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There is now a per-column COMPRESSION option which can be set to pglz (the default, and the only option in up until now) or lz4. Or, if you like, you can set the new default_toast_compression GUC to lz4, and then that will be the default for new table columns for which no value is specified. We don't have lz4 support in the PostgreSQL code, so to use lz4 compression, PostgreSQL must be built --with-lz4. In general, TOAST compression means compression of individual column values, not the whole tuple, and those values can either be compressed inline within the tuple or compressed and then stored externally in the TOAST table, so those properties also apply to this feature. Prior to this commit, a TOAST pointer has two unused bits as part of the va_extsize field, and a compessed datum has two unused bits as part of the va_rawsize field. These bits are unused because the length of a varlena is limited to 1GB; we now use them to indicate the compression type that was used. This means we only have bit space for 2 more built-in compresison types, but we could work around that problem, if necessary, by introducing a new vartag_external value for any further types we end up wanting to add. Hopefully, it won't be too important to offer a wide selection of algorithms here, since each one we add not only takes more coding but also adds a build dependency for every packager. Nevertheless, it seems worth doing at least this much, because LZ4 gets better compression than PGLZ with less CPU usage. It's possible for LZ4-compressed datums to leak into composite type values stored on disk, just as it is for PGLZ. It's also possible for LZ4-compressed attributes to be copied into a different table via SQL commands such as CREATE TABLE AS or INSERT .. SELECT. It would be expensive to force such values to be decompressed, so PostgreSQL has never done so. For the same reasons, we also don't force recompression of already-compressed values even if the target table prefers a different compression method than was used for the source data. These architectural decisions are perhaps arguable but revisiting them is well beyond the scope of what seemed possible to do as part of this project. However, it's relatively cheap to recompress as part of VACUUM FULL or CLUSTER, so this commit adjusts those commands to do so, if the configured compression method of the table happens not to match what was used for some column value stored therein. Dilip Kumar. The original patches on which this work was based were written by Ildus Kurbangaliev, and those were patches were based on even earlier work by Nikita Glukhov, but the design has since changed very substantially, since allow a potentially large number of compression methods that could be added and dropped on a running system proved too problematic given some of the architectural issues mentioned above; the choice of which specific compression method to add first is now different; and a lot of the code has been heavily refactored. More recently, Justin Przyby helped quite a bit with testing and reviewing and this version also includes some code contributions from him. Other design input and review from Tomas Vondra, Álvaro Herrera, Andres Freund, Oleg Bartunov, Alexander Korotkov, and me. Discussion: http://postgr.es/m/20170907194236.4cefce96%40wp.localdomain Discussion: http://postgr.es/m/CAFiTN-uUpX3ck%3DK0mLEk-G_kUQY%3DSNOTeqdaNRR9FMdQrHKebw%40mail.gmail.com
1464 lines
46 KiB
C
1464 lines
46 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_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 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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/*
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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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/* Values for iterating over toast for the attribute */
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int32 chunkno;
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int32 attrsize;
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int32 endchunk;
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int32 totalchunks;
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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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static bool check_tuple_attribute(HeapCheckContext *ctx);
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static bool check_tuple_header_and_visibilty(HeapTupleHeader tuphdr,
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HeapCheckContext *ctx);
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static void report_corruption(HeapCheckContext *ctx, 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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/*
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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, and check privileges */
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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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|
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/* It should be safe to examine the tuple's header, at least */
|
|
ctx.tuphdr = (HeapTupleHeader) PageGetItem(ctx.page, ctx.itemid);
|
|
ctx.natts = HeapTupleHeaderGetNatts(ctx.tuphdr);
|
|
|
|
/* Ok, ready to check this next tuple */
|
|
check_tuple(&ctx);
|
|
}
|
|
|
|
/* clean up */
|
|
UnlockReleaseBuffer(ctx.buffer);
|
|
|
|
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,
|
|
* and that the caller has select privilege on the 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")));
|
|
}
|
|
|
|
/*
|
|
* Record a single corruption found in the table. The values in ctx should
|
|
* reflect 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)
|
|
{
|
|
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(ctx->blkno);
|
|
values[1] = Int32GetDatum(ctx->offnum);
|
|
values[2] = Int32GetDatum(ctx->attnum);
|
|
nulls[2] = (ctx->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(ctx->tupdesc, values, nulls);
|
|
tuplestore_puttuple(ctx->tupstore, tuple);
|
|
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 and tuple visibility.
|
|
*
|
|
* Since we do not hold a snapshot, tuple visibility is not a question of
|
|
* whether we should be able to see the tuple relative to any particular
|
|
* snapshot, but rather a question of whether it is safe and reasonable to
|
|
* check the tuple attributes.
|
|
*
|
|
* 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 visible) 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 do not base our visibility determination on them. (In
|
|
* other words, we do not return false merely because we detected them.)
|
|
*
|
|
* For visibility determination not specifically related to corruption, what we
|
|
* want to know is if a tuple is potentially visible to any running
|
|
* transaction. If you are tempted to replace this function's visibility logic
|
|
* with a call to another visibility checking function, keep in mind that this
|
|
* function does not update hint bits, as it seems imprudent to write hint bits
|
|
* (or anything at all) to a table during a corruption check. Nor does this
|
|
* function bother classifying tuple visibility beyond a boolean visible vs.
|
|
* not visible.
|
|
*
|
|
* The caller should already have checked that xmin and xmax are not out of
|
|
* bounds for the relation.
|
|
*
|
|
* Returns whether the tuple is both visible and sufficiently sensible to
|
|
* undergo attribute checks.
|
|
*/
|
|
static bool
|
|
check_tuple_header_and_visibilty(HeapTupleHeader tuphdr, HeapCheckContext *ctx)
|
|
{
|
|
uint16 infomask = tuphdr->t_infomask;
|
|
bool header_garbled = false;
|
|
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));
|
|
header_garbled = true;
|
|
}
|
|
|
|
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 we do not consider the header
|
|
* garbled, because we don't rely on this property for determining if
|
|
* the tuple is visible or for interpreting 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));
|
|
header_garbled = true;
|
|
}
|
|
|
|
if (header_garbled)
|
|
return false; /* checking of this tuple should not continue */
|
|
|
|
/*
|
|
* Ok, we can examine the header for tuple visibility purposes, though we
|
|
* still need to be careful about a few remaining types of header
|
|
* corruption. This logic roughly follows that of
|
|
* HeapTupleSatisfiesVacuum. Where possible the comments indicate which
|
|
* HTSV_Result we think that function might return for this tuple.
|
|
*/
|
|
if (!HeapTupleHeaderXminCommitted(tuphdr))
|
|
{
|
|
TransactionId raw_xmin = HeapTupleHeaderGetRawXmin(tuphdr);
|
|
|
|
if (HeapTupleHeaderXminInvalid(tuphdr))
|
|
return false; /* HEAPTUPLE_DEAD */
|
|
/* Used by pre-9.0 binary upgrades */
|
|
else if (infomask & HEAP_MOVED_OFF ||
|
|
infomask & HEAP_MOVED_IN)
|
|
{
|
|
XidCommitStatus status;
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuphdr);
|
|
|
|
switch (get_xid_status(xvac, ctx, &status))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("old-style VACUUM FULL transaction ID is invalid"));
|
|
return false; /* corrupt */
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u equals or exceeds next valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false; /* corrupt */
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u precedes relation freeze threshold %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false; /* corrupt */
|
|
break;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("old-style VACUUM FULL transaction ID %u precedes oldest valid transaction ID %u:%u",
|
|
xvac,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false; /* corrupt */
|
|
break;
|
|
case XID_BOUNDS_OK:
|
|
switch (status)
|
|
{
|
|
case XID_IN_PROGRESS:
|
|
return true; /* HEAPTUPLE_DELETE_IN_PROGRESS */
|
|
case XID_COMMITTED:
|
|
case XID_ABORTED:
|
|
return false; /* HEAPTUPLE_DEAD */
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
XidCommitStatus status;
|
|
|
|
switch (get_xid_status(raw_xmin, ctx, &status))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("raw xmin is invalid"));
|
|
return false;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("raw xmin %u equals or exceeds next valid transaction ID %u:%u",
|
|
raw_xmin,
|
|
EpochFromFullTransactionId(ctx->next_fxid),
|
|
XidFromFullTransactionId(ctx->next_fxid)));
|
|
return false; /* corrupt */
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("raw xmin %u precedes relation freeze threshold %u:%u",
|
|
raw_xmin,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
return false; /* corrupt */
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("raw xmin %u precedes oldest valid transaction ID %u:%u",
|
|
raw_xmin,
|
|
EpochFromFullTransactionId(ctx->oldest_fxid),
|
|
XidFromFullTransactionId(ctx->oldest_fxid)));
|
|
return false; /* corrupt */
|
|
case XID_BOUNDS_OK:
|
|
switch (status)
|
|
{
|
|
case XID_COMMITTED:
|
|
break;
|
|
case XID_IN_PROGRESS:
|
|
return true; /* insert or delete in progress */
|
|
case XID_ABORTED:
|
|
return false; /* HEAPTUPLE_DEAD */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!(infomask & HEAP_XMAX_INVALID) && !HEAP_XMAX_IS_LOCKED_ONLY(infomask))
|
|
{
|
|
if (infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
XidCommitStatus status;
|
|
TransactionId xmax = HeapTupleGetUpdateXid(tuphdr);
|
|
|
|
switch (get_xid_status(xmax, ctx, &status))
|
|
{
|
|
/* not LOCKED_ONLY, so it has to have an xmax */
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("xmax is invalid"));
|
|
return false; /* corrupt */
|
|
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:
|
|
switch (status)
|
|
{
|
|
case XID_IN_PROGRESS:
|
|
return true; /* HEAPTUPLE_DELETE_IN_PROGRESS */
|
|
case XID_COMMITTED:
|
|
case XID_ABORTED:
|
|
return false; /* HEAPTUPLE_RECENTLY_DEAD or
|
|
* HEAPTUPLE_DEAD */
|
|
}
|
|
}
|
|
|
|
/* Ok, the tuple is live */
|
|
}
|
|
else if (!(infomask & HEAP_XMAX_COMMITTED))
|
|
return true; /* HEAPTUPLE_DELETE_IN_PROGRESS or
|
|
* HEAPTUPLE_LIVE */
|
|
else
|
|
return false; /* HEAPTUPLE_RECENTLY_DEAD or HEAPTUPLE_DEAD */
|
|
}
|
|
return true; /* not dead */
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void
|
|
check_toast_tuple(HeapTuple toasttup, HeapCheckContext *ctx)
|
|
{
|
|
int32 curchunk;
|
|
Pointer chunk;
|
|
bool isnull;
|
|
int32 chunksize;
|
|
int32 expected_size;
|
|
|
|
/*
|
|
* Have a chunk, extract the sequence number and the data
|
|
*/
|
|
curchunk = DatumGetInt32(fastgetattr(toasttup, 2,
|
|
ctx->toast_rel->rd_att, &isnull));
|
|
if (isnull)
|
|
{
|
|
report_corruption(ctx,
|
|
pstrdup("toast chunk sequence number is null"));
|
|
return;
|
|
}
|
|
chunk = DatumGetPointer(fastgetattr(toasttup, 3,
|
|
ctx->toast_rel->rd_att, &isnull));
|
|
if (isnull)
|
|
{
|
|
report_corruption(ctx,
|
|
pstrdup("toast chunk data is null"));
|
|
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_corruption(ctx,
|
|
psprintf("corrupt extended toast chunk has invalid varlena header: %0x (sequence number %d)",
|
|
header, curchunk));
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Some checks on the data we've found
|
|
*/
|
|
if (curchunk != ctx->chunkno)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toast chunk sequence number %u does not match the expected sequence number %u",
|
|
curchunk, ctx->chunkno));
|
|
return;
|
|
}
|
|
if (curchunk > ctx->endchunk)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toast chunk sequence number %u exceeds the end chunk sequence number %u",
|
|
curchunk, ctx->endchunk));
|
|
return;
|
|
}
|
|
|
|
expected_size = curchunk < ctx->totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
|
|
: ctx->attrsize - ((ctx->totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
|
|
if (chunksize != expected_size)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("toast chunk size %u differs from the expected size %u",
|
|
chunksize, expected_size));
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 continues along 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.
|
|
* 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)
|
|
{
|
|
struct varatt_external toast_pointer;
|
|
ScanKeyData toastkey;
|
|
SysScanDesc toastscan;
|
|
SnapshotData SnapshotToast;
|
|
HeapTuple toasttup;
|
|
bool found_toasttup;
|
|
Datum attdatum;
|
|
struct varlena *attr;
|
|
char *tp; /* pointer to the tuple data */
|
|
uint16 infomask;
|
|
Form_pg_attribute thisatt;
|
|
|
|
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 %u with length %u starts at offset %u beyond total tuple length %u",
|
|
ctx->attnum,
|
|
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 %u with length %u ends at offset %u beyond total tuple length %u",
|
|
ctx->attnum,
|
|
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 %u has unexpected TOAST tag %u",
|
|
ctx->attnum,
|
|
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 %u with length %u ends at offset %u beyond total tuple length %u",
|
|
ctx->attnum,
|
|
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 */
|
|
|
|
/* The tuple header better claim to contain toasted values */
|
|
if (!(infomask & HEAP_HASEXTERNAL))
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("attribute %u is external but tuple header flag HEAP_HASEXTERNAL not set",
|
|
ctx->attnum));
|
|
return true;
|
|
}
|
|
|
|
/* The relation better have a toast table */
|
|
if (!ctx->rel->rd_rel->reltoastrelid)
|
|
{
|
|
report_corruption(ctx,
|
|
psprintf("attribute %u is external but relation has no toast relation",
|
|
ctx->attnum));
|
|
return true;
|
|
}
|
|
|
|
/* If we were told to skip toast checking, then we're done. */
|
|
if (ctx->toast_rel == NULL)
|
|
return true;
|
|
|
|
/*
|
|
* Must copy attr into toast_pointer for alignment considerations
|
|
*/
|
|
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
|
|
|
|
ctx->attrsize = VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer);
|
|
ctx->endchunk = (ctx->attrsize - 1) / TOAST_MAX_CHUNK_SIZE;
|
|
ctx->totalchunks = ctx->endchunk + 1;
|
|
|
|
/*
|
|
* Setup a scan key to find chunks in toast table with matching va_valueid
|
|
*/
|
|
ScanKeyInit(&toastkey,
|
|
(AttrNumber) 1,
|
|
BTEqualStrategyNumber, F_OIDEQ,
|
|
ObjectIdGetDatum(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);
|
|
ctx->chunkno = 0;
|
|
found_toasttup = false;
|
|
while ((toasttup =
|
|
systable_getnext_ordered(toastscan,
|
|
ForwardScanDirection)) != NULL)
|
|
{
|
|
found_toasttup = true;
|
|
check_toast_tuple(toasttup, ctx);
|
|
ctx->chunkno++;
|
|
}
|
|
if (!found_toasttup)
|
|
report_corruption(ctx,
|
|
psprintf("toasted value for attribute %u missing from toast table",
|
|
ctx->attnum));
|
|
else if (ctx->chunkno != (ctx->endchunk + 1))
|
|
report_corruption(ctx,
|
|
psprintf("final toast chunk number %u differs from expected value %u",
|
|
ctx->chunkno, (ctx->endchunk + 1)));
|
|
systable_endscan_ordered(toastscan);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Check the current tuple as tracked in ctx, recording any corruption found in
|
|
* ctx->tupstore.
|
|
*/
|
|
static void
|
|
check_tuple(HeapCheckContext *ctx)
|
|
{
|
|
TransactionId xmin;
|
|
TransactionId xmax;
|
|
bool fatal = false;
|
|
uint16 infomask = ctx->tuphdr->t_infomask;
|
|
|
|
/* If xmin is normal, it should be within valid range */
|
|
xmin = HeapTupleHeaderGetXmin(ctx->tuphdr);
|
|
switch (get_xid_status(xmin, ctx, NULL))
|
|
{
|
|
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)));
|
|
fatal = true;
|
|
break;
|
|
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)));
|
|
fatal = true;
|
|
break;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmin %u precedes relation freeze threshold %u:%u",
|
|
xmin,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
fatal = true;
|
|
break;
|
|
}
|
|
|
|
xmax = HeapTupleHeaderGetRawXmax(ctx->tuphdr);
|
|
|
|
if (infomask & HEAP_XMAX_IS_MULTI)
|
|
{
|
|
/* xmax is a multixact, so it should be within valid MXID range */
|
|
switch (check_mxid_valid_in_rel(xmax, ctx))
|
|
{
|
|
case XID_INVALID:
|
|
report_corruption(ctx,
|
|
pstrdup("multitransaction ID is invalid"));
|
|
fatal = true;
|
|
break;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u precedes relation minimum multitransaction ID threshold %u",
|
|
xmax, ctx->relminmxid));
|
|
fatal = true;
|
|
break;
|
|
case XID_PRECEDES_CLUSTERMIN:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u precedes oldest valid multitransaction ID threshold %u",
|
|
xmax, ctx->oldest_mxact));
|
|
fatal = true;
|
|
break;
|
|
case XID_IN_FUTURE:
|
|
report_corruption(ctx,
|
|
psprintf("multitransaction ID %u equals or exceeds next valid multitransaction ID %u",
|
|
xmax,
|
|
ctx->next_mxact));
|
|
fatal = true;
|
|
break;
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* xmax is not a multixact and is normal, so it should be within the
|
|
* valid XID range.
|
|
*/
|
|
switch (get_xid_status(xmax, ctx, NULL))
|
|
{
|
|
case XID_INVALID:
|
|
case XID_BOUNDS_OK:
|
|
break;
|
|
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)));
|
|
fatal = true;
|
|
break;
|
|
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)));
|
|
fatal = true;
|
|
break;
|
|
case XID_PRECEDES_RELMIN:
|
|
report_corruption(ctx,
|
|
psprintf("xmax %u precedes relation freeze threshold %u:%u",
|
|
xmax,
|
|
EpochFromFullTransactionId(ctx->relfrozenfxid),
|
|
XidFromFullTransactionId(ctx->relfrozenfxid)));
|
|
fatal = true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Cannot process tuple data if tuple header was corrupt, as the offsets
|
|
* within the page cannot be trusted, leaving too much risk of reading
|
|
* garbage if we continue.
|
|
*
|
|
* We also cannot process the tuple if the xmin or xmax were invalid
|
|
* relative to relfrozenxid or relminmxid, as clog entries for the xids
|
|
* may already be gone.
|
|
*/
|
|
if (fatal)
|
|
return;
|
|
|
|
/*
|
|
* Check various forms of tuple header corruption. If the header is too
|
|
* corrupt to continue checking, or if the tuple is not visible to anyone,
|
|
* we cannot continue with other checks.
|
|
*/
|
|
if (!check_tuple_header_and_visibilty(ctx->tuphdr, 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.
|
|
*/
|
|
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_IN_PROGRESS;
|
|
else if (TransactionIdDidCommit(xid))
|
|
*status = XID_COMMITTED;
|
|
else if (TransactionIdDidAbort(xid))
|
|
*status = XID_ABORTED;
|
|
else
|
|
*status = XID_IN_PROGRESS;
|
|
}
|
|
LWLockRelease(XactTruncationLock);
|
|
ctx->cached_xid = xid;
|
|
ctx->cached_status = *status;
|
|
return XID_BOUNDS_OK;
|
|
}
|