diff options
| -rw-r--r-- | src/backend/commands/vacuum.c | 281 |
1 files changed, 154 insertions, 127 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 8d2cd4da58c..4fc3b1d3d90 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -13,7 +13,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.233 2002/08/06 02:36:34 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.234 2002/08/13 20:14:24 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1298,7 +1298,8 @@ scan_heap(VRelStats *vacrelstats, Relation onerel, usable_free_size = 0; } - if (usable_free_size > 0 && num_vtlinks > 0) + /* don't bother to save vtlinks if we will not call repair_frag */ + if (fraged_pages->num_pages > 0 && num_vtlinks > 0) { qsort((char *) vtlinks, num_vtlinks, sizeof(VTupleLinkData), vac_cmp_vtlinks); @@ -1322,7 +1323,6 @@ Re-using: Free/Avail. Space %.0f/%.0f; EndEmpty/Avail. Pages %u/%u.\n\t%s", free_size, usable_free_size, empty_end_pages, fraged_pages->num_pages, vac_show_rusage(&ru0)); - } @@ -1577,42 +1577,65 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, * If this tuple is in the chain of tuples created in updates * by "recent" transactions then we have to move all chain of * tuples to another places. + * + * NOTE: this test is not 100% accurate: it is possible for + * a tuple to be an updated one with recent xmin, and yet not + * have a corresponding tuple in the vtlinks list. Presumably + * there was once a parent tuple with xmax matching the xmin, + * but it's possible that that tuple has been removed --- for + * example, if it had xmin = xmax then HeapTupleSatisfiesVacuum + * would deem it removable as soon as the xmin xact completes. + * + * To be on the safe side, we abandon the repair_frag process if + * we cannot find the parent tuple in vtlinks. This may be overly + * conservative; AFAICS it would be safe to move the chain. */ - if ((tuple.t_data->t_infomask & HEAP_UPDATED && + if (((tuple.t_data->t_infomask & HEAP_UPDATED) && !TransactionIdPrecedes(HeapTupleHeaderGetXmin(tuple.t_data), OldestXmin)) || - (!(tuple.t_data->t_infomask & HEAP_XMAX_INVALID) && + (!(tuple.t_data->t_infomask & (HEAP_XMAX_INVALID | + HEAP_MARKED_FOR_UPDATE)) && !(ItemPointerEquals(&(tuple.t_self), &(tuple.t_data->t_ctid))))) { Buffer Cbuf = buf; + bool freeCbuf = false; + bool chain_move_failed = false; Page Cpage; ItemId Citemid; ItemPointerData Ctid; HeapTupleData tp = tuple; Size tlen = tuple_len; - VTupleMove vtmove = (VTupleMove) - palloc(100 * sizeof(VTupleMoveData)); - int num_vtmove = 0; - int free_vtmove = 100; + VTupleMove vtmove; + int num_vtmove; + int free_vtmove; VacPage to_vacpage = NULL; int to_item = 0; - bool freeCbuf = false; int ti; - if (vacrelstats->vtlinks == NULL) - elog(ERROR, "No one parent tuple was found"); if (cur_buffer != InvalidBuffer) { WriteBuffer(cur_buffer); cur_buffer = InvalidBuffer; } + /* Quick exit if we have no vtlinks to search in */ + if (vacrelstats->vtlinks == NULL) + { + elog(WARNING, "Parent item in update-chain not found - can't continue repair_frag"); + break; /* out of walk-along-page loop */ + } + + vtmove = (VTupleMove) palloc(100 * sizeof(VTupleMoveData)); + num_vtmove = 0; + free_vtmove = 100; + /* * If this tuple is in the begin/middle of the chain then * we have to move to the end of chain. */ - while (!(tp.t_data->t_infomask & HEAP_XMAX_INVALID) && + while (!(tp.t_data->t_infomask & (HEAP_XMAX_INVALID | + HEAP_MARKED_FOR_UPDATE)) && !(ItemPointerEquals(&(tp.t_self), &(tp.t_data->t_ctid)))) { @@ -1636,22 +1659,35 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, * in scan_heap(), but it's not implemented at the * moment and so we just stop shrinking here. */ - ReleaseBuffer(Cbuf); - pfree(vtmove); - vtmove = NULL; elog(WARNING, "Child itemid in update-chain marked as unused - can't continue repair_frag"); - break; + chain_move_failed = true; + break; /* out of loop to move to chain end */ } tp.t_datamcxt = NULL; tp.t_data = (HeapTupleHeader) PageGetItem(Cpage, Citemid); tp.t_self = Ctid; tlen = tp.t_len = ItemIdGetLength(Citemid); } - if (vtmove == NULL) - break; - /* first, can chain be moved ? */ + if (chain_move_failed) + { + if (freeCbuf) + ReleaseBuffer(Cbuf); + pfree(vtmove); + break; /* out of walk-along-page loop */ + } + + /* + * Check if all items in chain can be moved + */ for (;;) { + Buffer Pbuf; + Page Ppage; + ItemId Pitemid; + HeapTupleData Ptp; + VTupleLinkData vtld, + *vtlp; + if (to_vacpage == NULL || !enough_space(to_vacpage, tlen)) { @@ -1664,13 +1700,8 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, if (i == num_fraged_pages) { /* can't move item anywhere */ - for (i = 0; i < num_vtmove; i++) - { - Assert(vtmove[i].vacpage->offsets_used > 0); - (vtmove[i].vacpage->offsets_used)--; - } - num_vtmove = 0; - break; + chain_move_failed = true; + break; /* out of check-all-items loop */ } to_item = i; to_vacpage = fraged_pages->pagedesc[to_item]; @@ -1682,9 +1713,10 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, if (free_vtmove == 0) { free_vtmove = 1000; - vtmove = (VTupleMove) repalloc(vtmove, - (free_vtmove + num_vtmove) * - sizeof(VTupleMoveData)); + vtmove = (VTupleMove) + repalloc(vtmove, + (free_vtmove + num_vtmove) * + sizeof(VTupleMoveData)); } vtmove[num_vtmove].tid = tp.t_self; vtmove[num_vtmove].vacpage = to_vacpage; @@ -1695,113 +1727,96 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, free_vtmove--; num_vtmove++; - /* All done ? */ + /* At beginning of chain? */ if (!(tp.t_data->t_infomask & HEAP_UPDATED) || TransactionIdPrecedes(HeapTupleHeaderGetXmin(tp.t_data), OldestXmin)) break; - /* Well, try to find tuple with old row version */ - for (;;) + /* No, move to tuple with prior row version */ + vtld.new_tid = tp.t_self; + vtlp = (VTupleLink) + vac_bsearch((void *) &vtld, + (void *) (vacrelstats->vtlinks), + vacrelstats->num_vtlinks, + sizeof(VTupleLinkData), + vac_cmp_vtlinks); + if (vtlp == NULL) { - Buffer Pbuf; - Page Ppage; - ItemId Pitemid; - HeapTupleData Ptp; - VTupleLinkData vtld, - *vtlp; - - vtld.new_tid = tp.t_self; - vtlp = (VTupleLink) - vac_bsearch((void *) &vtld, - (void *) (vacrelstats->vtlinks), - vacrelstats->num_vtlinks, - sizeof(VTupleLinkData), - vac_cmp_vtlinks); - if (vtlp == NULL) - elog(ERROR, "Parent tuple was not found"); - tp.t_self = vtlp->this_tid; - Pbuf = ReadBuffer(onerel, - ItemPointerGetBlockNumber(&(tp.t_self))); - Ppage = BufferGetPage(Pbuf); - Pitemid = PageGetItemId(Ppage, - ItemPointerGetOffsetNumber(&(tp.t_self))); - if (!ItemIdIsUsed(Pitemid)) - elog(ERROR, "Parent itemid marked as unused"); - Ptp.t_datamcxt = NULL; - Ptp.t_data = (HeapTupleHeader) PageGetItem(Ppage, Pitemid); - Assert(ItemPointerEquals(&(vtld.new_tid), - &(Ptp.t_data->t_ctid))); - - /* - * Read above about cases when - * !ItemIdIsUsed(Citemid) (child item is - * removed)... Due to the fact that at the moment - * we don't remove unuseful part of update-chain, - * it's possible to get too old parent row here. - * Like as in the case which caused this problem, - * we stop shrinking here. I could try to find - * real parent row but want not to do it because - * of real solution will be implemented anyway, - * latter, and we are too close to 6.5 release. - - * vadim 06/11/99 - */ - if (!(TransactionIdEquals(HeapTupleHeaderGetXmax(Ptp.t_data), - HeapTupleHeaderGetXmin(tp.t_data)))) - { - if (freeCbuf) - ReleaseBuffer(Cbuf); - freeCbuf = false; - ReleaseBuffer(Pbuf); - for (i = 0; i < num_vtmove; i++) - { - Assert(vtmove[i].vacpage->offsets_used > 0); - (vtmove[i].vacpage->offsets_used)--; - } - num_vtmove = 0; - elog(WARNING, "Too old parent tuple found - can't continue repair_frag"); - break; - } -#ifdef NOT_USED /* I'm not sure that this will wotk - * properly... */ + /* see discussion above */ + elog(WARNING, "Parent item in update-chain not found - can't continue repair_frag"); + chain_move_failed = true; + break; /* out of check-all-items loop */ + } + tp.t_self = vtlp->this_tid; + Pbuf = ReadBuffer(onerel, + ItemPointerGetBlockNumber(&(tp.t_self))); + Ppage = BufferGetPage(Pbuf); + Pitemid = PageGetItemId(Ppage, + ItemPointerGetOffsetNumber(&(tp.t_self))); + /* this can't happen since we saw tuple earlier: */ + if (!ItemIdIsUsed(Pitemid)) + elog(ERROR, "Parent itemid marked as unused"); + Ptp.t_datamcxt = NULL; + Ptp.t_data = (HeapTupleHeader) PageGetItem(Ppage, Pitemid); + + /* ctid should not have changed since we saved it */ + Assert(ItemPointerEquals(&(vtld.new_tid), + &(Ptp.t_data->t_ctid))); - /* - * If this tuple is updated version of row and it - * was created by the same transaction then no one - * is interested in this tuple - mark it as - * removed. - */ - if (Ptp.t_data->t_infomask & HEAP_UPDATED && - TransactionIdEquals(HeapTupleHeaderGetXmin(Ptp.t_data), - HeapTupleHeaderGetXmax(Ptp.t_data))) - { - Ptp.t_data->t_infomask &= - ~(HEAP_XMIN_COMMITTED | HEAP_XMIN_INVALID | HEAP_MOVED_IN); - Ptp.t_data->t_infomask |= HEAP_MOVED_OFF; - HeapTupleHeaderSetXvac(Ptp.t_data, myXID); - WriteBuffer(Pbuf); - continue; - } -#endif - tp.t_datamcxt = Ptp.t_datamcxt; - tp.t_data = Ptp.t_data; - tlen = tp.t_len = ItemIdGetLength(Pitemid); - if (freeCbuf) - ReleaseBuffer(Cbuf); - Cbuf = Pbuf; - freeCbuf = true; - break; + /* + * Read above about cases when + * !ItemIdIsUsed(Citemid) (child item is + * removed)... Due to the fact that at the moment + * we don't remove unuseful part of update-chain, + * it's possible to get too old parent row here. + * Like as in the case which caused this problem, + * we stop shrinking here. I could try to find + * real parent row but want not to do it because + * of real solution will be implemented anyway, + * later, and we are too close to 6.5 release. - + * vadim 06/11/99 + */ + if (!(TransactionIdEquals(HeapTupleHeaderGetXmax(Ptp.t_data), + HeapTupleHeaderGetXmin(tp.t_data)))) + { + ReleaseBuffer(Pbuf); + elog(WARNING, "Too old parent tuple found - can't continue repair_frag"); + chain_move_failed = true; + break; /* out of check-all-items loop */ } - if (num_vtmove == 0) - break; - } + tp.t_datamcxt = Ptp.t_datamcxt; + tp.t_data = Ptp.t_data; + tlen = tp.t_len = ItemIdGetLength(Pitemid); + if (freeCbuf) + ReleaseBuffer(Cbuf); + Cbuf = Pbuf; + freeCbuf = true; + } /* end of check-all-items loop */ + if (freeCbuf) ReleaseBuffer(Cbuf); - if (num_vtmove == 0) /* chain can't be moved */ + freeCbuf = false; + + if (chain_move_failed) { + /* + * Undo changes to offsets_used state. We don't bother + * cleaning up the amount-free state, since we're not + * going to do any further tuple motion. + */ + for (i = 0; i < num_vtmove; i++) + { + Assert(vtmove[i].vacpage->offsets_used > 0); + (vtmove[i].vacpage->offsets_used)--; + } pfree(vtmove); - break; + break; /* out of walk-along-page loop */ } + + /* + * Okay, move the whle tuple chain + */ ItemPointerSetInvalid(&Ctid); for (ti = 0; ti < num_vtmove; ti++) { @@ -1962,12 +1977,15 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, WriteBuffer(cur_buffer); WriteBuffer(Cbuf); - } + } /* end of move-the-tuple-chain loop */ + cur_buffer = InvalidBuffer; pfree(vtmove); chain_tuple_moved = true; + + /* advance to next tuple in walk-along-page loop */ continue; - } + } /* end of is-tuple-in-chain test */ /* try to find new page for this tuple */ if (cur_buffer == InvalidBuffer || @@ -2089,10 +2107,19 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, } } /* walk along page */ + /* + * If we broke out of the walk-along-page loop early (ie, still have + * offnum <= maxoff), then we failed to move some tuple off + * this page. No point in shrinking any more, so clean up and + * exit the per-page loop. + */ if (offnum < maxoff && keep_tuples > 0) { OffsetNumber off; + /* + * Fix vacpage state for any unvisited tuples remaining on page + */ for (off = OffsetNumberNext(offnum); off <= maxoff; off = OffsetNumberNext(off)) @@ -2154,7 +2181,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel, ReleaseBuffer(buf); if (offnum <= maxoff) - break; /* some item(s) left */ + break; /* had to quit early, see above note */ } /* walk along relation */ |