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Consolidate ereport boolean visibility flags into a "flags" field #3

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dwsteele opened this issue Mar 11, 2016 · 0 comments
Open

Consolidate ereport boolean visibility flags into a "flags" field #3

dwsteele opened this issue Mar 11, 2016 · 0 comments
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@dwsteele
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enhancement
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10.0

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@dwsteele
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Combine these booleans in elog.h into a single int flags field:

    bool        output_to_server;       /* will report to server log? */
    bool        output_to_client;       /* will report to client? */
    bool        show_funcname;  /* true to force funcname inclusion */
    bool        hide_stmt;      /* true to prevent STATEMENT: inclusion */
    bool        hide_ctx;       /* true to prevent CONTEXT: inclusion */
    bool        hide_from_client;   /* true to prevent client output */
@dwsteele dwsteele self-assigned this Mar 11, 2016
@dwsteele dwsteele added this to the 9.7 milestone Mar 11, 2016
dwsteele pushed a commit that referenced this issue Mar 20, 2018
@tglsfdc
Fix some corner-case issues in REFRESH MATERIALIZED VIEW CONCURRENTLY.
6497a18 
refresh_by_match_merge() has some issues in the way it builds a SQL
query to construct the "diff" table:

1. It doesn't require the selected unique index(es) to be indimmediate.
2. It doesn't pay attention to the particular equality semantics enforced
by a given index, but just assumes that they must be those of the column
datatype's default btree opclass.
3. It doesn't check that the indexes are btrees.
4. It's insufficiently careful to ensure that the parser will pick the
intended operator when parsing the query.  (This would have been a
security bug before CVE-2018-1058.)
5. It's not careful about indexes on system columns.

The way to fix #4 is to make use of the existing code in ri_triggers.c
for generating an arbitrary binary operator clause.  I chose to move
that to ruleutils.c, since that seems a more reasonable place to be
exporting such functionality from than ri_triggers.c.

While #1, #3, and #5 are just latent given existing feature restrictions,
and #2 doesn't arise in the core system for lack of alternate opclasses
with different equality behaviors, #4 seems like an issue worth
back-patching.  That's the bulk of the change anyway, so just back-patch
the whole thing to 9.4 where this code was introduced.

Discussion: https://postgr.es/m/[email protected]
dwsteele pushed a commit that referenced this issue Nov 14, 2023
@tglsfdc
Don't try to dump RLS policies or security labels for extension objects.
a70f2a5 
checkExtensionMembership() set the DUMP_COMPONENT_SECLABEL and
DUMP_COMPONENT_POLICY flags for extension member objects, even though
we lack any infrastructure for tracking extensions' initial settings
of these properties.  This is not OK.  The result was that a dump
would always include commands to set these properties for extension
objects that have them, with at least three negative consequences:

1. The restoring user might not have privilege to set these properties
on these objects.

2. The properties might be incorrect/irrelevant for the version of the
extension that's installed in the destination database.

3. The dump itself might fail, in the case of RLS properties attached
to extension tables that the dumping user lacks privilege to LOCK.
(That's because we must get at least AccessShareLock to ensure that
we don't fail while trying to decompile the RLS expressions.)

When and if somebody cares to invent initial-state infrastructure for
extensions' RLS policies and security labels, we could think about
finding another way around problem #3.  But in the absence of such
infrastructure, this whole thing is just wrong and we shouldn't do it.

(Note: this applies only to ordinary dumps; binary-upgrade dumps
still dump and restore extension member objects separately, with
all properties.)

Tom Lane and Jacob Champion.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/[email protected]
dwsteele pushed a commit that referenced this issue Oct 2, 2024
@hlinnaka
Fix bugs in MultiXact truncation
b1ffe3f 
1. TruncateMultiXact() performs the SLRU truncations in a critical
section. Deleting the SLRU segments calls ForwardSyncRequest(), which
will try to compact the request queue if it's full
(CompactCheckpointerRequestQueue()). That in turn allocates memory,
which is not allowed in a critical section. Backtrace:

    TRAP: failed Assert("CritSectionCount == 0 || (context)->allowInCritSection"), File: "../src/backend/utils/mmgr/mcxt.c", Line: 1353, PID: 920981
    postgres: autovacuum worker template0(ExceptionalCondition+0x6e)[0x560a501e866e]
    postgres: autovacuum worker template0(+0x5dce3d)[0x560a50217e3d]
    postgres: autovacuum worker template0(ForwardSyncRequest+0x8e)[0x560a4ffec95e]
    postgres: autovacuum worker template0(RegisterSyncRequest+0x2b)[0x560a50091eeb]
    postgres: autovacuum worker template0(+0x187b0a)[0x560a4fdc2b0a]
    postgres: autovacuum worker template0(SlruDeleteSegment+0x101)[0x560a4fdc2ab1]
    postgres: autovacuum worker template0(TruncateMultiXact+0x2fb)[0x560a4fdbde1b]
    postgres: autovacuum worker template0(vac_update_datfrozenxid+0x4b3)[0x560a4febd2f3]
    postgres: autovacuum worker template0(+0x3adf66)[0x560a4ffe8f66]
    postgres: autovacuum worker template0(AutoVacWorkerMain+0x3ed)[0x560a4ffe7c2d]
    postgres: autovacuum worker template0(+0x3b1ead)[0x560a4ffecead]
    postgres: autovacuum worker template0(+0x3b620e)[0x560a4fff120e]
    postgres: autovacuum worker template0(+0x3b3fbb)[0x560a4ffeefbb]
    postgres: autovacuum worker template0(+0x2f724e)[0x560a4ff3224e]
    /lib/x86_64-linux-gnu/libc.so.6(+0x27c8a)[0x7f62cc642c8a]
    /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x85)[0x7f62cc642d45]
    postgres: autovacuum worker template0(_start+0x21)[0x560a4fd16f31]

To fix, bail out in CompactCheckpointerRequestQueue() without doing
anything, if it's called in a critical section. That covers the above
call path, as well as any other similar cases where
RegisterSyncRequest might be called in a critical section.

2. After fixing that, another problem became apparent: Autovacuum
process doing that truncation can deadlock with the checkpointer
process. TruncateMultiXact() sets "MyProc->delayChkptFlags |=
DELAY_CHKPT_START". If the sync request queue is full and cannot be
compacted, the process will repeatedly sleep and retry, until there is
room in the queue. However, if the checkpointer is trying to start a
checkpoint at the same time, and is waiting for the DELAY_CHKPT_START
processes to finish, the queue will never shrink.

More concretely, the autovacuum process is stuck here:

    #0  0x00007fc934926dc3 in epoll_wait () from /lib/x86_64-linux-gnu/libc.so.6
    #1  0x000056220b24348b in WaitEventSetWaitBlock (set=0x56220c2e4b50, occurred_events=0x7ffe7856d040, nevents=1, cur_timeout=<optimized out>) at ../src/backend/storage/ipc/latch.c:1570
    #2  WaitEventSetWait (set=0x56220c2e4b50, timeout=timeout@entry=10, occurred_events=<optimized out>, occurred_events@entry=0x7ffe7856d040, nevents=nevents@entry=1,
        wait_event_info=wait_event_info@entry=150994949) at ../src/backend/storage/ipc/latch.c:1516
    #3  0x000056220b243224 in WaitLatch (latch=<optimized out>, latch@entry=0x0, wakeEvents=wakeEvents@entry=40, timeout=timeout@entry=10, wait_event_info=wait_event_info@entry=150994949)
        at ../src/backend/storage/ipc/latch.c:538
    #4  0x000056220b26cf46 in RegisterSyncRequest (ftag=ftag@entry=0x7ffe7856d0a0, type=type@entry=SYNC_FORGET_REQUEST, retryOnError=true) at ../src/backend/storage/sync/sync.c:614
    #5  0x000056220af9db0a in SlruInternalDeleteSegment (ctl=ctl@entry=0x56220b7beb60 <MultiXactMemberCtlData>, segno=segno@entry=11350) at ../src/backend/access/transam/slru.c:1495
    #6  0x000056220af9dab1 in SlruDeleteSegment (ctl=ctl@entry=0x56220b7beb60 <MultiXactMemberCtlData>, segno=segno@entry=11350) at ../src/backend/access/transam/slru.c:1566
    #7  0x000056220af98e1b in PerformMembersTruncation (oldestOffset=<optimized out>, newOldestOffset=<optimized out>) at ../src/backend/access/transam/multixact.c:3006
    #8  TruncateMultiXact (newOldestMulti=newOldestMulti@entry=3221225472, newOldestMultiDB=newOldestMultiDB@entry=4) at ../src/backend/access/transam/multixact.c:3201
    #9  0x000056220b098303 in vac_truncate_clog (frozenXID=749, minMulti=<optimized out>, lastSaneFrozenXid=749, lastSaneMinMulti=3221225472) at ../src/backend/commands/vacuum.c:1917
    #10 vac_update_datfrozenxid () at ../src/backend/commands/vacuum.c:1760
    #11 0x000056220b1c3f76 in do_autovacuum () at ../src/backend/postmaster/autovacuum.c:2550
    #12 0x000056220b1c2c3d in AutoVacWorkerMain (startup_data=<optimized out>, startup_data_len=<optimized out>) at ../src/backend/postmaster/autovacuum.c:1569

and the checkpointer is stuck here:

    #0  0x00007fc9348ebf93 in clock_nanosleep () from /lib/x86_64-linux-gnu/libc.so.6
    #1  0x00007fc9348fe353 in nanosleep () from /lib/x86_64-linux-gnu/libc.so.6
    #2  0x000056220b40ecb4 in pg_usleep (microsec=microsec@entry=10000) at ../src/port/pgsleep.c:50
    #3  0x000056220afb43c3 in CreateCheckPoint (flags=flags@entry=108) at ../src/backend/access/transam/xlog.c:7098
    #4  0x000056220b1c6e86 in CheckpointerMain (startup_data=<optimized out>, startup_data_len=<optimized out>) at ../src/backend/postmaster/checkpointer.c:464

To fix, add AbsorbSyncRequests() to the loops where the checkpointer
waits for DELAY_CHKPT_START or DELAY_CHKPT_COMPLETE operations to
finish.

Backpatch to v14. Before that, SLRU deletion didn't call
RegisterSyncRequest, which avoided this failure. I'm not sure if there
are other similar scenarios on older versions, but we haven't had
any such reports.

Discussion: https://www.postgresql.org/message-id/[email protected]
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