v1.0.0

CSV v1.0.0

Diff since v0.10.17

CSV.jl 1.0.0

CSV.jl 1.0 rewrites the parsing and writing internals while keeping the main CSV.File, CSV.read, CSV.Rows, CSV.Chunks, CSV.write, and CSV.RowWriter entry points.

Highlights

• A shared, quote-aware structural index supports parallel typed parsing, eager tables, row views, lazy access, and batches.
• New CSV.lazy indexes a source once and parses cells on access. CSV.File(lazyfile) reuses the index.
• Tables.Scan pushes column selection, renaming, conversion, filtering, offset, and limit into the reader.
• CSV.problems(file) exposes structured parse problems. on_error selects summary warnings, silent collection, or a CSV.ParseError.
• The writer supports deterministic parallel output, explicit quote styles, Printf-style float formatting, automatic gzip suffix detection, and parallel gzip and partition output.
• Faster string, time, and floating-point writing reduces formatting overhead and temporary allocations.
• Julia trim compilation is covered by compile-and-execute tests.

Breaking changes

• Julia 1.10 or later is required. Use CSV.jl 0.10 for older Julia versions.
• Inferred text uses DataStrings.DataString. It is an AbstractString; eager columns own their text bytes. Use stringtype=String, or load InlineStrings and request an explicit type, when a consumer requires a particular representation. PosLenString output is retired.
• Pooling is disabled by default. Pass pool=(0.2, 500) to restore the old policy.
• Unquoted empty fields are always missing. Quote a field to represent present empty text. The writer preserves this distinction.
• Date-time inference preserves fractional precision. It normally returns Timestamp{Nanosecond} from Durations.jl instead of Dates.DateTime. Wider date ranges use an exact microsecond representation when possible, otherwise text. Explicit types=DateTime reports sub-millisecond values as parse problems rather than truncating them.
• Default Boolean spellings are true, True, TRUE, false, False, and FALSE. Set truestrings and falsestrings for other spellings.
• Parse recovery records structured problems and emits one summary warning. Use on_error=:collect instead of silencewarnings=true, or on_error=:error to fail fast. Long rows report extra fields rather than widening the schema.
• Some old options and APIs are removed or replaced. types, select, drop, and pool no longer accept functions. CSV.detect is removed; use delim=nothing. See the migration guide for the complete option mapping.
• Source-memory behavior changes. CSV.Rows, CSV.Chunks, and CSV.lazy retain source bytes and a complete structural index. Gzip and non-file sources are fully buffered. These interfaces reduce value materialization but do not provide unbounded stream processing.
• Writer behavior is stricter. An IO is written at its current position. .gz paths enable gzip by default; use compress=:none to disable it. Unknown writer keywords are errors, and quotestyle=:none rejects values that need structural quoting.

Migration guide and upgrade examples · Full release notes

Merged pull requests:

• Rewrite CSV.jl internals for 1.0 (#1196) (@quinnj)
• Improve vector input parsing performance (#1198) (@quinnj)
• Fix chunk detection with short row samples (#1200) (@quinnj)

Closed issues:

• 10-20x slowdown reading multiple files via CSV.read(::Vector{String}, DataFrame) (#1197)
• Regression in 0.10.17: CSV.Chunks fails on well-formed files when chunks hold fewer than rows_to_check rows (#1199)