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CSV.jl 1.0 release notes

CSV.jl 1.0 replaces the parsing and writing internals while keeping the main CSV.jl entry points. It requires Julia 1.10 or later.

Highlights

  • A quote-aware structural index separates row and field discovery from typed value parsing. The same index drives eager files, row views, lazy access, and batches.
  • CSV.lazy returns an indexed table that parses cells only when they are accessed. CSV.File(lazyfile) reuses the existing index.
  • Inferred text uses DataStrings.DataString by default. Short text is stored in the value; longer text lives in column-owned buffers, so eager tables never refer to the source or to a mapped file.
  • Typed value parsing uses the low-level parsers of Parsers, now even faster in version 3.
  • Parse recovery produces structured CSV.problems(file) data. on_error selects one summary warning (:warn, the default), silent collection (:collect), or fail-fast CSV.ParseError (:error).
  • CSV.Chunks uses one stable schema for its complete row window.
  • A Tables.Scan projection, filter, type request, offset, and limit go into the parser.
  • The writer has deterministic parallel output, explicit quote styles, Printf-style floating-point formatting, bounded row-block memory, gzip suffix detection, parallel gzip compression (one member per row block), and parallel partition output.
  • String conversion (stringtype=String, types=String, InlineStrings), CSV.Chunks batch parsing, and gzip output run in parallel. Files with comment rows, skipto, and footerskip use the vector scanner, and so do files with a separate escapechar or distinct openquotechar and closequotechar. CSV.Rows carries its schema in its type, so row.name on a typed column returns a typed value without allocation. Transposed reads parse each row as a typed column. Several sources concatenate text as DataString columns.

Compatibility changes

The most important default changes are:

  • Julia 1.10 is the minimum runtime;
  • DataStrings.DataString replaces InlineStrings.jl as the default text type;
  • pooling is off unless requested;
  • an unquoted empty field is always missing;
  • true, True, TRUE, false, False, and FALSE are the default Boolean spellings;
  • a date-time column is a Timestamp{Nanosecond} (Durations.jl) instead of a Dates.DateTime, ISO date-times accept T or a space, and no fraction digit is truncated; and
  • parse problems are retained as problem objects, with one summary warning per read instead of one warning per problem.

See Migrating from 0.10 to 1.0 for option mappings, writer compatibility, source-memory behavior, and upgrade examples.