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Diffstat (limited to 'contrib/pg_surgery/heap_surgery.c')
| -rw-r--r-- | contrib/pg_surgery/heap_surgery.c | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/contrib/pg_surgery/heap_surgery.c b/contrib/pg_surgery/heap_surgery.c new file mode 100644 index 0000000..d31e5f3 --- /dev/null +++ b/contrib/pg_surgery/heap_surgery.c @@ -0,0 +1,428 @@ +/*------------------------------------------------------------------------- + * + * heap_surgery.c + * Functions to perform surgery on the damaged heap table. + * + * Copyright (c) 2020-2021, PostgreSQL Global Development Group + * + * IDENTIFICATION + * contrib/pg_surgery/heap_surgery.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/heapam.h" +#include "access/visibilitymap.h" +#include "catalog/pg_am_d.h" +#include "catalog/pg_proc_d.h" +#include "miscadmin.h" +#include "storage/bufmgr.h" +#include "utils/acl.h" +#include "utils/rel.h" + +PG_MODULE_MAGIC; + +/* Options to forcefully change the state of a heap tuple. */ +typedef enum HeapTupleForceOption +{ + HEAP_FORCE_KILL, + HEAP_FORCE_FREEZE +} HeapTupleForceOption; + +PG_FUNCTION_INFO_V1(heap_force_kill); +PG_FUNCTION_INFO_V1(heap_force_freeze); + +static int32 tidcmp(const void *a, const void *b); +static Datum heap_force_common(FunctionCallInfo fcinfo, + HeapTupleForceOption heap_force_opt); +static void sanity_check_tid_array(ArrayType *ta, int *ntids); +static void sanity_check_relation(Relation rel); +static BlockNumber find_tids_one_page(ItemPointer tids, int ntids, + OffsetNumber *next_start_ptr); + +/*------------------------------------------------------------------------- + * heap_force_kill() + * + * Force kill the tuple(s) pointed to by the item pointer(s) stored in the + * given TID array. + * + * Usage: SELECT heap_force_kill(regclass, tid[]); + *------------------------------------------------------------------------- + */ +Datum +heap_force_kill(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(heap_force_common(fcinfo, HEAP_FORCE_KILL)); +} + +/*------------------------------------------------------------------------- + * heap_force_freeze() + * + * Force freeze the tuple(s) pointed to by the item pointer(s) stored in the + * given TID array. + * + * Usage: SELECT heap_force_freeze(regclass, tid[]); + *------------------------------------------------------------------------- + */ +Datum +heap_force_freeze(PG_FUNCTION_ARGS) +{ + PG_RETURN_DATUM(heap_force_common(fcinfo, HEAP_FORCE_FREEZE)); +} + +/*------------------------------------------------------------------------- + * heap_force_common() + * + * Common code for heap_force_kill and heap_force_freeze + *------------------------------------------------------------------------- + */ +static Datum +heap_force_common(FunctionCallInfo fcinfo, HeapTupleForceOption heap_force_opt) +{ + Oid relid = PG_GETARG_OID(0); + ArrayType *ta = PG_GETARG_ARRAYTYPE_P_COPY(1); + ItemPointer tids; + int ntids, + nblocks; + Relation rel; + OffsetNumber curr_start_ptr, + next_start_ptr; + bool include_this_tid[MaxHeapTuplesPerPage]; + + if (RecoveryInProgress()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("recovery is in progress"), + errhint("heap surgery functions cannot be executed during recovery."))); + + /* Check inputs. */ + sanity_check_tid_array(ta, &ntids); + + rel = relation_open(relid, RowExclusiveLock); + + /* Check target relation. */ + sanity_check_relation(rel); + + tids = ((ItemPointer) ARR_DATA_PTR(ta)); + + /* + * If there is more than one TID in the array, sort them so that we can + * easily fetch all the TIDs belonging to one particular page from the + * array. + */ + if (ntids > 1) + qsort((void *) tids, ntids, sizeof(ItemPointerData), tidcmp); + + curr_start_ptr = next_start_ptr = 0; + nblocks = RelationGetNumberOfBlocks(rel); + + /* + * Loop, performing the necessary actions for each block. + */ + while (next_start_ptr != ntids) + { + Buffer buf; + Buffer vmbuf = InvalidBuffer; + Page page; + BlockNumber blkno; + OffsetNumber curoff; + OffsetNumber maxoffset; + int i; + bool did_modify_page = false; + bool did_modify_vm = false; + + CHECK_FOR_INTERRUPTS(); + + /* + * Find all the TIDs belonging to one particular page starting from + * next_start_ptr and process them one by one. + */ + blkno = find_tids_one_page(tids, ntids, &next_start_ptr); + + /* Check whether the block number is valid. */ + if (blkno >= nblocks) + { + /* Update the current_start_ptr before moving to the next page. */ + curr_start_ptr = next_start_ptr; + + ereport(NOTICE, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("skipping block %u for relation \"%s\" because the block number is out of range", + blkno, RelationGetRelationName(rel)))); + continue; + } + + buf = ReadBuffer(rel, blkno); + LockBufferForCleanup(buf); + + page = BufferGetPage(buf); + + maxoffset = PageGetMaxOffsetNumber(page); + + /* + * Figure out which TIDs we are going to process and which ones we are + * going to skip. + */ + memset(include_this_tid, 0, sizeof(include_this_tid)); + for (i = curr_start_ptr; i < next_start_ptr; i++) + { + OffsetNumber offno = ItemPointerGetOffsetNumberNoCheck(&tids[i]); + ItemId itemid; + + /* Check whether the offset number is valid. */ + if (offno == InvalidOffsetNumber || offno > maxoffset) + { + ereport(NOTICE, + errmsg("skipping tid (%u, %u) for relation \"%s\" because the item number is out of range", + blkno, offno, RelationGetRelationName(rel))); + continue; + } + + itemid = PageGetItemId(page, offno); + + /* Only accept an item ID that is used. */ + if (ItemIdIsRedirected(itemid)) + { + ereport(NOTICE, + errmsg("skipping tid (%u, %u) for relation \"%s\" because it redirects to item %u", + blkno, offno, RelationGetRelationName(rel), + ItemIdGetRedirect(itemid))); + continue; + } + else if (ItemIdIsDead(itemid)) + { + ereport(NOTICE, + (errmsg("skipping tid (%u, %u) for relation \"%s\" because it is marked dead", + blkno, offno, RelationGetRelationName(rel)))); + continue; + } + else if (!ItemIdIsUsed(itemid)) + { + ereport(NOTICE, + (errmsg("skipping tid (%u, %u) for relation \"%s\" because it is marked unused", + blkno, offno, RelationGetRelationName(rel)))); + continue; + } + + /* Mark it for processing. */ + Assert(offno < MaxHeapTuplesPerPage); + include_this_tid[offno] = true; + } + + /* + * Before entering the critical section, pin the visibility map page + * if it appears to be necessary. + */ + if (heap_force_opt == HEAP_FORCE_KILL && PageIsAllVisible(page)) + visibilitymap_pin(rel, blkno, &vmbuf); + + /* No ereport(ERROR) from here until all the changes are logged. */ + START_CRIT_SECTION(); + + for (curoff = FirstOffsetNumber; curoff <= maxoffset; + curoff = OffsetNumberNext(curoff)) + { + ItemId itemid; + + if (!include_this_tid[curoff]) + continue; + + itemid = PageGetItemId(page, curoff); + Assert(ItemIdIsNormal(itemid)); + + did_modify_page = true; + + if (heap_force_opt == HEAP_FORCE_KILL) + { + ItemIdSetDead(itemid); + + /* + * If the page is marked all-visible, we must clear + * PD_ALL_VISIBLE flag on the page header and an all-visible + * bit on the visibility map corresponding to the page. + */ + if (PageIsAllVisible(page)) + { + PageClearAllVisible(page); + visibilitymap_clear(rel, blkno, vmbuf, + VISIBILITYMAP_VALID_BITS); + did_modify_vm = true; + } + } + else + { + HeapTupleHeader htup; + + Assert(heap_force_opt == HEAP_FORCE_FREEZE); + + htup = (HeapTupleHeader) PageGetItem(page, itemid); + + /* + * Reset all visibility-related fields of the tuple. This + * logic should mimic heap_execute_freeze_tuple(), but we + * choose to reset xmin and ctid just to be sure that no + * potentially-garbled data is left behind. + */ + ItemPointerSet(&htup->t_ctid, blkno, curoff); + HeapTupleHeaderSetXmin(htup, FrozenTransactionId); + HeapTupleHeaderSetXmax(htup, InvalidTransactionId); + if (htup->t_infomask & HEAP_MOVED) + { + if (htup->t_infomask & HEAP_MOVED_OFF) + HeapTupleHeaderSetXvac(htup, InvalidTransactionId); + else + HeapTupleHeaderSetXvac(htup, FrozenTransactionId); + } + + /* + * Clear all the visibility-related bits of this tuple and + * mark it as frozen. Also, get rid of HOT_UPDATED and + * KEYS_UPDATES bits. + */ + htup->t_infomask &= ~HEAP_XACT_MASK; + htup->t_infomask |= (HEAP_XMIN_FROZEN | HEAP_XMAX_INVALID); + htup->t_infomask2 &= ~HEAP_HOT_UPDATED; + htup->t_infomask2 &= ~HEAP_KEYS_UPDATED; + } + } + + /* + * If the page was modified, only then, we mark the buffer dirty or do + * the WAL logging. + */ + if (did_modify_page) + { + /* Mark buffer dirty before we write WAL. */ + MarkBufferDirty(buf); + + /* XLOG stuff */ + if (RelationNeedsWAL(rel)) + log_newpage_buffer(buf, true); + } + + /* WAL log the VM page if it was modified. */ + if (did_modify_vm && RelationNeedsWAL(rel)) + log_newpage_buffer(vmbuf, false); + + END_CRIT_SECTION(); + + UnlockReleaseBuffer(buf); + + if (vmbuf != InvalidBuffer) + ReleaseBuffer(vmbuf); + + /* Update the current_start_ptr before moving to the next page. */ + curr_start_ptr = next_start_ptr; + } + + relation_close(rel, RowExclusiveLock); + + pfree(ta); + + PG_RETURN_VOID(); +} + +/*------------------------------------------------------------------------- + * tidcmp() + * + * Compare two item pointers, return -1, 0, or +1. + * + * See ItemPointerCompare for details. + * ------------------------------------------------------------------------ + */ +static int32 +tidcmp(const void *a, const void *b) +{ + ItemPointer iptr1 = ((const ItemPointer) a); + ItemPointer iptr2 = ((const ItemPointer) b); + + return ItemPointerCompare(iptr1, iptr2); +} + +/*------------------------------------------------------------------------- + * sanity_check_tid_array() + * + * Perform sanity checks on the given tid array, and set *ntids to the + * number of items in the array. + * ------------------------------------------------------------------------ + */ +static void +sanity_check_tid_array(ArrayType *ta, int *ntids) +{ + if (ARR_HASNULL(ta) && array_contains_nulls(ta)) + ereport(ERROR, + (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), + errmsg("array must not contain nulls"))); + + if (ARR_NDIM(ta) > 1) + ereport(ERROR, + (errcode(ERRCODE_DATA_EXCEPTION), + errmsg("argument must be empty or one-dimensional array"))); + + *ntids = ArrayGetNItems(ARR_NDIM(ta), ARR_DIMS(ta)); +} + +/*------------------------------------------------------------------------- + * sanity_check_relation() + * + * Perform sanity checks on the given relation. + * ------------------------------------------------------------------------ + */ +static void +sanity_check_relation(Relation rel) +{ + if (rel->rd_rel->relkind != RELKIND_RELATION && + rel->rd_rel->relkind != RELKIND_MATVIEW && + rel->rd_rel->relkind != RELKIND_TOASTVALUE) + ereport(ERROR, + (errcode(ERRCODE_WRONG_OBJECT_TYPE), + errmsg("\"%s\" is not a table, materialized view, or TOAST table", + RelationGetRelationName(rel)))); + + if (rel->rd_rel->relam != HEAP_TABLE_AM_OID) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("only heap AM is supported"))); + + /* Must be owner of the table or superuser. */ + if (!pg_class_ownercheck(RelationGetRelid(rel), GetUserId())) + aclcheck_error(ACLCHECK_NOT_OWNER, + get_relkind_objtype(rel->rd_rel->relkind), + RelationGetRelationName(rel)); +} + +/*------------------------------------------------------------------------- + * find_tids_one_page() + * + * Find all the tids residing in the same page as tids[next_start_ptr], and + * update next_start_ptr so that it points to the first tid in the next page. + * + * NOTE: The input tids[] array must be sorted. + * ------------------------------------------------------------------------ + */ +static BlockNumber +find_tids_one_page(ItemPointer tids, int ntids, OffsetNumber *next_start_ptr) +{ + int i; + BlockNumber prev_blkno, + blkno; + + prev_blkno = blkno = InvalidBlockNumber; + + for (i = *next_start_ptr; i < ntids; i++) + { + ItemPointerData tid = tids[i]; + + blkno = ItemPointerGetBlockNumberNoCheck(&tid); + + if (i == *next_start_ptr) + prev_blkno = blkno; + + if (prev_blkno != blkno) + break; + } + + *next_start_ptr = i; + return prev_blkno; +} |