The trouble with doing this is that an apparently-constant subquery
output column isn't really constant if it is a grouping column that
appears in only some of the grouping sets. A qual using such a
column would be subject to incorrect const-folding after push-down,
as seen in bug #16585 from Paul Sivash.
To fix, just disable qual pushdown altogether if the sub-query has
nonempty groupingSets. While we could imagine far less restrictive
solutions, there is not much point in working harder right now,
because subquery_planner() won't move HAVING clauses to WHERE within
such a subquery. If the qual stays in HAVING it's not going to be
a lot more useful than if we'd kept it at the outer level.
Having said that, this restriction could be removed if we used a
parsetree representation that distinguished such outputs from actual
constants, which is something I hope to do in future. Hence, make
the patch a minimal addition rather than integrating it more tightly
(e.g. by renumbering the existing items in subquery_is_pushdown_safe's
comment).
Back-patch to 9.5 where grouping sets were introduced.
Discussion: https://postgr.es/m/16585-9d8c340d23ade8c1@postgresql.org
If a CREATE TABLE command uses both LIKE and traditional inheritance,
Vars in CHECK constraints and expression indexes that are absorbed
from a LIKE parent table tended to get mis-numbered, resulting in
wrong answers and/or bizarre error messages (though probably not any
actual crashes, thanks to validation occurring in the executor).
In v12 and up, the same could happen to Vars in GENERATED expressions,
even in cases with no LIKE clause but multiple traditional-inheritance
parents.
The cause of the problem for LIKE is that parse_utilcmd.c supposed
it could renumber such Vars correctly during transformCreateStmt(),
which it cannot since we have not yet accounted for columns added via
inheritance. Fix that by postponing processing of LIKE INCLUDING
CONSTRAINTS, DEFAULTS, GENERATED, INDEXES till after we've performed
DefineRelation().
The error with GENERATED and multiple inheritance is a simple oversight
in MergeAttributes(); it knows it has to renumber Vars in inherited
CHECK constraints, but forgot to apply the same processing to inherited
GENERATED expressions (a/k/a defaults).
Per bug #16272 from Tom Gottfried. The non-GENERATED variants of the
issue are ancient, presumably dating right back to the addition of
CREATE TABLE LIKE; hence back-patch to all supported branches.
Discussion: https://postgr.es/m/16272-6e32da020e9a9381@postgresql.org
Several PGXN modules reference LockTagType values; renumbering would
force a recompile of those modules. Oversight in back-patch of today's
commit 566372b3d6. Back-patch to released
branches, v12 through 9.5.
Reported by Tom Lane.
Discussion: https://postgr.es/m/921383.1597523945@sss.pgh.pa.us
The SimpleLruTruncate() header comment states the new coding rule. To
achieve this, add locktype "frozenid" and two LWLocks. This closes a
rare opportunity for data loss, which manifested as "apparent
wraparound" or "could not access status of transaction" errors. Data
loss is more likely in pg_multixact, due to released branches' thin
margin between multiStopLimit and multiWrapLimit. If a user's physical
replication primary logged ": apparent wraparound" messages, the user
should rebuild standbys of that primary regardless of symptoms. At less
risk is a cluster having emitted "not accepting commands" errors or
"must be vacuumed" warnings at some point. One can test a cluster for
this data loss by running VACUUM FREEZE in every database. Back-patch
to 9.5 (all supported versions).
Discussion: https://postgr.es/m/20190218073103.GA1434723@rfd.leadboat.com
nodeSubplan.c expects that the testexpr for a hashable ANY SubPlan
has the form of one or more OpExprs whose LHS is an expression of the
outer query's, while the RHS is an expression over Params representing
output columns of the subquery. However, the planner only went as far
as verifying that the clauses were all binary OpExprs. This works
99.99% of the time, because the clauses have the right shape when
emitted by the parser --- but it's possible for function inlining to
break that, as reported by PegoraroF10. To fix, teach the planner
to check that the LHS and RHS contain the right things, or more
accurately don't contain the wrong things. Given that this has been
broken for years without anyone noticing, it seems sufficient to just
give up hashing when it happens, rather than go to the trouble of
commuting the clauses back again (which wouldn't necessarily work
anyway).
While poking at that, I also noticed that nodeSubplan.c had a baked-in
assumption that the number of hash clauses is identical to the number
of subquery output columns. Again, that's fine as far as parser output
goes, but it's not hard to break it via function inlining. There seems
little reason for that assumption though --- AFAICS, the only thing
it's buying us is not having to store the number of hash clauses
explicitly. Adding code to the planner to reject such cases would take
more code than getting nodeSubplan.c to cope, so I fixed it that way.
This has been broken for as long as we've had hashable SubPlans,
so back-patch to all supported branches.
Discussion: https://postgr.es/m/1549209182255-0.post@n3.nabble.com
Up to now, upon receipt of a SIGTERM ("smart shutdown" command), the
postmaster has immediately killed all "optional" background processes,
and subsequently refused to launch new ones while it's waiting for
foreground client processes to exit. No doubt this seemed like an OK
policy at some point; but it's a pretty bad one now, because it makes
for a seriously degraded environment for the remaining clients:
* Parallel queries are killed, and new ones fail to launch. (And our
parallel-query infrastructure utterly fails to deal with the case
in a reasonable way --- it just hangs waiting for workers that are
not going to arrive. There is more work needed in that area IMO.)
* Autovacuum ceases to function. We can tolerate that for awhile,
but if bulk-update queries continue to run in the surviving client
sessions, there's eventually going to be a mess. In the worst case
the system could reach a forced shutdown to prevent XID wraparound.
* The bgwriter and walwriter are also stopped immediately, likely
resulting in performance degradation.
Hence, let's rearrange things so that the only immediate change in
behavior is refusing to let in new normal connections. Once the last
normal connection is gone, shut everything down as though we'd received
a "fast" shutdown. To implement this, remove the PM_WAIT_BACKUP and
PM_WAIT_READONLY states, instead staying in PM_RUN or PM_HOT_STANDBY
while normal connections remain. A subsidiary state variable tracks
whether or not we're letting in new connections in those states.
This also allows having just one copy of the logic for killing child
processes in smart and fast shutdown modes. I moved that logic into
PostmasterStateMachine() by inventing a new state PM_STOP_BACKENDS.
Back-patch to 9.6 where parallel query was added. In principle
this'd be a good idea in 9.5 as well, but the risk/reward ratio
is not as good there, since lack of autovacuum is not a problem
during typical uses of smart shutdown.
Per report from Bharath Rupireddy.
Patch by me, reviewed by Thomas Munro
Discussion: https://postgr.es/m/CALj2ACXAZ5vKxT9P7P89D87i3MDO9bfS+_bjMHgnWJs8uwUOOw@mail.gmail.com
When a table is scanned by heapam_index_build_range_scan (née
IndexBuildHeapScan) and the table lock being held allows concurrent data
changes, it is possible for new HOT chains to sprout in a page that were
unknown when the scan of a page happened. This leads to an error such
as
ERROR: failed to find parent tuple for heap-only tuple at (X,Y) in table "tbl"
because the root tuple was not present when we first obtained the list
of the page's root tuples. This can be fixed by re-obtaining the list
of root tuples, if we see that a heap-only tuple appears to point to a
non-existing root.
This was reported by Anastasia as occurring for BRIN summarization
(which exists since 9.5), but I think it could theoretically also happen
with CREATE INDEX CONCURRENTLY (much older) or REINDEX CONCURRENTLY
(very recent). It seems a happy coincidence that BRIN forces us to
backpatch this all the way to 9.5.
Reported-by: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Diagnosed-by: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Co-authored-by: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Co-authored-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/602d8487-f0b2-5486-0088-0f372b2549fa@postgrespro.ru
Backpatch: 9.5 - master
If a page range is desummarized at just the right time concurrently with
an index walk, BRIN would raise an error indicating index corruption.
This is scary and unhelpful; silently returning that the page range is
not summarized is sufficient reaction.
This bug was introduced by commit 975ad4e602 as additional protection
against a bug whose actual fix was elsewhere. Backpatch equally.
Reported-By: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Diagnosed-By: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/2588667e-d07d-7e10-74e2-7e1e46194491@postgrespro.ru
Backpatch: 9.5 - master
This is like CVE-2018-1058 commit
582edc369c. Today, a malicious user of a
publisher or subscriber database can invoke arbitrary SQL functions
under an identity running replication, often a superuser. This fix may
cause "does not exist" or "no schema has been selected to create in"
errors in a replication process. After upgrading, consider watching
server logs for these errors. Objects accruing schema qualification in
the wake of the earlier commit are unlikely to need further correction.
Back-patch to v10, which introduced logical replication.
Security: CVE-2020-14349
Any libpq client can use the header. Clients include backend components
postgres_fdw, dblink, and logical replication apply worker. Back-patch
to v10, because another fix needs this. In released branches, just copy
the header and keep the original.
Hostile objects located within the installation-time search_path could
capture references in an extension's installation or upgrade script.
If the extension is being installed with superuser privileges, this
opens the door to privilege escalation. While such hazards have existed
all along, their urgency increases with the v13 "trusted extensions"
feature, because that lets a non-superuser control the installation path
for a superuser-privileged script. Therefore, make a number of changes
to make such situations more secure:
* Tweak the construction of the installation-time search_path to ensure
that references to objects in pg_catalog can't be subverted; and
explicitly add pg_temp to the end of the path to prevent attacks using
temporary objects.
* Disable check_function_bodies within installation/upgrade scripts,
so that any security gaps in SQL-language or PL-language function bodies
cannot create a risk of unwanted installation-time code execution.
* Adjust lookup of type input/receive functions and join estimator
functions to complain if there are multiple candidate functions. This
prevents capture of references to functions whose signature is not the
first one checked; and it's arguably more user-friendly anyway.
* Modify various contrib upgrade scripts to ensure that catalog
modification queries are executed with secure search paths. (These
are in-place modifications with no extension version changes, since
it is the update process itself that is at issue, not the end result.)
Extensions that depend on other extensions cannot be made fully secure
by these methods alone; therefore, revert the "trusted" marking that
commit eb67623c9 applied to earthdistance and hstore_plperl, pending
some better solution to that set of issues.
Also add documentation around these issues, to help extension authors
write secure installation scripts.
Patch by me, following an observation by Andres Freund; thanks
to Noah Misch for review.
Security: CVE-2020-14350
Coverity pointed out, not unreasonably, that we checked fseeko's
result at every other call site but these. Failure to seek in the
temp file (note this is NOT pg_dump's output file) seems quite
unlikely, and even if it did happen the file length cross-check
further down would probably detect the problem. Still, that's a
poor excuse for not checking the result of a system call.
Ashutosh Bapat noticed that when logical walsender needs to wait for
WAL, and it realizes that it must send a keepalive message to
walreceiver to update the sent-LSN, which *does not* request a reply
from walreceiver, it wrongly sets the flag that it's going to wait for
that reply. That means that any future would-be sender of feedback
messages ends up not sending a feedback message, because they all
believe that a reply is expected.
With built-in logical replication there's not much harm in this, because
WalReceiverMain will send a ping-back every wal_receiver_timeout/2
anyway; but with other logical replication systems (e.g. pglogical) it
can cause significant pain.
This problem was introduced in commit 41d5f8ad73, where the
request-reply flag was changed from true to false to WalSndKeepalive,
without at the same time removing the line that sets
waiting_for_ping_response.
Just removing that line would be a sufficient fix, but it seems better
to shift the responsibility of setting the flag to WalSndKeepalive
itself instead of requiring caller to do it; this is clearly less
error-prone.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reported-by: Ashutosh Bapat <ashutosh.bapat@2ndquadrant.com>
Backpatch: 9.5 and up
Discussion: https://postgr.es/m/20200806225558.GA22401@alvherre.pgsql
Commit 13838740f fixed some issues with step generation in partition
pruning, but there was yet another one: get_steps_using_prefix() assumes
that clauses in the passed-in prefix list are sorted in ascending order
of their partition key numbers, but the caller failed to ensure this for
range partitioning, which led to an assertion failure in debug builds.
Adjust the caller function to arrange the clauses in the prefix list in
the required order for range partitioning.
Back-patch to v11, like the previous commit.
Patch by me, reviewed by Amit Langote.
Discussion: https://postgr.es/m/CAPmGK16jkXiFG0YqMbU66wte-oJTfW6D1HaNvQf%3D%2B5o9%3Dm55wQ%40mail.gmail.com
The previous coding imagined that it could call before_shmem_exit()
when a non-exclusive backup began and then remove the previously-added
handler by calling cancel_before_shmem_exit() when that backup
ended. However, this only works provided that nothing else in the
system has registered a before_shmem_exit() hook in the interim,
because cancel_before_shmem_exit() is documented to remove a callback
only if it is the latest callback registered. It also only works
if nothing can ERROR out between the time that sessionBackupState
is reset and the time that cancel_before_shmem_exit(), which doesn't
seem to be strictly true.
To fix, leave the handler installed for the lifetime of the session,
arrange to install it just once, and teach it to quietly do nothing if
there isn't a non-exclusive backup in process.
This was originally committed to master as
303640199d, but I did not back-patch
at the time because the consequences were minor. However, now
there's been a second report of this causing trouble with a slightly
different test case than the one I reported originally, so now
I'm back-patching as far as v11 where JIT was introduced.
Patch by me, reviewed by Kyotaro Horiguchi, Michael Paquier (who
preferred a different approach, but got outvoted), Fujii Masao,
and Tom Lane, and with comments by various others. New problem
report from Bharath Rupireddy.
Discussion: http://postgr.es/m/CA+TgmobMjnyBfNhGTKQEDbqXYE3_rXWpc4CM63fhyerNCes3mA@mail.gmail.com
Discussion: http://postgr.es/m/CALj2ACWk7j4F2v2fxxYfrroOF=AdFNPr1WsV+AGtHAFQOqm_pw@mail.gmail.com
A couple of test cases had connect_timeout=14, a value that seems
to have been plucked from a hat. While it's more than sufficient
for normal cases, slow/overloaded buildfarm machines can get a timeout
failure here, as per recent report from "sungazer". Increase to 180
seconds, which is in line with our typical timeouts elsewhere in
the regression tests.
Back-patch to 9.6; the code looks different in 9.5, and this doesn't
seem to be quite worth the effort to adapt to that.
Report: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=sungazer&dt=2020-08-04%2007%3A12%3A22
Instead of writing a query to psql's stdin, use -c. This avoids a
failure where psql exits before we write, seen a few times on the build
farm. Thanks to Tom Lane for the suggestion.
Back-patch to 11, where the LDAP tests arrived.
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/CA%2BhUKGLFmW%2BHQYPeKiwSp5sdFFHtFViCpw4Mh6yAgEx74r5-Cw%40mail.gmail.com
These files were missed when commit a3ab7a707 added a new test query.
Understandable considering these files no longer exist in HEAD.
Per buildfarm member pademelon.
Commit eba77534 fixed an amcheck false positive bug involving
inconsistencies in TOAST input state between table and index. A test
case was added that verified that such an inconsistency didn't result in
a spurious corruption related error.
Test coverage from the test was accidentally lost by commit 501e41dd,
which propagated ALTER TABLE ... SET STORAGE attstorage state to
indexes. This broke the test because the test specifically relied on
attstorage not being propagated. This artificially forced there to be
index tuples whose datums were equivalent to the datums in the heap
without the datums actually being bitwise equal.
Fix this by updating pg_attribute directly instead. Commit 501e41dd
made similar changes to a test_decoding TOAST-related test case which
made the same assumption, but overlooked the amcheck test case.
Backpatch: 11-, just like commit eba77534 (and commit 501e41dd).
The new hlCover() algorithm that I introduced in commit c9b0c678d
turns out to potentially take O(N^2) or worse time on long documents,
if there are many occurrences of individual query words but few or no
substrings that actually satisfy the query. (One way to hit this
behavior is with a "common_word & rare_word" type of query.) This
seems unavoidable given the original goal of checking every substring
of the document, so we have to back off that idea. Fortunately, it
seems unlikely that anyone would really want headlines spanning all of
a long document, so we can avoid the worse-than-linear behavior by
imposing a maximum length of substring that we'll consider.
For now, just hard-wire that maximum length as a multiple of max_words
times max_fragments. Perhaps at some point somebody will argue for
exposing it as a ts_headline parameter, but I'm hesitant to make such
a feature addition in a back-patched bug fix.
I also noted that the hlFirstIndex() function I'd added in that
commit was unnecessarily stupid: it really only needs to check whether
a HeadlineWordEntry's item pointer is null or not. This wouldn't make
all that much difference in typical cases with queries having just
a few terms, but a cycle shaved is a cycle earned.
In addition, add a CHECK_FOR_INTERRUPTS call in TS_execute_recurse.
This ensures that hlCover's loop is cancellable if it manages to take
a long time, and it may protect some other TS_execute callers as well.
Back-patch to 9.6 as the previous commit was. I also chose to add the
CHECK_FOR_INTERRUPTS call to 9.5. The old hlCover() algorithm seems
to avoid the O(N^2) behavior, at least on the test case I tried, but
nonetheless it's not very quick on a long document.
Per report from Stephen Frost.
Discussion: https://postgr.es/m/20200724160535.GW12375@tamriel.snowman.net
In "High Availability, Load Balancing, and Replication" chapter,
certain descriptions of Pgpool-II were not correct at this point. It
does not need conflict resolution. Also "Multiple-Server Parallel
Query Execution" is not supported anymore.
Discussion: https://postgr.es/m/20200726.230128.53842489850344110.t-ishii%40sraoss.co.jp
Author: Tatsuo Ishii
Reviewed-by: Bruce Momjian
Backpatch-through: 9.5
Partitioned indexes are also registered in pg_inherits, but the
description of this catalog did not reflect that.
Author: Dagfinn Ilmari Mannsåker
Discussion: https://postgr.es/m/87k0ynj35y.fsf@wibble.ilmari.org
Backpatch-through: 11
Backpatch an assertion (that was originally added to Postgres 12 by
commit dd299df818) that seems broadly useful. The assertion can detect
violations of the HOT invariant (i.e. no two index tuples can point to
the same heap TID) when CREATE INDEX somehow incorrectly allows that to
take place.
For example, a IndexBuildHeapScan/heapam_index_build_range_scan bug
might result in two tuples that both point to the same heap TID. If
these two tuples also happen to be duplicates, the assertion will fail.
Discussion: https://postgr.es/m/CAH2-WzmBxu4o=pMsniur+bwHqCGCmV_AOLkuK6BuU7ngA6evqw@mail.gmail.com
Backpatch: 9.5-11 only
In the case of range partitioning, get_steps_using_prefix() assumes that
the passed-in prefix list contains at least one clause for each of the
partition keys earlier than one specified in the passed-in
step_lastkeyno, but the caller (ie, gen_prune_steps_from_opexps())
didn't take it into account, which led to a server crash or incorrect
results when the list contained no clauses for such partition keys, as
reported in bug #16500 and #16501 from Kobayashi Hisanori. Update the
caller to call that function only when the list created there contains
at least one clause for each of the earlier partition keys in the case
of range partitioning.
While at it, fix some other issues:
* The list to pass to get_steps_using_prefix() is allowed to contain
multiple clauses for the same partition key, as described in the
comment for that function, but that function actually assumed that the
list contained just a single clause for each of middle partition keys,
which led to an assertion failure when the list contained multiple
clauses for such partition keys. Update that function to match the
comment.
* In the case of hash partitioning, partition keys are allowed to be
NULL, in which case the list to pass to get_steps_using_prefix()
contains no clauses for NULL partition keys, but that function treats
that case as like the case of range partitioning, which led to the
assertion failure. Update the assertion test to take into account
NULL partition keys in the case of hash partitioning.
* Fix a typo in a comment in get_steps_using_prefix_recurse().
* gen_partprune_steps() failed to detect self-contradiction from
strict-qual clauses and an IS NULL clause for the same partition key
in some cases, producing incorrect partition-pruning steps, which led
to incorrect results of partition pruning, but didn't cause any
user-visible problems fortunately, as the self-contradiction is
detected later in the query planning. Update that function to detect
the self-contradiction.
Per bug #16500 and #16501 from Kobayashi Hisanori. Patch by me, initial
diagnosis for the reported issue and review by Dmitry Dolgov.
Back-patch to v11, where partition pruning was introduced.
Discussion: https://postgr.es/m/16500-d1613f2a78e1e090%40postgresql.org
Discussion: https://postgr.es/m/16501-5234a9a0394f6754%40postgresql.org
A compressed stream may end with an empty packet. In this case
decompression finishes before reading the empty packet and the
remaining stream packet causes a failure in reading the following
data. This commit makes sure to consume such extra data, avoiding a
failure when decompression the data. This corner case was reproducible
easily with a data length of 16kB, and existed since e94dd6a. A cheap
regression test is added to cover this case based on a random,
incompressible string.
The first attempt of this patch has allowed to find an older failure
within the compression logic of pgcrypto, fixed by b9b6105. This
involved SLES 15 with z390 where a custom flavor of libz gets used.
Bonus thanks to Mark Wong for providing access to the specific
environment.
Reported-by: Frank Gagnepain
Author: Kyotaro Horiguchi, Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/16476-692ef7b84e5fb893@postgresql.org
Backpatch-through: 9.5
Commit 85c9d347 addressed a similar problem for Gather and Gather
Merge nodes but forgot to account for nodes above parallel nodes. This
still works for nodes above Gather node because we shut down the workers
for Gather node as soon as there are no more tuples. We can do a similar
thing for Gather Merge as well but it seems better to account for stats
during nodes shutdown after completing the execution.
Reported-by: Stéphane Lorek, Jehan-Guillaume de Rorthais
Author: Jehan-Guillaume de Rorthais <jgdr@dalibo.com>
Reviewed-by: Amit Kapila
Backpatch-through: 10, where it was introduced
Discussion: https://postgr.es/m/20200718160206.584532a2@firost
contrib/pgcrypto mishandled the case where deflate() does not consume
all of the offered input on the first try. It reset the next_in pointer
to the start of the input instead of leaving it alone, causing the wrong
data to be fed to the next deflate() call.
This has been broken since pgcrypto was committed. The reason for the
lack of complaints seems to be that it's fairly hard to get stock zlib
to not consume all the input, so long as the output buffer is big enough
(which it normally would be in pgcrypto's usage; AFAICT the input is
always going to be packetized into packets no larger than ZIP_OUT_BUF).
However, IBM's zlibNX implementation for AIX evidently will do it
in some cases.
I did not add a test case for this, because I couldn't find one that
would fail with stock zlib. When we put back the test case for
bug #16476, that will cover the zlibNX situation well enough.
While here, write deflate()'s second argument as Z_NO_FLUSH per its
API spec, instead of hard-wiring the value zero.
Per buildfarm results and subsequent investigation.
Discussion: https://postgr.es/m/16476-692ef7b84e5fb893@postgresql.org
TLS 1.3 uses a different way of specifying ciphers and a different
OpenSSL API. PostgreSQL currently does not support setting those
ciphers. For now, just document this. In the future, support for
this might be added somehow.
Reviewed-by: Jonathan S. Katz <jkatz@postgresql.org>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
This reverts commit 9e10898, after finding out that buildfarm members
running SLES 15 on z390 complain on the compression and decompression
logic of the new test: pipistrelles, barbthroat and steamerduck.
Those hosts are visibly using hardware-specific changes to improve zlib
performance, requiring more investigation.
Thanks to Tom Lane for the discussion.
Discussion: https://postgr.es/m/20200722093749.GA2564@paquier.xyz
Backpatch-through: 9.5
A compressed stream may end with an empty packet, and PGP decompression
finished before reading this empty packet in the remaining stream. This
caused a failure in pgcrypto, handling this case as corrupted data.
This commit makes sure to consume such extra data, avoiding a failure
when decompression the entire stream. This corner case was reproducible
with a data length of 16kB, and existed since its introduction in
e94dd6a. A cheap regression test is added to cover this case.
Thanks to Jeff Janes for the extra investigation.
Reported-by: Frank Gagnepain
Author: Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/16476-692ef7b84e5fb893@postgresql.org
Backpatch-through: 9.5
The executor checks for this error, and so does the bootstrap catalog
loader, but we never checked for it in retail catalog manipulations.
The folly of that has now been exposed, so let's add assertions
checking it. Checking in CatalogTupleInsert[WithInfo] and
CatalogTupleUpdate[WithInfo] should be enough to cover this.
Back-patch to v10; the aforesaid functions didn't exist before that,
and it didn't seem worth adapting the patch to the oldest branches.
But given the risk of JIT crashes, I think we certainly need this
as far back as v11.
Pre-v13, we have to explicitly exclude pg_subscription.subslotname
and pg_subscription_rel.srsublsn from the checks, since they are
mismarked. (Even if we change our mind about applying BKI_FORCE_NULL
in the branch tips, it doesn't seem wise to have assertions that
would fire in existing databases.)
Discussion: https://postgr.es/m/298837.1595196283@sss.pgh.pa.us
This coding technique is unsafe, since we'd be accessing off the end
of the tuple if the field is null. SIGSEGV is pretty improbable, but
perhaps not impossible. Also, returning garbage for the LSN doesn't
seem like a great idea, even if callers aren't looking at it today.
Also update docs to point out explicitly that
pg_subscription.subslotname and pg_subscription_rel.srsublsn
can be null.
Perhaps we should mark these two fields BKI_FORCE_NULL, so that
they'd be correctly labeled in databases that are initdb'd in the
future. But we can't force that for existing databases, and on
balance it's not too clear that having a mix of different catalog
contents in the field would be wise.
Apply to v10 (where this code came in) through v12. Already
fixed in v13 and HEAD.
Discussion: https://postgr.es/m/732838.1595278439@sss.pgh.pa.us
