr = XLogInsert(RM_BTREE_ID, xlinfo, rdata);
|
|
|
|
PageSetLSN(leftpage, recptr);
|
|
PageSetSUI(leftpage, ThisStartUpID);
|
|
PageSetLSN(rightpage, recptr);
|
|
PageSetSUI(rightpage, ThisStartUpID);
|
|
if (!P_RIGHTMOST(ropaque))
|
|
{
|
|
PageSetLSN(spage, recptr);
|
|
PageSetSUI(spage, ThisStartUpID);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* By here, the original data page has been split into two new halves,
|
|
* and these are correct. The algorithm requires that the left page
|
|
* never move during a split, so we copy the new left page back on top
|
|
* of the original. Note that this is not a waste of time, since we
|
|
* also require (in the page management code) that the center of a
|
|
* page always be clean, and the most efficient way to guarantee this
|
|
* is just to compact the data by reinserting it into a new left page.
|
|
*/
|
|
|
|
PageRestoreTempPage(leftpage, origpage);
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/* write and release the old right sibling */
|
|
if (!P_RIGHTMOST(ropaque))
|
|
_bt_wrtbuf(rel, sbuf);
|
|
|
|
/* split's done */
|
|
return rbuf;
|
|
}
|
|
|
|
/*
|
|
* _bt_findsplitloc() -- find an appropriate place to split a page.
|
|
*
|
|
* The idea here is to equalize the free space that will be on each split
|
|
* page, *after accounting for the inserted tuple*. (If we fail to account
|
|
* for it, we might find ourselves with too little room on the page that
|
|
* it needs to go into!)
|
|
*
|
|
* If the page is the rightmost page on its level, we instead try to arrange
|
|
* for twice as much free space on the right as on the left. In this way,
|
|
* when we are inserting successively increasing keys (consider sequences,
|
|
* timestamps, etc) we will end up with a tree whose pages are about 67% full,
|
|
* instead of the 50% full result that we'd get without this special case.
|
|
* (We could bias it even further to make the initially-loaded tree more full.
|
|
* But since the steady-state load for a btree is about 70%, we'd likely just
|
|
* be making more page-splitting work for ourselves later on, when we start
|
|
* seeing updates to existing tuples.)
|
|
*
|
|
* We are passed the intended insert position of the new tuple, expressed as
|
|
* the offsetnumber of the tuple it must go in front of. (This could be
|
|
* maxoff+1 if the tuple is to go at the end.)
|
|
*
|
|
* We return the index of the first existing tuple that should go on the
|
|
* righthand page, plus a boolean indicating whether the new tuple goes on
|
|
* the left or right page. The bool is necessary to disambiguate the case
|
|
* where firstright == newitemoff.
|
|
*/
|
|
static OffsetNumber
|
|
_bt_findsplitloc(Relation rel,
|
|
Page page,
|
|
OffsetNumber newitemoff,
|
|
Size newitemsz,
|
|
bool *newitemonleft)
|
|
{
|
|
BTPageOpaque opaque;
|
|
OffsetNumber offnum;
|
|
OffsetNumber maxoff;
|
|
ItemId itemid;
|
|
FindSplitData state;
|
|
int leftspace,
|
|
rightspace,
|
|
goodenough,
|
|
dataitemtotal,
|
|
dataitemstoleft;
|
|
|
|
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
|
|
|
|
/* Passed-in newitemsz is MAXALIGNED but does not include line pointer */
|
|
newitemsz += sizeof(ItemIdData);
|
|
state.newitemsz = newitemsz;
|
|
state.is_leaf = P_ISLEAF(opaque);
|
|
state.is_rightmost = P_RIGHTMOST(opaque);
|
|
state.have_split = false;
|
|
|
|
/* Total free space available on a btree page, after fixed overhead */
|
|
leftspace = rightspace =
|
|
PageGetPageSize(page) - SizeOfPageHeaderData -
|
|
MAXALIGN(sizeof(BTPageOpaqueData));
|
|
|
|
/*
|
|
* Finding the best possible split would require checking all the
|
|
* possible split points, because of the high-key and left-key special
|
|
* cases. That's probably more work than it's worth; instead, stop as
|
|
* soon as we find a "good-enough" split, where good-enough is defined
|
|
* as an imbalance in free space of no more than pagesize/16
|
|
* (arbitrary...) This should let us stop near the middle on most
|
|
* pages, instead of plowing to the end.
|
|
*/
|
|
goodenough = leftspace / 16;
|
|
|
|
/* The right page will have the same high key as the old page */
|
|
if (!P_RIGHTMOST(opaque))
|
|
{
|
|
itemid = PageGetItemId(page, P_HIKEY);
|
|
rightspace -= (int) (MAXALIGN(ItemIdGetLength(itemid)) +
|
|
sizeof(ItemIdData));
|
|
}
|
|
|
|
/* Count up total space in data items without actually scanning 'em */
|
|
dataitemtotal = rightspace - (int) PageGetFreeSpace(page);
|
|
|
|
/*
|
|
* Scan through the data items and calculate space usage for a split
|
|
* at each possible position.
|
|
*/
|
|
dataitemstoleft = 0;
|
|
maxoff = PageGetMaxOffsetNumber(page);
|
|
|
|
for (offnum = P_FIRSTDATAKEY(opaque);
|
|
offnum <= maxoff;
|
|
offnum = OffsetNumberNext(offnum))
|
|
{
|
|
Size itemsz;
|
|
int leftfree,
|
|
rightfree;
|
|
|
|
itemid = PageGetItemId(page, offnum);
|
|
itemsz = MAXALIGN(ItemIdGetLength(itemid)) + sizeof(ItemIdData);
|
|
|
|
/*
|
|
* We have to allow for the current item becoming the high key of
|
|
* the left page; therefore it counts against left space as well
|
|
* as right space.
|
|
*/
|
|
leftfree = leftspace - dataitemstoleft - (int) itemsz;
|
|
rightfree = rightspace - (dataitemtotal - dataitemstoleft);
|
|
|
|
/*
|
|
* Will the new item go to left or right of split?
|
|
*/
|
|
if (offnum > newitemoff)
|
|
_bt_checksplitloc(&state, offnum, leftfree, rightfree,
|
|
true, itemsz);
|
|
else if (offnum < newitemoff)
|
|
_bt_checksplitloc(&state, offnum, leftfree, rightfree,
|
|
false, itemsz);
|
|
else
|
|
{
|
|
/* need to try it both ways! */
|
|
_bt_checksplitloc(&state, offnum, leftfree, rightfree,
|
|
true, itemsz);
|
|
/* here we are contemplating newitem as first on right */
|
|
_bt_checksplitloc(&state, offnum, leftfree, rightfree,
|
|
false, newitemsz);
|
|
}
|
|
|
|
/* Abort scan once we find a good-enough choice */
|
|
if (state.have_split && state.best_delta <= goodenough)
|
|
break;
|
|
|
|
dataitemstoleft += itemsz;
|
|
}
|
|
|
|
/*
|
|
* I believe it is not possible to fail to find a feasible split, but
|
|
* just in case ...
|
|
*/
|
|
if (!state.have_split)
|
|
elog(ERROR, "could not find a feasible split point for \"%s\"",
|
|
RelationGetRelationName(rel));
|
|
|
|
*newitemonleft = state.newitemonleft;
|
|
return state.firstright;
|
|
}
|
|
|
|
/*
|
|
* Subroutine to analyze a particular possible split choice (ie, firstright
|
|
* and newitemonleft settings), and record the best split so far in *state.
|
|
*/
|
|
static void
|
|
_bt_checksplitloc(FindSplitData *state, OffsetNumber firstright,
|
|
int leftfree, int rightfree,
|
|
bool newitemonleft, Size firstrightitemsz)
|
|
{
|
|
/*
|
|
* Account for the new item on whichever side it is to be put.
|
|
*/
|
|
if (newitemonleft)
|
|
leftfree -= (int) state->newitemsz;
|
|
else
|
|
rightfree -= (int) state->newitemsz;
|
|
|
|
/*
|
|
* If we are not on the leaf level, we will be able to discard the key
|
|
* data from the first item that winds up on the right page.
|
|
*/
|
|
if (!state->is_leaf)
|
|
rightfree += (int) firstrightitemsz -
|
|
(int) (MAXALIGN(sizeof(BTItemData)) + sizeof(ItemIdData));
|
|
|
|
/*
|
|
* If feasible split point, remember best delta.
|
|
*/
|
|
if (leftfree >= 0 && rightfree >= 0)
|
|
{
|
|
int delta;
|
|
|
|
if (state->is_rightmost)
|
|
{
|
|
/*
|
|
* On a rightmost page, try to equalize right free space with
|
|
* twice the left free space. See comments for
|
|
* _bt_findsplitloc.
|
|
*/
|
|
delta = (2 * leftfree) - rightfree;
|
|
}
|
|
else
|
|
{
|
|
/* Otherwise, aim for equal free space on both sides */
|
|
delta = leftfree - rightfree;
|
|
}
|
|
|
|
if (delta < 0)
|
|
delta = -delta;
|
|
if (!state->have_split || delta < state->best_delta)
|
|
{
|
|
state->have_split = true;
|
|
state->newitemonleft = newitemonleft;
|
|
state->firstright = firstright;
|
|
state->best_delta = delta;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* _bt_insert_parent() -- Insert downlink into parent after a page split.
|
|
*
|
|
* On entry, buf and rbuf are the left and right split pages, which we
|
|
* still hold write locks on per the L&Y algorithm. We release the
|
|
* write locks once we have write lock on the parent page. (Any sooner,
|
|
* and it'd be possible for some other process to try to split or delete
|
|
* one of these pages, and get confused because it cannot find the downlink.)
|
|
*
|
|
* stack - stack showing how we got here. May be NULL in cases that don't
|
|
* have to be efficient (concurrent ROOT split, WAL recovery)
|
|
* is_root - we split the true root
|
|
* is_only - we split a page alone on its level (might have been fast root)
|
|
*
|
|
* This is exported so it can be called by nbtxlog.c.
|
|
*/
|
|
void
|
|
_bt_insert_parent(Relation rel,
|
|
Buffer buf,
|
|
Buffer rbuf,
|
|
BTStack stack,
|
|
bool is_root,
|
|
bool is_only)
|
|
{
|
|
/*
|
|
* Here we have to do something Lehman and Yao don't talk about: deal
|
|
* with a root split and construction of a new root. If our stack is
|
|
* empty then we have just split a node on what had been the root
|
|
* level when we descended the tree. If it was still the root then we
|
|
* perform a new-root construction. If it *wasn't* the root anymore,
|
|
* search to find the next higher level that someone constructed
|
|
* meanwhile, and find the right place to insert as for the normal
|
|
* case.
|
|
*
|
|
* If we have to search for the parent level, we do so by re-descending
|
|
* from the root. This is not super-efficient, but it's rare enough
|
|
* not to matter. (This path is also taken when called from WAL
|
|
* recovery --- we have no stack in that case.)
|
|
*/
|
|
if (is_root)
|
|
{
|
|
Buffer rootbuf;
|
|
|
|
Assert(stack == (BTStack) NULL);
|
|
Assert(is_only);
|
|
/* create a new root node and update the metapage */
|
|
rootbuf = _bt_newroot(rel, buf, rbuf);
|
|
/* release the split buffers */
|
|
_bt_wrtbuf(rel, rootbuf);
|
|
_bt_wrtbuf(rel, rbuf);
|
|
_bt_wrtbuf(rel, buf);
|
|
}
|
|
else
|
|
{
|
|
BlockNumber bknum = BufferGetBlockNumber(buf);
|
|
BlockNumber rbknum = BufferGetBlockNumber(rbuf);
|
|
Page page = BufferGetPage(buf);
|
|
InsertIndexResult newres;
|
|
BTItem new_item;
|
|
BTStackData fakestack;
|
|
BTItem ritem;
|
|
Buffer pbuf;
|
|
|
|
if (stack == (BTStack) NULL)
|
|
{
|
|
BTPageOpaque lpageop;
|
|
|
|
if (!InRecovery)
|
|
elog(DEBUG2, "concurrent ROOT page split");
|
|
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
|
|
/* Find the leftmost page at the next level up */
|
|
pbuf = _bt_get_endpoint(rel, lpageop->btpo.level + 1, false);
|
|
/* Set up a phony stack entry pointing there */
|
|
stack = &fakestack;
|
|
stack->bts_blkno = BufferGetBlockNumber(pbuf);
|
|
stack->bts_offset = InvalidOffsetNumber;
|
|
/* bts_btitem will be initialized below */
|
|
stack->bts_parent = NULL;
|
|
_bt_relbuf(rel, pbuf);
|
|
}
|
|
|
|
/* get high key from left page == lowest key on new right page */
|
|
ritem = (BTItem) PageGetItem(page,
|
|
PageGetItemId(page, P_HIKEY));
|
|
|
|
/* form an index tuple that points at the new right page */
|
|
new_item = _bt_formitem(&(ritem->bti_itup));
|
|
ItemPointerSet(&(new_item->bti_itup.t_tid), rbknum, P_HIKEY);
|
|
|
|
/*
|
|
* Find the parent buffer and get the parent page.
|
|
*
|
|
* Oops - if we were moved right then we need to change stack item!
|
|
* We want to find parent pointing to where we are, right ? -
|
|
* vadim 05/27/97
|
|
*/
|
|
ItemPointerSet(&(stack->bts_btitem.bti_itup.t_tid),
|
|
bknum, P_HIKEY);
|
|
|
|
pbuf = _bt_getstackbuf(rel, stack, BT_WRITE);
|
|
|
|
/* Now we can write and unlock the children */
|
|
_bt_wrtbuf(rel, rbuf);
|
|
_bt_wrtbuf(rel, buf);
|
|
|
|
/* Check for error only after writing children */
|
|
if (pbuf == InvalidBuffer)
|
|
elog(ERROR, "failed to re-find parent key in \"%s\"",
|
|
RelationGetRelationName(rel));
|
|
|
|
/* Recursively update the parent */
|
|
newres = _bt_insertonpg(rel, pbuf, stack->bts_parent,
|
|
0, NULL, new_item, stack->bts_offset,
|
|
is_only);
|
|
|
|
/* be tidy */
|
|
pfree(newres);
|
|
pfree(new_item);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* _bt_getstackbuf() -- Walk back up the tree one step, and find the item
|
|
* we last looked at in the parent.
|
|
*
|
|
* This is possible because we save the downlink from the parent item,
|
|
* which is enough to uniquely identify it. Insertions into the parent
|
|
* level could cause the item to move right; deletions could cause it
|
|
* to move left, but not left of the page we previously found it in.
|
|
*
|
|
* Adjusts bts_blkno & bts_offset if changed.
|
|
*
|
|
* Returns InvalidBuffer if item not found (should not happen).
|
|
*/
|
|
Buffer
|
|
_bt_getstackbuf(Relation rel, BTStack stack, int access)
|
|
{
|
|
BlockNumber blkno;
|
|
OffsetNumber start;
|
|
|
|
blkno = stack->bts_blkno;
|
|
start = stack->bts_offset;
|
|
|
|
for (;;)
|
|
{
|
|
Buffer buf;
|
|
Page page;
|
|
BTPageOpaque opaque;
|
|
|
|
buf = _bt_getbuf(rel, blkno, access);
|
|
page = BufferGetPage(buf);
|
|
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
|
|
|
|
if (!P_IGNORE(opaque))
|
|
{
|
|
OffsetNumber offnum,
|
|
minoff,
|
|
maxoff;
|
|
ItemId itemid;
|
|
BTItem item;
|
|
|
|
minoff = P_FIRSTDATAKEY(opaque);
|
|
maxoff = PageGetMaxOffsetNumber(page);
|
|
|
|
/*
|
|
* start = InvalidOffsetNumber means "search the whole page".
|
|
* We need this test anyway due to possibility that page has a
|
|
* high key now when it didn't before.
|
|
*/
|
|
if (start < minoff)
|
|
start = minoff;
|
|
|
|
/*
|
|
* These loops will check every item on the page --- but in an
|
|
* order that's attuned to the probability of where it
|
|
* actually is. Scan to the right first, then to the left.
|
|
*/
|
|
for (offnum = start;
|
|
offnum <= maxoff;
|
|
offnum = OffsetNumberNext(offnum))
|
|
{
|
|
itemid = PageGetItemId(page, offnum);
|
|
item = (BTItem) PageGetItem(page, itemid);
|
|
if (BTItemSame(item, &stack->bts_btitem))
|
|
{
|
|
/* Return accurate pointer to where link is now */
|
|
stack->bts_blkno = blkno;
|
|
stack->bts_offset = offnum;
|
|
return buf;
|
|
}
|
|
}
|
|
|
|
for (offnum = OffsetNumberPrev(start);
|
|
offnum >= minoff;
|
|
offnum = OffsetNumberPrev(offnum))
|
|
{
|
|
itemid = PageGetItemId(page, offnum);
|
|
item = (BTItem) PageGetItem(page, itemid);
|
|
if (BTItemSame(item, &stack->bts_btitem))
|
|
{
|
|
/* Return accurate pointer to where link is now */
|
|
stack->bts_blkno = blkno;
|
|
stack->bts_offset = offnum;
|
|
return buf;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The item we're looking for moved right at least one page.
|
|
*/
|
|
if (P_RIGHTMOST(opaque))
|
|
{
|
|
_bt_relbuf(rel, buf);
|
|
return (InvalidBuffer);
|
|
}
|
|
blkno = opaque->btpo_next;
|
|
start = InvalidOffsetNumber;
|
|
_bt_relbuf(rel, buf);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* _bt_newroot() -- Create a new root page for the index.
|
|
*
|
|
* We've just split the old root page and need to create a new one.
|
|
* In order to do this, we add a new root page to the file, then lock
|
|
* the metadata page and update it. This is guaranteed to be deadlock-
|
|
* free, because all readers release their locks on the metadata page
|
|
* before trying to lock the root, and all writers lock the root before
|
|
* trying to lock the metadata page. We have a write lock on the old
|
|
* root page, so we have not introduced any cycles into the waits-for
|
|
* graph.
|
|
*
|
|
* On entry, lbuf (the old root) and rbuf (its new peer) are write-
|
|
* locked. On exit, a new root page exists with entries for the
|
|
* two new children, metapage is updated and unlocked/unpinned.
|
|
* The new root buffer is returned to caller which has to unlock/unpin
|
|
* lbuf, rbuf & rootbuf.
|
|
*/
|
|
static Buffer
|
|
_bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
|
|
{
|
|
Buffer rootbuf;
|
|
Page lpage,
|
|
rpage,
|
|
rootpage;
|
|
BlockNumber lbkno,
|
|
rbkno;
|
|
BlockNumber rootblknum;
|
|
BTPageOpaque rootopaque;
|
|
ItemId itemid;
|
|
BTItem item;
|
|
Size itemsz;
|
|
BTItem new_item;
|
|
Buffer metabuf;
|
|
Page metapg;
|
|
BTMetaPageData *metad;
|
|
|
|
lbkno = BufferGetBlockNumber(lbuf);
|
|
rbkno = BufferGetBlockNumber(rbuf);
|
|
lpage = BufferGetPage(lbuf);
|
|
rpage = BufferGetPage(rbuf);
|
|
|
|
/* get a new root page */
|
|
rootbuf = _bt_getbuf(rel, P_NEW, BT_WRITE);
|
|
rootpage = BufferGetPage(rootbuf);
|
|
rootblknum = BufferGetBlockNumber(rootbuf);
|
|
|
|
/* acquire lock on the metapage */
|
|
metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
|
|
metapg = BufferGetPage(metabuf);
|
|
metad = BTPageGetMeta(metapg);
|
|
|
|
/* NO EREPORT(ERROR) from here till newroot op is logged */
|
|
START_CRIT_SECTION();
|
|
|
|
/* set btree special data */
|
|
rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
|
|
rootopaque->btpo_prev = rootopaque->btpo_next = P_NONE;
|
|
rootopaque->btpo_flags = BTP_ROOT;
|
|
rootopaque->btpo.level =
|
|
((BTPageOpaque) PageGetSpecialPointer(lpage))->btpo.level + 1;
|
|
|
|
/* update metapage data */
|
|
metad->btm_root = rootblknum;
|
|
metad->btm_level = rootopaque->btpo.level;
|
|
metad->btm_fastroot = rootblknum;
|
|
metad->btm_fastlevel = rootopaque->btpo.level;
|
|
|
|
/*
|
|
* Create downlink item for left page (old root). Since this will be
|
|
* the first item in a non-leaf page, it implicitly has minus-infinity
|
|
* key value, so we need not store any actual key in it.
|
|
*/
|
|
itemsz = sizeof(BTItemData);
|
|
new_item = (BTItem) palloc(itemsz);
|
|
new_item->bti_itup.t_info = itemsz;
|
|
ItemPointerSet(&(new_item->bti_itup.t_tid), lbkno, P_HIKEY);
|
|
|
|
/*
|
|
* Insert the left page pointer into the new root page. The root page
|
|
* is the rightmost page on its level so there is no "high key" in it;
|
|
* the two items will go into positions P_HIKEY and P_FIRSTKEY.
|
|
*/
|
|
if (PageAddItem(rootpage, (Item) new_item, itemsz, P_HIKEY, LP_USED) == InvalidOffsetNumber)
|
|
elog(PANIC, "failed to add leftkey to new root page");
|
|
pfree(new_item);
|
|
|
|
/*
|
|
* Create downlink item for right page. The key for it is obtained
|
|
* from the "high key" position in the left page.
|
|
*/
|
|
itemid = PageGetItemId(lpage, P_HIKEY);
|
|
itemsz = ItemIdGetLength(itemid);
|
|
item = (BTItem) PageGetItem(lpage, itemid);
|
|
new_item = _bt_formitem(&(item->bti_itup));
|
|
ItemPointerSet(&(new_item->bti_itup.t_tid), rbkno, P_HIKEY);
|
|
|
|
/*
|
|
* insert the right page pointer into the new root page.
|
|
*/
|
|
if (PageAddItem(rootpage, (Item) new_item, itemsz, P_FIRSTKEY, LP_USED) == InvalidOffsetNumber)
|
|
elog(PANIC, "failed to add rightkey to new root page");
|
|
pfree(new_item);
|
|
|
|
/* XLOG stuff */
|
|
if (!rel->rd_istemp)
|
|
{
|
|
xl_btree_newroot xlrec;
|
|
XLogRecPtr recptr;
|
|
XLogRecData rdata[2];
|
|
|
|
xlrec.node = rel->rd_node;
|
|
xlrec.rootblk = rootblknum;
|
|
xlrec.level = metad->btm_level;
|
|
|
|
rdata[0].buffer = InvalidBuffer;
|
|
rdata[0].data = (char *) &xlrec;
|
|
rdata[0].len = SizeOfBtreeNewroot;
|
|
rdata[0].next = &(rdata[1]);
|
|
|
|
/*
|
|
* Direct access to page is not good but faster - we should
|
|
* implement some new func in page API.
|
|
*/
|
|
rdata[1].buffer = InvalidBuffer;
|
|
rdata[1].data = (char *) rootpage + ((PageHeader) rootpage)->pd_upper;
|
|
rdata[1].len = ((PageHeader) rootpage)->pd_special -
|
|
((PageHeader) rootpage)->pd_upper;
|
|
rdata[1].next = NULL;
|
|
|
|
recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_NEWROOT, rdata);
|
|
|
|
PageSetLSN(rootpage, recptr);
|
|
PageSetSUI(rootpage, ThisStartUpID);
|
|
PageSetLSN(metapg, recptr);
|
|
PageSetSUI(metapg, ThisStartUpID);
|
|
PageSetLSN(lpage, recptr);
|
|
PageSetSUI(lpage, ThisStartUpID);
|
|
PageSetLSN(rpage, recptr);
|
|
PageSetSUI(rpage, ThisStartUpID);
|
|
}
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/* write and let go of metapage buffer */
|
|
_bt_wrtbuf(rel, metabuf);
|
|
|
|
return (rootbuf);
|
|
}
|
|
|
|
/*
|
|
* _bt_pgaddtup() -- add a tuple to a particular page in the index.
|
|
*
|
|
* This routine adds the tuple to the page as requested. It does
|
|
* not affect pin/lock status, but you'd better have a write lock
|
|
* and pin on the target buffer! Don't forget to write and release
|
|
* the buffer afterwards, either.
|
|
*
|
|
* The main difference between this routine and a bare PageAddItem call
|
|
* is that this code knows that the leftmost data item on a non-leaf
|
|
* btree page doesn't need to have a key. Therefore, it strips such
|
|
* items down to just the item header. CAUTION: this works ONLY if
|
|
* we insert the items in order, so that the given itup_off does
|
|
* represent the final position of the item!
|
|
*/
|
|
static void
|
|
_bt_pgaddtup(Relation rel,
|
|
Page page,
|
|
Size itemsize,
|
|
BTItem btitem,
|
|
OffsetNumber itup_off,
|
|
const char *where)
|
|
{
|
|
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
|
|
BTItemData truncitem;
|
|
|
|
if (!P_ISLEAF(opaque) && itup_off == P_FIRSTDATAKEY(opaque))
|
|
{
|
|
memcpy(&truncitem, btitem, sizeof(BTItemData));
|
|
truncitem.bti_itup.t_info = sizeof(BTItemData);
|
|
btitem = &truncitem;
|
|
itemsize = sizeof(BTItemData);
|
|
}
|
|
|
|
if (PageAddItem(page, (Item) btitem, itemsize, itup_off,
|
|
LP_USED) == InvalidOffsetNumber)
|
|
elog(PANIC, "failed to add item to the %s for \"%s\"",
|
|
where, RelationGetRelationName(rel));
|
|
}
|
|
|
|
/*
|
|
* _bt_isequal - used in _bt_doinsert in check for duplicates.
|
|
*
|
|
* This is very similar to _bt_compare, except for NULL handling.
|
|
* Rule is simple: NOT_NULL not equal NULL, NULL not equal NULL too.
|
|
*/
|
|
static bool
|
|
_bt_isequal(TupleDesc itupdesc, Page page, OffsetNumber offnum,
|
|
int keysz, ScanKey scankey)
|
|
{
|
|
BTItem btitem;
|
|
IndexTuple itup;
|
|
int i;
|
|
|
|
/* Better be comparing to a leaf item */
|
|
Assert(P_ISLEAF((BTPageOpaque) PageGetSpecialPointer(page)));
|
|
|
|
btitem = (BTItem) PageGetItem(page, PageGetItemId(page, offnum));
|
|
itup = &(btitem->bti_itup);
|
|
|
|
for (i = 1; i <= keysz; i++)
|
|
{
|
|
ScanKey entry = &scankey[i - 1];
|
|
AttrNumber attno;
|
|
Datum datum;
|
|
bool isNull;
|
|
int32 result;
|
|
|
|
attno = entry->sk_attno;
|
|
Assert(attno == i);
|
|
datum = index_getattr(itup, attno, itupdesc, &isNull);
|
|
|
|
/* NULLs are never equal to anything */
|
|
if ((entry->sk_flags & SK_ISNULL) || isNull)
|
|
return false;
|
|
|
|
result = DatumGetInt32(FunctionCall2(&entry->sk_func,
|
|
entry->sk_argument,
|
|
datum));
|
|
|
|
if (result != 0)
|
|
return false;
|
|
}
|
|
|
|
/* if we get here, the keys are equal */
|
|
return true;
|
|
}
|