Wrap signatures and long expressions to the 100-column limit and make every
file zig fmt clean. Semantics-preserving throughout: ignoring whitespace and
the trailing commas that wrapping introduces, every file here is byte-identical
to its predecessor, and the one apparent exception is a warning string split
with `++`, which concatenates at comptime to the same bytes.
src/index.zig and src/commands.zig are reformatted in the commits that follow,
because their reformat is interleaved with in-flight changes to them and
separating the two would need the reformat re-derived rather than moved.
Documents live as canonical BSON bytes in a segmented per-collection slab
(fixed 8 MiB segments keep capacity slack under one segment); the docs map
holds flat offsets that stay valid across segment growth, and removed
documents leave garbage bytes until compaction rewrites. The per-document
ArenaAllocator and its second full Pair-tree copy are gone.
The matcher walks the stored bytes directly, skipping by length any field
the filter does not name (a new bson byte-walker: element_key, skip_value,
read_value with borrowed leaves, get_at, and a borrowed spine parse). The
byte matcher is differential-tested against the tree matcher on a corpus
and shares its operator logic. Stored documents are never materialized on
the scan path or in aggregate $match; $group reads group keys and sums
straight off the bytes. Sort, projection, findAndModify, updates and
index entry generation use a borrowed spine into the slab (or the byte
collector, which also replaced collect_values in build_entries). The
compaction threshold now counts uncompressed data volume, since a
compressed log would otherwise never trigger.
Measured (tests/e2e/results/phase5.txt): server RSS 1979 -> 539 MB (2.4x
smaller than MongoDB; phase1 baseline 2.0 GB), range-scan 22.5 -> ~12 ms
(parity, best run faster than MongoDB), proj 4.1 -> 3.4 ms, createIndex
parity. Verified: unit suite in all three modes with zero leaks, the
crash pair, e2e6, and the stress/spill programs.
Matching allocated an ArrayList per filter field per candidate document,
on the process-wide allocator, to hold what is almost always a single
value. Candidates now collect into a stack buffer that spills to the heap
only for arrays: measured 15.7 -> 12.0ms on a 65,536-document range scan.
The OOM-propagation test moves with it. Its point is that a failed
collection must surface as an error rather than an empty candidate list,
which would make $ne and $exists:false report a match -- a wrong answer
rather than a failed one. That invariant still holds on the spill path, so
the test now uses an array long enough to reach the allocator, and a new
test pins the flip side: the common single-value match now completes
correctly even when the allocator always fails, because it never calls it.
Query operators were dispatched by a chain of up to fourteen mem.eql per
value per document, with $gt/$gte/$lt/$lte re-comparing the operator name
inside the loop over candidate values. Names resolve to an enum once per
filter field. Command dispatch likewise walked a 30-entry table comparing
strings; it is a comptime StaticStringMap now.
Each request built a fresh reply arena and handed its pages straight back.
One reply per connection, reset between requests, keeps them.
countDocuments() arrives as [{$match: F}?, {$group: {_id: <literal>,
n: {$sum: 1}}}], which the general path answered by materializing every
matching document and discarding them all. It is now recognized and
answered from a counting scan: countDocuments({}) 2.3 -> 1.5ms.
The detector is deliberately conservative -- grouping by "$field", summing
a field, an unmodelled accumulator or any extra stage all fall through to
the general path, since those need the documents themselves. A unit test
pins each accept and reject, and the whole count path was checked against
the general one through the real driver, including the shapes that must
not take it.
The filtered range-scan row does not move: it is bound by walking 65,536
documents that each live in their own arena, not by the matcher. That is
Phase 4 work.
Verified: 77 unit tests under ReleaseFast and ReleaseSafe, e2e
29/16/17/3/2, the crash pair, e2e6 72/72.
sort+limit ordered the entire result set to return one page: 65,536
documents sorted to hand back 20. Two independent costs.
The decorate pass built, per document per sort key, an ArrayList of every
value at the path -- but the comparator only ever reads element 0. Added
first_value_at, which mirrors collect_values' traversal exactly (same
order, same depth cutoff) and stops at the first hit, and moved the
decorated values into one flat allocation. That equivalence is the whole
correctness argument, so it is pinned by a test covering dotted paths,
arrays of documents, numeric element addressing, repeated keys, missing
paths and the depth cutoff.
sort_docs_top_k keeps a k-element max-heap instead of ordering
everything: one comparison against the heap root per document, and only
the survivors are ever sorted. cmd_find uses it when the page is at most
a quarter of the matches, where the heap's bookkeeping still pays for
itself, and falls back to a full sort otherwise. It leaves docs[k..]
unordered, which is safe because the page is a prefix of the first k.
cmd_aggregate's $sort is deliberately untouched: a later stage can read
the whole stream, and top-k would silently corrupt the tail.
find({}).sort({_id:-1}).limit(20) over 65,536 x 16 KB documents:
baseline 40.0ms
decorate only (top-k disabled) 23.9ms
decorate + top-k 4.3ms
Correctness checked end to end as well: the limited page is identical to
the prefix of the equivalent full sort. The top-k test compares against a
full sort across ascending, descending and compound keys, for k of 1, 2,
20, n-1, n and n+1, over data with heavy ties; verified it fails when the
heap's child comparison is inverted.
Cleanup pass over the secondary-index feature.
add_doc is now the one entry-commit path. create_index and
build_all_indexes each hand-rolled build -> check_unique -> reserve ->
insert, and had already drifted on whether multikey is set before or
after the unique check; add_doc gained an enforce_unique flag so the
rebuild path keeps its tolerate-and-warn behavior. reserve_for and
insert_entries are now the only way the engine touches Index.entries.
One definition each for: prefix comparison and the prefix binary
searches (prefix_order + std.sort), the cartesian-product odometer
(advance_choice), the spec pair list (write_spec builds on spec_pairs,
so the log format and the listIndexes reply share one schema), the _id
clause parser (plan_id reuses analyze_clause), key-pattern direction
(index.descending, which desc_dir already disagreed with on non-numeric
values), option truthiness (query.truthy), the E11000 message, and
index-removal-by-name (Collection.find_index/remove_index). Key-pattern
matching moved out of the dispatcher into index.find_by_key_pattern.
Dead or redundant: ParallelArraysError, the unread `dropped` counter,
insert_entries' discarded gpa, a third pass computing multikey, the
has_id/is_id_index flag pair, Plan.key_len (always lookup_keys[0].len,
now a method), first_match_consumed (now stages = stages[1..]).
Cheaper hot paths: remove_id compacts in one pass instead of an
orderedRemove per hit; Plan.search skips the sort/dedupe when neither
multikey nor multiple lookup keys can produce a repeat; the _id fast
path reuses one scratch key buffer (bson.write_serialized_value); the
plan loop uses the bound collection instead of re-resolving it through
two hash lookups per candidate.
Behavior is unchanged except that dropping plan_id's fixed 16-clause
buffer enables the _id fast path on filters that previously exceeded it.
Adds src/index.zig with the full secondary-index machinery: entry
generation mirroring field_matches (array value + elements), BSON-order
sorted entries with binary search, compound prefix and range lookups,
unique/sparse options, the query planner (longest equality/$in run +
optional range, $in cartesian cap, sparse/null bail), and the _id_ fast
path guarded against serialization-ambiguous values (numbers, strings,
symbols, codes, opaque payloads).
query.collect_values is now pub so entry generation can mirror it exactly.
storage.zig gains record_type_index_create/drop; lib.zig exports index.
The Node driver sends {field: /re/} as a BSON regex element (type 0x0B),
which the matcher previously only handled via the $regex operator form;
and dot paths with numeric segments (tags.0) were ignored because array
descent only recursed into embedded docs. Both are part of standard
MongoDB query semantics and were caught by the driver e2e suite.
server: unbounded Io async limit so the accept loop never wedges, and
treat header-read failures (client RST on pool teardown) as clean
disconnects. With the default cpu_count-1 limit, groupAsync's eager
fallback ran connection handlers inline on the accept-loop fiber once
that many connections were alive, stalling accept() and timing out
handshakes for further clients.
Add tests/e2e/: official driver CRUD, concurrency, and kill -9 recovery
suites (29 + 2 + 3 checks), plus unit tests for the query fixes.
