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Code comments were claiming that verify_heapam() was checking privileges on the relation it was operating on, but it didn't actually do that. Perhaps earlier versions of the patch did that, but now the access is regulated by privileges on the function. Remove the wrong comments.
1735 lines
54 KiB
C
1735 lines
54 KiB
C
/*-------------------------------------------------------------------------
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*
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* verify_heapam.c
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* Functions to check postgresql heap relations for corruption
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*
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* Copyright (c) 2016-2021, PostgreSQL Global Development Group
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*
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* contrib/amcheck/verify_heapam.c
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/detoast.h"
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#include "access/genam.h"
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#include "access/heapam.h"
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#include "access/heaptoast.h"
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#include "access/multixact.h"
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#include "access/toast_internals.h"
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#include "access/visibilitymap.h"
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#include "catalog/pg_am.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/bufmgr.h"
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#include "storage/procarray.h"
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#include "utils/builtins.h"
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#include "utils/fmgroids.h"
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PG_FUNCTION_INFO_V1(verify_heapam);
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/* The number of columns in tuples returned by verify_heapam */
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#define HEAPCHECK_RELATION_COLS 4
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/*
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* Despite the name, we use this for reporting problems with both XIDs and
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* MXIDs.
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*/
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typedef enum XidBoundsViolation
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{
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XID_INVALID,
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XID_IN_FUTURE,
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XID_PRECEDES_CLUSTERMIN,
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XID_PRECEDES_RELMIN,
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XID_BOUNDS_OK
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} XidBoundsViolation;
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typedef enum XidCommitStatus
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{
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XID_COMMITTED,
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XID_IS_CURRENT_XID,
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XID_IN_PROGRESS,
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XID_ABORTED
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} XidCommitStatus;
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typedef enum SkipPages
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{
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SKIP_PAGES_ALL_FROZEN,
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SKIP_PAGES_ALL_VISIBLE,
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SKIP_PAGES_NONE
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} SkipPages;
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/*
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* Struct holding information about a toasted attribute sufficient to both
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* check the toasted attribute and, if found to be corrupt, to report where it
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* was encountered in the main table.
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*/
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typedef struct ToastedAttribute
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{
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struct varatt_external toast_pointer;
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BlockNumber blkno; /* block in main table */
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OffsetNumber offnum; /* offset in main table */
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AttrNumber attnum; /* attribute in main table */
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} ToastedAttribute;
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/*
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* Struct holding the running context information during
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* a lifetime of a verify_heapam execution.
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*/
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typedef struct HeapCheckContext
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{
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/*
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* Cached copies of values from ShmemVariableCache and computed values
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* from them.
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*/
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FullTransactionId next_fxid; /* ShmemVariableCache->nextXid */
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TransactionId next_xid; /* 32-bit version of next_fxid */
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TransactionId oldest_xid; /* ShmemVariableCache->oldestXid */
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FullTransactionId oldest_fxid; /* 64-bit version of oldest_xid, computed
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* relative to next_fxid */
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TransactionId safe_xmin; /* this XID and newer ones can't become
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* all-visible while we're running */
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/*
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* Cached copy of value from MultiXactState
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*/
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MultiXactId next_mxact; /* MultiXactState->nextMXact */
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MultiXactId oldest_mxact; /* MultiXactState->oldestMultiXactId */
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/*
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* Cached copies of the most recently checked xid and its status.
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*/
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TransactionId cached_xid;
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XidCommitStatus cached_status;
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/* Values concerning the heap relation being checked */
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Relation rel;
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TransactionId relfrozenxid;
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FullTransactionId relfrozenfxid;
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TransactionId relminmxid;
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Relation toast_rel;
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Relation *toast_indexes;
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Relation valid_toast_index;
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int num_toast_indexes;
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/* Values for iterating over pages in the relation */
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BlockNumber blkno;
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BufferAccessStrategy bstrategy;
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Buffer buffer;
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Page page;
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/* Values for iterating over tuples within a page */
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OffsetNumber offnum;
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ItemId itemid;
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uint16 lp_len;
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uint16 lp_off;
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HeapTupleHeader tuphdr;
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int natts;
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/* Values for iterating over attributes within the tuple */
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uint32 offset; /* offset in tuple data */
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AttrNumber attnum;
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/* True if tuple's xmax makes it eligible for pruning */
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bool tuple_could_be_pruned;
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/*
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* List of ToastedAttribute structs for toasted attributes which are not
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* eligible for pruning and should be checked
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*/
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List *toasted_attributes;
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/* Whether verify_heapam has yet encountered any corrupt tuples */
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bool is_corrupt;
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/* The descriptor and tuplestore for verify_heapam's result tuples */
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TupleDesc tupdesc;
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Tuplestorestate *tupstore;
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} HeapCheckContext;
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/* Internal implementation */
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static void sanity_check_relation(Relation rel);
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static void check_tuple(HeapCheckContext *ctx);
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static void check_toast_tuple(HeapTuple toasttup, HeapCheckContext *ctx,
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ToastedAttribute *ta, int32 *expected_chunk_seq,
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uint32 extsize);
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static bool check_tuple_attribute(HeapCheckContext *ctx);
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static void check_toasted_attribute(HeapCheckContext *ctx,
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ToastedAttribute *ta);
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static bool check_tuple_header(HeapCheckContext *ctx);
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static bool check_tuple_visibility(HeapCheckContext *ctx);
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static void report_corruption(HeapCheckContext *ctx, char *msg);
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static void report_toast_corruption(HeapCheckContext *ctx,
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ToastedAttribute *ta, char *msg);
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static TupleDesc verify_heapam_tupdesc(void);
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static FullTransactionId FullTransactionIdFromXidAndCtx(TransactionId xid,
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const HeapCheckContext *ctx);
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static void update_cached_xid_range(HeapCheckContext *ctx);
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static void update_cached_mxid_range(HeapCheckContext *ctx);
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static XidBoundsViolation check_mxid_in_range(MultiXactId mxid,
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HeapCheckContext *ctx);
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static XidBoundsViolation check_mxid_valid_in_rel(MultiXactId mxid,
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HeapCheckContext *ctx);
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static XidBoundsViolation get_xid_status(TransactionId xid,
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HeapCheckContext *ctx,
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XidCommitStatus *status);
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/*
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* Scan and report corruption in heap pages, optionally reconciling toasted
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* attributes with entries in the associated toast table. Intended to be
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* called from SQL with the following parameters:
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*
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* relation:
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* The Oid of the heap relation to be checked.
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*
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* on_error_stop:
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* Whether to stop at the end of the first page for which errors are
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* detected. Note that multiple rows may be returned.
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*
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* check_toast:
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* Whether to check each toasted attribute against the toast table to
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* verify that it can be found there.
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*
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* skip:
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* What kinds of pages in the heap relation should be skipped. Valid
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* options are "all-visible", "all-frozen", and "none".
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*
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* Returns to the SQL caller a set of tuples, each containing the location
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* and a description of a corruption found in the heap.
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*
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* This code goes to some trouble to avoid crashing the server even if the
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* table pages are badly corrupted, but it's probably not perfect. If
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* check_toast is true, we'll use regular index lookups to try to fetch TOAST
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* tuples, which can certainly cause crashes if the right kind of corruption
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* exists in the toast table or index. No matter what parameters you pass,
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* we can't protect against crashes that might occur trying to look up the
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* commit status of transaction IDs (though we avoid trying to do such lookups
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* for transaction IDs that can't legally appear in the table).
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*/
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Datum
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verify_heapam(PG_FUNCTION_ARGS)
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{
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ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
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MemoryContext old_context;
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bool random_access;
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HeapCheckContext ctx;
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Buffer vmbuffer = InvalidBuffer;
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Oid relid;
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bool on_error_stop;
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bool check_toast;
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SkipPages skip_option = SKIP_PAGES_NONE;
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BlockNumber first_block;
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BlockNumber last_block;
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BlockNumber nblocks;
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const char *skip;
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/* Check to see if caller supports us returning a tuplestore */
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if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("set-valued function called in context that cannot accept a set")));
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if (!(rsinfo->allowedModes & SFRM_Materialize))
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("materialize mode required, but it is not allowed in this context")));
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/* Check supplied arguments */
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if (PG_ARGISNULL(0))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("relation cannot be null")));
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relid = PG_GETARG_OID(0);
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if (PG_ARGISNULL(1))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("on_error_stop cannot be null")));
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on_error_stop = PG_GETARG_BOOL(1);
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if (PG_ARGISNULL(2))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("check_toast cannot be null")));
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check_toast = PG_GETARG_BOOL(2);
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if (PG_ARGISNULL(3))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("skip cannot be null")));
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skip = text_to_cstring(PG_GETARG_TEXT_PP(3));
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if (pg_strcasecmp(skip, "all-visible") == 0)
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skip_option = SKIP_PAGES_ALL_VISIBLE;
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else if (pg_strcasecmp(skip, "all-frozen") == 0)
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skip_option = SKIP_PAGES_ALL_FROZEN;
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else if (pg_strcasecmp(skip, "none") == 0)
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skip_option = SKIP_PAGES_NONE;
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else
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid skip option"),
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errhint("Valid skip options are \"all-visible\", \"all-frozen\", and \"none\".")));
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memset(&ctx, 0, sizeof(HeapCheckContext));
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ctx.cached_xid = InvalidTransactionId;
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ctx.toasted_attributes = NIL;
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/*
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* Any xmin newer than the xmin of our snapshot can't become all-visible
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* while we're running.
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*/
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ctx.safe_xmin = GetTransactionSnapshot()->xmin;
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/*
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* If we report corruption when not examining some individual attribute,
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* we need attnum to be reported as NULL. Set that up before any
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* corruption reporting might happen.
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*/
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ctx.attnum = -1;
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/* The tupdesc and tuplestore must be created in ecxt_per_query_memory */
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old_context = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
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random_access = (rsinfo->allowedModes & SFRM_Materialize_Random) != 0;
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ctx.tupdesc = verify_heapam_tupdesc();
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ctx.tupstore = tuplestore_begin_heap(random_access, false, work_mem);
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rsinfo->returnMode = SFRM_Materialize;
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rsinfo->setResult = ctx.tupstore;
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rsinfo->setDesc = ctx.tupdesc;
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MemoryContextSwitchTo(old_context);
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/* Open relation, check relkind and access method */
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ctx.rel = relation_open(relid, AccessShareLock);
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sanity_check_relation(ctx.rel);
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/* Early exit if the relation is empty */
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nblocks = RelationGetNumberOfBlocks(ctx.rel);
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if (!nblocks)
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{
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relation_close(ctx.rel, AccessShareLock);
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PG_RETURN_NULL();
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}
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ctx.bstrategy = GetAccessStrategy(BAS_BULKREAD);
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ctx.buffer = InvalidBuffer;
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ctx.page = NULL;
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/* Validate block numbers, or handle nulls. */
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if (PG_ARGISNULL(4))
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first_block = 0;
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else
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{
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int64 fb = PG_GETARG_INT64(4);
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if (fb < 0 || fb >= nblocks)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("starting block number must be between 0 and %u",
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nblocks - 1)));
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first_block = (BlockNumber) fb;
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}
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if (PG_ARGISNULL(5))
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last_block = nblocks - 1;
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else
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{
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int64 lb = PG_GETARG_INT64(5);
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if (lb < 0 || lb >= nblocks)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("ending block number must be between 0 and %u",
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nblocks - 1)));
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last_block = (BlockNumber) lb;
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}
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/* Optionally open the toast relation, if any. */
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if (ctx.rel->rd_rel->reltoastrelid && check_toast)
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{
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int offset;
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/* Main relation has associated toast relation */
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ctx.toast_rel = table_open(ctx.rel->rd_rel->reltoastrelid,
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AccessShareLock);
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offset = toast_open_indexes(ctx.toast_rel,
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AccessShareLock,
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&(ctx.toast_indexes),
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&(ctx.num_toast_indexes));
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ctx.valid_toast_index = ctx.toast_indexes[offset];
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}
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else
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{
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/*
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* Main relation has no associated toast relation, or we're
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* intentionally skipping it.
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*/
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ctx.toast_rel = NULL;
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ctx.toast_indexes = NULL;
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ctx.num_toast_indexes = 0;
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}
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update_cached_xid_range(&ctx);
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update_cached_mxid_range(&ctx);
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ctx.relfrozenxid = ctx.rel->rd_rel->relfrozenxid;
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ctx.relfrozenfxid = FullTransactionIdFromXidAndCtx(ctx.relfrozenxid, &ctx);
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ctx.relminmxid = ctx.rel->rd_rel->relminmxid;
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if (TransactionIdIsNormal(ctx.relfrozenxid))
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ctx.oldest_xid = ctx.relfrozenxid;
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for (ctx.blkno = first_block; ctx.blkno <= last_block; ctx.blkno++)
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{
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OffsetNumber maxoff;
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/* Optionally skip over all-frozen or all-visible blocks */
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if (skip_option != SKIP_PAGES_NONE)
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{
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int32 mapbits;
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mapbits = (int32) visibilitymap_get_status(ctx.rel, ctx.blkno,
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&vmbuffer);
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if (skip_option == SKIP_PAGES_ALL_FROZEN)
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{
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if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
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continue;
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}
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if (skip_option == SKIP_PAGES_ALL_VISIBLE)
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{
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if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
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continue;
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}
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}
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/* Read and lock the next page. */
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ctx.buffer = ReadBufferExtended(ctx.rel, MAIN_FORKNUM, ctx.blkno,
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RBM_NORMAL, ctx.bstrategy);
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LockBuffer(ctx.buffer, BUFFER_LOCK_SHARE);
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ctx.page = BufferGetPage(ctx.buffer);
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/* Perform tuple checks */
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maxoff = PageGetMaxOffsetNumber(ctx.page);
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for (ctx.offnum = FirstOffsetNumber; ctx.offnum <= maxoff;
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ctx.offnum = OffsetNumberNext(ctx.offnum))
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{
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ctx.itemid = PageGetItemId(ctx.page, ctx.offnum);
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/* Skip over unused/dead line pointers */
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if (!ItemIdIsUsed(ctx.itemid) || ItemIdIsDead(ctx.itemid))
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continue;
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/*
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* If this line pointer has been redirected, check that it
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* redirects to a valid offset within the line pointer array
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*/
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if (ItemIdIsRedirected(ctx.itemid))
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{
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OffsetNumber rdoffnum = ItemIdGetRedirect(ctx.itemid);
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ItemId rditem;
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if (rdoffnum < FirstOffsetNumber)
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{
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report_corruption(&ctx,
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psprintf("line pointer redirection to item at offset %u precedes minimum offset %u",
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(unsigned) rdoffnum,
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(unsigned) FirstOffsetNumber));
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continue;
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}
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if (rdoffnum > maxoff)
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{
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report_corruption(&ctx,
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psprintf("line pointer redirection to item at offset %u exceeds maximum offset %u",
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(unsigned) rdoffnum,
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(unsigned) maxoff));
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continue;
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}
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rditem = PageGetItemId(ctx.page, rdoffnum);
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if (!ItemIdIsUsed(rditem))
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report_corruption(&ctx,
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psprintf("line pointer redirection to unused item at offset %u",
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(unsigned) rdoffnum));
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continue;
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}
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/* Sanity-check the line pointer's offset and length values */
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ctx.lp_len = ItemIdGetLength(ctx.itemid);
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ctx.lp_off = ItemIdGetOffset(ctx.itemid);
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if (ctx.lp_off != MAXALIGN(ctx.lp_off))
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{
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report_corruption(&ctx,
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psprintf("line pointer to page offset %u is not maximally aligned",
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ctx.lp_off));
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continue;
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}
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if (ctx.lp_len < MAXALIGN(SizeofHeapTupleHeader))
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{
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report_corruption(&ctx,
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psprintf("line pointer length %u is less than the minimum tuple header size %u",
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ctx.lp_len,
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(unsigned) MAXALIGN(SizeofHeapTupleHeader)));
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continue;
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}
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if (ctx.lp_off + ctx.lp_len > BLCKSZ)
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{
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report_corruption(&ctx,
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psprintf("line pointer to page offset %u with length %u ends beyond maximum page offset %u",
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ctx.lp_off,
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ctx.lp_len,
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(unsigned) BLCKSZ));
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continue;
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}
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/* It should be safe to examine the tuple's header, at least */
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ctx.tuphdr = (HeapTupleHeader) PageGetItem(ctx.page, ctx.itemid);
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ctx.natts = HeapTupleHeaderGetNatts(ctx.tuphdr);
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/* Ok, ready to check this next tuple */
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check_tuple(&ctx);
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}
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/* clean up */
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UnlockReleaseBuffer(ctx.buffer);
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/*
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* Check any toast pointers from the page whose lock we just released
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*/
|
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if (ctx.toasted_attributes != NIL)
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{
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ListCell *cell;
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|
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foreach(cell, ctx.toasted_attributes)
|
|
check_toasted_attribute(&ctx, lfirst(cell));
|
|
list_free_deep(ctx.toasted_attributes);
|
|
ctx.toasted_attributes = NIL;
|
|
}
|
|
|
|
if (on_error_stop && ctx.is_corrupt)
|
|
break;
|
|
}
|
|
|
|
if (vmbuffer != InvalidBuffer)
|
|
ReleaseBuffer(vmbuffer);
|
|
|
|
/* Close the associated toast table and indexes, if any. */
|
|
if (ctx.toast_indexes)
|
|
toast_close_indexes(ctx.toast_indexes, ctx.num_toast_indexes,
|
|
AccessShareLock);
|
|
if (ctx.toast_rel)
|
|
table_close(ctx.toast_rel, AccessShareLock);
|
|
|
|
/* Close the main relation */
|
|
relation_close(ctx.rel, AccessShareLock);
|
|
|
|
PG_RETURN_NULL();
|
|
}
|
|
|
|
/*
|
|
* Check that a relation's relkind and access method are both supported.
|
|
*/
|
|
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")));
|
|
}
|
|
|
|
/*
|
|
* Shared internal implementation for report_corruption and
|
|
* report_toast_corruption.
|
|
*/
|
|
static void
|
|
report_corruption_internal(Tuplestorestate *tupstore, TupleDesc tupdesc,
|
|
BlockNumber blkno, OffsetNumber offnum,
|
|
AttrNumber attnum, char *msg)
|
|
{
|
|
Datum values[HEAPCHECK_RELATION_COLS];
|
|
bool nulls[HEAPCHECK_RELATION_COLS];
|
|
HeapTuple tuple;
|
|
|
|
MemSet(values, 0, sizeof(values));
|
|
MemSet(nulls, 0, sizeof(nulls));
|
|
values[0] = Int64GetDatum(blkno);
|
|
values[1] = Int32GetDatum(offnum);
|
|
values[2] = Int32GetDatum(attnum);
|
|
nulls[2] = (attnum < 0);
|
|
values[3] = CStringGetTextDatum(msg);
|
|
|
|
/*
|
|
* In principle, there is nothing to prevent a scan over a large, highly
|
|
* corrupted table from using work_mem worth of memory building up the
|
|
* tuplestore. That's ok, but if we also leak the msg argument memory
|
|
* until the end of the query, we could exceed work_mem by more than a
|
|
* trivial amount. Therefore, free the msg argument each time we are
|
|
* called rather than waiting for our current memory context to be freed.
|
|
*/
|
|
pfree(msg);
|
|
|
|
tuple = heap_form_tuple(tupdesc, values, nulls);
|
|
tuplestore_puttuple(tupstore, tuple);
|
|
}
|
|
|
|
/*
|
|
* Record a single corruption found in the main table. The values in ctx should
|
|
* indicate the location of the corruption, and the msg argument should contain
|
|
* a human-readable description of the corruption.
|
|
*
|
|
* The msg argument is pfree'd by this function.
|
|
*/
|
|
static void
|
|
report_corruption(HeapCheckContext *ctx, char *msg)
|
|
{
|
|
report_corruption_internal(ctx->tupstore, ctx->tupdesc, ctx->blkno,
|
|
ctx->offnum, ctx->attnum, msg);
|
|
ctx->is_corrupt = true;
|
|
}
|
|
|
|
/*
|
|
* Record corruption found in the toast table. The values in ta should
|
|
* indicate the location in the main table where the toast pointer was
|
|
* encountered, and the msg argument should contain a human-readable
|
|
* description of the toast table corruption.
|
|
*
|
|
* As above, the msg argument is pfree'd by this function.
|
|
*/
|
|
static void
|
|
report_toast_corruption(HeapCheckContext *ctx, ToastedAttribute *ta,
|
|
char *msg)
|
|
{
|
|
report_corruption_internal(ctx->tupstore, ctx->tupdesc, ta->blkno,
|
|
ta->offnum, ta->attnum, msg);
|
|
ctx->is_corrupt = true;
|
|
}
|
|
|
|
/*
|
|
* Construct the TupleDesc used to report messages about corruptions found
|
|
* while scanning the heap.
|
|
*/
|
|
static TupleDesc
|
|
verify_heapam_tupdesc(void)
|
|
{
|
|
TupleDesc tupdesc;
|
|
AttrNumber a = 0;
|
|
|
|
tupdesc = CreateTemplateTupleDesc(HEAPCHECK_RELATION_COLS);
|
|
TupleDescInitEntry(tupdesc, ++a, "blkno", INT8OID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, ++a, "offnum", INT4OID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, ++a, "attnum", INT4OID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, ++a, "msg", TEXTOID, -1, 0);
|
|
Assert(a == HEAPCHECK_RELATION_COLS);
|
|
|
|
return BlessTupleDesc(tupdesc);
|
|
}
|
|
|
|
/*
|
|
* Check for tuple header corruption.
|
|
*
|
|
* Some kinds of corruption make it unsafe to check the tuple attributes, for
|
|
* example when the line pointer refers to a range of bytes outside the page.
|
|
* In such cases, we return false (not checkable) after recording appropriate
|
|
* corruption messages.
|
|
*
|
|
* Some other kinds of tuple header corruption confuse the question of where
|
|
* the tuple attributes begin, or how long the nulls bitmap is, etc., making it
|
|
* unreasonable to attempt to check attributes, even if all candidate answers
|
|
* to those questions would not result in reading past the end of the line
|
|
* pointer or page. In such cases, like above, we record corruption messages
|
|
* about the header and then return false.
|
|
*
|
|
* Other kinds of tuple header corruption do not bear on the question of
|
|
* whether the tuple attributes can be checked, so we record corruption
|
|
* messages for them but we do not return false merely because we detected
|
|
* them.
|
|
*
|
|
* Returns whether the tuple is sufficiently sensible to undergo visibility and
|
|
* attribute checks.
|
|
*/
|
|
static bool
|
|
check_tuple_header(HeapCheckContext *ctx)
|
|
{
|
|
HeapTupleHeader tuphdr = ctx->tuphdr;
|
|
uint16 infomask = tuphdr->t_infomask;
|
|
bool result = true;
|
|
unsigned expected_hoff;
|
|
|
|
if (ctx->tuphdr->t_hoff > ctx->lp_len)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("data begins at offset %u beyond the tuple length %u",
|
|
ctx->tuphdr->t_hoff, ctx->lp_len));
|
|
result = false;
|
|
}
|
|
|
|
if ((ctx->tuphdr->t_infomask & HEAP_XMAX_COMMITTED) &&
|
|
(ctx->tuphdr->t_infomask & HEAP_XMAX_IS_MULTI))
|
|
{
|
|
report_corruption(ctx,
|
|
pstrdup("multixact should not be marked committed"));
|
|
|
|
/*
|
|
* This condition is clearly wrong, but it's not enough to justify
|
|
* skipping further checks, because we don't rely on this to determine
|
|
* whether the tuple is visible or to interpret other relevant header
|
|
* fields.
|
|
*/
|
|
}
|
|
|
|
if (infomask & HEAP_HASNULL)
|
|
expected_hoff = MAXALIGN(SizeofHeapTupleHeader + BITMAPLEN(ctx->natts));
|
|
else
|
|
expected_hoff = MAXALIGN(SizeofHeapTupleHeader);
|
|
if (ctx->tuphdr->t_hoff != expected_hoff)
|
|
{
|
|
if ((infomask & HEAP_HASNULL) && ctx->natts == 1)
|
|
report_corruption(ctx,
|
|
psprintf("tuple data should begin at byte %u, but actually begins at byte %u (1 attribute, has nulls)",
|
|
expected_hoff, ctx->tuphdr->t_hoff));
|
|
else if ((infomask & HEAP_HASNULL))
|
|
report_corruption(ctx,
|
|
psprintf("tuple data should begin at byte %u, but actually begins at byte %u (%u attributes, has nulls)",
|
|
expected_hoff, ctx->tuphdr->t_hoff, ctx->natts));
|
|
else if (ctx->natts == 1)
|
|
report_corruption(ctx,
|
|
psprintf("tuple data should begin at byte %u, but actually begins at byte %u (1 attribute, no nulls)",
|
|
expected_hoff, ctx->tuphdr->t_hoff));
|
|
else
|
|
report_corruption(ctx,
|
|
psprintf("tuple data should begin at byte %u, but actually begins at byte %u (%u attributes, no nulls)",
|
|
expected_hoff, ctx->tuphdr->t_hoff, ctx->natts));
|
|
result = false;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* Checks tuple visibility so we know which further checks are safe to
|
|
* perform.
|
|
*
|
|
* If a tuple could have been inserted by a transaction that also added a
|
|
* column to the table, but which ultimately did not commit, or which has not
|
|
* yet committed, then the table's current TupleDesc might differ from the one
|
|
* used to construct this tuple, so we must not check it.
|
|
*
|
|
* As a special case, if our own transaction inserted the tuple, even if we
|
|
* added a column to the table, our TupleDesc should match. We could check the
|
|
* tuple, but choose not to do so.
|
|
*
|
|
* If a tuple has been updated or deleted, we can still read the old tuple for
|
|
* corruption checking purposes, as long as we are careful about concurrent
|
|
* vacuums. The main table tuple itself cannot be vacuumed away because we
|
|
* hold a buffer lock on the page, but if the deleting transaction is older
|
|
* than our transaction snapshot's xmin, then vacuum could remove the toast at
|
|
* any time, so we must not try to follow TOAST pointers.
|
|
*
|
|
* If xmin or xmax values are older than can be checked against clog, or appear
|
|
* to be in the future (possibly due to wrap-around), then we cannot make a
|
|
* determination about the visibility of the tuple, so we skip further checks.
|
|
*
|
|
* Returns true if the tuple itself should be checked, false otherwise. Sets
|
|
* ctx->tuple_could_be_pruned if the tuple -- and thus also any associated
|
|
* TOAST tuples -- are eligible for pruning.
|
|
*/
|
|
static bool
|
|
check_tuple_visibility(HeapCheckContext *ctx)
|
|
{
|
|
TransactionId xmin;
|
|
TransactionId xvac;
|
|
TransactionId xmax;
|
|
XidCommitStatus xmin_status;
|
|
XidCommitStatus xvac_status;
|
|
XidCommitStatus xmax_status;
|
|
HeapTupleHeader tuphdr = ctx->tuphdr;
|
|
|
|
ctx->tuple_could_be_pruned = true; /* have not yet proven otherwise */
|
|
|
|
/* If xmin is normal, it should be within valid range */
|
|
xmin = HeapTupleHeaderGetXmin(tuphdr);
|
|
switch (get_xid_status(xmin, ctx, &xmin_status))
|
|
{
|
|
case XID_INVALID:
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("xmin %u equals or exceeds next valid transaction ID %u:%u",
|
|
xmin,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmin %u precedes oldest valid transaction ID %u:%u",
|
|
xmin,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmin %u precedes relation freeze threshold %u:%u",
|
|
xmin,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Has inserting transaction committed?
|
|
*/
|
|
if (!HeapTupleHeaderXminCommitted(tuphdr))
|
|
{
|
|
if (HeapTupleHeaderXminInvalid(tuphdr))
|
|
return false; /* inserter aborted, don't check */
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuphdr->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
xvac = HeapTupleHeaderGetXvac(tuphdr);
|
|
|
|
switch (get_xid_status(xvac, ctx, &xvac_status))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("old-style VACUUM FULL transaction ID for moved off tuple is invalid"));
|
|
return false;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple equals or exceeds next valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple precedes relation freeze threshold %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple precedes oldest valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false;
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
}
|
|
|
|
switch (xvac_status)
|
|
{
|
|
case XID_IS_CURRENT_XID:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple matches our current transaction ID",
|
|
xvac));
|
|
return false;
|
|
case XID_IN_PROGRESS:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved off tuple appears to be in progress",
|
|
xvac));
|
|
return false;
|
|
|
|
case XID_COMMITTED:
|
|
|
|
/*
|
|
* The tuple is dead, because the xvac transaction moved
|
|
* it off and committed. It's checkable, but also
|
|
* prunable.
|
|
*/
|
|
return true;
|
|
|
|
case XID_ABORTED:
|
|
|
|
/*
|
|
* The original xmin must have committed, because the xvac
|
|
* transaction tried to move it later. Since xvac is
|
|
* aborted, whether it's still alive now depends on the
|
|
* status of xmax.
|
|
*/
|
|
break;
|
|
}
|
|
}
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (tuphdr->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
xvac = HeapTupleHeaderGetXvac(tuphdr);
|
|
|
|
switch (get_xid_status(xvac, ctx, &xvac_status))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("old-style VACUUM FULL transaction ID for moved in tuple is invalid"));
|
|
return false;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple equals or exceeds next valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple precedes relation freeze threshold %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple precedes oldest valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false;
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
}
|
|
|
|
switch (xvac_status)
|
|
{
|
|
case XID_IS_CURRENT_XID:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple matches our current transaction ID",
|
|
xvac));
|
|
return false;
|
|
case XID_IN_PROGRESS:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u for moved in tuple appears to be in progress",
|
|
xvac));
|
|
return false;
|
|
|
|
case XID_COMMITTED:
|
|
|
|
/*
|
|
* The original xmin must have committed, because the xvac
|
|
* transaction moved it later. Whether it's still alive
|
|
* now depends on the status of xmax.
|
|
*/
|
|
break;
|
|
|
|
case XID_ABORTED:
|
|
|
|
/*
|
|
* The tuple is dead, because the xvac transaction moved
|
|
* it off and committed. It's checkable, but also
|
|
* prunable.
|
|
*/
|
|
return true;
|
|
}
|
|
}
|
|
else if (xmin_status != XID_COMMITTED)
|
|
{
|
|
/*
|
|
* Inserting transaction is not in progress, and not committed, so
|
|
* it might have changed the TupleDesc in ways we don't know
|
|
* about. Thus, don't try to check the tuple structure.
|
|
*
|
|
* If xmin_status happens to be XID_IS_CURRENT_XID, then in theory
|
|
* any such DDL changes ought to be visible to us, so perhaps we
|
|
* could check anyway in that case. But, for now, let's be
|
|
* conservative and treat this like any other uncommitted insert.
|
|
*/
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Okay, the inserter committed, so it was good at some point. Now what
|
|
* about the deleting transaction?
|
|
*/
|
|
|
|
if (tuphdr->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
/*
|
|
* xmax is a multixact, so sanity-check the MXID. Note that we do this
|
|
* prior to checking for HEAP_XMAX_INVALID or
|
|
* HEAP_XMAX_IS_LOCKED_ONLY. This might therefore complain about
|
|
* things that wouldn't actually be a problem during a normal scan,
|
|
* but eventually we're going to have to freeze, and that process will
|
|
* ignore hint bits.
|
|
*
|
|
* Even if the MXID is out of range, we still know that the original
|
|
* insert committed, so we can check the tuple itself. However, we
|
|
* can't rule out the possibility that this tuple is dead, so don't
|
|
* clear ctx->tuple_could_be_pruned. Possibly we should go ahead and
|
|
* clear that flag anyway if HEAP_XMAX_INVALID is set or if
|
|
* HEAP_XMAX_IS_LOCKED_ONLY is true, but for now we err on the side of
|
|
* avoiding possibly-bogus complaints about missing TOAST entries.
|
|
*/
|
|
xmax = HeapTupleHeaderGetRawXmax(tuphdr);
|
|
switch (check_mxid_valid_in_rel(xmax, ctx))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("multitransaction ID is invalid"));
|
|
return true;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u precedes relation minimum multitransaction ID threshold %u",
|
|
xmax, ctx->relminmxid));
|
|
return true;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u precedes oldest valid multitransaction ID threshold %u",
|
|
xmax, ctx->oldest_mxact));
|
|
return true;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u equals or exceeds next valid multitransaction ID %u",
|
|
xmax,
|
|
ctx->next_mxact));
|
|
return true;
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (tuphdr->t_infomask & HEAP_XMAX_INVALID)
|
|
{
|
|
/*
|
|
* This tuple is live. A concurrently running transaction could
|
|
* delete it before we get around to checking the toast, but any such
|
|
* running transaction is surely not less than our safe_xmin, so the
|
|
* toast cannot be vacuumed out from under us.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
return true;
|
|
}
|
|
|
|
if (HEAP_XMAX_IS_LOCKED_ONLY(tuphdr->t_infomask))
|
|
{
|
|
/*
|
|
* "Deleting" xact really only locked it, so the tuple is live in any
|
|
* case. As above, a concurrently running transaction could delete
|
|
* it, but it cannot be vacuumed out from under us.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
return true;
|
|
}
|
|
|
|
if (tuphdr->t_infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
/*
|
|
* We already checked above that this multixact is within limits for
|
|
* this table. Now check the update xid from this multixact.
|
|
*/
|
|
xmax = HeapTupleGetUpdateXid(tuphdr);
|
|
switch (get_xid_status(xmax, ctx, &xmax_status))
|
|
{
|
|
case XID_INVALID:
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
report_corruption(ctx,
|
|
pstrdup("update xid is invalid"));
|
|
return true;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("update xid %u equals or exceeds next valid transaction ID %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return true;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("update xid %u precedes relation freeze threshold %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return true;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("update xid %u precedes oldest valid transaction ID %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return true;
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
}
|
|
|
|
switch (xmax_status)
|
|
{
|
|
case XID_IS_CURRENT_XID:
|
|
case XID_IN_PROGRESS:
|
|
|
|
/*
|
|
* The delete is in progress, so it cannot be visible to our
|
|
* snapshot.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
break;
|
|
case XID_COMMITTED:
|
|
|
|
/*
|
|
* The delete committed. Whether the toast can be vacuumed
|
|
* away depends on how old the deleting transaction is.
|
|
*/
|
|
ctx->tuple_could_be_pruned = TransactionIdPrecedes(xmax,
|
|
ctx->safe_xmin);
|
|
break;
|
|
case XID_ABORTED:
|
|
|
|
/*
|
|
* The delete aborted or crashed. The tuple is still live.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
break;
|
|
}
|
|
|
|
/* Tuple itself is checkable even if it's dead. */
|
|
return true;
|
|
}
|
|
|
|
/* xmax is an XID, not a MXID. Sanity check it. */
|
|
xmax = HeapTupleHeaderGetRawXmax(tuphdr);
|
|
switch (get_xid_status(xmax, ctx, &xmax_status))
|
|
{
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("xmax %u equals or exceeds next valid transaction ID %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false; /* corrupt */
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmax %u precedes relation freeze threshold %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false; /* corrupt */
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmax %u precedes oldest valid transaction ID %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false; /* corrupt */
|
|
case XID_BOUNDS_OK:
|
|
case XID_INVALID:
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Whether the toast can be vacuumed away depends on how old the deleting
|
|
* transaction is.
|
|
*/
|
|
switch (xmax_status)
|
|
{
|
|
case XID_IS_CURRENT_XID:
|
|
case XID_IN_PROGRESS:
|
|
|
|
/*
|
|
* The delete is in progress, so it cannot be visible to our
|
|
* snapshot.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
break;
|
|
|
|
case XID_COMMITTED:
|
|
|
|
/*
|
|
* The delete committed. Whether the toast can be vacuumed away
|
|
* depends on how old the deleting transaction is.
|
|
*/
|
|
ctx->tuple_could_be_pruned = TransactionIdPrecedes(xmax,
|
|
ctx->safe_xmin);
|
|
break;
|
|
|
|
case XID_ABORTED:
|
|
|
|
/*
|
|
* The delete aborted or crashed. The tuple is still live.
|
|
*/
|
|
ctx->tuple_could_be_pruned = false;
|
|
break;
|
|
}
|
|
|
|
/* Tuple itself is checkable even if it's dead. */
|
|
return true;
|
|
}
|
|
|
|
|
|
/*
|
|
* Check the current toast tuple against the state tracked in ctx, recording
|
|
* any corruption found in ctx->tupstore.
|
|
*
|
|
* This is not equivalent to running verify_heapam on the toast table itself,
|
|
* and is not hardened against corruption of the toast table. Rather, when
|
|
* validating a toasted attribute in the main table, the sequence of toast
|
|
* tuples that store the toasted value are retrieved and checked in order, with
|
|
* each toast tuple being checked against where we are in the sequence, as well
|
|
* as each toast tuple having its varlena structure sanity checked.
|
|
*
|
|
* On entry, *expected_chunk_seq should be the chunk_seq value that we expect
|
|
* to find in toasttup. On exit, it will be updated to the value the next call
|
|
* to this function should expect to see.
|
|
*/
|
|
static void
|
|
check_toast_tuple(HeapTuple toasttup, HeapCheckContext *ctx,
|
|
ToastedAttribute *ta, int32 *expected_chunk_seq,
|
|
uint32 extsize)
|
|
{
|
|
int32 chunk_seq;
|
|
int32 last_chunk_seq = (extsize - 1) / TOAST_MAX_CHUNK_SIZE;
|
|
Pointer chunk;
|
|
bool isnull;
|
|
int32 chunksize;
|
|
int32 expected_size;
|
|
|
|
/* Sanity-check the sequence number. */
|
|
chunk_seq = DatumGetInt32(fastgetattr(toasttup, 2,
|
|
ctx->toast_rel->rd_att, &isnull));
|
|
if (isnull)
|
|
{
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u has toast chunk with null sequence number",
|
|
ta->toast_pointer.va_valueid));
|
|
return;
|
|
}
|
|
if (chunk_seq != *expected_chunk_seq)
|
|
{
|
|
/* Either the TOAST index is corrupt, or we don't have all chunks. */
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u index scan returned chunk %d when expecting chunk %d",
|
|
ta->toast_pointer.va_valueid,
|
|
chunk_seq, *expected_chunk_seq));
|
|
}
|
|
*expected_chunk_seq = chunk_seq + 1;
|
|
|
|
/* Sanity-check the chunk data. */
|
|
chunk = DatumGetPointer(fastgetattr(toasttup, 3,
|
|
ctx->toast_rel->rd_att, &isnull));
|
|
if (isnull)
|
|
{
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u chunk %d has null data",
|
|
ta->toast_pointer.va_valueid,
|
|
chunk_seq));
|
|
return;
|
|
}
|
|
if (!VARATT_IS_EXTENDED(chunk))
|
|
chunksize = VARSIZE(chunk) - VARHDRSZ;
|
|
else if (VARATT_IS_SHORT(chunk))
|
|
{
|
|
/*
|
|
* could happen due to heap_form_tuple doing its thing
|
|
*/
|
|
chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
|
|
}
|
|
else
|
|
{
|
|
/* should never happen */
|
|
uint32 header = ((varattrib_4b *) chunk)->va_4byte.va_header;
|
|
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u chunk %d has invalid varlena header %0x",
|
|
ta->toast_pointer.va_valueid,
|
|
chunk_seq, header));
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Some checks on the data we've found
|
|
*/
|
|
if (chunk_seq > last_chunk_seq)
|
|
{
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u chunk %d follows last expected chunk %d",
|
|
ta->toast_pointer.va_valueid,
|
|
chunk_seq, last_chunk_seq));
|
|
return;
|
|
}
|
|
|
|
expected_size = chunk_seq < last_chunk_seq ? TOAST_MAX_CHUNK_SIZE
|
|
: extsize - (last_chunk_seq * TOAST_MAX_CHUNK_SIZE);
|
|
|
|
if (chunksize != expected_size)
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u chunk %d has size %u, but expected size %u",
|
|
ta->toast_pointer.va_valueid,
|
|
chunk_seq, chunksize, expected_size));
|
|
}
|
|
|
|
/*
|
|
* Check the current attribute as tracked in ctx, recording any corruption
|
|
* found in ctx->tupstore.
|
|
*
|
|
* This function follows the logic performed by heap_deform_tuple(), and in the
|
|
* case of a toasted value, optionally stores the toast pointer so later it can
|
|
* be checked following the logic of detoast_external_attr(), checking for any
|
|
* conditions that would result in either of those functions Asserting or
|
|
* crashing the backend. The checks performed by Asserts present in those two
|
|
* functions are also performed here and in check_toasted_attribute. In cases
|
|
* where those two functions are a bit cavalier in their assumptions about data
|
|
* being correct, we perform additional checks not present in either of those
|
|
* two functions. Where some condition is checked in both of those functions,
|
|
* we perform it here twice, as we parallel the logical flow of those two
|
|
* functions. The presence of duplicate checks seems a reasonable price to pay
|
|
* for keeping this code tightly coupled with the code it protects.
|
|
*
|
|
* Returns true if the tuple attribute is sane enough for processing to
|
|
* continue on to the next attribute, false otherwise.
|
|
*/
|
|
static bool
|
|
check_tuple_attribute(HeapCheckContext *ctx)
|
|
{
|
|
Datum attdatum;
|
|
struct varlena *attr;
|
|
char *tp; /* pointer to the tuple data */
|
|
uint16 infomask;
|
|
Form_pg_attribute thisatt;
|
|
struct varatt_external toast_pointer;
|
|
|
|
infomask = ctx->tuphdr->t_infomask;
|
|
thisatt = TupleDescAttr(RelationGetDescr(ctx->rel), ctx->attnum);
|
|
|
|
tp = (char *) ctx->tuphdr + ctx->tuphdr->t_hoff;
|
|
|
|
if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("attribute with length %u starts at offset %u beyond total tuple length %u",
|
|
thisatt->attlen,
|
|
ctx->tuphdr->t_hoff + ctx->offset,
|
|
ctx->lp_len));
|
|
return false;
|
|
}
|
|
|
|
/* Skip null values */
|
|
if (infomask & HEAP_HASNULL && att_isnull(ctx->attnum, ctx->tuphdr->t_bits))
|
|
return true;
|
|
|
|
/* Skip non-varlena values, but update offset first */
|
|
if (thisatt->attlen != -1)
|
|
{
|
|
ctx->offset = att_align_nominal(ctx->offset, thisatt->attalign);
|
|
ctx->offset = att_addlength_pointer(ctx->offset, thisatt->attlen,
|
|
tp + ctx->offset);
|
|
if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("attribute with length %u ends at offset %u beyond total tuple length %u",
|
|
thisatt->attlen,
|
|
ctx->tuphdr->t_hoff + ctx->offset,
|
|
ctx->lp_len));
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* Ok, we're looking at a varlena attribute. */
|
|
ctx->offset = att_align_pointer(ctx->offset, thisatt->attalign, -1,
|
|
tp + ctx->offset);
|
|
|
|
/* Get the (possibly corrupt) varlena datum */
|
|
attdatum = fetchatt(thisatt, tp + ctx->offset);
|
|
|
|
/*
|
|
* We have the datum, but we cannot decode it carelessly, as it may still
|
|
* be corrupt.
|
|
*/
|
|
|
|
/*
|
|
* Check that VARTAG_SIZE won't hit a TrapMacro on a corrupt va_tag before
|
|
* risking a call into att_addlength_pointer
|
|
*/
|
|
if (VARATT_IS_EXTERNAL(tp + ctx->offset))
|
|
{
|
|
uint8 va_tag = VARTAG_EXTERNAL(tp + ctx->offset);
|
|
|
|
if (va_tag != VARTAG_ONDISK)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toasted attribute has unexpected TOAST tag %u",
|
|
va_tag));
|
|
/* We can't know where the next attribute begins */
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* Ok, should be safe now */
|
|
ctx->offset = att_addlength_pointer(ctx->offset, thisatt->attlen,
|
|
tp + ctx->offset);
|
|
|
|
if (ctx->tuphdr->t_hoff + ctx->offset > ctx->lp_len)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("attribute with length %u ends at offset %u beyond total tuple length %u",
|
|
thisatt->attlen,
|
|
ctx->tuphdr->t_hoff + ctx->offset,
|
|
ctx->lp_len));
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* heap_deform_tuple would be done with this attribute at this point,
|
|
* having stored it in values[], and would continue to the next attribute.
|
|
* We go further, because we need to check if the toast datum is corrupt.
|
|
*/
|
|
|
|
attr = (struct varlena *) DatumGetPointer(attdatum);
|
|
|
|
/*
|
|
* Now we follow the logic of detoast_external_attr(), with the same
|
|
* caveats about being paranoid about corruption.
|
|
*/
|
|
|
|
/* Skip values that are not external */
|
|
if (!VARATT_IS_EXTERNAL(attr))
|
|
return true;
|
|
|
|
/* It is external, and we're looking at a page on disk */
|
|
|
|
/*
|
|
* Must copy attr into toast_pointer for alignment considerations
|
|
*/
|
|
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
|
|
|
|
/* The tuple header better claim to contain toasted values */
|
|
if (!(infomask & HEAP_HASEXTERNAL))
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toast value %u is external but tuple header flag HEAP_HASEXTERNAL not set",
|
|
toast_pointer.va_valueid));
|
|
return true;
|
|
}
|
|
|
|
/* The relation better have a toast table */
|
|
if (!ctx->rel->rd_rel->reltoastrelid)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toast value %u is external but relation has no toast relation",
|
|
toast_pointer.va_valueid));
|
|
return true;
|
|
}
|
|
|
|
/* If we were told to skip toast checking, then we're done. */
|
|
if (ctx->toast_rel == NULL)
|
|
return true;
|
|
|
|
/*
|
|
* If this tuple is eligible to be pruned, we cannot check the toast.
|
|
* Otherwise, we push a copy of the toast tuple so we can check it after
|
|
* releasing the main table buffer lock.
|
|
*/
|
|
if (!ctx->tuple_could_be_pruned)
|
|
{
|
|
ToastedAttribute *ta;
|
|
|
|
ta = (ToastedAttribute *) palloc0(sizeof(ToastedAttribute));
|
|
|
|
VARATT_EXTERNAL_GET_POINTER(ta->toast_pointer, attr);
|
|
ta->blkno = ctx->blkno;
|
|
ta->offnum = ctx->offnum;
|
|
ta->attnum = ctx->attnum;
|
|
ctx->toasted_attributes = lappend(ctx->toasted_attributes, ta);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* For each attribute collected in ctx->toasted_attributes, look up the value
|
|
* in the toast table and perform checks on it. This function should only be
|
|
* called on toast pointers which cannot be vacuumed away during our
|
|
* processing.
|
|
*/
|
|
static void
|
|
check_toasted_attribute(HeapCheckContext *ctx, ToastedAttribute *ta)
|
|
{
|
|
SnapshotData SnapshotToast;
|
|
ScanKeyData toastkey;
|
|
SysScanDesc toastscan;
|
|
bool found_toasttup;
|
|
HeapTuple toasttup;
|
|
uint32 extsize;
|
|
int32 expected_chunk_seq = 0;
|
|
int32 last_chunk_seq;
|
|
|
|
extsize = VARATT_EXTERNAL_GET_EXTSIZE(ta->toast_pointer);
|
|
last_chunk_seq = (extsize - 1) / TOAST_MAX_CHUNK_SIZE;
|
|
|
|
/*
|
|
* Setup a scan key to find chunks in toast table with matching va_valueid
|
|
*/
|
|
ScanKeyInit(&toastkey,
|
|
(AttrNumber) 1,
|
|
BTEqualStrategyNumber, F_OIDEQ,
|
|
ObjectIdGetDatum(ta->toast_pointer.va_valueid));
|
|
|
|
/*
|
|
* Check if any chunks for this toasted object exist in the toast table,
|
|
* accessible via the index.
|
|
*/
|
|
init_toast_snapshot(&SnapshotToast);
|
|
toastscan = systable_beginscan_ordered(ctx->toast_rel,
|
|
ctx->valid_toast_index,
|
|
&SnapshotToast, 1,
|
|
&toastkey);
|
|
found_toasttup = false;
|
|
while ((toasttup =
|
|
systable_getnext_ordered(toastscan,
|
|
ForwardScanDirection)) != NULL)
|
|
{
|
|
found_toasttup = true;
|
|
check_toast_tuple(toasttup, ctx, ta, &expected_chunk_seq, extsize);
|
|
}
|
|
systable_endscan_ordered(toastscan);
|
|
|
|
if (!found_toasttup)
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u not found in toast table",
|
|
ta->toast_pointer.va_valueid));
|
|
else if (expected_chunk_seq <= last_chunk_seq)
|
|
report_toast_corruption(ctx, ta,
|
|
psprintf("toast value %u was expected to end at chunk %d, but ended while expecting chunk %d",
|
|
ta->toast_pointer.va_valueid,
|
|
last_chunk_seq, expected_chunk_seq));
|
|
}
|
|
|
|
/*
|
|
* Check the current tuple as tracked in ctx, recording any corruption found in
|
|
* ctx->tupstore.
|
|
*/
|
|
static void
|
|
check_tuple(HeapCheckContext *ctx)
|
|
{
|
|
/*
|
|
* Check various forms of tuple header corruption, and if the header is
|
|
* too corrupt, do not continue with other checks.
|
|
*/
|
|
if (!check_tuple_header(ctx))
|
|
return;
|
|
|
|
/*
|
|
* Check tuple visibility. If the inserting transaction aborted, we
|
|
* cannot assume our relation description matches the tuple structure, and
|
|
* therefore cannot check it.
|
|
*/
|
|
if (!check_tuple_visibility(ctx))
|
|
return;
|
|
|
|
/*
|
|
* The tuple is visible, so it must be compatible with the current version
|
|
* of the relation descriptor. It might have fewer columns than are
|
|
* present in the relation descriptor, but it cannot have more.
|
|
*/
|
|
if (RelationGetDescr(ctx->rel)->natts < ctx->natts)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("number of attributes %u exceeds maximum expected for table %u",
|
|
ctx->natts,
|
|
RelationGetDescr(ctx->rel)->natts));
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check each attribute unless we hit corruption that confuses what to do
|
|
* next, at which point we abort further attribute checks for this tuple.
|
|
* Note that we don't abort for all types of corruption, only for those
|
|
* types where we don't know how to continue. We also don't abort the
|
|
* checking of toasted attributes collected from the tuple prior to
|
|
* aborting. Those will still be checked later along with other toasted
|
|
* attributes collected from the page.
|
|
*/
|
|
ctx->offset = 0;
|
|
for (ctx->attnum = 0; ctx->attnum < ctx->natts; ctx->attnum++)
|
|
if (!check_tuple_attribute(ctx))
|
|
break; /* cannot continue */
|
|
|
|
/* revert attnum to -1 until we again examine individual attributes */
|
|
ctx->attnum = -1;
|
|
}
|
|
|
|
/*
|
|
* Convert a TransactionId into a FullTransactionId using our cached values of
|
|
* the valid transaction ID range. It is the caller's responsibility to have
|
|
* already updated the cached values, if necessary.
|
|
*/
|
|
static FullTransactionId
|
|
FullTransactionIdFromXidAndCtx(TransactionId xid, const HeapCheckContext *ctx)
|
|
{
|
|
uint32 epoch;
|
|
|
|
if (!TransactionIdIsNormal(xid))
|
|
return FullTransactionIdFromEpochAndXid(0, xid);
|
|
epoch = EpochFromFullTransactionId(ctx->next_fxid);
|
|
if (xid > ctx->next_xid)
|
|
epoch--;
|
|
return FullTransactionIdFromEpochAndXid(epoch, xid);
|
|
}
|
|
|
|
/*
|
|
* Update our cached range of valid transaction IDs.
|
|
*/
|
|
static void
|
|
update_cached_xid_range(HeapCheckContext *ctx)
|
|
{
|
|
/* Make cached copies */
|
|
LWLockAcquire(XidGenLock, LW_SHARED);
|
|
ctx->next_fxid = ShmemVariableCache->nextXid;
|
|
ctx->oldest_xid = ShmemVariableCache->oldestXid;
|
|
LWLockRelease(XidGenLock);
|
|
|
|
/* And compute alternate versions of the same */
|
|
ctx->oldest_fxid = FullTransactionIdFromXidAndCtx(ctx->oldest_xid, ctx);
|
|
ctx->next_xid = XidFromFullTransactionId(ctx->next_fxid);
|
|
}
|
|
|
|
/*
|
|
* Update our cached range of valid multitransaction IDs.
|
|
*/
|
|
static void
|
|
update_cached_mxid_range(HeapCheckContext *ctx)
|
|
{
|
|
ReadMultiXactIdRange(&ctx->oldest_mxact, &ctx->next_mxact);
|
|
}
|
|
|
|
/*
|
|
* Return whether the given FullTransactionId is within our cached valid
|
|
* transaction ID range.
|
|
*/
|
|
static inline bool
|
|
fxid_in_cached_range(FullTransactionId fxid, const HeapCheckContext *ctx)
|
|
{
|
|
return (FullTransactionIdPrecedesOrEquals(ctx->oldest_fxid, fxid) &&
|
|
FullTransactionIdPrecedes(fxid, ctx->next_fxid));
|
|
}
|
|
|
|
/*
|
|
* Checks whether a multitransaction ID is in the cached valid range, returning
|
|
* the nature of the range violation, if any.
|
|
*/
|
|
static XidBoundsViolation
|
|
check_mxid_in_range(MultiXactId mxid, HeapCheckContext *ctx)
|
|
{
|
|
if (!TransactionIdIsValid(mxid))
|
|
return XID_INVALID;
|
|
if (MultiXactIdPrecedes(mxid, ctx->relminmxid))
|
|
return XID_PRECEDES_RELMIN;
|
|
if (MultiXactIdPrecedes(mxid, ctx->oldest_mxact))
|
|
return XID_PRECEDES_CLUSTERMIN;
|
|
if (MultiXactIdPrecedesOrEquals(ctx->next_mxact, mxid))
|
|
return XID_IN_FUTURE;
|
|
return XID_BOUNDS_OK;
|
|
}
|
|
|
|
/*
|
|
* Checks whether the given mxid is valid to appear in the heap being checked,
|
|
* returning the nature of the range violation, if any.
|
|
*
|
|
* This function attempts to return quickly by caching the known valid mxid
|
|
* range in ctx. Callers should already have performed the initial setup of
|
|
* the cache prior to the first call to this function.
|
|
*/
|
|
static XidBoundsViolation
|
|
check_mxid_valid_in_rel(MultiXactId mxid, HeapCheckContext *ctx)
|
|
{
|
|
XidBoundsViolation result;
|
|
|
|
result = check_mxid_in_range(mxid, ctx);
|
|
if (result == XID_BOUNDS_OK)
|
|
return XID_BOUNDS_OK;
|
|
|
|
/* The range may have advanced. Recheck. */
|
|
update_cached_mxid_range(ctx);
|
|
return check_mxid_in_range(mxid, ctx);
|
|
}
|
|
|
|
/*
|
|
* Checks whether the given transaction ID is (or was recently) valid to appear
|
|
* in the heap being checked, or whether it is too old or too new to appear in
|
|
* the relation, returning information about the nature of the bounds violation.
|
|
*
|
|
* We cache the range of valid transaction IDs. If xid is in that range, we
|
|
* conclude that it is valid, even though concurrent changes to the table might
|
|
* invalidate it under certain corrupt conditions. (For example, if the table
|
|
* contains corrupt all-frozen bits, a concurrent vacuum might skip the page(s)
|
|
* containing the xid and then truncate clog and advance the relfrozenxid
|
|
* beyond xid.) Reporting the xid as valid under such conditions seems
|
|
* acceptable, since if we had checked it earlier in our scan it would have
|
|
* truly been valid at that time.
|
|
*
|
|
* If the status argument is not NULL, and if and only if the transaction ID
|
|
* appears to be valid in this relation, the status argument will be set with
|
|
* the commit status of the transaction ID.
|
|
*/
|
|
static XidBoundsViolation
|
|
get_xid_status(TransactionId xid, HeapCheckContext *ctx,
|
|
XidCommitStatus *status)
|
|
{
|
|
FullTransactionId fxid;
|
|
FullTransactionId clog_horizon;
|
|
|
|
/* Quick check for special xids */
|
|
if (!TransactionIdIsValid(xid))
|
|
return XID_INVALID;
|
|
else if (xid == BootstrapTransactionId || xid == FrozenTransactionId)
|
|
{
|
|
if (status != NULL)
|
|
*status = XID_COMMITTED;
|
|
return XID_BOUNDS_OK;
|
|
}
|
|
|
|
/* Check if the xid is within bounds */
|
|
fxid = FullTransactionIdFromXidAndCtx(xid, ctx);
|
|
if (!fxid_in_cached_range(fxid, ctx))
|
|
{
|
|
/*
|
|
* We may have been checking against stale values. Update the cached
|
|
* range to be sure, and since we relied on the cached range when we
|
|
* performed the full xid conversion, reconvert.
|
|
*/
|
|
update_cached_xid_range(ctx);
|
|
fxid = FullTransactionIdFromXidAndCtx(xid, ctx);
|
|
}
|
|
|
|
if (FullTransactionIdPrecedesOrEquals(ctx->next_fxid, fxid))
|
|
return XID_IN_FUTURE;
|
|
if (FullTransactionIdPrecedes(fxid, ctx->oldest_fxid))
|
|
return XID_PRECEDES_CLUSTERMIN;
|
|
if (FullTransactionIdPrecedes(fxid, ctx->relfrozenfxid))
|
|
return XID_PRECEDES_RELMIN;
|
|
|
|
/* Early return if the caller does not request clog checking */
|
|
if (status == NULL)
|
|
return XID_BOUNDS_OK;
|
|
|
|
/* Early return if we just checked this xid in a prior call */
|
|
if (xid == ctx->cached_xid)
|
|
{
|
|
*status = ctx->cached_status;
|
|
return XID_BOUNDS_OK;
|
|
}
|
|
|
|
*status = XID_COMMITTED;
|
|
LWLockAcquire(XactTruncationLock, LW_SHARED);
|
|
clog_horizon =
|
|
FullTransactionIdFromXidAndCtx(ShmemVariableCache->oldestClogXid,
|
|
ctx);
|
|
if (FullTransactionIdPrecedesOrEquals(clog_horizon, fxid))
|
|
{
|
|
if (TransactionIdIsCurrentTransactionId(xid))
|
|
*status = XID_IS_CURRENT_XID;
|
|
else if (TransactionIdIsInProgress(xid))
|
|
*status = XID_IN_PROGRESS;
|
|
else if (TransactionIdDidCommit(xid))
|
|
*status = XID_COMMITTED;
|
|
else
|
|
*status = XID_ABORTED;
|
|
}
|
|
LWLockRelease(XactTruncationLock);
|
|
ctx->cached_xid = xid;
|
|
ctx->cached_status = *status;
|
|
return XID_BOUNDS_OK;
|
|
}
|