fix(largeobject): correct BlobInputStream mark/reset position and add efficient skip by vlsi · Pull Request #4204 · pgjdbc/pgjdbc

vlsi · 2026-06-19T21:43:38Z

Why

BlobInputStream computed mark/reset offsets from position 0, so reset() returned to the wrong byte when the stream was created from a LargeObject that had already been seeked (BlobInputStream does not reset() to correct position if LargeObject was not at position 0. #3149).
skip(long) used the default InputStream implementation, which reads and discards the bytes, so skipping a large distance cost a full read (BlobInputStream should implement skip #3144).

What

Initialise the stream position lazily from the LargeObject's current position (lo_tell64, or lo_tell below 9.3) and make the read limit relative to that position.
Override skip(long) to seek with lo_lseek/lo_lseek64; skips that stay within the current buffer advance the buffer pointer without a round-trip. Large objects are sparse, so skipping past the end is allowed and later reads return -1, as the InputStream.skip contract permits.
Select the 64-bit fastpath functions by server version through the new Fastpath#getServerVersionNum and LargeObject#supports64BitOffsets, rather than calling lo_tell64 and recovering from the failure. Older servers pay no extra round-trip, and the public tell64 semantics are unchanged.

This takes over and reworks #3148 by @OrangeDog, whose commits are credited via Co-authored-by. Differences from that PR:

version-based dispatch instead of try { tell64 } catch { tell }, which removes the extra round-trip on pre-9.3 servers that the original review flagged;
drop the castNonNull calls — assigning the field to a local satisfies the nullness checker;
simplify the skip-past-max test: the original asserted that a second close() throws, but LargeObject.close() is idempotent, so the assertion could not hold.

Closes #3144
Closes #3149

How to verify

./gradlew :postgresql:test --tests "org.postgresql.test.jdbc2.BlobTest"

All 27 BlobTest cases pass locally against PostgreSQL 18; autostyleCheck, checkstyleMain, and checkstyleTest are clean.

lo_tell64 and lo_lseek64 require PostgreSQL 9.3+. Expose the cached server version through Fastpath#getServerVersionNum and add LargeObject#supports64BitOffsets so callers can pick the 64-bit fastpath functions by version instead of calling them and recovering from the failure on older servers. The version is negotiated at connection startup, so the check costs no extra round-trip.

…osition BlobInputStream assumed the underlying LargeObject was positioned at the start, so mark() and reset() computed offsets from the wrong origin when the stream was created from a LargeObject that had already been seeked. reset() then repositioned to the wrong byte. Initialise the stream position from the LargeObject's current position (lo_tell64, or lo_tell on servers older than 9.3) on first use, and make the read limit relative to that position. The initialisation is deferred out of the constructor so the failure surfaces as a checked IOException. Also invalidate the read buffer before seeking in reset(), so a failed seek cannot leave stale buffered data behind. Closes pgjdbc#3149 Co-authored-by: James Howe <[email protected]>

InputStream.skip on a BlobInputStream used the default implementation, which reads and discards the bytes, so skipping a large distance cost a full read. Override skip(long) to seek with lo_lseek/lo_lseek64, making the cost independent of the distance. Large objects are sparse, so skipping past the current end is allowed: later reads return -1 and the returned count still reflects the requested distance, as the InputStream.skip contract permits. Skips that stay within the current buffer advance the buffer pointer without a round-trip. Closes pgjdbc#3144 Co-authored-by: James Howe <[email protected]>

codecov · 2026-06-26T06:51:30Z

Codecov Report

❌ Patch coverage is 76.08696% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.88%. Comparing base (40b6b07) to head (070636d).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #4204      +/-   ##
============================================
+ Coverage     70.86%   70.88%   +0.02%     
- Complexity     5323     5333      +10     
============================================
  Files           244      244              
  Lines         21932    21973      +41     
  Branches       3685     3692       +7     
============================================
+ Hits          15542    15576      +34     
- Misses         4741     4742       +1     
- Partials       1649     1655       +6

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

Rename the release notes to 2026-07-06 to reflect the release date, and add the remaining PR links (flushCacheOnDdl pgjdbc#4067, connectExecutor pgjdbc#4165, reWriteBatchedInserts cap pgjdbc#4207, OID constants pgjdbc#4220, 64-bit LO pgjdbc#4204, and the refactor entries pgjdbc#4160/pgjdbc#4166/pgjdbc#4215).

* docs: add 42.7.12 release changelog Covers all changes since REL42.7.11: search_path GUC_REPORT cache invalidation (PG 18+), flushCacheOnDdl, connectExecutor, classLoaderStrategy, reWriteBatchedInserts protocol-limit cap, large object 64-bit API, updatable ResultSet search_path fix, XA autoCommit fix, FIPS trust anchors, SSL key-format auto-detection, batching improvements, and numerous other bug fixes. docs: prepare 42.7.13 release notes after 42.7.12 security release 42.7.12 shipped as a security-only release for the silent channel-binding downgrade (CVE-2026-54291), so the feature and bug-fix notes that had been drafted for 42.7.12 now belong to 42.7.13. - bump pgjdbc.version to 42.7.13 - add a published 42.7.12 changelog entry covering CVE-2026-54291 - retitle the drafted maintenance notes from 42.7.12 to 42.7.13 (CHANGELOG.md and the website changelog) - record PR #4248 (LargeObject.close() flushes before marking closed, and lo_close no longer masks a flush failure) under 42.7.13 docs: fix PR links and add missing entries in 42.7.13 release notes Point each changelog entry at the PR that merged the change rather than at the issue or at the superseded #3400. Add two entries that were missing: the reWriteBatchedInserts parameterless-INSERT fix (#4207) and the GitHub release jar/signature fix (#3814). Drop the stray connectThreadFactory entry from CHANGELOG.md, which connectExecutor replaced before release. Co-Authored-By: Claude Opus 4.8 <[email protected]> docs: credit translators and attribute large-object commits to James Howe Move the BlobInputStream skip and reset commits to James Howe, who co-authored them, and add a short contributors note crediting the Italian, Simplified Chinese, and Russian-review translators. Co-Authored-By: Claude Opus 4.8 <[email protected]> docs: add the empty-timestamp fix (#4278) to the 42.7.13 release notes Reflect PR #4278, merged after the release-notes branch was opened: an empty timestamp/timestamptz/date value now yields a clear SQLException instead of ArrayIndexOutOfBoundsException. Co-Authored-By: Claude Opus 4.8 <[email protected]> * docs: diarize all 42.7.13 changes in CHANGELOG.md The root CHANGELOG.md [42.7.13] section listed only 20 entries while about 50 user-facing changes have landed since the 42.7.12 baseline. Bring it in line with the reviewed website changelog: add the missing feat/fix/refactor entries and correct PR references. Newly diarized items include getSchemas() on a hot standby (#4274), getColumnPrivileges()/CHAR_OCTET_LENGTH (#4231), FIPS PKIX trust anchors (#4193), SSL key-format auto-detection (#3946), GSS response timeout, autosave savepoints for SET LOCAL (#4203), BatchResultHandler on a closed connection (#4187), SQL_TSI_FRAC_SECOND (#4229), the batching/describe fixes, NumberParser/PGInterval validation, connectThreadFactory, OID constants, and getPrimaryKeys derivation. Docs, i18n, build, ci, test, and dependency-bump commits are omitted, consistent with the file's existing "Notable changes" scope. * docs: date the 42.7.13 website changelog to its release date Rename the release notes to 2026-07-06 to reflect the release date, and add the remaining PR links (flushCacheOnDdl #4067, connectExecutor #4165, reWriteBatchedInserts cap #4207, OID constants #4220, 64-bit LO #4204, and the refactor entries #4160/#4166/#4215). * docs: correct the 42.7.13 commits-by-author counts Reconcile the "Commits by author" section with git history: - Vladimir Sitnikov: 100 -> 104 (stale count carried from the 42.7.12 draft) - Dave Cramer: 4 -> 5, add the missing "maintainer vs committer" (#4234) entry - add Michael Baumgartner (1 commit), previously omitted James Howe remains credited for the two co-authored large-object commits. * remove connectThread as it was replaced by connectExecutor --------- Co-authored-by: Vladimir Sitnikov <[email protected]>

* docs: add 42.7.12 release changelog Covers all changes since REL42.7.11: search_path GUC_REPORT cache invalidation (PG 18+), flushCacheOnDdl, connectExecutor, classLoaderStrategy, reWriteBatchedInserts protocol-limit cap, large object 64-bit API, updatable ResultSet search_path fix, XA autoCommit fix, FIPS trust anchors, SSL key-format auto-detection, batching improvements, and numerous other bug fixes. docs: prepare 42.7.13 release notes after 42.7.12 security release 42.7.12 shipped as a security-only release for the silent channel-binding downgrade (CVE-2026-54291), so the feature and bug-fix notes that had been drafted for 42.7.12 now belong to 42.7.13. - bump pgjdbc.version to 42.7.13 - add a published 42.7.12 changelog entry covering CVE-2026-54291 - retitle the drafted maintenance notes from 42.7.12 to 42.7.13 (CHANGELOG.md and the website changelog) - record PR pgjdbc#4248 (LargeObject.close() flushes before marking closed, and lo_close no longer masks a flush failure) under 42.7.13 docs: fix PR links and add missing entries in 42.7.13 release notes Point each changelog entry at the PR that merged the change rather than at the issue or at the superseded pgjdbc#3400. Add two entries that were missing: the reWriteBatchedInserts parameterless-INSERT fix (pgjdbc#4207) and the GitHub release jar/signature fix (pgjdbc#3814). Drop the stray connectThreadFactory entry from CHANGELOG.md, which connectExecutor replaced before release. Co-Authored-By: Claude Opus 4.8 <[email protected]> docs: credit translators and attribute large-object commits to James Howe Move the BlobInputStream skip and reset commits to James Howe, who co-authored them, and add a short contributors note crediting the Italian, Simplified Chinese, and Russian-review translators. Co-Authored-By: Claude Opus 4.8 <[email protected]> docs: add the empty-timestamp fix (pgjdbc#4278) to the 42.7.13 release notes Reflect PR pgjdbc#4278, merged after the release-notes branch was opened: an empty timestamp/timestamptz/date value now yields a clear SQLException instead of ArrayIndexOutOfBoundsException. Co-Authored-By: Claude Opus 4.8 <[email protected]> * docs: diarize all 42.7.13 changes in CHANGELOG.md The root CHANGELOG.md [42.7.13] section listed only 20 entries while about 50 user-facing changes have landed since the 42.7.12 baseline. Bring it in line with the reviewed website changelog: add the missing feat/fix/refactor entries and correct PR references. Newly diarized items include getSchemas() on a hot standby (pgjdbc#4274), getColumnPrivileges()/CHAR_OCTET_LENGTH (pgjdbc#4231), FIPS PKIX trust anchors (pgjdbc#4193), SSL key-format auto-detection (pgjdbc#3946), GSS response timeout, autosave savepoints for SET LOCAL (pgjdbc#4203), BatchResultHandler on a closed connection (pgjdbc#4187), SQL_TSI_FRAC_SECOND (pgjdbc#4229), the batching/describe fixes, NumberParser/PGInterval validation, connectThreadFactory, OID constants, and getPrimaryKeys derivation. Docs, i18n, build, ci, test, and dependency-bump commits are omitted, consistent with the file's existing "Notable changes" scope. * docs: date the 42.7.13 website changelog to its release date Rename the release notes to 2026-07-06 to reflect the release date, and add the remaining PR links (flushCacheOnDdl pgjdbc#4067, connectExecutor pgjdbc#4165, reWriteBatchedInserts cap pgjdbc#4207, OID constants pgjdbc#4220, 64-bit LO pgjdbc#4204, and the refactor entries pgjdbc#4160/pgjdbc#4166/pgjdbc#4215). * docs: correct the 42.7.13 commits-by-author counts Reconcile the "Commits by author" section with git history: - Vladimir Sitnikov: 100 -> 104 (stale count carried from the 42.7.12 draft) - Dave Cramer: 4 -> 5, add the missing "maintainer vs committer" (pgjdbc#4234) entry - add Michael Baumgartner (1 commit), previously omitted James Howe remains credited for the two co-authored large-object commits. * remove connectThread as it was replaced by connectExecutor --------- Co-authored-by: Vladimir Sitnikov <[email protected]>

vlsi added bug performance labels Jun 19, 2026

vlsi mentioned this pull request Jun 19, 2026

BlobInputStream improvements #3148

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9 tasks done

vlsi and others added 3 commits June 26, 2026 09:42

vlsi force-pushed the feat/blobinputstream-skip-reset branch from 83c4afe to 070636d Compare June 26, 2026 06:43

vlsi merged commit 007d4c2 into pgjdbc:master Jun 26, 2026
17 checks passed

vlsi mentioned this pull request Aug 23, 2026

fix(largeobject): stop BlobInputStream.skip from aborting the transaction #4361

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fix(largeobject): correct BlobInputStream mark/reset position and add efficient skip - #4204

fix(largeobject): correct BlobInputStream mark/reset position and add efficient skip#4204
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vlsi commented Jun 19, 2026

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