codope opened a new pull request, #13177:
URL: https://github.com/apache/hudi/pull/13177
### Change Logs
When performing random access lookups against an HFile, callers often do:
1. seekTo() to position at the first record at the start of the file.
2. seekTo(key) to floor or find an exact match.
3. examine the return code (SEEK_TO_FOUND / SEEK_TO_IN_RANGE /
SEEK_TO_BEFORE_FIRST_KEY / SEEK_TO_EOF).
However, if you issue two non‐existent lookups in a row, and the second
lookup is for a key that is lexicographically smaller than the key where cursor
is pointed after the first lookup, then the second seekTo(key) would throw an
exception:
```
Caused by: java.lang.IllegalStateException: The current lookup key is less
than the current position of the cursor, i.e., backward seekTo, which is not
supported and should be avoided.
key=UTF8StringKey{aZud4Oj9wxA=AZcHyzibzy8=bJfAFKIt2udY/eEKkDkFbg==}
cursor=HFilePosition{offset=10503431,
keyValue=Option{val=KeyValue{key=Key{aZud4Oj9wxA=AZcHyzibzy8=bLXWAR+d0ui0DMuh0uAXbw==}}}}
at
org.apache.hudi.io.hfile.HFileReaderImpl.seekTo(HFileReaderImpl.java:173)
at
org.apache.hudi.io.storage.HoodieNativeAvroHFileReader$RecordByKeyIterator.hasNext(HoodieNativeAvroHFileReader.java:404)
...
```
That happened because we only treated "backward" relative to the very first
block in the file, not relative to whichever block we’d just loaded via
`floorEntry(key)`.
This PR fixes the check for `isAtFirstKey` (now renamed to `isAtBlockStart`)
to also consider whether the cursor’s offset equals the start of the
_**current**_ data block.
So, the changed behavior is as follows;
- Lookups < block’s first key now yield SEEK_TO_BEFORE_FIRST_KEY instead of
exception.
- All other semantics (exact match, in‐range, beyond‐last => IN_RANGE or EOF
as before) remain unchanged.
- No additional I/O overhead; only a small offset comparison in the guard.
### Impact
Downstream readers (e.g., RecordByKeyIterator for index lookups) now safely
handle arbitrary lookup without reader re‐initialization or catch‐and‐reset
hacks.
### Risk level (write none, low medium or high below)
low
### Documentation Update
_Describe any necessary documentation update if there is any new feature,
config, or user-facing change. If not, put "none"._
- _The config description must be updated if new configs are added or the
default value of the configs are changed_
- _Any new feature or user-facing change requires updating the Hudi website.
Please create a Jira ticket, attach the
ticket number here and follow the
[instruction](https://hudi.apache.org/contribute/developer-setup#website) to
make
changes to the website._
### Contributor's checklist
- [ ] Read through [contributor's
guide](https://hudi.apache.org/contribute/how-to-contribute)
- [ ] Change Logs and Impact were stated clearly
- [ ] Adequate tests were added if applicable
- [ ] CI passed
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