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Diffstat (limited to 'src/backend/access/heap/heapam_handler.c')
| -rw-r--r-- | src/backend/access/heap/heapam_handler.c | 2608 |
1 files changed, 2608 insertions, 0 deletions
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c new file mode 100644 index 0000000..2168259 --- /dev/null +++ b/src/backend/access/heap/heapam_handler.c @@ -0,0 +1,2608 @@ +/*------------------------------------------------------------------------- + * + * heapam_handler.c + * heap table access method code + * + * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/backend/access/heap/heapam_handler.c + * + * + * NOTES + * This files wires up the lower level heapam.c et al routines with the + * tableam abstraction. + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/genam.h" +#include "access/heapam.h" +#include "access/heaptoast.h" +#include "access/multixact.h" +#include "access/rewriteheap.h" +#include "access/syncscan.h" +#include "access/tableam.h" +#include "access/tsmapi.h" +#include "access/xact.h" +#include "catalog/catalog.h" +#include "catalog/index.h" +#include "catalog/storage.h" +#include "catalog/storage_xlog.h" +#include "commands/progress.h" +#include "executor/executor.h" +#include "miscadmin.h" +#include "pgstat.h" +#include "storage/bufmgr.h" +#include "storage/bufpage.h" +#include "storage/lmgr.h" +#include "storage/predicate.h" +#include "storage/procarray.h" +#include "storage/smgr.h" +#include "utils/builtins.h" +#include "utils/rel.h" + +static void reform_and_rewrite_tuple(HeapTuple tuple, + Relation OldHeap, Relation NewHeap, + Datum *values, bool *isnull, RewriteState rwstate); + +static bool SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer, + HeapTuple tuple, + OffsetNumber tupoffset); + +static BlockNumber heapam_scan_get_blocks_done(HeapScanDesc hscan); + +static const TableAmRoutine heapam_methods; + + +/* ------------------------------------------------------------------------ + * Slot related callbacks for heap AM + * ------------------------------------------------------------------------ + */ + +static const TupleTableSlotOps * +heapam_slot_callbacks(Relation relation) +{ + return &TTSOpsBufferHeapTuple; +} + + +/* ------------------------------------------------------------------------ + * Index Scan Callbacks for heap AM + * ------------------------------------------------------------------------ + */ + +static IndexFetchTableData * +heapam_index_fetch_begin(Relation rel) +{ + IndexFetchHeapData *hscan = palloc0(sizeof(IndexFetchHeapData)); + + hscan->xs_base.rel = rel; + hscan->xs_cbuf = InvalidBuffer; + + return &hscan->xs_base; +} + +static void +heapam_index_fetch_reset(IndexFetchTableData *scan) +{ + IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan; + + if (BufferIsValid(hscan->xs_cbuf)) + { + ReleaseBuffer(hscan->xs_cbuf); + hscan->xs_cbuf = InvalidBuffer; + } +} + +static void +heapam_index_fetch_end(IndexFetchTableData *scan) +{ + IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan; + + heapam_index_fetch_reset(scan); + + pfree(hscan); +} + +static bool +heapam_index_fetch_tuple(struct IndexFetchTableData *scan, + ItemPointer tid, + Snapshot snapshot, + TupleTableSlot *slot, + bool *call_again, bool *all_dead) +{ + IndexFetchHeapData *hscan = (IndexFetchHeapData *) scan; + BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot; + bool got_heap_tuple; + + Assert(TTS_IS_BUFFERTUPLE(slot)); + + /* We can skip the buffer-switching logic if we're in mid-HOT chain. */ + if (!*call_again) + { + /* Switch to correct buffer if we don't have it already */ + Buffer prev_buf = hscan->xs_cbuf; + + hscan->xs_cbuf = ReleaseAndReadBuffer(hscan->xs_cbuf, + hscan->xs_base.rel, + ItemPointerGetBlockNumber(tid)); + + /* + * Prune page, but only if we weren't already on this page + */ + if (prev_buf != hscan->xs_cbuf) + heap_page_prune_opt(hscan->xs_base.rel, hscan->xs_cbuf); + } + + /* Obtain share-lock on the buffer so we can examine visibility */ + LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_SHARE); + got_heap_tuple = heap_hot_search_buffer(tid, + hscan->xs_base.rel, + hscan->xs_cbuf, + snapshot, + &bslot->base.tupdata, + all_dead, + !*call_again); + bslot->base.tupdata.t_self = *tid; + LockBuffer(hscan->xs_cbuf, BUFFER_LOCK_UNLOCK); + + if (got_heap_tuple) + { + /* + * Only in a non-MVCC snapshot can more than one member of the HOT + * chain be visible. + */ + *call_again = !IsMVCCSnapshot(snapshot); + + slot->tts_tableOid = RelationGetRelid(scan->rel); + ExecStoreBufferHeapTuple(&bslot->base.tupdata, slot, hscan->xs_cbuf); + } + else + { + /* We've reached the end of the HOT chain. */ + *call_again = false; + } + + return got_heap_tuple; +} + + +/* ------------------------------------------------------------------------ + * Callbacks for non-modifying operations on individual tuples for heap AM + * ------------------------------------------------------------------------ + */ + +static bool +heapam_fetch_row_version(Relation relation, + ItemPointer tid, + Snapshot snapshot, + TupleTableSlot *slot) +{ + BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot; + Buffer buffer; + + Assert(TTS_IS_BUFFERTUPLE(slot)); + + bslot->base.tupdata.t_self = *tid; + if (heap_fetch(relation, snapshot, &bslot->base.tupdata, &buffer, false)) + { + /* store in slot, transferring existing pin */ + ExecStorePinnedBufferHeapTuple(&bslot->base.tupdata, slot, buffer); + slot->tts_tableOid = RelationGetRelid(relation); + + return true; + } + + return false; +} + +static bool +heapam_tuple_tid_valid(TableScanDesc scan, ItemPointer tid) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + + return ItemPointerIsValid(tid) && + ItemPointerGetBlockNumber(tid) < hscan->rs_nblocks; +} + +static bool +heapam_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot, + Snapshot snapshot) +{ + BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot; + bool res; + + Assert(TTS_IS_BUFFERTUPLE(slot)); + Assert(BufferIsValid(bslot->buffer)); + + /* + * We need buffer pin and lock to call HeapTupleSatisfiesVisibility. + * Caller should be holding pin, but not lock. + */ + LockBuffer(bslot->buffer, BUFFER_LOCK_SHARE); + res = HeapTupleSatisfiesVisibility(bslot->base.tuple, snapshot, + bslot->buffer); + LockBuffer(bslot->buffer, BUFFER_LOCK_UNLOCK); + + return res; +} + + +/* ---------------------------------------------------------------------------- + * Functions for manipulations of physical tuples for heap AM. + * ---------------------------------------------------------------------------- + */ + +static void +heapam_tuple_insert(Relation relation, TupleTableSlot *slot, CommandId cid, + int options, BulkInsertState bistate) +{ + bool shouldFree = true; + HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree); + + /* Update the tuple with table oid */ + slot->tts_tableOid = RelationGetRelid(relation); + tuple->t_tableOid = slot->tts_tableOid; + + /* Perform the insertion, and copy the resulting ItemPointer */ + heap_insert(relation, tuple, cid, options, bistate); + ItemPointerCopy(&tuple->t_self, &slot->tts_tid); + + if (shouldFree) + pfree(tuple); +} + +static void +heapam_tuple_insert_speculative(Relation relation, TupleTableSlot *slot, + CommandId cid, int options, + BulkInsertState bistate, uint32 specToken) +{ + bool shouldFree = true; + HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree); + + /* Update the tuple with table oid */ + slot->tts_tableOid = RelationGetRelid(relation); + tuple->t_tableOid = slot->tts_tableOid; + + HeapTupleHeaderSetSpeculativeToken(tuple->t_data, specToken); + options |= HEAP_INSERT_SPECULATIVE; + + /* Perform the insertion, and copy the resulting ItemPointer */ + heap_insert(relation, tuple, cid, options, bistate); + ItemPointerCopy(&tuple->t_self, &slot->tts_tid); + + if (shouldFree) + pfree(tuple); +} + +static void +heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot, + uint32 specToken, bool succeeded) +{ + bool shouldFree = true; + HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree); + + /* adjust the tuple's state accordingly */ + if (succeeded) + heap_finish_speculative(relation, &slot->tts_tid); + else + heap_abort_speculative(relation, &slot->tts_tid); + + if (shouldFree) + pfree(tuple); +} + +static TM_Result +heapam_tuple_delete(Relation relation, ItemPointer tid, CommandId cid, + Snapshot snapshot, Snapshot crosscheck, bool wait, + TM_FailureData *tmfd, bool changingPart) +{ + /* + * Currently Deleting of index tuples are handled at vacuum, in case if + * the storage itself is cleaning the dead tuples by itself, it is the + * time to call the index tuple deletion also. + */ + return heap_delete(relation, tid, cid, crosscheck, wait, tmfd, changingPart); +} + + +static TM_Result +heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot, + CommandId cid, Snapshot snapshot, Snapshot crosscheck, + bool wait, TM_FailureData *tmfd, + LockTupleMode *lockmode, bool *update_indexes) +{ + bool shouldFree = true; + HeapTuple tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree); + TM_Result result; + + /* Update the tuple with table oid */ + slot->tts_tableOid = RelationGetRelid(relation); + tuple->t_tableOid = slot->tts_tableOid; + + result = heap_update(relation, otid, tuple, cid, crosscheck, wait, + tmfd, lockmode); + ItemPointerCopy(&tuple->t_self, &slot->tts_tid); + + /* + * Decide whether new index entries are needed for the tuple + * + * Note: heap_update returns the tid (location) of the new tuple in the + * t_self field. + * + * If it's a HOT update, we mustn't insert new index entries. + */ + *update_indexes = result == TM_Ok && !HeapTupleIsHeapOnly(tuple); + + if (shouldFree) + pfree(tuple); + + return result; +} + +static TM_Result +heapam_tuple_lock(Relation relation, ItemPointer tid, Snapshot snapshot, + TupleTableSlot *slot, CommandId cid, LockTupleMode mode, + LockWaitPolicy wait_policy, uint8 flags, + TM_FailureData *tmfd) +{ + BufferHeapTupleTableSlot *bslot = (BufferHeapTupleTableSlot *) slot; + TM_Result result; + Buffer buffer; + HeapTuple tuple = &bslot->base.tupdata; + bool follow_updates; + + follow_updates = (flags & TUPLE_LOCK_FLAG_LOCK_UPDATE_IN_PROGRESS) != 0; + tmfd->traversed = false; + + Assert(TTS_IS_BUFFERTUPLE(slot)); + +tuple_lock_retry: + tuple->t_self = *tid; + result = heap_lock_tuple(relation, tuple, cid, mode, wait_policy, + follow_updates, &buffer, tmfd); + + if (result == TM_Updated && + (flags & TUPLE_LOCK_FLAG_FIND_LAST_VERSION)) + { + /* Should not encounter speculative tuple on recheck */ + Assert(!HeapTupleHeaderIsSpeculative(tuple->t_data)); + + ReleaseBuffer(buffer); + + if (!ItemPointerEquals(&tmfd->ctid, &tuple->t_self)) + { + SnapshotData SnapshotDirty; + TransactionId priorXmax; + + /* it was updated, so look at the updated version */ + *tid = tmfd->ctid; + /* updated row should have xmin matching this xmax */ + priorXmax = tmfd->xmax; + + /* signal that a tuple later in the chain is getting locked */ + tmfd->traversed = true; + + /* + * fetch target tuple + * + * Loop here to deal with updated or busy tuples + */ + InitDirtySnapshot(SnapshotDirty); + for (;;) + { + if (ItemPointerIndicatesMovedPartitions(tid)) + ereport(ERROR, + (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE), + errmsg("tuple to be locked was already moved to another partition due to concurrent update"))); + + tuple->t_self = *tid; + if (heap_fetch(relation, &SnapshotDirty, tuple, &buffer, true)) + { + /* + * If xmin isn't what we're expecting, the slot must have + * been recycled and reused for an unrelated tuple. This + * implies that the latest version of the row was deleted, + * so we need do nothing. (Should be safe to examine xmin + * without getting buffer's content lock. We assume + * reading a TransactionId to be atomic, and Xmin never + * changes in an existing tuple, except to invalid or + * frozen, and neither of those can match priorXmax.) + */ + if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple->t_data), + priorXmax)) + { + ReleaseBuffer(buffer); + return TM_Deleted; + } + + /* otherwise xmin should not be dirty... */ + if (TransactionIdIsValid(SnapshotDirty.xmin)) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("t_xmin %u is uncommitted in tuple (%u,%u) to be updated in table \"%s\"", + SnapshotDirty.xmin, + ItemPointerGetBlockNumber(&tuple->t_self), + ItemPointerGetOffsetNumber(&tuple->t_self), + RelationGetRelationName(relation)))); + + /* + * If tuple is being updated by other transaction then we + * have to wait for its commit/abort, or die trying. + */ + if (TransactionIdIsValid(SnapshotDirty.xmax)) + { + ReleaseBuffer(buffer); + switch (wait_policy) + { + case LockWaitBlock: + XactLockTableWait(SnapshotDirty.xmax, + relation, &tuple->t_self, + XLTW_FetchUpdated); + break; + case LockWaitSkip: + if (!ConditionalXactLockTableWait(SnapshotDirty.xmax)) + /* skip instead of waiting */ + return TM_WouldBlock; + break; + case LockWaitError: + if (!ConditionalXactLockTableWait(SnapshotDirty.xmax)) + ereport(ERROR, + (errcode(ERRCODE_LOCK_NOT_AVAILABLE), + errmsg("could not obtain lock on row in relation \"%s\"", + RelationGetRelationName(relation)))); + break; + } + continue; /* loop back to repeat heap_fetch */ + } + + /* + * If tuple was inserted by our own transaction, we have + * to check cmin against cid: cmin >= current CID means + * our command cannot see the tuple, so we should ignore + * it. Otherwise heap_lock_tuple() will throw an error, + * and so would any later attempt to update or delete the + * tuple. (We need not check cmax because + * HeapTupleSatisfiesDirty will consider a tuple deleted + * by our transaction dead, regardless of cmax.) We just + * checked that priorXmax == xmin, so we can test that + * variable instead of doing HeapTupleHeaderGetXmin again. + */ + if (TransactionIdIsCurrentTransactionId(priorXmax) && + HeapTupleHeaderGetCmin(tuple->t_data) >= cid) + { + tmfd->xmax = priorXmax; + + /* + * Cmin is the problematic value, so store that. See + * above. + */ + tmfd->cmax = HeapTupleHeaderGetCmin(tuple->t_data); + ReleaseBuffer(buffer); + return TM_SelfModified; + } + + /* + * This is a live tuple, so try to lock it again. + */ + ReleaseBuffer(buffer); + goto tuple_lock_retry; + } + + /* + * If the referenced slot was actually empty, the latest + * version of the row must have been deleted, so we need do + * nothing. + */ + if (tuple->t_data == NULL) + { + Assert(!BufferIsValid(buffer)); + return TM_Deleted; + } + + /* + * As above, if xmin isn't what we're expecting, do nothing. + */ + if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple->t_data), + priorXmax)) + { + ReleaseBuffer(buffer); + return TM_Deleted; + } + + /* + * If we get here, the tuple was found but failed + * SnapshotDirty. Assuming the xmin is either a committed xact + * or our own xact (as it certainly should be if we're trying + * to modify the tuple), this must mean that the row was + * updated or deleted by either a committed xact or our own + * xact. If it was deleted, we can ignore it; if it was + * updated then chain up to the next version and repeat the + * whole process. + * + * As above, it should be safe to examine xmax and t_ctid + * without the buffer content lock, because they can't be + * changing. We'd better hold a buffer pin though. + */ + if (ItemPointerEquals(&tuple->t_self, &tuple->t_data->t_ctid)) + { + /* deleted, so forget about it */ + ReleaseBuffer(buffer); + return TM_Deleted; + } + + /* updated, so look at the updated row */ + *tid = tuple->t_data->t_ctid; + /* updated row should have xmin matching this xmax */ + priorXmax = HeapTupleHeaderGetUpdateXid(tuple->t_data); + ReleaseBuffer(buffer); + /* loop back to fetch next in chain */ + } + } + else + { + /* tuple was deleted, so give up */ + return TM_Deleted; + } + } + + slot->tts_tableOid = RelationGetRelid(relation); + tuple->t_tableOid = slot->tts_tableOid; + + /* store in slot, transferring existing pin */ + ExecStorePinnedBufferHeapTuple(tuple, slot, buffer); + + return result; +} + + +/* ------------------------------------------------------------------------ + * DDL related callbacks for heap AM. + * ------------------------------------------------------------------------ + */ + +static void +heapam_relation_set_new_filenode(Relation rel, + const RelFileNode *newrnode, + char persistence, + TransactionId *freezeXid, + MultiXactId *minmulti) +{ + SMgrRelation srel; + + /* + * Initialize to the minimum XID that could put tuples in the table. We + * know that no xacts older than RecentXmin are still running, so that + * will do. + */ + *freezeXid = RecentXmin; + + /* + * Similarly, initialize the minimum Multixact to the first value that + * could possibly be stored in tuples in the table. Running transactions + * could reuse values from their local cache, so we are careful to + * consider all currently running multis. + * + * XXX this could be refined further, but is it worth the hassle? + */ + *minmulti = GetOldestMultiXactId(); + + srel = RelationCreateStorage(*newrnode, persistence, true); + + /* + * If required, set up an init fork for an unlogged table so that it can + * be correctly reinitialized on restart. An immediate sync is required + * even if the page has been logged, because the write did not go through + * shared_buffers and therefore a concurrent checkpoint may have moved the + * redo pointer past our xlog record. Recovery may as well remove it + * while replaying, for example, XLOG_DBASE_CREATE* or XLOG_TBLSPC_CREATE + * record. Therefore, logging is necessary even if wal_level=minimal. + */ + if (persistence == RELPERSISTENCE_UNLOGGED) + { + Assert(rel->rd_rel->relkind == RELKIND_RELATION || + rel->rd_rel->relkind == RELKIND_MATVIEW || + rel->rd_rel->relkind == RELKIND_TOASTVALUE); + smgrcreate(srel, INIT_FORKNUM, false); + log_smgrcreate(newrnode, INIT_FORKNUM); + smgrimmedsync(srel, INIT_FORKNUM); + } + + smgrclose(srel); +} + +static void +heapam_relation_nontransactional_truncate(Relation rel) +{ + RelationTruncate(rel, 0); +} + +static void +heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode) +{ + SMgrRelation dstrel; + + dstrel = smgropen(*newrnode, rel->rd_backend); + + /* + * Since we copy the file directly without looking at the shared buffers, + * we'd better first flush out any pages of the source relation that are + * in shared buffers. We assume no new changes will be made while we are + * holding exclusive lock on the rel. + */ + FlushRelationBuffers(rel); + + /* + * Create and copy all forks of the relation, and schedule unlinking of + * old physical files. + * + * NOTE: any conflict in relfilenode value will be caught in + * RelationCreateStorage(). + */ + RelationCreateStorage(*newrnode, rel->rd_rel->relpersistence, true); + + /* copy main fork */ + RelationCopyStorage(RelationGetSmgr(rel), dstrel, MAIN_FORKNUM, + rel->rd_rel->relpersistence); + + /* copy those extra forks that exist */ + for (ForkNumber forkNum = MAIN_FORKNUM + 1; + forkNum <= MAX_FORKNUM; forkNum++) + { + if (smgrexists(RelationGetSmgr(rel), forkNum)) + { + smgrcreate(dstrel, forkNum, false); + + /* + * WAL log creation if the relation is persistent, or this is the + * init fork of an unlogged relation. + */ + if (RelationIsPermanent(rel) || + (rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED && + forkNum == INIT_FORKNUM)) + log_smgrcreate(newrnode, forkNum); + RelationCopyStorage(RelationGetSmgr(rel), dstrel, forkNum, + rel->rd_rel->relpersistence); + } + } + + + /* drop old relation, and close new one */ + RelationDropStorage(rel); + smgrclose(dstrel); +} + +static void +heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, + Relation OldIndex, bool use_sort, + TransactionId OldestXmin, + TransactionId *xid_cutoff, + MultiXactId *multi_cutoff, + double *num_tuples, + double *tups_vacuumed, + double *tups_recently_dead) +{ + RewriteState rwstate; + IndexScanDesc indexScan; + TableScanDesc tableScan; + HeapScanDesc heapScan; + bool is_system_catalog; + Tuplesortstate *tuplesort; + TupleDesc oldTupDesc = RelationGetDescr(OldHeap); + TupleDesc newTupDesc = RelationGetDescr(NewHeap); + TupleTableSlot *slot; + int natts; + Datum *values; + bool *isnull; + BufferHeapTupleTableSlot *hslot; + BlockNumber prev_cblock = InvalidBlockNumber; + + /* Remember if it's a system catalog */ + is_system_catalog = IsSystemRelation(OldHeap); + + /* + * Valid smgr_targblock implies something already wrote to the relation. + * This may be harmless, but this function hasn't planned for it. + */ + Assert(RelationGetTargetBlock(NewHeap) == InvalidBlockNumber); + + /* Preallocate values/isnull arrays */ + natts = newTupDesc->natts; + values = (Datum *) palloc(natts * sizeof(Datum)); + isnull = (bool *) palloc(natts * sizeof(bool)); + + /* Initialize the rewrite operation */ + rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, *xid_cutoff, + *multi_cutoff); + + + /* Set up sorting if wanted */ + if (use_sort) + tuplesort = tuplesort_begin_cluster(oldTupDesc, OldIndex, + maintenance_work_mem, + NULL, TUPLESORT_NONE); + else + tuplesort = NULL; + + /* + * Prepare to scan the OldHeap. To ensure we see recently-dead tuples + * that still need to be copied, we scan with SnapshotAny and use + * HeapTupleSatisfiesVacuum for the visibility test. + */ + if (OldIndex != NULL && !use_sort) + { + const int ci_index[] = { + PROGRESS_CLUSTER_PHASE, + PROGRESS_CLUSTER_INDEX_RELID + }; + int64 ci_val[2]; + + /* Set phase and OIDOldIndex to columns */ + ci_val[0] = PROGRESS_CLUSTER_PHASE_INDEX_SCAN_HEAP; + ci_val[1] = RelationGetRelid(OldIndex); + pgstat_progress_update_multi_param(2, ci_index, ci_val); + + tableScan = NULL; + heapScan = NULL; + indexScan = index_beginscan(OldHeap, OldIndex, SnapshotAny, 0, 0); + index_rescan(indexScan, NULL, 0, NULL, 0); + } + else + { + /* In scan-and-sort mode and also VACUUM FULL, set phase */ + pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE, + PROGRESS_CLUSTER_PHASE_SEQ_SCAN_HEAP); + + tableScan = table_beginscan(OldHeap, SnapshotAny, 0, (ScanKey) NULL); + heapScan = (HeapScanDesc) tableScan; + indexScan = NULL; + + /* Set total heap blocks */ + pgstat_progress_update_param(PROGRESS_CLUSTER_TOTAL_HEAP_BLKS, + heapScan->rs_nblocks); + } + + slot = table_slot_create(OldHeap, NULL); + hslot = (BufferHeapTupleTableSlot *) slot; + + /* + * Scan through the OldHeap, either in OldIndex order or sequentially; + * copy each tuple into the NewHeap, or transiently to the tuplesort + * module. Note that we don't bother sorting dead tuples (they won't get + * to the new table anyway). + */ + for (;;) + { + HeapTuple tuple; + Buffer buf; + bool isdead; + + CHECK_FOR_INTERRUPTS(); + + if (indexScan != NULL) + { + if (!index_getnext_slot(indexScan, ForwardScanDirection, slot)) + break; + + /* Since we used no scan keys, should never need to recheck */ + if (indexScan->xs_recheck) + elog(ERROR, "CLUSTER does not support lossy index conditions"); + } + else + { + if (!table_scan_getnextslot(tableScan, ForwardScanDirection, slot)) + { + /* + * If the last pages of the scan were empty, we would go to + * the next phase while heap_blks_scanned != heap_blks_total. + * Instead, to ensure that heap_blks_scanned is equivalent to + * total_heap_blks after the table scan phase, this parameter + * is manually updated to the correct value when the table + * scan finishes. + */ + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED, + heapScan->rs_nblocks); + break; + } + + /* + * In scan-and-sort mode and also VACUUM FULL, set heap blocks + * scanned + * + * Note that heapScan may start at an offset and wrap around, i.e. + * rs_startblock may be >0, and rs_cblock may end with a number + * below rs_startblock. To prevent showing this wraparound to the + * user, we offset rs_cblock by rs_startblock (modulo rs_nblocks). + */ + if (prev_cblock != heapScan->rs_cblock) + { + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED, + (heapScan->rs_cblock + + heapScan->rs_nblocks - + heapScan->rs_startblock + ) % heapScan->rs_nblocks + 1); + prev_cblock = heapScan->rs_cblock; + } + } + + tuple = ExecFetchSlotHeapTuple(slot, false, NULL); + buf = hslot->buffer; + + LockBuffer(buf, BUFFER_LOCK_SHARE); + + switch (HeapTupleSatisfiesVacuum(tuple, OldestXmin, buf)) + { + case HEAPTUPLE_DEAD: + /* Definitely dead */ + isdead = true; + break; + case HEAPTUPLE_RECENTLY_DEAD: + *tups_recently_dead += 1; + /* fall through */ + case HEAPTUPLE_LIVE: + /* Live or recently dead, must copy it */ + isdead = false; + break; + case HEAPTUPLE_INSERT_IN_PROGRESS: + + /* + * Since we hold exclusive lock on the relation, normally the + * only way to see this is if it was inserted earlier in our + * own transaction. However, it can happen in system + * catalogs, since we tend to release write lock before commit + * there. Give a warning if neither case applies; but in any + * case we had better copy it. + */ + if (!is_system_catalog && + !TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data))) + elog(WARNING, "concurrent insert in progress within table \"%s\"", + RelationGetRelationName(OldHeap)); + /* treat as live */ + isdead = false; + break; + case HEAPTUPLE_DELETE_IN_PROGRESS: + + /* + * Similar situation to INSERT_IN_PROGRESS case. + */ + if (!is_system_catalog && + !TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tuple->t_data))) + elog(WARNING, "concurrent delete in progress within table \"%s\"", + RelationGetRelationName(OldHeap)); + /* treat as recently dead */ + *tups_recently_dead += 1; + isdead = false; + break; + default: + elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result"); + isdead = false; /* keep compiler quiet */ + break; + } + + LockBuffer(buf, BUFFER_LOCK_UNLOCK); + + if (isdead) + { + *tups_vacuumed += 1; + /* heap rewrite module still needs to see it... */ + if (rewrite_heap_dead_tuple(rwstate, tuple)) + { + /* A previous recently-dead tuple is now known dead */ + *tups_vacuumed += 1; + *tups_recently_dead -= 1; + } + continue; + } + + *num_tuples += 1; + if (tuplesort != NULL) + { + tuplesort_putheaptuple(tuplesort, tuple); + + /* + * In scan-and-sort mode, report increase in number of tuples + * scanned + */ + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_TUPLES_SCANNED, + *num_tuples); + } + else + { + const int ct_index[] = { + PROGRESS_CLUSTER_HEAP_TUPLES_SCANNED, + PROGRESS_CLUSTER_HEAP_TUPLES_WRITTEN + }; + int64 ct_val[2]; + + reform_and_rewrite_tuple(tuple, OldHeap, NewHeap, + values, isnull, rwstate); + + /* + * In indexscan mode and also VACUUM FULL, report increase in + * number of tuples scanned and written + */ + ct_val[0] = *num_tuples; + ct_val[1] = *num_tuples; + pgstat_progress_update_multi_param(2, ct_index, ct_val); + } + } + + if (indexScan != NULL) + index_endscan(indexScan); + if (tableScan != NULL) + table_endscan(tableScan); + if (slot) + ExecDropSingleTupleTableSlot(slot); + + /* + * In scan-and-sort mode, complete the sort, then read out all live tuples + * from the tuplestore and write them to the new relation. + */ + if (tuplesort != NULL) + { + double n_tuples = 0; + + /* Report that we are now sorting tuples */ + pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE, + PROGRESS_CLUSTER_PHASE_SORT_TUPLES); + + tuplesort_performsort(tuplesort); + + /* Report that we are now writing new heap */ + pgstat_progress_update_param(PROGRESS_CLUSTER_PHASE, + PROGRESS_CLUSTER_PHASE_WRITE_NEW_HEAP); + + for (;;) + { + HeapTuple tuple; + + CHECK_FOR_INTERRUPTS(); + + tuple = tuplesort_getheaptuple(tuplesort, true); + if (tuple == NULL) + break; + + n_tuples += 1; + reform_and_rewrite_tuple(tuple, + OldHeap, NewHeap, + values, isnull, + rwstate); + /* Report n_tuples */ + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_TUPLES_WRITTEN, + n_tuples); + } + + tuplesort_end(tuplesort); + } + + /* Write out any remaining tuples, and fsync if needed */ + end_heap_rewrite(rwstate); + + /* Clean up */ + pfree(values); + pfree(isnull); +} + +static bool +heapam_scan_analyze_next_block(TableScanDesc scan, BlockNumber blockno, + BufferAccessStrategy bstrategy) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + + /* + * We must maintain a pin on the target page's buffer to ensure that + * concurrent activity - e.g. HOT pruning - doesn't delete tuples out from + * under us. Hence, pin the page until we are done looking at it. We + * also choose to hold sharelock on the buffer throughout --- we could + * release and re-acquire sharelock for each tuple, but since we aren't + * doing much work per tuple, the extra lock traffic is probably better + * avoided. + */ + hscan->rs_cblock = blockno; + hscan->rs_cindex = FirstOffsetNumber; + hscan->rs_cbuf = ReadBufferExtended(scan->rs_rd, MAIN_FORKNUM, + blockno, RBM_NORMAL, bstrategy); + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + + /* in heap all blocks can contain tuples, so always return true */ + return true; +} + +static bool +heapam_scan_analyze_next_tuple(TableScanDesc scan, TransactionId OldestXmin, + double *liverows, double *deadrows, + TupleTableSlot *slot) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + Page targpage; + OffsetNumber maxoffset; + BufferHeapTupleTableSlot *hslot; + + Assert(TTS_IS_BUFFERTUPLE(slot)); + + hslot = (BufferHeapTupleTableSlot *) slot; + targpage = BufferGetPage(hscan->rs_cbuf); + maxoffset = PageGetMaxOffsetNumber(targpage); + + /* Inner loop over all tuples on the selected page */ + for (; hscan->rs_cindex <= maxoffset; hscan->rs_cindex++) + { + ItemId itemid; + HeapTuple targtuple = &hslot->base.tupdata; + bool sample_it = false; + + itemid = PageGetItemId(targpage, hscan->rs_cindex); + + /* + * We ignore unused and redirect line pointers. DEAD line pointers + * should be counted as dead, because we need vacuum to run to get rid + * of them. Note that this rule agrees with the way that + * heap_page_prune() counts things. + */ + if (!ItemIdIsNormal(itemid)) + { + if (ItemIdIsDead(itemid)) + *deadrows += 1; + continue; + } + + ItemPointerSet(&targtuple->t_self, hscan->rs_cblock, hscan->rs_cindex); + + targtuple->t_tableOid = RelationGetRelid(scan->rs_rd); + targtuple->t_data = (HeapTupleHeader) PageGetItem(targpage, itemid); + targtuple->t_len = ItemIdGetLength(itemid); + + switch (HeapTupleSatisfiesVacuum(targtuple, OldestXmin, + hscan->rs_cbuf)) + { + case HEAPTUPLE_LIVE: + sample_it = true; + *liverows += 1; + break; + + case HEAPTUPLE_DEAD: + case HEAPTUPLE_RECENTLY_DEAD: + /* Count dead and recently-dead rows */ + *deadrows += 1; + break; + + case HEAPTUPLE_INSERT_IN_PROGRESS: + + /* + * Insert-in-progress rows are not counted. We assume that + * when the inserting transaction commits or aborts, it will + * send a stats message to increment the proper count. This + * works right only if that transaction ends after we finish + * analyzing the table; if things happen in the other order, + * its stats update will be overwritten by ours. However, the + * error will be large only if the other transaction runs long + * enough to insert many tuples, so assuming it will finish + * after us is the safer option. + * + * A special case is that the inserting transaction might be + * our own. In this case we should count and sample the row, + * to accommodate users who load a table and analyze it in one + * transaction. (pgstat_report_analyze has to adjust the + * numbers we report to the cumulative stats system to make + * this come out right.) + */ + if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(targtuple->t_data))) + { + sample_it = true; + *liverows += 1; + } + break; + + case HEAPTUPLE_DELETE_IN_PROGRESS: + + /* + * We count and sample delete-in-progress rows the same as + * live ones, so that the stats counters come out right if the + * deleting transaction commits after us, per the same + * reasoning given above. + * + * If the delete was done by our own transaction, however, we + * must count the row as dead to make pgstat_report_analyze's + * stats adjustments come out right. (Note: this works out + * properly when the row was both inserted and deleted in our + * xact.) + * + * The net effect of these choices is that we act as though an + * IN_PROGRESS transaction hasn't happened yet, except if it + * is our own transaction, which we assume has happened. + * + * This approach ensures that we behave sanely if we see both + * the pre-image and post-image rows for a row being updated + * by a concurrent transaction: we will sample the pre-image + * but not the post-image. We also get sane results if the + * concurrent transaction never commits. + */ + if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(targtuple->t_data))) + *deadrows += 1; + else + { + sample_it = true; + *liverows += 1; + } + break; + + default: + elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result"); + break; + } + + if (sample_it) + { + ExecStoreBufferHeapTuple(targtuple, slot, hscan->rs_cbuf); + hscan->rs_cindex++; + + /* note that we leave the buffer locked here! */ + return true; + } + } + + /* Now release the lock and pin on the page */ + UnlockReleaseBuffer(hscan->rs_cbuf); + hscan->rs_cbuf = InvalidBuffer; + + /* also prevent old slot contents from having pin on page */ + ExecClearTuple(slot); + + return false; +} + +static double +heapam_index_build_range_scan(Relation heapRelation, + Relation indexRelation, + IndexInfo *indexInfo, + bool allow_sync, + bool anyvisible, + bool progress, + BlockNumber start_blockno, + BlockNumber numblocks, + IndexBuildCallback callback, + void *callback_state, + TableScanDesc scan) +{ + HeapScanDesc hscan; + bool is_system_catalog; + bool checking_uniqueness; + HeapTuple heapTuple; + Datum values[INDEX_MAX_KEYS]; + bool isnull[INDEX_MAX_KEYS]; + double reltuples; + ExprState *predicate; + TupleTableSlot *slot; + EState *estate; + ExprContext *econtext; + Snapshot snapshot; + bool need_unregister_snapshot = false; + TransactionId OldestXmin; + BlockNumber previous_blkno = InvalidBlockNumber; + BlockNumber root_blkno = InvalidBlockNumber; + OffsetNumber root_offsets[MaxHeapTuplesPerPage]; + + /* + * sanity checks + */ + Assert(OidIsValid(indexRelation->rd_rel->relam)); + + /* Remember if it's a system catalog */ + is_system_catalog = IsSystemRelation(heapRelation); + + /* See whether we're verifying uniqueness/exclusion properties */ + checking_uniqueness = (indexInfo->ii_Unique || + indexInfo->ii_ExclusionOps != NULL); + + /* + * "Any visible" mode is not compatible with uniqueness checks; make sure + * only one of those is requested. + */ + Assert(!(anyvisible && checking_uniqueness)); + + /* + * Need an EState for evaluation of index expressions and partial-index + * predicates. Also a slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + slot = table_slot_create(heapRelation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = slot; + + /* Set up execution state for predicate, if any. */ + predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate); + + /* + * Prepare for scan of the base relation. In a normal index build, we use + * SnapshotAny because we must retrieve all tuples and do our own time + * qual checks (because we have to index RECENTLY_DEAD tuples). In a + * concurrent build, or during bootstrap, we take a regular MVCC snapshot + * and index whatever's live according to that. + */ + OldestXmin = InvalidTransactionId; + + /* okay to ignore lazy VACUUMs here */ + if (!IsBootstrapProcessingMode() && !indexInfo->ii_Concurrent) + OldestXmin = GetOldestNonRemovableTransactionId(heapRelation); + + if (!scan) + { + /* + * Serial index build. + * + * Must begin our own heap scan in this case. We may also need to + * register a snapshot whose lifetime is under our direct control. + */ + if (!TransactionIdIsValid(OldestXmin)) + { + snapshot = RegisterSnapshot(GetTransactionSnapshot()); + need_unregister_snapshot = true; + } + else + snapshot = SnapshotAny; + + scan = table_beginscan_strat(heapRelation, /* relation */ + snapshot, /* snapshot */ + 0, /* number of keys */ + NULL, /* scan key */ + true, /* buffer access strategy OK */ + allow_sync); /* syncscan OK? */ + } + else + { + /* + * Parallel index build. + * + * Parallel case never registers/unregisters own snapshot. Snapshot + * is taken from parallel heap scan, and is SnapshotAny or an MVCC + * snapshot, based on same criteria as serial case. + */ + Assert(!IsBootstrapProcessingMode()); + Assert(allow_sync); + snapshot = scan->rs_snapshot; + } + + hscan = (HeapScanDesc) scan; + + /* + * Must have called GetOldestNonRemovableTransactionId() if using + * SnapshotAny. Shouldn't have for an MVCC snapshot. (It's especially + * worth checking this for parallel builds, since ambuild routines that + * support parallel builds must work these details out for themselves.) + */ + Assert(snapshot == SnapshotAny || IsMVCCSnapshot(snapshot)); + Assert(snapshot == SnapshotAny ? TransactionIdIsValid(OldestXmin) : + !TransactionIdIsValid(OldestXmin)); + Assert(snapshot == SnapshotAny || !anyvisible); + + /* Publish number of blocks to scan */ + if (progress) + { + BlockNumber nblocks; + + if (hscan->rs_base.rs_parallel != NULL) + { + ParallelBlockTableScanDesc pbscan; + + pbscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel; + nblocks = pbscan->phs_nblocks; + } + else + nblocks = hscan->rs_nblocks; + + pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_TOTAL, + nblocks); + } + + /* set our scan endpoints */ + if (!allow_sync) + heap_setscanlimits(scan, start_blockno, numblocks); + else + { + /* syncscan can only be requested on whole relation */ + Assert(start_blockno == 0); + Assert(numblocks == InvalidBlockNumber); + } + + reltuples = 0; + + /* + * Scan all tuples in the base relation. + */ + while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + { + bool tupleIsAlive; + + CHECK_FOR_INTERRUPTS(); + + /* Report scan progress, if asked to. */ + if (progress) + { + BlockNumber blocks_done = heapam_scan_get_blocks_done(hscan); + + if (blocks_done != previous_blkno) + { + pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE, + blocks_done); + previous_blkno = blocks_done; + } + } + + /* + * When dealing with a HOT-chain of updated tuples, we want to index + * the values of the live tuple (if any), but index it under the TID + * of the chain's root tuple. This approach is necessary to preserve + * the HOT-chain structure in the heap. So we need to be able to find + * the root item offset for every tuple that's in a HOT-chain. When + * first reaching a new page of the relation, call + * heap_get_root_tuples() to build a map of root item offsets on the + * page. + * + * It might look unsafe to use this information across buffer + * lock/unlock. However, we hold ShareLock on the table so no + * ordinary insert/update/delete should occur; and we hold pin on the + * buffer continuously while visiting the page, so no pruning + * operation can occur either. + * + * In cases with only ShareUpdateExclusiveLock on the table, it's + * possible for some HOT tuples to appear that we didn't know about + * when we first read the page. To handle that case, we re-obtain the + * list of root offsets when a HOT tuple points to a root item that we + * don't know about. + * + * Also, although our opinions about tuple liveness could change while + * we scan the page (due to concurrent transaction commits/aborts), + * the chain root locations won't, so this info doesn't need to be + * rebuilt after waiting for another transaction. + * + * Note the implied assumption that there is no more than one live + * tuple per HOT-chain --- else we could create more than one index + * entry pointing to the same root tuple. + */ + if (hscan->rs_cblock != root_blkno) + { + Page page = BufferGetPage(hscan->rs_cbuf); + + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + heap_get_root_tuples(page, root_offsets); + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + + root_blkno = hscan->rs_cblock; + } + + if (snapshot == SnapshotAny) + { + /* do our own time qual check */ + bool indexIt; + TransactionId xwait; + + recheck: + + /* + * We could possibly get away with not locking the buffer here, + * since caller should hold ShareLock on the relation, but let's + * be conservative about it. (This remark is still correct even + * with HOT-pruning: our pin on the buffer prevents pruning.) + */ + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + + /* + * The criteria for counting a tuple as live in this block need to + * match what analyze.c's heapam_scan_analyze_next_tuple() does, + * otherwise CREATE INDEX and ANALYZE may produce wildly different + * reltuples values, e.g. when there are many recently-dead + * tuples. + */ + switch (HeapTupleSatisfiesVacuum(heapTuple, OldestXmin, + hscan->rs_cbuf)) + { + case HEAPTUPLE_DEAD: + /* Definitely dead, we can ignore it */ + indexIt = false; + tupleIsAlive = false; + break; + case HEAPTUPLE_LIVE: + /* Normal case, index and unique-check it */ + indexIt = true; + tupleIsAlive = true; + /* Count it as live, too */ + reltuples += 1; + break; + case HEAPTUPLE_RECENTLY_DEAD: + + /* + * If tuple is recently deleted then we must index it + * anyway to preserve MVCC semantics. (Pre-existing + * transactions could try to use the index after we finish + * building it, and may need to see such tuples.) + * + * However, if it was HOT-updated then we must only index + * the live tuple at the end of the HOT-chain. Since this + * breaks semantics for pre-existing snapshots, mark the + * index as unusable for them. + * + * We don't count recently-dead tuples in reltuples, even + * if we index them; see heapam_scan_analyze_next_tuple(). + */ + if (HeapTupleIsHotUpdated(heapTuple)) + { + indexIt = false; + /* mark the index as unsafe for old snapshots */ + indexInfo->ii_BrokenHotChain = true; + } + else + indexIt = true; + /* In any case, exclude the tuple from unique-checking */ + tupleIsAlive = false; + break; + case HEAPTUPLE_INSERT_IN_PROGRESS: + + /* + * In "anyvisible" mode, this tuple is visible and we + * don't need any further checks. + */ + if (anyvisible) + { + indexIt = true; + tupleIsAlive = true; + reltuples += 1; + break; + } + + /* + * Since caller should hold ShareLock or better, normally + * the only way to see this is if it was inserted earlier + * in our own transaction. However, it can happen in + * system catalogs, since we tend to release write lock + * before commit there. Give a warning if neither case + * applies. + */ + xwait = HeapTupleHeaderGetXmin(heapTuple->t_data); + if (!TransactionIdIsCurrentTransactionId(xwait)) + { + if (!is_system_catalog) + elog(WARNING, "concurrent insert in progress within table \"%s\"", + RelationGetRelationName(heapRelation)); + + /* + * If we are performing uniqueness checks, indexing + * such a tuple could lead to a bogus uniqueness + * failure. In that case we wait for the inserting + * transaction to finish and check again. + */ + if (checking_uniqueness) + { + /* + * Must drop the lock on the buffer before we wait + */ + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + XactLockTableWait(xwait, heapRelation, + &heapTuple->t_self, + XLTW_InsertIndexUnique); + CHECK_FOR_INTERRUPTS(); + goto recheck; + } + } + else + { + /* + * For consistency with + * heapam_scan_analyze_next_tuple(), count + * HEAPTUPLE_INSERT_IN_PROGRESS tuples as live only + * when inserted by our own transaction. + */ + reltuples += 1; + } + + /* + * We must index such tuples, since if the index build + * commits then they're good. + */ + indexIt = true; + tupleIsAlive = true; + break; + case HEAPTUPLE_DELETE_IN_PROGRESS: + + /* + * As with INSERT_IN_PROGRESS case, this is unexpected + * unless it's our own deletion or a system catalog; but + * in anyvisible mode, this tuple is visible. + */ + if (anyvisible) + { + indexIt = true; + tupleIsAlive = false; + reltuples += 1; + break; + } + + xwait = HeapTupleHeaderGetUpdateXid(heapTuple->t_data); + if (!TransactionIdIsCurrentTransactionId(xwait)) + { + if (!is_system_catalog) + elog(WARNING, "concurrent delete in progress within table \"%s\"", + RelationGetRelationName(heapRelation)); + + /* + * If we are performing uniqueness checks, assuming + * the tuple is dead could lead to missing a + * uniqueness violation. In that case we wait for the + * deleting transaction to finish and check again. + * + * Also, if it's a HOT-updated tuple, we should not + * index it but rather the live tuple at the end of + * the HOT-chain. However, the deleting transaction + * could abort, possibly leaving this tuple as live + * after all, in which case it has to be indexed. The + * only way to know what to do is to wait for the + * deleting transaction to finish and check again. + */ + if (checking_uniqueness || + HeapTupleIsHotUpdated(heapTuple)) + { + /* + * Must drop the lock on the buffer before we wait + */ + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + XactLockTableWait(xwait, heapRelation, + &heapTuple->t_self, + XLTW_InsertIndexUnique); + CHECK_FOR_INTERRUPTS(); + goto recheck; + } + + /* + * Otherwise index it but don't check for uniqueness, + * the same as a RECENTLY_DEAD tuple. + */ + indexIt = true; + + /* + * Count HEAPTUPLE_DELETE_IN_PROGRESS tuples as live, + * if they were not deleted by the current + * transaction. That's what + * heapam_scan_analyze_next_tuple() does, and we want + * the behavior to be consistent. + */ + reltuples += 1; + } + else if (HeapTupleIsHotUpdated(heapTuple)) + { + /* + * It's a HOT-updated tuple deleted by our own xact. + * We can assume the deletion will commit (else the + * index contents don't matter), so treat the same as + * RECENTLY_DEAD HOT-updated tuples. + */ + indexIt = false; + /* mark the index as unsafe for old snapshots */ + indexInfo->ii_BrokenHotChain = true; + } + else + { + /* + * It's a regular tuple deleted by our own xact. Index + * it, but don't check for uniqueness nor count in + * reltuples, the same as a RECENTLY_DEAD tuple. + */ + indexIt = true; + } + /* In any case, exclude the tuple from unique-checking */ + tupleIsAlive = false; + break; + default: + elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result"); + indexIt = tupleIsAlive = false; /* keep compiler quiet */ + break; + } + + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + + if (!indexIt) + continue; + } + else + { + /* heap_getnext did the time qual check */ + tupleIsAlive = true; + reltuples += 1; + } + + MemoryContextReset(econtext->ecxt_per_tuple_memory); + + /* Set up for predicate or expression evaluation */ + ExecStoreBufferHeapTuple(heapTuple, slot, hscan->rs_cbuf); + + /* + * In a partial index, discard tuples that don't satisfy the + * predicate. + */ + if (predicate != NULL) + { + if (!ExecQual(predicate, econtext)) + continue; + } + + /* + * For the current heap tuple, extract all the attributes we use in + * this index, and note which are null. This also performs evaluation + * of any expressions needed. + */ + FormIndexDatum(indexInfo, + slot, + estate, + values, + isnull); + + /* + * You'd think we should go ahead and build the index tuple here, but + * some index AMs want to do further processing on the data first. So + * pass the values[] and isnull[] arrays, instead. + */ + + if (HeapTupleIsHeapOnly(heapTuple)) + { + /* + * For a heap-only tuple, pretend its TID is that of the root. See + * src/backend/access/heap/README.HOT for discussion. + */ + ItemPointerData tid; + OffsetNumber offnum; + + offnum = ItemPointerGetOffsetNumber(&heapTuple->t_self); + + /* + * If a HOT tuple points to a root that we don't know about, + * obtain root items afresh. If that still fails, report it as + * corruption. + */ + if (root_offsets[offnum - 1] == InvalidOffsetNumber) + { + Page page = BufferGetPage(hscan->rs_cbuf); + + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + heap_get_root_tuples(page, root_offsets); + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + } + + if (!OffsetNumberIsValid(root_offsets[offnum - 1])) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"", + ItemPointerGetBlockNumber(&heapTuple->t_self), + offnum, + RelationGetRelationName(heapRelation)))); + + ItemPointerSet(&tid, ItemPointerGetBlockNumber(&heapTuple->t_self), + root_offsets[offnum - 1]); + + /* Call the AM's callback routine to process the tuple */ + callback(indexRelation, &tid, values, isnull, tupleIsAlive, + callback_state); + } + else + { + /* Call the AM's callback routine to process the tuple */ + callback(indexRelation, &heapTuple->t_self, values, isnull, + tupleIsAlive, callback_state); + } + } + + /* Report scan progress one last time. */ + if (progress) + { + BlockNumber blks_done; + + if (hscan->rs_base.rs_parallel != NULL) + { + ParallelBlockTableScanDesc pbscan; + + pbscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel; + blks_done = pbscan->phs_nblocks; + } + else + blks_done = hscan->rs_nblocks; + + pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE, + blks_done); + } + + table_endscan(scan); + + /* we can now forget our snapshot, if set and registered by us */ + if (need_unregister_snapshot) + UnregisterSnapshot(snapshot); + + ExecDropSingleTupleTableSlot(slot); + + FreeExecutorState(estate); + + /* These may have been pointing to the now-gone estate */ + indexInfo->ii_ExpressionsState = NIL; + indexInfo->ii_PredicateState = NULL; + + return reltuples; +} + +static void +heapam_index_validate_scan(Relation heapRelation, + Relation indexRelation, + IndexInfo *indexInfo, + Snapshot snapshot, + ValidateIndexState *state) +{ + TableScanDesc scan; + HeapScanDesc hscan; + HeapTuple heapTuple; + Datum values[INDEX_MAX_KEYS]; + bool isnull[INDEX_MAX_KEYS]; + ExprState *predicate; + TupleTableSlot *slot; + EState *estate; + ExprContext *econtext; + BlockNumber root_blkno = InvalidBlockNumber; + OffsetNumber root_offsets[MaxHeapTuplesPerPage]; + bool in_index[MaxHeapTuplesPerPage]; + BlockNumber previous_blkno = InvalidBlockNumber; + + /* state variables for the merge */ + ItemPointer indexcursor = NULL; + ItemPointerData decoded; + bool tuplesort_empty = false; + + /* + * sanity checks + */ + Assert(OidIsValid(indexRelation->rd_rel->relam)); + + /* + * Need an EState for evaluation of index expressions and partial-index + * predicates. Also a slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + slot = MakeSingleTupleTableSlot(RelationGetDescr(heapRelation), + &TTSOpsHeapTuple); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = slot; + + /* Set up execution state for predicate, if any. */ + predicate = ExecPrepareQual(indexInfo->ii_Predicate, estate); + + /* + * Prepare for scan of the base relation. We need just those tuples + * satisfying the passed-in reference snapshot. We must disable syncscan + * here, because it's critical that we read from block zero forward to + * match the sorted TIDs. + */ + scan = table_beginscan_strat(heapRelation, /* relation */ + snapshot, /* snapshot */ + 0, /* number of keys */ + NULL, /* scan key */ + true, /* buffer access strategy OK */ + false); /* syncscan not OK */ + hscan = (HeapScanDesc) scan; + + pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_TOTAL, + hscan->rs_nblocks); + + /* + * Scan all tuples matching the snapshot. + */ + while ((heapTuple = heap_getnext(scan, ForwardScanDirection)) != NULL) + { + ItemPointer heapcursor = &heapTuple->t_self; + ItemPointerData rootTuple; + OffsetNumber root_offnum; + + CHECK_FOR_INTERRUPTS(); + + state->htups += 1; + + if ((previous_blkno == InvalidBlockNumber) || + (hscan->rs_cblock != previous_blkno)) + { + pgstat_progress_update_param(PROGRESS_SCAN_BLOCKS_DONE, + hscan->rs_cblock); + previous_blkno = hscan->rs_cblock; + } + + /* + * As commented in table_index_build_scan, we should index heap-only + * tuples under the TIDs of their root tuples; so when we advance onto + * a new heap page, build a map of root item offsets on the page. + * + * This complicates merging against the tuplesort output: we will + * visit the live tuples in order by their offsets, but the root + * offsets that we need to compare against the index contents might be + * ordered differently. So we might have to "look back" within the + * tuplesort output, but only within the current page. We handle that + * by keeping a bool array in_index[] showing all the + * already-passed-over tuplesort output TIDs of the current page. We + * clear that array here, when advancing onto a new heap page. + */ + if (hscan->rs_cblock != root_blkno) + { + Page page = BufferGetPage(hscan->rs_cbuf); + + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + heap_get_root_tuples(page, root_offsets); + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + + memset(in_index, 0, sizeof(in_index)); + + root_blkno = hscan->rs_cblock; + } + + /* Convert actual tuple TID to root TID */ + rootTuple = *heapcursor; + root_offnum = ItemPointerGetOffsetNumber(heapcursor); + + if (HeapTupleIsHeapOnly(heapTuple)) + { + root_offnum = root_offsets[root_offnum - 1]; + if (!OffsetNumberIsValid(root_offnum)) + ereport(ERROR, + (errcode(ERRCODE_DATA_CORRUPTED), + errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"", + ItemPointerGetBlockNumber(heapcursor), + ItemPointerGetOffsetNumber(heapcursor), + RelationGetRelationName(heapRelation)))); + ItemPointerSetOffsetNumber(&rootTuple, root_offnum); + } + + /* + * "merge" by skipping through the index tuples until we find or pass + * the current root tuple. + */ + while (!tuplesort_empty && + (!indexcursor || + ItemPointerCompare(indexcursor, &rootTuple) < 0)) + { + Datum ts_val; + bool ts_isnull; + + if (indexcursor) + { + /* + * Remember index items seen earlier on the current heap page + */ + if (ItemPointerGetBlockNumber(indexcursor) == root_blkno) + in_index[ItemPointerGetOffsetNumber(indexcursor) - 1] = true; + } + + tuplesort_empty = !tuplesort_getdatum(state->tuplesort, true, + &ts_val, &ts_isnull, NULL); + Assert(tuplesort_empty || !ts_isnull); + if (!tuplesort_empty) + { + itemptr_decode(&decoded, DatumGetInt64(ts_val)); + indexcursor = &decoded; + + /* If int8 is pass-by-ref, free (encoded) TID Datum memory */ +#ifndef USE_FLOAT8_BYVAL + pfree(DatumGetPointer(ts_val)); +#endif + } + else + { + /* Be tidy */ + indexcursor = NULL; + } + } + + /* + * If the tuplesort has overshot *and* we didn't see a match earlier, + * then this tuple is missing from the index, so insert it. + */ + if ((tuplesort_empty || + ItemPointerCompare(indexcursor, &rootTuple) > 0) && + !in_index[root_offnum - 1]) + { + MemoryContextReset(econtext->ecxt_per_tuple_memory); + + /* Set up for predicate or expression evaluation */ + ExecStoreHeapTuple(heapTuple, slot, false); + + /* + * In a partial index, discard tuples that don't satisfy the + * predicate. + */ + if (predicate != NULL) + { + if (!ExecQual(predicate, econtext)) + continue; + } + + /* + * For the current heap tuple, extract all the attributes we use + * in this index, and note which are null. This also performs + * evaluation of any expressions needed. + */ + FormIndexDatum(indexInfo, + slot, + estate, + values, + isnull); + + /* + * You'd think we should go ahead and build the index tuple here, + * but some index AMs want to do further processing on the data + * first. So pass the values[] and isnull[] arrays, instead. + */ + + /* + * If the tuple is already committed dead, you might think we + * could suppress uniqueness checking, but this is no longer true + * in the presence of HOT, because the insert is actually a proxy + * for a uniqueness check on the whole HOT-chain. That is, the + * tuple we have here could be dead because it was already + * HOT-updated, and if so the updating transaction will not have + * thought it should insert index entries. The index AM will + * check the whole HOT-chain and correctly detect a conflict if + * there is one. + */ + + index_insert(indexRelation, + values, + isnull, + &rootTuple, + heapRelation, + indexInfo->ii_Unique ? + UNIQUE_CHECK_YES : UNIQUE_CHECK_NO, + false, + indexInfo); + + state->tups_inserted += 1; + } + } + + table_endscan(scan); + + ExecDropSingleTupleTableSlot(slot); + + FreeExecutorState(estate); + + /* These may have been pointing to the now-gone estate */ + indexInfo->ii_ExpressionsState = NIL; + indexInfo->ii_PredicateState = NULL; +} + +/* + * Return the number of blocks that have been read by this scan since + * starting. This is meant for progress reporting rather than be fully + * accurate: in a parallel scan, workers can be concurrently reading blocks + * further ahead than what we report. + */ +static BlockNumber +heapam_scan_get_blocks_done(HeapScanDesc hscan) +{ + ParallelBlockTableScanDesc bpscan = NULL; + BlockNumber startblock; + BlockNumber blocks_done; + + if (hscan->rs_base.rs_parallel != NULL) + { + bpscan = (ParallelBlockTableScanDesc) hscan->rs_base.rs_parallel; + startblock = bpscan->phs_startblock; + } + else + startblock = hscan->rs_startblock; + + /* + * Might have wrapped around the end of the relation, if startblock was + * not zero. + */ + if (hscan->rs_cblock > startblock) + blocks_done = hscan->rs_cblock - startblock; + else + { + BlockNumber nblocks; + + nblocks = bpscan != NULL ? bpscan->phs_nblocks : hscan->rs_nblocks; + blocks_done = nblocks - startblock + + hscan->rs_cblock; + } + + return blocks_done; +} + + +/* ------------------------------------------------------------------------ + * Miscellaneous callbacks for the heap AM + * ------------------------------------------------------------------------ + */ + +/* + * Check to see whether the table needs a TOAST table. It does only if + * (1) there are any toastable attributes, and (2) the maximum length + * of a tuple could exceed TOAST_TUPLE_THRESHOLD. (We don't want to + * create a toast table for something like "f1 varchar(20)".) + */ +static bool +heapam_relation_needs_toast_table(Relation rel) +{ + int32 data_length = 0; + bool maxlength_unknown = false; + bool has_toastable_attrs = false; + TupleDesc tupdesc = rel->rd_att; + int32 tuple_length; + int i; + + for (i = 0; i < tupdesc->natts; i++) + { + Form_pg_attribute att = TupleDescAttr(tupdesc, i); + + if (att->attisdropped) + continue; + data_length = att_align_nominal(data_length, att->attalign); + if (att->attlen > 0) + { + /* Fixed-length types are never toastable */ + data_length += att->attlen; + } + else + { + int32 maxlen = type_maximum_size(att->atttypid, + att->atttypmod); + + if (maxlen < 0) + maxlength_unknown = true; + else + data_length += maxlen; + if (att->attstorage != TYPSTORAGE_PLAIN) + has_toastable_attrs = true; + } + } + if (!has_toastable_attrs) + return false; /* nothing to toast? */ + if (maxlength_unknown) + return true; /* any unlimited-length attrs? */ + tuple_length = MAXALIGN(SizeofHeapTupleHeader + + BITMAPLEN(tupdesc->natts)) + + MAXALIGN(data_length); + return (tuple_length > TOAST_TUPLE_THRESHOLD); +} + +/* + * TOAST tables for heap relations are just heap relations. + */ +static Oid +heapam_relation_toast_am(Relation rel) +{ + return rel->rd_rel->relam; +} + + +/* ------------------------------------------------------------------------ + * Planner related callbacks for the heap AM + * ------------------------------------------------------------------------ + */ + +#define HEAP_OVERHEAD_BYTES_PER_TUPLE \ + (MAXALIGN(SizeofHeapTupleHeader) + sizeof(ItemIdData)) +#define HEAP_USABLE_BYTES_PER_PAGE \ + (BLCKSZ - SizeOfPageHeaderData) + +static void +heapam_estimate_rel_size(Relation rel, int32 *attr_widths, + BlockNumber *pages, double *tuples, + double *allvisfrac) +{ + table_block_relation_estimate_size(rel, attr_widths, pages, + tuples, allvisfrac, + HEAP_OVERHEAD_BYTES_PER_TUPLE, + HEAP_USABLE_BYTES_PER_PAGE); +} + + +/* ------------------------------------------------------------------------ + * Executor related callbacks for the heap AM + * ------------------------------------------------------------------------ + */ + +static bool +heapam_scan_bitmap_next_block(TableScanDesc scan, + TBMIterateResult *tbmres) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + BlockNumber page = tbmres->blockno; + Buffer buffer; + Snapshot snapshot; + int ntup; + + hscan->rs_cindex = 0; + hscan->rs_ntuples = 0; + + /* + * Ignore any claimed entries past what we think is the end of the + * relation. It may have been extended after the start of our scan (we + * only hold an AccessShareLock, and it could be inserts from this + * backend). We don't take this optimization in SERIALIZABLE isolation + * though, as we need to examine all invisible tuples reachable by the + * index. + */ + if (!IsolationIsSerializable() && page >= hscan->rs_nblocks) + return false; + + /* + * Acquire pin on the target heap page, trading in any pin we held before. + */ + hscan->rs_cbuf = ReleaseAndReadBuffer(hscan->rs_cbuf, + scan->rs_rd, + page); + hscan->rs_cblock = page; + buffer = hscan->rs_cbuf; + snapshot = scan->rs_snapshot; + + ntup = 0; + + /* + * Prune and repair fragmentation for the whole page, if possible. + */ + heap_page_prune_opt(scan->rs_rd, buffer); + + /* + * We must hold share lock on the buffer content while examining tuple + * visibility. Afterwards, however, the tuples we have found to be + * visible are guaranteed good as long as we hold the buffer pin. + */ + LockBuffer(buffer, BUFFER_LOCK_SHARE); + + /* + * We need two separate strategies for lossy and non-lossy cases. + */ + if (tbmres->ntuples >= 0) + { + /* + * Bitmap is non-lossy, so we just look through the offsets listed in + * tbmres; but we have to follow any HOT chain starting at each such + * offset. + */ + int curslot; + + for (curslot = 0; curslot < tbmres->ntuples; curslot++) + { + OffsetNumber offnum = tbmres->offsets[curslot]; + ItemPointerData tid; + HeapTupleData heapTuple; + + ItemPointerSet(&tid, page, offnum); + if (heap_hot_search_buffer(&tid, scan->rs_rd, buffer, snapshot, + &heapTuple, NULL, true)) + hscan->rs_vistuples[ntup++] = ItemPointerGetOffsetNumber(&tid); + } + } + else + { + /* + * Bitmap is lossy, so we must examine each line pointer on the page. + * But we can ignore HOT chains, since we'll check each tuple anyway. + */ + Page dp = (Page) BufferGetPage(buffer); + OffsetNumber maxoff = PageGetMaxOffsetNumber(dp); + OffsetNumber offnum; + + for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum)) + { + ItemId lp; + HeapTupleData loctup; + bool valid; + + lp = PageGetItemId(dp, offnum); + if (!ItemIdIsNormal(lp)) + continue; + loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp); + loctup.t_len = ItemIdGetLength(lp); + loctup.t_tableOid = scan->rs_rd->rd_id; + ItemPointerSet(&loctup.t_self, page, offnum); + valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer); + if (valid) + { + hscan->rs_vistuples[ntup++] = offnum; + PredicateLockTID(scan->rs_rd, &loctup.t_self, snapshot, + HeapTupleHeaderGetXmin(loctup.t_data)); + } + HeapCheckForSerializableConflictOut(valid, scan->rs_rd, &loctup, + buffer, snapshot); + } + } + + LockBuffer(buffer, BUFFER_LOCK_UNLOCK); + + Assert(ntup <= MaxHeapTuplesPerPage); + hscan->rs_ntuples = ntup; + + return ntup > 0; +} + +static bool +heapam_scan_bitmap_next_tuple(TableScanDesc scan, + TBMIterateResult *tbmres, + TupleTableSlot *slot) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + OffsetNumber targoffset; + Page dp; + ItemId lp; + + /* + * Out of range? If so, nothing more to look at on this page + */ + if (hscan->rs_cindex < 0 || hscan->rs_cindex >= hscan->rs_ntuples) + return false; + + targoffset = hscan->rs_vistuples[hscan->rs_cindex]; + dp = (Page) BufferGetPage(hscan->rs_cbuf); + lp = PageGetItemId(dp, targoffset); + Assert(ItemIdIsNormal(lp)); + + hscan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp); + hscan->rs_ctup.t_len = ItemIdGetLength(lp); + hscan->rs_ctup.t_tableOid = scan->rs_rd->rd_id; + ItemPointerSet(&hscan->rs_ctup.t_self, hscan->rs_cblock, targoffset); + + pgstat_count_heap_fetch(scan->rs_rd); + + /* + * Set up the result slot to point to this tuple. Note that the slot + * acquires a pin on the buffer. + */ + ExecStoreBufferHeapTuple(&hscan->rs_ctup, + slot, + hscan->rs_cbuf); + + hscan->rs_cindex++; + + return true; +} + +static bool +heapam_scan_sample_next_block(TableScanDesc scan, SampleScanState *scanstate) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + TsmRoutine *tsm = scanstate->tsmroutine; + BlockNumber blockno; + + /* return false immediately if relation is empty */ + if (hscan->rs_nblocks == 0) + return false; + + if (tsm->NextSampleBlock) + { + blockno = tsm->NextSampleBlock(scanstate, hscan->rs_nblocks); + hscan->rs_cblock = blockno; + } + else + { + /* scanning table sequentially */ + + if (hscan->rs_cblock == InvalidBlockNumber) + { + Assert(!hscan->rs_inited); + blockno = hscan->rs_startblock; + } + else + { + Assert(hscan->rs_inited); + + blockno = hscan->rs_cblock + 1; + + if (blockno >= hscan->rs_nblocks) + { + /* wrap to beginning of rel, might not have started at 0 */ + blockno = 0; + } + + /* + * Report our new scan position for synchronization purposes. + * + * Note: we do this before checking for end of scan so that the + * final state of the position hint is back at the start of the + * rel. That's not strictly necessary, but otherwise when you run + * the same query multiple times the starting position would shift + * a little bit backwards on every invocation, which is confusing. + * We don't guarantee any specific ordering in general, though. + */ + if (scan->rs_flags & SO_ALLOW_SYNC) + ss_report_location(scan->rs_rd, blockno); + + if (blockno == hscan->rs_startblock) + { + blockno = InvalidBlockNumber; + } + } + } + + if (!BlockNumberIsValid(blockno)) + { + if (BufferIsValid(hscan->rs_cbuf)) + ReleaseBuffer(hscan->rs_cbuf); + hscan->rs_cbuf = InvalidBuffer; + hscan->rs_cblock = InvalidBlockNumber; + hscan->rs_inited = false; + + return false; + } + + heapgetpage(scan, blockno); + hscan->rs_inited = true; + + return true; +} + +static bool +heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate, + TupleTableSlot *slot) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + TsmRoutine *tsm = scanstate->tsmroutine; + BlockNumber blockno = hscan->rs_cblock; + bool pagemode = (scan->rs_flags & SO_ALLOW_PAGEMODE) != 0; + + Page page; + bool all_visible; + OffsetNumber maxoffset; + + /* + * When not using pagemode, we must lock the buffer during tuple + * visibility checks. + */ + if (!pagemode) + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE); + + page = (Page) BufferGetPage(hscan->rs_cbuf); + all_visible = PageIsAllVisible(page) && + !scan->rs_snapshot->takenDuringRecovery; + maxoffset = PageGetMaxOffsetNumber(page); + + for (;;) + { + OffsetNumber tupoffset; + + CHECK_FOR_INTERRUPTS(); + + /* Ask the tablesample method which tuples to check on this page. */ + tupoffset = tsm->NextSampleTuple(scanstate, + blockno, + maxoffset); + + if (OffsetNumberIsValid(tupoffset)) + { + ItemId itemid; + bool visible; + HeapTuple tuple = &(hscan->rs_ctup); + + /* Skip invalid tuple pointers. */ + itemid = PageGetItemId(page, tupoffset); + if (!ItemIdIsNormal(itemid)) + continue; + + tuple->t_data = (HeapTupleHeader) PageGetItem(page, itemid); + tuple->t_len = ItemIdGetLength(itemid); + ItemPointerSet(&(tuple->t_self), blockno, tupoffset); + + + if (all_visible) + visible = true; + else + visible = SampleHeapTupleVisible(scan, hscan->rs_cbuf, + tuple, tupoffset); + + /* in pagemode, heapgetpage did this for us */ + if (!pagemode) + HeapCheckForSerializableConflictOut(visible, scan->rs_rd, tuple, + hscan->rs_cbuf, scan->rs_snapshot); + + /* Try next tuple from same page. */ + if (!visible) + continue; + + /* Found visible tuple, return it. */ + if (!pagemode) + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + + ExecStoreBufferHeapTuple(tuple, slot, hscan->rs_cbuf); + + /* Count successfully-fetched tuples as heap fetches */ + pgstat_count_heap_getnext(scan->rs_rd); + + return true; + } + else + { + /* + * If we get here, it means we've exhausted the items on this page + * and it's time to move to the next. + */ + if (!pagemode) + LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK); + + ExecClearTuple(slot); + return false; + } + } + + Assert(0); +} + + +/* ---------------------------------------------------------------------------- + * Helper functions for the above. + * ---------------------------------------------------------------------------- + */ + +/* + * Reconstruct and rewrite the given tuple + * + * We cannot simply copy the tuple as-is, for several reasons: + * + * 1. We'd like to squeeze out the values of any dropped columns, both + * to save space and to ensure we have no corner-case failures. (It's + * possible for example that the new table hasn't got a TOAST table + * and so is unable to store any large values of dropped cols.) + * + * 2. The tuple might not even be legal for the new table; this is + * currently only known to happen as an after-effect of ALTER TABLE + * SET WITHOUT OIDS. + * + * So, we must reconstruct the tuple from component Datums. + */ +static void +reform_and_rewrite_tuple(HeapTuple tuple, + Relation OldHeap, Relation NewHeap, + Datum *values, bool *isnull, RewriteState rwstate) +{ + TupleDesc oldTupDesc = RelationGetDescr(OldHeap); + TupleDesc newTupDesc = RelationGetDescr(NewHeap); + HeapTuple copiedTuple; + int i; + + heap_deform_tuple(tuple, oldTupDesc, values, isnull); + + /* Be sure to null out any dropped columns */ + for (i = 0; i < newTupDesc->natts; i++) + { + if (TupleDescAttr(newTupDesc, i)->attisdropped) + isnull[i] = true; + } + + copiedTuple = heap_form_tuple(newTupDesc, values, isnull); + + /* The heap rewrite module does the rest */ + rewrite_heap_tuple(rwstate, tuple, copiedTuple); + + heap_freetuple(copiedTuple); +} + +/* + * Check visibility of the tuple. + */ +static bool +SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer, + HeapTuple tuple, + OffsetNumber tupoffset) +{ + HeapScanDesc hscan = (HeapScanDesc) scan; + + if (scan->rs_flags & SO_ALLOW_PAGEMODE) + { + /* + * In pageatatime mode, heapgetpage() already did visibility checks, + * so just look at the info it left in rs_vistuples[]. + * + * We use a binary search over the known-sorted array. Note: we could + * save some effort if we insisted that NextSampleTuple select tuples + * in increasing order, but it's not clear that there would be enough + * gain to justify the restriction. + */ + int start = 0, + end = hscan->rs_ntuples - 1; + + while (start <= end) + { + int mid = (start + end) / 2; + OffsetNumber curoffset = hscan->rs_vistuples[mid]; + + if (tupoffset == curoffset) + return true; + else if (tupoffset < curoffset) + end = mid - 1; + else + start = mid + 1; + } + + return false; + } + else + { + /* Otherwise, we have to check the tuple individually. */ + return HeapTupleSatisfiesVisibility(tuple, scan->rs_snapshot, + buffer); + } +} + + +/* ------------------------------------------------------------------------ + * Definition of the heap table access method. + * ------------------------------------------------------------------------ + */ + +static const TableAmRoutine heapam_methods = { + .type = T_TableAmRoutine, + + .slot_callbacks = heapam_slot_callbacks, + + .scan_begin = heap_beginscan, + .scan_end = heap_endscan, + .scan_rescan = heap_rescan, + .scan_getnextslot = heap_getnextslot, + + .scan_set_tidrange = heap_set_tidrange, + .scan_getnextslot_tidrange = heap_getnextslot_tidrange, + + .parallelscan_estimate = table_block_parallelscan_estimate, + .parallelscan_initialize = table_block_parallelscan_initialize, + .parallelscan_reinitialize = table_block_parallelscan_reinitialize, + + .index_fetch_begin = heapam_index_fetch_begin, + .index_fetch_reset = heapam_index_fetch_reset, + .index_fetch_end = heapam_index_fetch_end, + .index_fetch_tuple = heapam_index_fetch_tuple, + + .tuple_insert = heapam_tuple_insert, + .tuple_insert_speculative = heapam_tuple_insert_speculative, + .tuple_complete_speculative = heapam_tuple_complete_speculative, + .multi_insert = heap_multi_insert, + .tuple_delete = heapam_tuple_delete, + .tuple_update = heapam_tuple_update, + .tuple_lock = heapam_tuple_lock, + + .tuple_fetch_row_version = heapam_fetch_row_version, + .tuple_get_latest_tid = heap_get_latest_tid, + .tuple_tid_valid = heapam_tuple_tid_valid, + .tuple_satisfies_snapshot = heapam_tuple_satisfies_snapshot, + .index_delete_tuples = heap_index_delete_tuples, + + .relation_set_new_filenode = heapam_relation_set_new_filenode, + .relation_nontransactional_truncate = heapam_relation_nontransactional_truncate, + .relation_copy_data = heapam_relation_copy_data, + .relation_copy_for_cluster = heapam_relation_copy_for_cluster, + .relation_vacuum = heap_vacuum_rel, + .scan_analyze_next_block = heapam_scan_analyze_next_block, + .scan_analyze_next_tuple = heapam_scan_analyze_next_tuple, + .index_build_range_scan = heapam_index_build_range_scan, + .index_validate_scan = heapam_index_validate_scan, + + .relation_size = table_block_relation_size, + .relation_needs_toast_table = heapam_relation_needs_toast_table, + .relation_toast_am = heapam_relation_toast_am, + .relation_fetch_toast_slice = heap_fetch_toast_slice, + + .relation_estimate_size = heapam_estimate_rel_size, + + .scan_bitmap_next_block = heapam_scan_bitmap_next_block, + .scan_bitmap_next_tuple = heapam_scan_bitmap_next_tuple, + .scan_sample_next_block = heapam_scan_sample_next_block, + .scan_sample_next_tuple = heapam_scan_sample_next_tuple +}; + + +const TableAmRoutine * +GetHeapamTableAmRoutine(void) +{ + return &heapam_methods; +} + +Datum +heap_tableam_handler(PG_FUNCTION_ARGS) +{ + PG_RETURN_POINTER(&heapam_methods); +} |