diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtree.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtree.c | 90 |
1 files changed, 47 insertions, 43 deletions
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c index 3c814725fef..7d0dea4e788 100644 --- a/src/backend/access/nbtree/nbtree.c +++ b/src/backend/access/nbtree/nbtree.c @@ -12,7 +12,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.103 2003/07/21 20:29:39 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtree.c,v 1.104 2003/08/04 00:43:15 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -580,19 +580,20 @@ btbulkdelete(PG_FUNCTION_ARGS) /* * The outer loop iterates over index leaf pages, the inner over items - * on a leaf page. We issue just one _bt_delitems() call per page, - * so as to minimize WAL traffic. + * on a leaf page. We issue just one _bt_delitems() call per page, so + * as to minimize WAL traffic. * - * Note that we exclusive-lock every leaf page containing data items, - * in sequence left to right. It sounds attractive to only exclusive-lock - * those containing items we need to delete, but unfortunately that - * is not safe: we could then pass a stopped indexscan, which could - * in rare cases lead to deleting the item it needs to find when it - * resumes. (See _bt_restscan --- this could only happen if an indexscan - * stops on a deletable item and then a page split moves that item - * into a page further to its right, which the indexscan will have no - * pin on.) We can skip obtaining exclusive lock on empty pages - * though, since no indexscan could be stopped on those. + * Note that we exclusive-lock every leaf page containing data items, in + * sequence left to right. It sounds attractive to only + * exclusive-lock those containing items we need to delete, but + * unfortunately that is not safe: we could then pass a stopped + * indexscan, which could in rare cases lead to deleting the item it + * needs to find when it resumes. (See _bt_restscan --- this could + * only happen if an indexscan stops on a deletable item and then a + * page split moves that item into a page further to its right, which + * the indexscan will have no pin on.) We can skip obtaining + * exclusive lock on empty pages though, since no indexscan could be + * stopped on those. */ buf = _bt_get_endpoint(rel, 0, false); if (BufferIsValid(buf)) /* check for empty index */ @@ -604,7 +605,7 @@ btbulkdelete(PG_FUNCTION_ARGS) OffsetNumber offnum, minoff, maxoff; - BlockNumber nextpage; + BlockNumber nextpage; CHECK_FOR_INTERRUPTS(); @@ -622,12 +623,14 @@ btbulkdelete(PG_FUNCTION_ARGS) */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); LockBufferForCleanup(buf); + /* - * Recompute minoff/maxoff, both of which could have changed - * while we weren't holding the lock. + * Recompute minoff/maxoff, both of which could have + * changed while we weren't holding the lock. */ minoff = P_FIRSTDATAKEY(opaque); maxoff = PageGetMaxOffsetNumber(page); + /* * Scan over all items to see which ones need deleted * according to the callback function. @@ -640,7 +643,7 @@ btbulkdelete(PG_FUNCTION_ARGS) ItemPointer htup; btitem = (BTItem) PageGetItem(page, - PageGetItemId(page, offnum)); + PageGetItemId(page, offnum)); htup = &(btitem->bti_itup.t_tid); if (callback(htup, callback_state)) { @@ -651,6 +654,7 @@ btbulkdelete(PG_FUNCTION_ARGS) num_index_tuples += 1; } } + /* * If we need to delete anything, do it and write the buffer; * else just release the buffer. @@ -662,9 +666,7 @@ btbulkdelete(PG_FUNCTION_ARGS) _bt_wrtbuf(rel, buf); } else - { _bt_relbuf(rel, buf); - } /* And advance to next page, if any */ if (nextpage == P_NONE) break; @@ -712,7 +714,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS) /* No point in remembering more than MaxFSMPages pages */ maxFreePages = MaxFSMPages; if ((BlockNumber) maxFreePages > num_pages) - maxFreePages = (int) num_pages + 1; /* +1 to avoid palloc(0) */ + maxFreePages = (int) num_pages + 1; /* +1 to avoid palloc(0) */ freePages = (BlockNumber *) palloc(maxFreePages * sizeof(BlockNumber)); nFreePages = 0; @@ -728,10 +730,10 @@ btvacuumcleanup(PG_FUNCTION_ARGS) * after we start the scan will not be examined; this should be fine, * since they can't possibly be empty.) */ - for (blkno = BTREE_METAPAGE+1; blkno < num_pages; blkno++) + for (blkno = BTREE_METAPAGE + 1; blkno < num_pages; blkno++) { - Buffer buf; - Page page; + Buffer buf; + Page page; BTPageOpaque opaque; buf = _bt_getbuf(rel, blkno, BT_READ); @@ -753,7 +755,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS) P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page)) { /* Empty, try to delete */ - int ndel; + int ndel; /* Run pagedel in a temp context to avoid memory leakage */ MemoryContextReset(mycontext); @@ -768,7 +770,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS) /* * During VACUUM FULL it's okay to recycle deleted pages * immediately, since there can be no other transactions - * scanning the index. Note that we will only recycle the + * scanning the index. Note that we will only recycle the * current page and not any parent pages that _bt_pagedel * might have recursed to; this seems reasonable in the name * of simplicity. (Trying to do otherwise would mean we'd @@ -787,16 +789,16 @@ btvacuumcleanup(PG_FUNCTION_ARGS) } /* - * During VACUUM FULL, we truncate off any recyclable pages at the - * end of the index. In a normal vacuum it'd be unsafe to do this - * except by acquiring exclusive lock on the index and then rechecking - * all the pages; doesn't seem worth it. + * During VACUUM FULL, we truncate off any recyclable pages at the end + * of the index. In a normal vacuum it'd be unsafe to do this except + * by acquiring exclusive lock on the index and then rechecking all + * the pages; doesn't seem worth it. */ if (info->vacuum_full && nFreePages > 0) { - BlockNumber new_pages = num_pages; + BlockNumber new_pages = num_pages; - while (nFreePages > 0 && freePages[nFreePages-1] == new_pages-1) + while (nFreePages > 0 && freePages[nFreePages - 1] == new_pages - 1) { new_pages--; pages_deleted--; @@ -810,9 +812,10 @@ btvacuumcleanup(PG_FUNCTION_ARGS) * Okay to truncate. * * First, flush any shared buffers for the blocks we intend to - * delete. FlushRelationBuffers is a bit more than we need for - * this, since it will also write out dirty buffers for blocks we - * aren't deleting, but it's the closest thing in bufmgr's API. + * delete. FlushRelationBuffers is a bit more than we need + * for this, since it will also write out dirty buffers for + * blocks we aren't deleting, but it's the closest thing in + * bufmgr's API. */ i = FlushRelationBuffers(rel, new_pages); if (i < 0) @@ -822,7 +825,8 @@ btvacuumcleanup(PG_FUNCTION_ARGS) * Do the physical truncation. */ new_pages = smgrtruncate(DEFAULT_SMGR, rel, new_pages); - rel->rd_nblocks = new_pages; /* update relcache immediately */ + rel->rd_nblocks = new_pages; /* update relcache + * immediately */ rel->rd_targblock = InvalidBlockNumber; num_pages = new_pages; } @@ -856,7 +860,7 @@ btvacuumcleanup(PG_FUNCTION_ARGS) * and so no deletion can have occurred on that page. * * On entry, we have a pin but no read lock on the buffer that contained - * the index tuple we stopped the scan on. On exit, we have pin and read + * the index tuple we stopped the scan on. On exit, we have pin and read * lock on the buffer that now contains that index tuple, and the scandesc's * current position is updated to point at it. */ @@ -877,8 +881,8 @@ _bt_restscan(IndexScanDesc scan) BlockNumber blkno; /* - * Reacquire read lock on the buffer. (We should still have - * a reference-count pin on it, so need not get that.) + * Reacquire read lock on the buffer. (We should still have a + * reference-count pin on it, so need not get that.) */ LockBuffer(buf, BT_READ); @@ -921,11 +925,11 @@ _bt_restscan(IndexScanDesc scan) /* * The item we're looking for moved right at least one page, so - * move right. We are careful here to pin and read-lock the next - * non-dead page before releasing the current one. This ensures that - * a concurrent btbulkdelete scan cannot pass our position --- if it - * did, it might be able to reach and delete our target item before - * we can find it again. + * move right. We are careful here to pin and read-lock the next + * non-dead page before releasing the current one. This ensures + * that a concurrent btbulkdelete scan cannot pass our position + * --- if it did, it might be able to reach and delete our target + * item before we can find it again. */ if (P_RIGHTMOST(opaque)) elog(ERROR, "failed to re-find previous key in \"%s\"", |