QuakeWang commented on code in PR #379:
URL: https://github.com/apache/paimon-rust/pull/379#discussion_r3400102401
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crates/paimon/src/table/mod.rs:
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@@ -184,7 +199,54 @@ impl Table {
schema: self.schema.copy_with_options(extra),
schema_manager: self.schema_manager.clone(),
rest_env: self.rest_env.clone(),
+ time_traveled: self.time_traveled,
Review Comment:
`copy_with_options` keeps `time_traveled` and the current schema, but clears
`travel_snapshot`. If this is called on a table already returned by
`copy_with_time_travel`, the result can keep the old snapshot schema while
resolving a different snapshot later during scan.
That can produce a mismatched table state: historical schema from one
snapshot, scan snapshot from another selector/latest. Please either make this
transition impossible, reset back to the base/latest schema, or re-resolve time
travel when options change.
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crates/paimon/src/table/write_builder.rs:
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@@ -80,6 +80,16 @@ impl<'a> WriteBuilder<'a> {
/// For primary-key tables, sequence numbers are lazily scanned per
partition
/// when the first writer for that partition is created.
pub fn new_write(&self) -> crate::Result<TableWrite> {
+ // A time-travelled table copy carries a historical schema; writing
+ // through it would silently produce data shaped like the old schema.
+ // Java avoids this structurally (write paths use
copyWithoutTimeTravel);
+ // here the same table copy can serve both reads and writes, so reject
+ // explicitly. Commit-only flows (new_commit) stay untouched.
+ if self.table.is_time_traveled() {
Review Comment:
This guard is too narrow. `is_time_traveled()` is only true when the
resolved snapshot uses a different schema id, so writes are still allowed when
`scan.version` / `scan.timestamp-millis` resolves to a snapshot with the same
schema id.
That leaves ordinary `INSERT` able to write the latest table while the
session is reading a historical snapshot. A minimal case is: create two
snapshots without schema evolution, `SET 'paimon.scan.version' = '1'`, then
`INSERT INTO ...` succeeds.
Please reject writes whenever the table options contain a time-travel
selector, not only when the table switched to a historical schema.
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