Fix DerefExpr sequence dispatch and iterator sharing - #109
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DerefExpr dispatched on the concrete ItemSequence/LazySequence classes and
silently derefed every other Sequence implementation to the empty
sequence — notably FlatteningSequence, which is what a parenthesized
expression (SequenceExpr) evaluates to. As a result
(for $x in 1 to 3 return {"a": $x}).a returned empty without ever
evaluating the pipeline.
Keep every original branch bit-identical and add the missing tail: any
other non-item Sequence is mapped lazily per item (non-record items still
deref to empty). Also open a FRESH base iterator per iterate() call on
the returned lazy sequence — the shared captured iterator previously made
a second iteration resume the exhausted first one.
Regression tests: parenthesized-FLWOR deref (count 3, was 0),
missing-field skip, plain parenthesized record sequence, and
double-iteration freshness.
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JohannesLichtenberger
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Jul 21, 2026
… per-IndexType container slots - Bump io.sirix:brackit to 1.0-alpha9-SNAPSHOT (main + tests artifacts), which carries the upstream DerefExpr sequence-dispatch fix (sirixdb/brackit#109): (pipe).field over parenthesized pipelines now evaluates the pipe and iterates freshly per pass. - Drop the temporary SirixDerefExpr port and its translator override — redundant now that the fix ships in brackit itself. - Sticky-winner codec election for the KEYVALUELEAFPAGE body bake-off: only probe pages (first 8 per thread, then every Nth, -Dsirix.codecBakeoff.probeInterval, default 16) run all three codecs and (re-)elect a winner; pages in between encode with the elected codec alone (~3x less encode work). The codec byte keeps the format self-describing; probeInterval=1 restores exhaustive pick-smallest for byte-identical golden files. Both body writers (template-dedup and inline) now share one emit helper instead of two copies. - Per-IndexType most-recent page-container slots in the storage engine writer: interleaved index streams during shredding no longer thrash the shared two-slot LRU into access-ordered HashMap probes. Slots are stamped only at the post-CoW site (never frozen), and invalidated at snapshot rotation, commit reset, and close.
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Problem
DerefExprdispatched on the concreteItemSequence/LazySequenceclasses and silently derefed every otherSequenceimplementation to the empty sequence — notablyFlatteningSequence, which is what a parenthesized expression (SequenceExpr) evaluates to. As a result:returned
0without ever evaluating the pipeline.A second latent issue: the lazy mapping sequence captured one shared base iterator, so a second
iterate()call resumed the exhausted first iteration (count($s) + count($s)over a let-bound deref returned 3 instead of 6).Fix
Sequenceis mapped lazily per item (non-record items still deref to empty, exactly like the original's per-item mapping).iterate()call on the returned lazy sequence.Tests
Four regressions in
JsonTest:count((for $i in 1 to 3 return {"a": $i}).a)→3(was0)2({"a": 1}, {"b": 2}, {"a": 3}).a→1 3count($s) + count($s)→6(was3)Full suite: 1262 tests, 0 failures, 0 errors.
Also bumps the version to
1.0-alpha9-SNAPSHOTso downstream consumers (sirix) can pin a snapshot version that provably contains this fix.Generated by Claude Code