v2.0.0

LMDB v2.0.0

Diff since v1.0.0

Revival of LMDB.jl, fixing many issues and adding a new mid-level API for more direct access to LMDB's features (i.e., where the Dict doesn't suffice, but without having to drop down to the C API).

Breaking changes:

• The minimum Julia version is now 1.10.
• The factory functions create(), environment(path), start(env), open(env, path), open(txn), open(txn, dbi) have been replaced by constructors: LMDB.Environment(path; mapsize, maxreaders, maxdbs, flags, mode), LMDB.Transaction(env; flags, parent), LMDB.Database(txn, name; flags), LMDB.Cursor(txn, dbi).
• The DBI struct was renamed to Database.
• Only LMDBDict and LMDBError are exported. Everything else moved to @public, so the wrapper types and operations are reached as LMDB.Environment, LMDB.Transaction, LMDB.Database, LMDB.Cursor, LMDB.set!, LMDB.sync, LMDB.info, LMDB.seek!, etc.
• The whole 1.x cursor iteration surface is gone: LMDBIterator, ReturnKeys, ReturnValues, ReturnBoth, ReturnValueSize, DirectoryLister, Base.iterate(cur, K, V), keys(cur, T; prefix), values(cur, T; prefix), and get(cur, key, T, op::MDB_cursor_op). Replaced by either iteration over LMDBDict (which is now <: AbstractDict) or, at the cursor level, explicit positioning with LMDB.seek! / LMDB.seek_range! / LMDB.next! / LMDB.prev! / the _dup/_nodup variants plus LMDB.key(cur, K) / LMDB.value(cur, V) / LMDB.item(cur, K, V). For bulk traversal, use LMDB.walk(f, cur; from).
• tryget(txn, dbi, key, T) is replaced by LMDB.get(txn, dbi, key, T, nothing), which is the canonical Base.get(d, k, default) shape. The throwing form LMDB.get(txn, dbi, key, T) and the new default-form LMDB.get(txn, dbi, key, T, default) are the two read primitives.
• The custom typed-decode extension point _mbd_unpack(T, ::MDB_val) is gone. Override Base.read(io::IO, ::Type{T}) instead.
• Base.keys(d::LMDBDict; prefix) and Base.values(d::LMDBDict; prefix) no longer return a collected Vector; they now return the standard KeySet / ValueIterator views from AbstractDict. For prefix-scoped collected results, use LMDB.scan_keys(d; prefix), LMDB.scan_values(d; prefix), or LMDB.scan(d; prefix) for pairs.
• Base.empty(d::LMDBDict) and Base.copy(d::LMDBDict) now throw ArgumentError: an LMDBDict needs an on-disk directory, so there's no path-less zero-argument form. Use Dict(d) for an in-memory snapshot or Base.copy(d.env, path) for an on-disk clone.
• info(env) previously returned an MDB_envinfo C struct with me_-prefixed fields. It now returns a NamedTuple with mapaddr, mapsize, last_pgno, last_txnid, maxreaders, numreaders.
• put!(txn, dbi, key, val) returns nothing instead of a Cint status. delete!(txn, dbi, key) returns Bool (true if removed, false if MDB_NOTFOUND) instead of throwing on missing. The optional val argument no longer has a C_NULL default; use delete!(txn, dbi, key, val) for DUPSORT-specific dup removal.
• LMDB.LibLMDB submodule is gone. C bindings live directly in LMDB now, reachable as LMDB.mdb_env_open, LMDB.MDB_val, LMDB.MDB_NOTFOUND, etc.
• env[:Unknown] and env[:Unknown] = v now throw ArgumentError instead of warning and returning a meaningless zero.

For an example, what looked like this in 1.0:

env = create()
env[:MapSize] = 1 << 30
open(env, "/tmp/db")
start(env) do txn
    dbi = open(txn)
    put!(txn, dbi, "k", "v")
    v = tryget(txn, dbi, "k", String)   # → Union{String,Nothing}
end
close(env)

... now looks like:

LMDB.Environment("/tmp/db"; mapsize = 1 << 30) do env
    LMDB.Transaction(env) do txn
        LMDB.Database(txn) do dbi
            put!(txn, dbi, "k", "v")
            v = LMDB.get(txn, dbi, "k", String, nothing)
        end
    end
end

Merged pull requests:

• Bump to Julia 1.10 and update CI. (#49) (@maleadt)
• Fix correctness bugs (#50) (@maleadt)
• Modernize Clang.jl-generated bindings. (#51) (@maleadt)
• Improve wrappers (#52) (@maleadt)
• Add a high-level API (#53) (@maleadt)
• Improve LMDBDict (#54) (@maleadt)
• Switch typed-read extension point to Base.read(::MDBValueIO, T). (#55) (@maleadt)
• Extend documentation (#56) (@maleadt)
• Improve tests (#57) (@maleadt)
• Get rid of some LLMisms. (#58) (@maleadt)
• Improve test coverage (#59) (@maleadt)
• Audit exports. (#60) (@maleadt)
• NFC clean-ups. (#61) (@maleadt)
• Bump codecov/codecov-action from 5 to 6 (#63) (@dependabot[bot])
• Bump julia-actions/cache from 2 to 3 (#64) (@dependabot[bot])
• Bump actions/checkout from 4 to 6 (#65) (@dependabot[bot])
• Bump JLL version. (#66) (@maleadt)
• Improvements to new Julia API (#67) (@maleadt)

Closed issues:

• Setting flags (#24)
• Release v1.0? (#35)
• uint32 limits mapsize (#38)
• apple silicon support (#39)
• Sketchy useage of unsafe_wrap/unsafe_string (#41)
• LMDBDict producing random data (#46)
• Move to JuliaDatabases org (#47)
• PSA: registry is trying to reach you (#48)