why the mooncake_create_table() files are found in /tmp/moonlink_temp_file, and restart pg will lost？

[tigerzhangyz]

pg_mooncake v0.2.0
then could I set the file path ？
any other parameter to adjust such as memory size and thread?

[tigerzhangyz]

further more , when login with normal user but not superuser, then error is : duckdb.postgres_role is needed. ; but the parameter in postgresql.conf does not work？

[dpxcc]

why the mooncake_create_table() files are found in /tmp/moonlink_temp_file, and restart pg will lost？

Those are for temp files, not actual data files, that's why they get deleted upon PG restart
We just changed it and also put temp files inside <PGDATA>/pg_mooncake dir: Mooncake-Labs/moonlink#568

then could I set the file path ？

The actual data files (Iceberg table) are stored in <PGDATA>/pg_mooncake/public/<table_id>
We plan to make it configurable in the future

any other parameter to adjust such as memory size and thread?

We will add it

further more , when login with normal user but not superuser, then error is : duckdb.postgres_role is needed. ; but the parameter in postgresql.conf does not work？

Thanks for the bug report. We will fix it

[tigerzhangyz]

/pg_mooncake/public/xx.id exist but nothing under the directory。
also，once pg restart， select * from the CS table throw error and maybe lost of /tmp/moonlink_temp_files is empty？

[dpxcc]

/pg_mooncake/public/xx.id exist but nothing under the directory

That directory is used for Iceberg snapshots. Moonlink creates an Iceberg snapshot either periodically or after enough data has been written since the last snapshot. In your case, it seems not enough data has been written. You can manually trigger one by running mooncake.create_snapshot("<table>")

also，once pg restart， select * from the CS table throw error and maybe lost of /tmp/moonlink_temp_files is empty

Moonlink recovery support is currently under development: Mooncake-Labs/moonlink#613. It should be available very soon

[tigerzhangyz]

CALL mooncake.create table('t2_iceberg ,'public.t2');
SUCEESS
insert into t2 values (2,2,2) ; # 1 row sucess
CALL mooncake.create_snapshot('public.t2');
ERROR: called Result::unwrap()* on an Err’ value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer"

insert into t2 #INSERT 100000 rows success
select count(*)from t2_iceberg;
#ERROR:
(PGDuckDB/Duckdb ExecCustomScan Cpp)Executor Error:(PGDuckDB/mooncake
scan table begin called Result::unwrap() on an Err' value:PoisonError

[dpxcc]

ERROR: called Result::unwrap()* on an Err’ value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer"

This happens when moonlink crashes (We will improve the error handling and error message very soon)
Can you provide the full repro? Or run with RUST_BACKTRACE="1" and paste the moonlink crash log from postgres log?

[tigerzhangyz]

export RUST_BACKTRACE=1 & restart PG

dbmooncaketest=# CALL mooncake.create_table('public.t2_iceberg', 'public.t2');
CALL
dbmooncaketest=# insert into t2 values(2,2,2);
INSERT 0 1
dbmooncaketest=# select * from public.t2_iceberg;
id | name | addr
----+------+------
2 | 2 | 2
(1 row)

dbmooncaketest=# select * from t2_iceberg;
id | name | addr
----+------+------
2 | 2 | 2
(1 row)

dbmooncaketest=# CALL mooncake.create_snapshot('public.t2');
ERROR: called Result::unwrap() on an Err value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer" }
DETAIL:
0: std::backtrace_rs::backtrace::libunwind::trace
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
1: std::backtrace_rs::backtrace::trace_unsynchronized
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
2: std::backtrace::Backtrace::create
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/backtrace.rs:331:13
3: pgrx_pg_sys::submodules::panic::register_pg_guard_panic_hook::{{closure}}::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:316:43
4: std::thread::local::LocalKey::try_with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:311:12
5: std::thread::local::LocalKey::with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:275:15
6: pgrx_pg_sys::submodules::panic::register_pg_guard_panic_hook::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:313:13
7: <alloc::boxed::Box<F,A> as core::ops::function::Fn>::call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/alloc/src/boxed.rs:1980:9
8: std::panicking::rust_panic_with_hook
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:841:13
9: std::panicking::begin_panic_handler::{{closure}}
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:706:13
10: std::sys::backtrace::__rust_end_short_backtrace
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/sys/backtrace.rs:168:18
11: __rustc::rust_begin_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:697:5
12: core::panicking::panic_fmt
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panicking.rs:75:14
13: core::result::unwrap_failed
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/result.rs:1704:5
14: core::result::Result<T,E>::unwrap
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/result.rs:1109:23
15: pg_mooncake::pgmoonlink::client::read
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/client.rs:58:5
16: pg_mooncake::pgmoonlink::client::create_snapshot
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/client.rs:17:5
17: pg_mooncake::table::functions::create_snapshot
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:39:5
18: pg_mooncake::table::functions::create_snapshot_wrapper::_internal_wrapper::{{closure}}
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
19: pgrx::memcxt::PgMemoryContexts::exec_in_context
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-0.14.3/src/memcxt.rs:592:22
20: pgrx::memcxt::PgMemoryContexts::switch_to
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-0.14.3/src/memcxt.rs:402:18
21: pg_mooncake::table::functions::create_snapshot_wrapper::_internal_wrapper
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
22: pg_mooncake::table::functions::create_snapshot_wrapper::{{closure}}
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
23: <core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panic/unwind_safe.rs:272:9
24: std::panicking::try::do_call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:589:40
25: std::panicking::try
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:552:19
26: std::panic::catch_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panic.rs:359:14
27: pgrx_pg_sys::submodules::panic::run_guarded
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:419:11
28: pgrx_pg_sys::submodules::panic::pgrx_extern_c_guard
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:394:20
29: create_snapshot_wrapper
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
30: ExecuteCallStmt
31: standard_ProcessUtility
32: pgss_ProcessUtility
33: ZN8pgduckdb20__CPPFunctionGuard__IPFvP11PlannedStmtPKcb21ProcessUtilityContextP17ParamListInfoDataP16QueryEnvironmentP13_DestReceiverP15QueryCompletionEXadL_ZL21DuckdbUtilityHook_CppS2_S4_bS5_S7_S9_SB_SD_EEJS2_S4_bS5_S7_S9_SB_SD_EEENSt13invoke_resultIT_JDpRT1_EE4typeES4_S4_iSK.constprop.0.isra.0
34: prev_ProcessUtility
35: timescaledb_ddl_command_start
36: PortalRunUtility
37: PortalRunMulti
38: PortalRun
39: exec_simple_query
40: PostgresMain
41: BackendMain
42: postmaster_child_launch
43: ServerLoop.isra.0
44: PostmasterMain
45: main
46:
47: __libc_start_main
48: _start

dbmooncaketest=#

[tigerzhangyz]

this is info of postgres.log

thread 'tokio-runtime-worker' panicked at /bigdata/pg17/pg_mooncake/moonlink/src/moonlink_connectors/src/replication_manager.rs:106:61:
table not found
stack backtrace:
0: __rustc::rust_begin_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:697:5
1: core::panicking::panic_fmt
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panicking.rs:75:14
2: core::panicking::panic_display
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panicking.rs:261:5
3: core::option::expect_failed
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/option.rs:2024:5
4: moonlink_connectors::replication_manager::ReplicationManager::get_iceberg_table_event_manager
5: moonlink_backend::MoonlinkBackend::create_iceberg_snapshot::{{closure}}
at /bigdata/pg17/pg_mooncake/moonlink/src/moonlink_backend/src/lib.rs:92:26
6: pg_mooncake::pgmoonlink::server::create_snapshot::{{closure}}
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/server.rs:56:10
7: pg_mooncake::pgmoonlink::server::handle_stream::{{closure}}
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/server.rs:36:61
8: pg_mooncake::pgmoonlink::server::start::{{closure}}::{{closure}}
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/server.rs:25:65
9: tokio::runtime::task::core::Core<T,S>::poll::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/core.rs:331:17
10: tokio::loom::std::unsafe_cell::UnsafeCell::with_mut
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/loom/std/unsafe_cell.rs:16:9
11: tokio::runtime::task::core::Core<T,S>::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/core.rs:320:30
12: tokio::runtime::task::harness::poll_future::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:532:19
13: <core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panic/unwind_safe.rs:272:9
14: std::panicking::try::do_call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:589:40
15: std::panicking::try
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:552:19
16: std::panic::catch_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panic.rs:359:14
17: tokio::runtime::task::harness::poll_future
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:520:18
18: tokio::runtime::task::harness::Harness<T,S>::poll_inner
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:209:27
19: tokio::runtime::task::harness::Harness<T,S>::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:154:15
20: tokio::runtime::task::raw::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/raw.rs:271:5
21: tokio::runtime::task::raw::RawTask::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/raw.rs:201:18
22: tokio::runtime::task::LocalNotified::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/mod.rs:463:9
23: tokio::runtime::scheduler::multi_thread::worker::Context::run_task::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:600:18
24: tokio::task::coop::with_budget
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/task/coop/mod.rs:167:5
25: tokio::task::coop::budget
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/task/coop/mod.rs:133:5
26: tokio::runtime::scheduler::multi_thread::worker::Context::run_task
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:594:9
27: tokio::runtime::scheduler::multi_thread::worker::Context::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:542:24
28: tokio::runtime::scheduler::multi_thread::worker::run::{{closure}}::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:507:21
29: tokio::runtime::context::scoped::Scoped::set
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/context/scoped.rs:40:9
30: tokio::runtime::context::set_scheduler::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/context.rs:176:26
31: std::thread::local::LocalKey::try_with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:311:12
32: std::thread::local::LocalKey::with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:275:15
33: tokio::runtime::context::set_scheduler
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/context.rs:176:9
34: tokio::runtime::scheduler::multi_thread::worker::run::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:502:9
35: tokio::runtime::context::runtime::enter_runtime
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/context/runtime.rs:65:16
36: tokio::runtime::scheduler::multi_thread::worker::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:494:5
37: tokio::runtime::scheduler::multi_thread::worker::Launch::launch::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/scheduler/multi_thread/worker.rs:460:45
38: <tokio::runtime::blocking::task::BlockingTask as core::future::future::Future>::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/blocking/task.rs:42:21
39: tokio::runtime::task::core::Core<T,S>::poll::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/core.rs:331:17
40: tokio::loom::std::unsafe_cell::UnsafeCell::with_mut
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/loom/std/unsafe_cell.rs:16:9
41: tokio::runtime::task::core::Core<T,S>::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/core.rs:320:30
42: tokio::runtime::task::harness::poll_future::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:532:19
43: <core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panic/unwind_safe.rs:272:9
44: std::panicking::try::do_call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:589:40
45: std::panicking::try
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:552:19
46: std::panic::catch_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panic.rs:359:14
47: tokio::runtime::task::harness::poll_future
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:520:18
48: tokio::runtime::task::harness::Harness<T,S>::poll_inner
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:209:27
49: tokio::runtime::task::harness::Harness<T,S>::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/harness.rs:154:15
50: tokio::runtime::task::raw::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/raw.rs:271:5
51: tokio::runtime::task::raw::RawTask::poll
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/raw.rs:201:18
52: tokio::runtime::task::UnownedTask::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/task/mod.rs:500:9
53: tokio::runtime::blocking::pool::Task::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/blocking/pool.rs:161:9
54: tokio::runtime::blocking::pool::Inner::run
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/blocking/pool.rs:511:17
55: tokio::runtime::blocking::pool::Spawner::spawn_thread::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.45.1/src/runtime/blocking/pool.rs:469:13
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.
2025-07-03 14:08:33.820 CST [38331: [3-1] user=postgres,db=dbmooncaketest,client=127.0.0.1 ]ERROR: called Result::unwrap() on an Err value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer" }
2025-07-03 14:08:33.820 CST [38331: [4-1] user=postgres,db=dbmooncaketest,client=127.0.0.1 ]DETAIL:
0: std::backtrace_rs::backtrace::libunwind::trace
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/../../backtrace/src/backtrace/libunwind.rs:117:9
1: std::backtrace_rs::backtrace::trace_unsynchronized
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/../../backtrace/src/backtrace/mod.rs:66:14
2: std::backtrace::Backtrace::create
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/backtrace.rs:331:13
3: pgrx_pg_sys::submodules::panic::register_pg_guard_panic_hook::{{closure}}::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:316:43
4: std::thread::local::LocalKey::try_with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:311:12
5: std::thread::local::LocalKey::with
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/thread/local.rs:275:15
6: pgrx_pg_sys::submodules::panic::register_pg_guard_panic_hook::{{closure}}
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:313:13
7: <alloc::boxed::Box<F,A> as core::ops::function::Fn>::call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/alloc/src/boxed.rs:1980:9
8: std::panicking::rust_panic_with_hook
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:841:13
9: std::panicking::begin_panic_handler::{{closure}}
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:706:13
10: std::sys::backtrace::__rust_end_short_backtrace
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/sys/backtrace.rs:168:18
11: __rustc::rust_begin_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:697:5
12: core::panicking::panic_fmt
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panicking.rs:75:14
13: core::result::unwrap_failed
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/result.rs:1704:5
14: core::result::Result<T,E>::unwrap
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/result.rs:1109:23
15: pg_mooncake::pgmoonlink::client::read
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/client.rs:58:5
16: pg_mooncake::pgmoonlink::client::create_snapshot
at /bigdata/pg17/pg_mooncake/src/pgmoonlink/client.rs:17:5
17: pg_mooncake::table::functions::create_snapshot
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:39:5
18: pg_mooncake::table::functions::create_snapshot_wrapper::_internal_wrapper::{{closure}}
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
19: pgrx::memcxt::PgMemoryContexts::exec_in_context
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-0.14.3/src/memcxt.rs:592:22
20: pgrx::memcxt::PgMemoryContexts::switch_to
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-0.14.3/src/memcxt.rs:402:18
21: pg_mooncake::table::functions::create_snapshot_wrapper::_internal_wrapper
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
22: pg_mooncake::table::functions::create_snapshot_wrapper::{{closure}}
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
23: <core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/core/src/panic/unwind_safe.rs:272:9
24: std::panicking::try::do_call
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:589:40
25: std::panicking::try
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panicking.rs:552:19
26: std::panic::catch_unwind
at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library/std/src/panic.rs:359:14
27: pgrx_pg_sys::submodules::panic::run_guarded
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:419:11
28: pgrx_pg_sys::submodules::panic::pgrx_extern_c_guard
at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/pgrx-pg-sys-0.14.3/src/submodules/panic.rs:394:20
29: create_snapshot_wrapper
at /bigdata/pg17/pg_mooncake/src/table/functions.rs:27:31
30: ExecuteCallStmt
31: standard_ProcessUtility
32: pgss_ProcessUtility
33: ZN8pgduckdb20__CPPFunctionGuard__IPFvP11PlannedStmtPKcb21ProcessUtilityContextP17ParamListInfoDataP16QueryEnvironmentP13_DestReceiverP15QueryCompletionEXadL_ZL21DuckdbUtilityHook_CppS2_S4_bS5_S7_S9_SB_SD_EEJS2_S4_bS5_S7_S9_SB_SD_EEENSt13invoke_resultIT_JDpRT1_EE4typeES4_S4_iSK.constprop.0.isra.0
34: prev_ProcessUtility
35: timescaledb_ddl_command_start
36: PortalRunUtility
37: PortalRunMulti
38: PortalRun
39: exec_simple_query
40: PostgresMain
41: BackendMain
42: postmaster_child_launch
43: ServerLoop.isra.0
44: PostmasterMain
45: main
46:
47: __libc_start_main
48: _start

[dpxcc]

Thanks for the info!
The snapshot should be taken on mooncake table, not PG table. CALL mooncake.create_snapshot('public.t2'); should be CALL mooncake.create_snapshot('public.t2_iceberg');
Again, we will improve the error handling very soon

[tigerzhangyz]

When you create a columnstore copy of your Postgres tables, Moonlink: Performs initial full table copy.
drop the cs table and recreate , no data will full-copy to cs from origin heap table

[tigerzhangyz]

by the way , how long will the v0.2 be a stable release?

[dpxcc]

We plan to release v0.2-rc by end of Aug

[tigerzhangyz]

that's great

[tigerzhangyz]

dear sir:
I read the limition : as the preview version, You cannot create columnstore tables from rowstore tables that already contain data,
then , v0.2-rc will solve the limition ? if not ,that is a problem: in case the cs table recreate , how to get the existing data?
thanks

[dpxcc]

Yes, this is supported in Mooncake-Labs/moonlink#421

[tigerzhangyz]

is it possible that pg_mooncake is not compatible with timescaledb 2.19.3 , as for the pg17.5.4 server restart repeatly once the two extension run together.

[dpxcc]

pg_duckdb alone is not compatible with timescale right now: duckdb/pg_duckdb#845

[tigerzhangyz]

then , will you plan to be compatible with timescaledb , and the timeline pls, thanks

[dpxcc]

We’ll do our best to remain compatible with other extensions, but we can’t make any guarantees
In this case, pg_duckdb isn’t currently compatible on its own, and we’re not sure when the upstream will address it

That said, pg_mooncake already covers many of the use cases TimescaleDB supports
I’d love to hear more about your use case and why you’re looking to use them together

[tigerzhangyz]

as I know, many function of duckdb is not same as the pg's, such as the to_timestamp(text,text) ---- to_timestamp(int) , and most of the window function as the olap system are not supported by duckdb , so the pg funcitons are difficult to be transformed, that is a hard work

[dpxcc]

Just a heads-up: TimescaleDB functions can’t be executed by DuckDB
So even if you use both extensions together, you’ll essentially be working with two separate systems within Postgres:

1. TimescaleDB functions only work on TimescaleDB or regular Postgres tables
2. and DuckDB can only operate on Mooncake or regular Postgres tables

Instead, I’d recommend submitting feature requests to pg_duckdb for any functions you’d like to see supported

[tigerzhangyz]

Is there any GUC to hint function such as strftime that should be forced to parsed by duckdb?
when I test the CS table , it is ok for "select * from cs",

but return error "select cs.*, strftime(x, '%y/%m/%D') from cs"

[dpxcc]

DuckDB-specific functions must be exposed to Postgres to work
pg_duckdb already exposes many, and we plan to do the same (including strftime()) but haven’t implemented it yet: https://github.com/Mooncake-Labs/pg_duckdb/blob/831db4c280ae54028f667f9039cd7fa4a748ba3d/sql/pg_duckdb--0.3.0--1.0.0.sql#L121

You can temporarily work around it by manually create placeholder functions yourself via psql. Something like

CREATE FUNCTION strftime(date, text)
RETURNS text AS $$
BEGIN                             
    RAISE EXCEPTION 'this is a placeholder';
END;
$$ LANGUAGE plpgsql;