From: Julien Rouhaud <rjuju123@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>
Subject: Re: Online checksums verification in the backend
Date: Wed, 11 Mar 2020 08:18:23 +0100
Message-ID: <20200311071823.GA4643@nol> (raw)
In-Reply-To: <CAOBaU_YOmFfO8Ow=EScWULku7CvUiNYdx_2QS8hfi92D=tv=OQ@mail.gmail.com>
References: <CAOBaU_aVvMjQn=ge5qPiJOPMmOj5=ii3st5Q0Y+WuLML5sR17w@mail.gmail.com>
<CA+TgmoavHnO20Stahs6MPe53qBqeiaCTwsktSVd7LDW+Z9pNtw@mail.gmail.com>
<CAOBaU_aiAaas1SLS6erWa0cJStxSt+QBRPah16CqXZY4mATbTQ@mail.gmail.com>
<20191210022633.GD72921@paquier.xyz>
<CAOBaU_YOmFfO8Ow=EScWULku7CvUiNYdx_2QS8hfi92D=tv=OQ@mail.gmail.com>
On Tue, Dec 10, 2019 at 11:12:34AM +0100, Julien Rouhaud wrote:
> On Tue, Dec 10, 2019 at 3:26 AM Michael Paquier <michael@paquier.xyz> wrote:
> >
> > On Mon, Dec 09, 2019 at 07:02:43PM +0100, Julien Rouhaud wrote:
> > > On Mon, Dec 9, 2019 at 5:21 PM Robert Haas <robertmhaas@gmail.com> wrote:
> > >> Some people might prefer notices, because you can get those while the
> > >> thing is still running, rather than a result set, which you will only
> > >> see when the query finishes. Other people might prefer an SRF, because
> > >> they want to have the data in structured form so that they can
> > >> postprocess it. Not sure what you mean by "more globally."
> > >
> > > I meant having the results available system-wide, not only to the
> > > caller. I think that emitting a log/notice level should always be
> > > done on top on whatever other communication facility we're using.
> >
> > The problem of notice and logs is that they tend to be ignored. Now I
> > don't see no problems either in adding something into the logs which
> > can be found later on for parsing on top of a SRF returned by the
> > caller which includes all the corruption details, say with pgbadger
> > or your friendly neighborhood grep. I think that any backend function
> > should also make sure to call pgstat_report_checksum_failure() to
> > report a report visible at database-level in the catalogs, so as it is
> > possible to use that as a cheap high-level warning. The details of
> > the failures could always be dug from the logs or the result of the
> > function itself after finding out that something is wrong in
> > pg_stat_database.
>
> I agree that adding extra information in the logs and calling
> pgstat_report_checksum_failure is a must do, and I changed that
> locally. However, I doubt that the logs is the right place to find
> the details of corrupted blocks. There's no guarantee that the file
> will be accessible to the DBA, nor that the content won't get
> truncated by the time it's needed. I really think that corruption is
> important enough to justify more specific location.
The cfbot reported a build failure, so here's a rebased v2 which also contains
the pg_stat_report_failure() call and extra log info.
Attachments:online_checksum_verification-v2.diff (text/plain, 30.0K) downloaddiff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sqlindex b8a3f46912..e266292b03 100644--- a/src/backend/catalog/system_views.sql+++ b/src/backend/catalog/system_views.sql@@ -1386,6 +1386,13 @@ LANGUAGE INTERNAL
STRICT STABLE PARALLEL SAFE
AS 'jsonb_path_query_first_tz';
+CREATE OR REPLACE FUNCTION pg_check_relation(+ IN relation regclass DEFAULT NULL::regclass, IN fork text DEFAULT NULL::text,+ OUT relid oid, OUT forknum integer, OUT failed_blocknum bigint,+ OUT expected_checksum integer, OUT found_checksum integer)+ RETURNS SETOF record VOLATILE LANGUAGE internal AS 'pg_check_relation'+ PARALLEL RESTRICTED;+
--
-- The default permissions for functions mean that anyone can execute them.
-- A number of functions shouldn't be executable by just anyone, but rather
diff --git a/src/backend/storage/page/checksum.c b/src/backend/storage/page/checksum.cindex e010691c9f..ed1a0c9b30 100644--- a/src/backend/storage/page/checksum.c+++ b/src/backend/storage/page/checksum.c@@ -15,8 +15,541 @@
#include "storage/checksum.h"
/*
- * The actual code is in storage/checksum_impl.h. This is done so that- * external programs can incorporate the checksum code by #include'ing- * that file from the exported Postgres headers. (Compare our CRC code.)+ * The actual checksum computation code is in storage/checksum_impl.h. This+ * is done so that external programs can incorporate the checksum code by+ * #include'ing that file from the exported Postgres headers. (Compare our+ * CRC code.)
*/
#include "storage/checksum_impl.h"
++#include "access/heapam.h"+#include "access/htup_details.h"+#include "catalog/pg_authid_d.h"+#include "commands/dbcommands.h"+#include "funcapi.h"+#include "miscadmin.h"+#include "pgstat.h"+#include "storage/buf_internals.h"+#include "storage/checksum.h"+#include "storage/lockdefs.h"+#include "utils/acl.h"+#include "utils/builtins.h"+#include "utils/guc.h"+#include "utils/lsyscache.h"+#include "utils/rel.h"+#include "utils/syscache.h"++/*+ * A zero checksum can never be computed, see pg_checksum_page() */+#define NoComputedChecksum 0++/* The rest of this module provides a set of functions that can be used to+ * safely check all checksums on a running cluster.+ *+ * Please note that those only perform standard buffered reads, and don't try+ * to bypass or discard the operating system cache. If you want to check the+ * actual storage, you have to discard the operating system cache before+ * running those functions.+ *+ * To avoid torn page and possible false postives when reading data, and+ * keeping overhead as low as possible, the following heuristics are used:+ *+ * - a shared LWLock is taken on the target buffer pool partition mapping, and+ * we detect if a block is in shared_buffers or not. See get_buffer()+ * comments for more details about the locking strategy.+ *+ * - if a block is dirty in shared_buffers, it's ignored as it'll be flushed to+ * disk either before the end of the next checkpoint or during recovery in+ * case of unsafe shutdown+ *+ * - if a block is otherwise found in shared_buffers, an IO lock is taken on+ * the block and the block is then read from storage, ignoring the block in+ * shared_buffers+ *+ * - if a block is not found in shared_buffers, the LWLock is relased and the+ * block is read from disk without taking any lock. If an error is detected,+ * the read block will be discarded and retrieved again while holding the+ * LWLock. This is because an error due to concurrent write is possible but+ * very unlikely, so it's better to have an optimistic approach to limit+ * locking overhead+ *+ * The check can be performed using an SQL function, returning the list of+ * problematic blocks.+ *+ * Vacuum's GUCs are used to avoid consuming too much resources while running+ * this tool.+ */++static void check_all_relations(TupleDesc tupdesc, Tuplestorestate *tupstore,+ ForkNumber forknum);+static bool check_buffer(char *buffer, uint32 blkno, uint16 *chk_expected,+ uint16 *chk_found);+static void check_one_relation(TupleDesc tupdesc, Tuplestorestate *tupstore,+ Oid relid, ForkNumber single_forknum);+static void check_relation_fork(TupleDesc tupdesc, Tuplestorestate *tupstore,+ Relation relation, ForkNumber forknum);+static void check_delay_point(void);+static void check_get_buffer(Relation relation, ForkNumber forknum,+ BlockNumber blkno, char *buffer, bool needlock,+ bool *checkit, bool *found_in_sb);++/*+ * Iterate over all relation having a physical storage in the current database+ * and perform a check for all of them. Note that this function can run for+ * a very long time, and as such can cause bloat or other issues. Client+ * should iterate over a local list of oid using the per-table mode if+ * keeping an open transaction for very long can be a concern.+ */+static void+check_all_relations(TupleDesc tupdesc, Tuplestorestate *tupstore,+ ForkNumber forknum)+{+ List *relids = NIL;+ ListCell *lc;+ Relation relation;+ TableScanDesc scan;+ HeapTuple tuple;++ relation = table_open(RelationRelationId, AccessShareLock);+ scan = table_beginscan_catalog(relation, 0, NULL);++ while (HeapTupleIsValid(tuple = heap_getnext(scan, ForwardScanDirection)))+ {+ Form_pg_class class = (Form_pg_class) GETSTRUCT(tuple);++ if (!RELKIND_HAS_STORAGE(class->relkind))+ continue;++ relids = lappend_oid(relids, class->oid);+ }++ table_endscan(scan);+ table_close(relation, AccessShareLock); /* release lock */++ foreach(lc, relids)+ {+ Oid relid = lfirst_oid(lc);++ check_one_relation(tupdesc, tupstore, relid, forknum);+ }+}++/*+ * Perform a checksum check on the passed page. Returns whether the page is+ * valid or not, and assign the expected and found checksum in chk_expected and+ * chk_found, respectively. Note that a page can look like new but could be+ * the result of a corruption. We still check for this case, but we can't+ * compute its checksum as pg_checksum_page() is explictly checking for non-new+ * pages, so NoComputedChecksum will be set in chk_found.+ */+static bool+check_buffer(char *buffer, uint32 blkno, uint16 *chk_expected,+ uint16 *chk_found)+{+ PageHeader hdr = (PageHeader) buffer;++ Assert(chk_expected && chk_found);++ if (PageIsNew(hdr))+ {+ if (PageIsVerified(buffer, blkno))+ {+ /*+ * If the page is really new, there won't by any checksum to be+ * computed or expected.+ */+ *chk_expected = *chk_found = NoComputedChecksum;+ return true;+ }+ else+ {+ /*+ * There's a corruption, but since this affect PageIsNew, we+ * can't compute a checksum, so set NoComputedChecksum for the+ * expected checksum.+ */+ *chk_expected = NoComputedChecksum;+ *chk_found = hdr->pd_checksum;+ }+ return false;+ }++ *chk_expected = pg_checksum_page(buffer, blkno);+ *chk_found = hdr->pd_checksum;++ return (*chk_expected == *chk_found);+}++/*+ * Perform the check on a single relation, possibly filtered with a single+ * fork. This function will check if the given relation exists or not, as+ * a relation could be dropped after checking for the list of relations and+ * before getting here, and we don't want to error out in this case.+ */+static void+check_one_relation(TupleDesc tupdesc, Tuplestorestate *tupstore,+ Oid relid, ForkNumber single_forknum)+{+ Relation relation = NULL;+ ForkNumber forknum;++ /* Check if the relation (still) exists */+ if (SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relid)))+ {+ /*+ * We use a standard relation_open() to acquire the initial lock. It+ * means that this will block until the lock is acquired, or will+ * raise an ERROR if lock_timeout has been set. If caller wants to+ * check multiple tables while relying on a maximum wait time, it+ * should process tables one by one instead of relying on a global+ * processing with the main SRF.+ */+ relation = relation_open(relid, AccessShareLock);+ }++ if (!RelationIsValid(relation))+ {+ elog(WARNING, "relation %u does not exists in database \"%s\"",+ relid, get_database_name(MyDatabaseId));+ return;+ }++ if (!RELKIND_HAS_STORAGE(relation->rd_rel->relkind))+ ereport(ERROR,+ (errcode(ERRCODE_WRONG_OBJECT_TYPE),+ errmsg("Relation \"%s\" does not have storage to be checked.",+ quote_qualified_identifier(+ get_namespace_name(get_rel_namespace(relid)),+ get_rel_name(relid)))));++ RelationOpenSmgr(relation);++ for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)+ {+ if (single_forknum != InvalidForkNumber && single_forknum != forknum)+ continue;++ if (smgrexists(relation->rd_smgr, forknum))+ check_relation_fork(tupdesc, tupstore, relation, forknum);+ }++ relation_close(relation, AccessShareLock); /* release the lock */+}++/*+ * For a given relation and fork, Do the real work of iterating over all pages+ * and doing the check. Caller must hold an AccessShareLock lock on the given+ * relation.+ */+static void+check_relation_fork(TupleDesc tupdesc, Tuplestorestate *tupstore,+ Relation relation, ForkNumber forknum)+{+ BlockNumber blkno,+ nblocks;+ char buffer[BLCKSZ];+ bool checkit,+ found_in_sb;++ /*+ * We remember the number of blocks here. Since caller must hold a lock on+ * the relation, we know that it won't be truncated while we're iterating+ * over the blocks. Any block added after this function started won't be+ * checked, but this is out of scope as such pages will be flushed before+ * the next checkpoint's completion.+ */+ nblocks = RelationGetNumberOfBlocksInFork(relation, forknum);++#define CRF_COLS 5 /* Number of output arguments in the SRF */+ for (blkno = 0; blkno < nblocks; blkno++)+ {+ bool force_lock = false;+ uint16 chk_expected,+ chk_found;+ Datum values[CRF_COLS];+ bool nulls[CRF_COLS];+ int i = 0;++ memset(values, 0, sizeof(values));+ memset(nulls, 0, sizeof(nulls));++ /*+ * To avoid too much overhead, the buffer will be first read without+ * the locks that would guarantee the lack of false positive, as such+ * events should be quite rare.+ */+Retry:+ check_get_buffer(relation, forknum, blkno, buffer, force_lock,+ &checkit, &found_in_sb);++ if (!checkit)+ continue;++ if (check_buffer(buffer, blkno, &chk_expected, &chk_found))+ continue;++ /*+ * If we get a failure and the buffer wasn't found in shared buffers,+ * reread the buffer with suitable lock to avoid false positive. See+ * check_get_buffer for more details.+ */+ if (!found_in_sb && !force_lock)+ {+ force_lock = true;+ goto Retry;+ }++ values[i++] = ObjectIdGetDatum(relation->rd_id);+ values[i++] = Int32GetDatum(forknum);+ values[i++] = UInt32GetDatum(blkno);+ /*+ * This can happen if a corruption makes the block appears as+ * PageIsNew() but isn't a new page.+ */+ if (chk_expected == NoComputedChecksum)+ nulls[i++] = true;+ else+ values[i++] = UInt16GetDatum(chk_expected);+ values[i++] = UInt16GetDatum(chk_found);++ Assert(i == CRF_COLS);++ /* Report the failure to the stat collector and the logs. */+ pgstat_report_checksum_failure();+ ereport(WARNING,+ (errcode(ERRCODE_DATA_CORRUPTED),+ errmsg("invalid page in block %u of relation %s",+ blkno,+ relpath(relation->rd_smgr->smgr_rnode, forknum))));++ /* Save the corrupted blocks in the tuplestore. */+ tuplestore_putvalues(tupstore, tupdesc, values, nulls);+ }+}++/*+ * Check for interrupts and cost-based delay.+ */+static void+check_delay_point(void)+{+ /* Always check for interrupts */+ CHECK_FOR_INTERRUPTS();++ /* Nap if appropriate */+ if (!InterruptPending && VacuumCostBalance >= VacuumCostLimit)+ {+ int msec;++ msec = VacuumCostDelay * VacuumCostBalance / VacuumCostLimit;+ if (msec > VacuumCostDelay * 4)+ msec = VacuumCostDelay * 4;++ pg_usleep(msec * 1000L);++ VacuumCostBalance = 0;++ /* Might have gotten an interrupt while sleeping */+ CHECK_FOR_INTERRUPTS();+ }+}++/*+ * Safely read the wanted buffer from disk, dealing with possible concurrency+ * issue. Note that if a buffer is found dirty in shared_buffers, no read will+ * be performed and the caller will be informed that no check should be done.+ * We can safely ignore such buffers as they'll be written before next+ * checkpoint's completion..+ *+ * The following locks can be used in this function:+ *+ * - shared LWLock on the target buffer pool partition mapping.+ * - IOLock on the buffer+ *+ * The IOLock is taken when reading the buffer from disk if it exists in+ * shared_buffers, to avoid torn pages.+ *+ * If the buffer isn't in shared_buffers, it'll be read from disk without any+ * lock unless caller asked otherwise, setting needlock. In this case, the+ * read will be done while the buffer mapping partition LWLock is still being+ * held. Reading with this lock is to avoid the unlikely but possible case+ * that a buffer wasn't present in shared buffers when we checked but it then+ * alloc'ed in shared_buffers, modified and flushed concurrently when we+ * later try to read it, leading to false positive due to torn page. Caller+ * can read first the buffer without holding the target buffer mapping+ * partition LWLock to have an optimistic approach, and reread the buffer+ * from disk in case of error.+ *+ * Caller should hold an AccessShareLock on the Relation+ */+static void+check_get_buffer(Relation relation, ForkNumber forknum,+ BlockNumber blkno, char *buffer, bool needlock, bool *checkit,+ bool *found_in_sb)+{+ BufferTag buf_tag; /* identity of requested block */+ uint32 buf_hash; /* hash value for buf_tag */+ LWLock *partLock; /* buffer partition lock for the buffer */+ BufferDesc *bufdesc;+ int buf_id;++ *checkit = true;+ *found_in_sb = false;++ /* Check for interrupts and take throttling into account. */+ check_delay_point();++ /* create a tag so we can lookup the buffer */+ INIT_BUFFERTAG(buf_tag, relation->rd_smgr->smgr_rnode.node, forknum, blkno);++ /* determine its hash code and partition lock ID */+ buf_hash = BufTableHashCode(&buf_tag);+ partLock = BufMappingPartitionLock(buf_hash);++ /* see if the block is in the buffer pool already */+ LWLockAcquire(partLock, LW_SHARED);+ buf_id = BufTableLookup(&buf_tag, buf_hash);+ if (buf_id >= 0)+ {+ uint32 buf_state;++ *found_in_sb = true;++ /*+ * Found it. Now, retrieve its state to know what to do with it, and+ * release the pin immediately. We do so to limit overhead as much+ * as possible. We'll keep the shared lightweight lock on the target+ * buffer mapping partition, so this buffer can't be evicted, and+ * we'll acquire an IOLock on the buffer if we need to read the+ * content on disk.+ */+ bufdesc = GetBufferDescriptor(buf_id);++ buf_state = LockBufHdr(bufdesc);+ UnlockBufHdr(bufdesc, buf_state);++ /* Dirty pages are ignored as they'll be flushed soon. */+ if (buf_state & BM_DIRTY)+ *checkit = false;++ /*+ * Read the buffer from disk, taking on IO lock to prevent torn-page+ * reads, in the unlikely event that it was concurrently dirted and+ * flushed.+ */+ if (*checkit)+ {+ LWLockAcquire(BufferDescriptorGetIOLock(bufdesc), LW_SHARED);+ smgrread(relation->rd_smgr, forknum, blkno, buffer);+ LWLockRelease(BufferDescriptorGetIOLock(bufdesc));++ /*+ * Add a page miss cost, as we're always reading outside the+ * shared buffers.+ */+ VacuumCostBalance += VacuumCostPageMiss;+ }+ }+ else if (needlock)+ {+ /*+ * Caller asked to read the buffer while we have a lock on the target+ * partition.+ */+ smgrread(relation->rd_smgr, forknum, blkno, buffer);++ /*+ * Add a page miss cost, as we're always reading outside the shared+ * buffers.+ */+ VacuumCostBalance += VacuumCostPageMiss;+ }++ LWLockRelease(partLock);++ if (*found_in_sb || needlock)+ return;++ /*+ * Didn't find it in the buffer pool and didn't read it while holding the+ * buffer mapping partition lock. We'll have to try to read it from+ * disk, after releasing the target partition lock to avoid too much+ * overhead. It means that it's possible to get a torn page later, so+ * we'll have to retry with a suitable lock in case of error to avoid+ * false positive.+ */+ smgrread(relation->rd_smgr, forknum, blkno, buffer);++ /*+ * Add a page miss cost, as we're always reading outside the shared+ * buffers.+ */+ VacuumCostBalance += VacuumCostPageMiss;+}++Datum+pg_check_relation(PG_FUNCTION_ARGS)+{+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;+ TupleDesc tupdesc;+ Tuplestorestate *tupstore;+ MemoryContext per_query_ctx;+ MemoryContext oldcontext;+ ForkNumber forknum = InvalidForkNumber;+ Oid relid = InvalidOid;+ const char *forkname;++ if (!is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_SERVER_FILES))+ ereport(ERROR,+ (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),+ errmsg("only superuser or a member of the pg_read_server_files role may use this function")));++ if (!DataChecksumsEnabled())+ elog(ERROR, "Data checksums are not enabled");++ /* check to see if caller supports us returning a tuplestore */+ if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))+ ereport(ERROR,+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),+ errmsg("set-valued function called in context that cannot accept a set")));+ if (!(rsinfo->allowedModes & SFRM_Materialize))+ ereport(ERROR,+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),+ errmsg("materialize mode required, but it is not " \+ "allowed in this context")));++ /* Switch into long-lived context to construct returned data structures */+ per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;+ oldcontext = MemoryContextSwitchTo(per_query_ctx);++ /* Build a tuple descriptor for our result type */+ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)+ elog(ERROR, "return type must be a row type");++ tupstore = tuplestore_begin_heap(true, false, work_mem);+ rsinfo->returnMode = SFRM_Materialize;+ rsinfo->setResult = tupstore;+ rsinfo->setDesc = tupdesc;++ MemoryContextSwitchTo(oldcontext);++ if (PG_NARGS() >= 1 && !PG_ARGISNULL(0))+ relid = PG_GETARG_OID(0);++ if (PG_NARGS() == 2 && !PG_ARGISNULL(1))+ {+ forkname = TextDatumGetCString(PG_GETARG_TEXT_PP(1));+ forknum = forkname_to_number(forkname);+ }++ VacuumCostBalance = 0;++ if (OidIsValid(relid))+ check_one_relation(tupdesc, tupstore, relid, forknum);+ else+ check_all_relations(tupdesc, tupstore, forknum);++ tuplestore_donestoring(tupstore);++ return (Datum) 0;+}diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.datindex 7fb574f9dc..73fa7cdf51 100644--- a/src/include/catalog/pg_proc.dat+++ b/src/include/catalog/pg_proc.dat@@ -10741,6 +10741,14 @@
proallargtypes => '{oid,text,int8,timestamptz}', proargmodes => '{i,o,o,o}',
proargnames => '{tablespace,name,size,modification}',
prosrc => 'pg_ls_tmpdir_1arg' },
+{ oid => '9147', descr => 'check data integrity for one or all relations',+ proname => 'pg_check_relation', proisstrict => 'f', procost => '10000',+ prorows => '20', proretset => 't', proparallel => 'r',+ provolatile => 'v', prorettype => 'record', proargtypes => 'regclass text',+ proallargtypes => '{regclass,text,oid,int4,int8,int4,int4}',+ proargmodes => '{i,i,o,o,o,o,o}',+ proargnames => '{relation,fork,relid,forknum,failed_blocknum,expected_checksum,found_checksum}',+ prosrc => 'pg_check_relation' },
# hash partitioning constraint function
{ oid => '5028', descr => 'hash partition CHECK constraint',
diff --git a/src/test/Makefile b/src/test/Makefileindex efb206aa75..832868099f 100644--- a/src/test/Makefile+++ b/src/test/Makefile@@ -12,7 +12,8 @@ subdir = src/test
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
-SUBDIRS = perl regress isolation modules authentication recovery subscription+SUBDIRS = perl regress isolation modules authentication check_relation \+ recovery subscription
# Test suites that are not safe by default but can be run if selected
# by the user via the whitespace-separated list in variable
diff --git a/src/test/check_relation/.gitignore b/src/test/check_relation/.gitignorenew file mode 100644index 0000000000..871e943d50--- /dev/null+++ b/src/test/check_relation/.gitignore@@ -0,0 +1,2 @@+# Generated by test suite+/tmp_check/diff --git a/src/test/check_relation/Makefile b/src/test/check_relation/Makefilenew file mode 100644index 0000000000..792098fa65--- /dev/null+++ b/src/test/check_relation/Makefile@@ -0,0 +1,23 @@+#-------------------------------------------------------------------------+#+# Makefile for src/test/check_relation+#+# Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group+# Portions Copyright (c) 1994, Regents of the University of California+#+# src/test/check_relation/Makefile+#+#-------------------------------------------------------------------------++subdir = src/test/check_relation+top_builddir = ../../..+include $(top_builddir)/src/Makefile.global++check:+ $(prove_check)++installcheck:+ $(prove_installcheck)++clean distclean maintainer-clean:+ rm -rf tmp_checkdiff --git a/src/test/check_relation/README b/src/test/check_relation/READMEnew file mode 100644index 0000000000..415c4b21ad--- /dev/null+++ b/src/test/check_relation/README@@ -0,0 +1,23 @@+src/test/check_relation/README++Regression tests for online checksums verification+==================================================++This directory contains a test suite for online checksums verification.++Running the tests+=================++NOTE: You must have given the --enable-tap-tests argument to configure.++Run+ make check+or+ make installcheck+You can use "make installcheck" if you previously did "make install".+In that case, the code in the installation tree is tested. With+"make check", a temporary installation tree is built from the current+sources and then tested.++Either way, this test initializes, starts, and stops a test Postgres+cluster.diff --git a/src/test/check_relation/t/01_checksums_check.pl b/src/test/check_relation/t/01_checksums_check.plnew file mode 100644index 0000000000..7944195489--- /dev/null+++ b/src/test/check_relation/t/01_checksums_check.pl@@ -0,0 +1,274 @@+use strict;+use warnings;++use PostgresNode;+use TestLib;+use Test::More tests => 59;++our $CHECKSUM_UINT16_OFFSET = 4;+our $PD_UPPER_UINT16_OFFSET = 7;+our $BLOCKSIZE;+our $TOTAL_NB_ERR = 0;++sub get_block+{+ my ($filename, $blkno) = @_;+ my $block;++ open(my $infile, '<', $filename) or die;+ binmode($infile);++ my $success = read($infile, $block, $BLOCKSIZE, ($blkno * $BLOCKSIZE));+ die($!) if not defined $success;++ close($infile);++ return($block);+}++sub overwrite_block+{+ my ($filename, $block, $blkno) = @_;++ open(my $outfile, '>', $filename) or die;+ binmode ($outfile);++ my $nb = syswrite($outfile, $block, $BLOCKSIZE, ($blkno * $BLOCKSIZE));++ die($!) if not defined $nb;+ die("Write error") if ($nb != $BLOCKSIZE);++ $outfile->flush();++ close($outfile);+}++sub get_uint16_from_page+{+ my ($block, $offset) = @_;++ return (unpack("S*", $block))[$offset];+}++sub set_uint16_to_page+{+ my ($block, $data, $offset) = @_;++ my $pack = pack("S", $data);++ # vec with 16B or more won't preserve endianness+ vec($block, 2*$offset, 8) = (unpack('C*', $pack))[0];+ vec($block, (2*$offset) + 1, 8) = (unpack('C*', $pack))[1];++ return $block;+}++sub check_checksums_call+{+ my ($node, $relname) = @_;++ my ($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT COUNT(*)"+ . " FROM pg_catalog.pg_check_relation('$relname')"+ );++ return ($stderr eq '');+}++sub check_checksums_nb_error+{+ my ($node, $nb, $pattern) = @_;++ my ($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT COUNT(*)"+ . " FROM pg_catalog.pg_check_relation()"+ );++ is($cmdret, 0, 'Function should run successfully');+ like($stderr, $pattern, 'Error output should match expectations');+ is($stdout, $nb, "Should have $nb error");++ $TOTAL_NB_ERR += $nb;+}++sub check_pg_stat_database_nb_error+{+ my ($node) = @_;++ my ($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT "+ . " sum(checksum_failures)"+ . " FROM pg_catalog.pg_stat_database"+ );++ is($cmdret, 0, 'Function should run successfully');+ is($stderr, '', 'Function should run successfully');+ is($stdout, $TOTAL_NB_ERR, "Should have $TOTAL_NB_ERR error");+}++sub get_checksums_errors+{+ my ($node, $pattern, $nb) = @_;++ my ($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT"+ . " relid::regclass::text, forknum, failed_blocknum,"+ . " expected_checksum, found_checksum"+ . " FROM pg_catalog.pg_check_relation()"+ );++ is($cmdret, '0', 'Function should run successfully');+ like($stderr, $pattern, 'Error output should match expectations');++ $TOTAL_NB_ERR += $nb;++ return $stdout;+}++# This function will perform various test by modifying the specified block at+# the specified uint16 offset, checking that the corruption is correctly+# detected, and finally restore the specified block to its original content.+sub corrupt_and_test_block+{+ my ($node, $filename, $blkno, $offset, $fake_data) = @_;++ check_checksums_nb_error($node, 0, qr/^$/);++check_pg_stat_database_nb_error($node);++ $node->stop();++ my $original_block = get_block($filename, 0);+ my $original_data = get_uint16_from_page($original_block, $offset);++ isnt($original_data, $fake_data,+ "The fake data at offset $offset should be different"+ . " from the existing one");++ my $new_block = set_uint16_to_page($original_block, $fake_data, $offset);+ isnt($original_data, get_uint16_from_page($new_block, $offset),+ "The fake data at offset $offset should have been changed in memory");++ overwrite_block($filename, $new_block, 0);++ my $written_data = get_uint16_from_page(get_block($filename, 0), $offset);+ isnt($original_data, $written_data,+ "The data written at offset $offset should be different"+ . " from the original one");+ is(get_uint16_from_page($new_block, $offset), $written_data,+ "The data written at offset $offset should be the same"+ . " as the one in memory");+ is($written_data, $fake_data,+ "The data written at offset $offset should be the one"+ . " we wanted to write");++ $node->start();++ check_checksums_nb_error($node, 1, qr/invalid page in block $blkno/);++ my $expected_checksum;+ my $found_checksum = get_uint16_from_page($new_block,+ $CHECKSUM_UINT16_OFFSET);+ if ($offset == $PD_UPPER_UINT16_OFFSET)+ {+ # A checksum can't be computed if it's detected as PageIsNew(), so the+ # function returns NULL for the computed checksum+ $expected_checksum = '';+ }+ else+ {+ $expected_checksum = get_uint16_from_page($original_block,+ $CHECKSUM_UINT16_OFFSET);+ }++ my $det = get_checksums_errors($node, qr/invalid page in block $blkno/, 1);+ is($det, "t1|0|0|$expected_checksum|$found_checksum",+ "The checksums error for modification at offset $offset"+ . " should be detected");++ $node->stop();++ $new_block = set_uint16_to_page($original_block, $original_data, $offset);+ is($original_data, get_uint16_from_page($new_block, $offset),+ "The data at offset $offset should have been restored in memory");++ overwrite_block($filename, $new_block, 0);+ is($original_data, get_uint16_from_page(get_block($filename, $blkno),+ $offset),+ "The data at offset $offset should have been restored on disk");++ $node->start();++ check_checksums_nb_error($node, 0, qr/^$/);+}++if (exists $ENV{MY_PG_REGRESS})+{+ $ENV{PG_REGRESS} = $ENV{MY_PG_REGRESS};+}++my $node = get_new_node('main');++my %params;+$params{'extra'} = ['--data-checksums'];+$node->init(%params);++$node->start();++$ENV{PGOPTIONS} = '--client-min-messages=WARNING';++my ($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT"+ . " current_setting('data_checksums')");++is($stdout, 'on', 'Data checksums shoud be enabled');++($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT"+ . " current_setting('block_size')");++$BLOCKSIZE = $stdout;++$node->safe_psql(+ 'postgres', q|+ CREATE TABLE public.t1(id integer);+ CREATE INDEX t1_id_idx ON public.t1 (id);+ INSERT INTO public.t1 SELECT generate_series(1, 100);+ CREATE VIEW public.v1 AS SELECT * FROM t1;+ CREATE MATERIALIZED VIEW public.mv1 AS SELECT * FROM t1;+ CREATE SEQUENCE public.s1;+ CREATE UNLOGGED TABLE public.u_t1(id integer);+ CREATE INDEX u_t1_id_idx ON public.u_t1 (id);+ INSERT INTO public.u_t1 SELECT generate_series(1, 100);+ CHECKPOINT;+|);++# Check sane behavior on various objects type, including those that don't have+# a storage.+is(check_checksums_call($node, 't1'), '1', 'Can check a table');+is(check_checksums_call($node, 't1_id_idx'), '1', 'Can check an index');+is(check_checksums_call($node, 'v1'), '', 'Cannot check a view');+is(check_checksums_call($node, 'mv1'), '1', 'Can check a materialized view');+is(check_checksums_call($node, 's1'), '1', 'Can check a sequence');+is(check_checksums_call($node, 'u_t1'), '1', 'Can check an unlogged table');+is(check_checksums_call($node, 'u_t1_id_idx'), '1', 'Can check an unlogged index');++# get the underlying heap absolute path+($cmdret, $stdout, $stderr) = $node->psql('postgres', "SELECT"+ . " current_setting('data_directory') || '/' || pg_relation_filepath('t1')"+);++isnt($stdout, '', 'A relfinode should be returned');++my $filename = $stdout;++check_checksums_nb_error($node, 0, qr/^$/);++check_pg_stat_database_nb_error($node);++my $fake_uint16 = hex '0x0000';++# Test with a modified checksum. We use a zero checksum here as it's the only+# one that cannot exist on a checksummed page. We also don't have an easy way+# to compute what the checksum would be after a modification in a random place+# in the block.+corrupt_and_test_block($node, $filename, 0, $CHECKSUM_UINT16_OFFSET,+ $fake_uint16);++# Test corruption making the block looks like it's PageIsNew().+corrupt_and_test_block($node, $filename, 0, $PD_UPPER_UINT16_OFFSET,+ $fake_uint16);
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To: pgsql-hackers@postgresql.org
Cc: rjuju123@gmail.com, michael@paquier.xyz, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org, sawada.mshk@gmail.com
Subject: Re: Online checksums verification in the backend
In-Reply-To: <20200311071823.GA4643@nol>
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