--- /dev/null
+create extension pg_surgery;
+-- create a normal heap table and insert some rows.
+-- note that we don't commit the transaction, so autovacuum can't interfere.
+begin;
+create table htab(a int);
+insert into htab values (100), (200), (300), (400), (500);
+-- test empty TID array
+select heap_force_freeze('htab'::regclass, ARRAY[]::tid[]);
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+-- nothing should be frozen yet
+select * from htab where xmin = 2;
+ a
+---
+(0 rows)
+
+-- freeze forcibly
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+-- now we should have one frozen tuple
+select ctid, xmax from htab where xmin = 2;
+ ctid | xmax
+-------+------
+ (0,4) | 0
+(1 row)
+
+-- kill forcibly
+select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+ heap_force_kill
+-----------------
+
+(1 row)
+
+-- should be gone now
+select * from htab where ctid = '(0, 4)';
+ a
+---
+(0 rows)
+
+-- should now be skipped because it's already dead
+select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+NOTICE: skipping tid (0, 4) for relation "htab" because it is marked dead
+ heap_force_kill
+-----------------
+
+(1 row)
+
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+NOTICE: skipping tid (0, 4) for relation "htab" because it is marked dead
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+-- freeze two TIDs at once while skipping an out-of-range block number
+select heap_force_freeze('htab'::regclass,
+ ARRAY['(0, 1)', '(0, 3)', '(1, 1)']::tid[]);
+NOTICE: skipping block 1 for relation "htab" because the block number is out of range
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+-- we should now have two frozen tuples
+select ctid, xmax from htab where xmin = 2;
+ ctid | xmax
+-------+------
+ (0,1) | 0
+ (0,3) | 0
+(2 rows)
+
+-- out-of-range TIDs should be skipped
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 0)', '(0, 6)']::tid[]);
+NOTICE: skipping tid (0, 0) for relation "htab" because the item number is out of range
+NOTICE: skipping tid (0, 6) for relation "htab" because the item number is out of range
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+rollback;
+-- set up a new table with a redirected line pointer
+create table htab2(a int) with (autovacuum_enabled = off);
+insert into htab2 values (100);
+update htab2 set a = 200;
+vacuum htab2;
+-- redirected TIDs should be skipped
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 1)']::tid[]);
+NOTICE: skipping tid (0, 1) for relation "htab2" because it redirects to item 2
+ heap_force_kill
+-----------------
+
+(1 row)
+
+-- now create an unused line pointer
+select ctid from htab2;
+ ctid
+-------
+ (0,2)
+(1 row)
+
+update htab2 set a = 300;
+select ctid from htab2;
+ ctid
+-------
+ (0,3)
+(1 row)
+
+vacuum freeze htab2;
+-- unused TIDs should be skipped
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 2)']::tid[]);
+NOTICE: skipping tid (0, 2) for relation "htab2" because it is marked unused
+ heap_force_kill
+-----------------
+
+(1 row)
+
+-- multidimensional TID array should be rejected
+select heap_force_kill('htab2'::regclass, ARRAY[['(0, 2)']]::tid[]);
+ERROR: argument must be empty or one-dimensional array
+-- TID array with nulls should be rejected
+select heap_force_kill('htab2'::regclass, ARRAY[NULL]::tid[]);
+ERROR: array must not contain nulls
+-- but we should be able to kill the one tuple we have
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 3)']::tid[]);
+ heap_force_kill
+-----------------
+
+(1 row)
+
+-- materialized view.
+-- note that we don't commit the transaction, so autovacuum can't interfere.
+begin;
+create materialized view mvw as select a from generate_series(1, 3) a;
+select * from mvw where xmin = 2;
+ a
+---
+(0 rows)
+
+select heap_force_freeze('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
+ heap_force_freeze
+-------------------
+
+(1 row)
+
+select * from mvw where xmin = 2;
+ a
+---
+ 3
+(1 row)
+
+select heap_force_kill('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
+ heap_force_kill
+-----------------
+
+(1 row)
+
+select * from mvw where ctid = '(0, 3)';
+ a
+---
+(0 rows)
+
+rollback;
+-- check that it fails on an unsupported relkind
+create view vw as select 1;
+select heap_force_kill('vw'::regclass, ARRAY['(0, 1)']::tid[]);
+ERROR: "vw" is not a table, materialized view, or TOAST table
+select heap_force_freeze('vw'::regclass, ARRAY['(0, 1)']::tid[]);
+ERROR: "vw" is not a table, materialized view, or TOAST table
+-- cleanup.
+drop table htab2;
+drop view vw;
+drop extension pg_surgery;
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * heap_surgery.c
+ * Functions to perform surgery on the damaged heap table.
+ *
+ * Copyright (c) 2020, 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;
+}
--- /dev/null
+create extension pg_surgery;
+
+-- create a normal heap table and insert some rows.
+-- note that we don't commit the transaction, so autovacuum can't interfere.
+begin;
+create table htab(a int);
+insert into htab values (100), (200), (300), (400), (500);
+
+-- test empty TID array
+select heap_force_freeze('htab'::regclass, ARRAY[]::tid[]);
+
+-- nothing should be frozen yet
+select * from htab where xmin = 2;
+
+-- freeze forcibly
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+
+-- now we should have one frozen tuple
+select ctid, xmax from htab where xmin = 2;
+
+-- kill forcibly
+select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+
+-- should be gone now
+select * from htab where ctid = '(0, 4)';
+
+-- should now be skipped because it's already dead
+select heap_force_kill('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 4)']::tid[]);
+
+-- freeze two TIDs at once while skipping an out-of-range block number
+select heap_force_freeze('htab'::regclass,
+ ARRAY['(0, 1)', '(0, 3)', '(1, 1)']::tid[]);
+
+-- we should now have two frozen tuples
+select ctid, xmax from htab where xmin = 2;
+
+-- out-of-range TIDs should be skipped
+select heap_force_freeze('htab'::regclass, ARRAY['(0, 0)', '(0, 6)']::tid[]);
+
+rollback;
+
+-- set up a new table with a redirected line pointer
+create table htab2(a int) with (autovacuum_enabled = off);
+insert into htab2 values (100);
+update htab2 set a = 200;
+vacuum htab2;
+
+-- redirected TIDs should be skipped
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 1)']::tid[]);
+
+-- now create an unused line pointer
+select ctid from htab2;
+update htab2 set a = 300;
+select ctid from htab2;
+vacuum freeze htab2;
+
+-- unused TIDs should be skipped
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 2)']::tid[]);
+
+-- multidimensional TID array should be rejected
+select heap_force_kill('htab2'::regclass, ARRAY[['(0, 2)']]::tid[]);
+
+-- TID array with nulls should be rejected
+select heap_force_kill('htab2'::regclass, ARRAY[NULL]::tid[]);
+
+-- but we should be able to kill the one tuple we have
+select heap_force_kill('htab2'::regclass, ARRAY['(0, 3)']::tid[]);
+
+-- materialized view.
+-- note that we don't commit the transaction, so autovacuum can't interfere.
+begin;
+create materialized view mvw as select a from generate_series(1, 3) a;
+
+select * from mvw where xmin = 2;
+select heap_force_freeze('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
+select * from mvw where xmin = 2;
+
+select heap_force_kill('mvw'::regclass, ARRAY['(0, 3)']::tid[]);
+select * from mvw where ctid = '(0, 3)';
+rollback;
+
+-- check that it fails on an unsupported relkind
+create view vw as select 1;
+select heap_force_kill('vw'::regclass, ARRAY['(0, 1)']::tid[]);
+select heap_force_freeze('vw'::regclass, ARRAY['(0, 1)']::tid[]);
+
+-- cleanup.
+drop table htab2;
+drop view vw;
+drop extension pg_surgery;
projects / postgresql.git / commitdiff