diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtpage.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtpage.c | 102 |
1 files changed, 52 insertions, 50 deletions
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c index c0ebb95ba8a..d357b33bc05 100644 --- a/src/backend/access/nbtree/nbtpage.c +++ b/src/backend/access/nbtree/nbtpage.c @@ -12,7 +12,7 @@ * src/backend/access/nbtree/nbtpage.c * * NOTES - * Postgres btree pages look like ordinary relation pages. The opaque + * 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. @@ -36,7 +36,7 @@ static bool _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, static bool _bt_lock_branch_parent(Relation rel, BlockNumber child, BTStack stack, Buffer *topparent, OffsetNumber *topoff, BlockNumber *target, BlockNumber *rightsib); -static void _bt_log_reuse_page(Relation rel, BlockNumber blkno, +static void _bt_log_reuse_page(Relation rel, BlockNumber blkno, TransactionId latestRemovedXid); /* @@ -62,7 +62,7 @@ _bt_initmetapage(Page page, BlockNumber rootbknum, uint32 level) metaopaque->btpo_flags = BTP_META; /* - * Set pd_lower just past the end of the metadata. This is not essential + * Set pd_lower just past the end of the metadata. This is not essential * but it makes the page look compressible to xlog.c. */ ((PageHeader) page)->pd_lower = @@ -80,7 +80,7 @@ _bt_initmetapage(Page page, BlockNumber rootbknum, uint32 level) * * 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 + * 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! @@ -197,7 +197,7 @@ _bt_getroot(Relation rel, int access) /* * Metadata initialized by someone else. In order to guarantee no * deadlocks, we have to release the metadata page and start all - * over again. (Is that really true? But it's hardly worth trying + * over again. (Is that really true? But it's hardly worth trying * to optimize this case.) */ _bt_relbuf(rel, metabuf); @@ -254,7 +254,7 @@ _bt_getroot(Relation rel, int access) END_CRIT_SECTION(); /* - * swap root write lock for read lock. There is no danger of anyone + * swap root write lock for read lock. There is no danger of anyone * else accessing the new root page while it's unlocked, since no one * else knows where it is yet. */ @@ -322,7 +322,7 @@ _bt_getroot(Relation rel, int access) * By the time we acquire lock on the root page, it might have been split and * not be the true root anymore. This is okay for the present uses of this * routine; we only really need to be able to move up at least one tree level - * from whatever non-root page we were at. If we ever do need to lock the + * from whatever non-root page we were at. If we ever do need to lock the * one true root page, we could loop here, re-reading the metapage on each * failure. (Note that it wouldn't do to hold the lock on the metapage while * moving to the root --- that'd deadlock against any concurrent root split.) @@ -497,7 +497,7 @@ _bt_checkpage(Relation rel, Buffer buf) /* * ReadBuffer verifies that every newly-read page passes * PageHeaderIsValid, which means it either contains a reasonably sane - * page header or is all-zero. We have to defend against the all-zero + * page header or is all-zero. We have to defend against the all-zero * case, however. */ if (PageIsNew(page)) @@ -564,7 +564,7 @@ _bt_log_reuse_page(Relation rel, BlockNumber blkno, TransactionId latestRemovedX /* * _bt_getbuf() -- Get a buffer by block number for read or write. * - * blkno == P_NEW means to get an unallocated index page. The page + * blkno == P_NEW means to get an unallocated index page. The page * will be initialized before returning it. * * When this routine returns, the appropriate lock is set on the @@ -595,7 +595,7 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access) * First see if the FSM knows of any free pages. * * We can't trust the FSM's report unreservedly; we have to check that - * the page is still free. (For example, an already-free page could + * the page is still free. (For example, an already-free page could * have been re-used between the time the last VACUUM scanned it and * the time the VACUUM made its FSM updates.) * @@ -774,7 +774,7 @@ _bt_page_recyclable(Page page) /* * Delete item(s) from a btree page during VACUUM. * - * This must only be used for deleting leaf items. Deleting an item on a + * This must only be used for deleting leaf items. Deleting an item on a * non-leaf page has to be done as part of an atomic action that includes * deleting the page it points to. * @@ -842,7 +842,7 @@ _bt_delitems_vacuum(Relation rel, Buffer buf, /* * The target-offsets array is not in the buffer, but pretend that it - * is. When XLogInsert stores the whole buffer, the offsets array + * is. When XLogInsert stores the whole buffer, the offsets array * need not be stored too. */ if (nitems > 0) @@ -1049,11 +1049,12 @@ _bt_lock_branch_parent(Relation rel, BlockNumber child, BTStack stack, lbuf = _bt_getbuf(rel, leftsib, BT_READ); lpage = BufferGetPage(lbuf); lopaque = (BTPageOpaque) PageGetSpecialPointer(lpage); + /* * If the left sibling was concurrently split, so that its - * next-pointer doesn't point to the current page anymore, - * the split that created the current page must be completed. - * (We don't allow splitting an incompletely split page again + * next-pointer doesn't point to the current page anymore, the + * split that created the current page must be completed. (We + * don't allow splitting an incompletely split page again * until the previous split has been completed) */ if (lopaque->btpo_next == parent && @@ -1066,7 +1067,7 @@ _bt_lock_branch_parent(Relation rel, BlockNumber child, BTStack stack, } return _bt_lock_branch_parent(rel, parent, stack->bts_parent, - topparent, topoff, target, rightsib); + topparent, topoff, target, rightsib); } else { @@ -1112,6 +1113,7 @@ _bt_pagedel(Relation rel, Buffer buf) bool rightsib_empty; Page page; BTPageOpaque opaque; + /* * "stack" is a search stack leading (approximately) to the target page. * It is initially NULL, but when iterating, we keep it to avoid @@ -1140,24 +1142,24 @@ _bt_pagedel(Relation rel, Buffer buf) * was never supposed to leave half-dead pages in the tree, it was * just a transient state, but it was nevertheless possible in * error scenarios. We don't know how to deal with them here. They - * are harmless as far as searches are considered, but inserts into - * the deleted keyspace could add out-of-order downlinks in the - * upper levels. Log a notice, hopefully the admin will notice and - * reindex. + * are harmless as far as searches are considered, but inserts + * into the deleted keyspace could add out-of-order downlinks in + * the upper levels. Log a notice, hopefully the admin will notice + * and reindex. */ if (P_ISHALFDEAD(opaque)) ereport(LOG, (errcode(ERRCODE_INDEX_CORRUPTED), - errmsg("index \"%s\" contains a half-dead internal page", - RelationGetRelationName(rel)), + errmsg("index \"%s\" contains a half-dead internal page", + RelationGetRelationName(rel)), errhint("This can be caused by an interrupt VACUUM in version 9.3 or older, before upgrade. Please REINDEX it."))); _bt_relbuf(rel, buf); return ndeleted; } /* - * We can never delete rightmost pages nor root pages. While at - * it, check that page is not already deleted and is empty. + * We can never delete rightmost pages nor root pages. While at it, + * check that page is not already deleted and is empty. * * To keep the algorithm simple, we also never delete an incompletely * split page (they should be rare enough that this doesn't make any @@ -1167,10 +1169,10 @@ _bt_pagedel(Relation rel, Buffer buf) * left half of an incomplete split, but ensuring that it's not the * right half is more complicated. For that, we have to check that * the left sibling doesn't have its INCOMPLETE_SPLIT flag set. On - * the first iteration, we temporarily release the lock on the - * current page, and check the left sibling and also construct a - * search stack to. On subsequent iterations, we know we stepped right - * from a page that passed these tests, so it's OK. + * the first iteration, we temporarily release the lock on the current + * page, and check the left sibling and also construct a search stack + * to. On subsequent iterations, we know we stepped right from a page + * that passed these tests, so it's OK. */ if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque) || P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page) || @@ -1184,9 +1186,9 @@ _bt_pagedel(Relation rel, Buffer buf) } /* - * First, remove downlink pointing to the page (or a parent of the page, - * if we are going to delete a taller branch), and mark the page as - * half-dead. + * First, remove downlink pointing to the page (or a parent of the + * page, if we are going to delete a taller branch), and mark the page + * as half-dead. */ if (!P_ISHALFDEAD(opaque)) { @@ -1205,7 +1207,7 @@ _bt_pagedel(Relation rel, Buffer buf) ItemId itemid; IndexTuple targetkey; Buffer lbuf; - BlockNumber leftsib; + BlockNumber leftsib; itemid = PageGetItemId(page, P_HIKEY); targetkey = CopyIndexTuple((IndexTuple) PageGetItem(page, itemid)); @@ -1219,9 +1221,9 @@ _bt_pagedel(Relation rel, Buffer buf) LockBuffer(buf, BUFFER_LOCK_UNLOCK); /* - * Fetch the left sibling, to check that it's not marked - * with INCOMPLETE_SPLIT flag. That would mean that the - * page to-be-deleted doesn't have a downlink, and the page + * Fetch the left sibling, to check that it's not marked with + * INCOMPLETE_SPLIT flag. That would mean that the page + * to-be-deleted doesn't have a downlink, and the page * deletion algorithm isn't prepared to handle that. */ if (!P_LEFTMOST(opaque)) @@ -1267,7 +1269,7 @@ _bt_pagedel(Relation rel, Buffer buf) /* * Then unlink it from its siblings. Each call to - *_bt_unlink_halfdead_page unlinks the topmost page from the branch, + * _bt_unlink_halfdead_page unlinks the topmost page from the branch, * making it shallower. Iterate until the leaf page is gone. */ rightsib_empty = false; @@ -1291,8 +1293,8 @@ _bt_pagedel(Relation rel, Buffer buf) * is that it was the rightmost child of the parent. Now that we * removed the downlink for this page, the right sibling might now be * the only child of the parent, and could be removed. It would be - * picked up by the next vacuum anyway, but might as well try to remove - * it now, so loop back to process the right sibling. + * picked up by the next vacuum anyway, but might as well try to + * remove it now, so loop back to process the right sibling. */ if (!rightsib_empty) break; @@ -1310,9 +1312,9 @@ _bt_pagedel(Relation rel, Buffer buf) static bool _bt_mark_page_halfdead(Relation rel, Buffer leafbuf, BTStack stack) { - BlockNumber leafblkno; + BlockNumber leafblkno; BlockNumber leafrightsib; - BlockNumber target; + BlockNumber target; BlockNumber rightsib; ItemId itemid; Page page; @@ -1351,7 +1353,7 @@ _bt_mark_page_halfdead(Relation rel, Buffer leafbuf, BTStack stack) /* * Check that the parent-page index items we're about to delete/overwrite - * contain what we expect. This can fail if the index has become corrupt + * contain what we expect. This can fail if the index has become corrupt * for some reason. We want to throw any error before entering the * critical section --- otherwise it'd be a PANIC. * @@ -1490,9 +1492,9 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) BlockNumber leafblkno = BufferGetBlockNumber(leafbuf); BlockNumber leafleftsib; BlockNumber leafrightsib; - BlockNumber target; - BlockNumber leftsib; - BlockNumber rightsib; + BlockNumber target; + BlockNumber leftsib; + BlockNumber rightsib; Buffer lbuf = InvalidBuffer; Buffer buf; Buffer rbuf; @@ -1506,7 +1508,7 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) int targetlevel; ItemPointer leafhikey; BlockNumber nextchild; - BlockNumber topblkno; + BlockNumber topblkno; page = BufferGetPage(leafbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); @@ -1596,7 +1598,7 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) lbuf = InvalidBuffer; /* - * Next write-lock the target page itself. It should be okay to take just + * Next write-lock the target page itself. It should be okay to take just * a write lock not a superexclusive lock, since no scans would stop on an * empty page. */ @@ -1605,9 +1607,9 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) opaque = (BTPageOpaque) PageGetSpecialPointer(page); /* - * Check page is still empty etc, else abandon deletion. This is just - * for paranoia's sake; a half-dead page cannot resurrect because there - * can be only one vacuum process running at a time. + * Check page is still empty etc, else abandon deletion. This is just for + * paranoia's sake; a half-dead page cannot resurrect because there can be + * only one vacuum process running at a time. */ if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque)) { @@ -1733,7 +1735,7 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) * we're in VACUUM and would not otherwise have an XID. Having already * updated links to the target, ReadNewTransactionId() suffices as an * upper bound. Any scan having retained a now-stale link is advertising - * in its PGXACT an xmin less than or equal to the value we read here. It + * in its PGXACT an xmin less than or equal to the value we read here. It * will continue to do so, holding back RecentGlobalXmin, for the duration * of that scan. */ |