API reference

Every name below is importable directly from the top-level colstore package.

Opening & reading

open	Open an existing .cstore file, or several as one logical dataset.
ColStoreReader	Memory-mapped columnar store with lazy, NumPy-style indexing.
ColumnView	Lazy view of a single column produced by indexing with a string name.
TableView	View of multiple columns produced by any non-string indexing.
info	Return a summary of the file at path without reading any record bodies.
schema	Return the column schema of path without reading any record bodies.
ColStoreInfo	Summary of a colstore file's contents and on-disk shape.

Writing

store	One-shot: write a single-record file and return an opened reader.
create	Open a new file for streaming writes; fail if it already exists.
recreate	Open a file for streaming writes, truncating any existing content.
update	Open an existing file for append.
ColStoreWriter	Append-only writer for a colstore file.
compact	Collapse a multi-record file into a single-record file.

Datasets & shards

ColStoreDataset	One or more same-schema .cstore files presented as one logical table.
concat	Combine several same-schema sources, lazily or into one written file.
append	Append data to the dataset at directory as one new shard.
appender	Open a streaming Appender for the dataset at directory.
Appender	Streaming append: roll new shards into a dataset directory from a batch stream.

Editing (frames)

ColStoreFrame	A deferred editing view over an opened store's columns.
col	A lazy reference to a column, for building filter expressions.

Format interop

convert	Convert files between colstore's format and another, one endpoint being .cstore.
saveas	Write a reader, dataset, or view to a file -- the function form of source.saveas.
to_root	Write a colstore reader, dataset, or selection out to a ROOT file.
from_parquet	Import a Parquet file into a .cstore (convert(..., format="parquet")).
from_feather	Import a Feather file into a .cstore (convert(..., format="feather")).
from_json	Import a JSON file into a .cstore (convert(..., format="json")).
from_npz	Import a NumPy .npz file into a .cstore (convert(..., format="npz")).
from_hdf	Import an HDF5 file into a .cstore (convert(..., format="hdf5")).
from_root	Convert a ROOT source into a .cstore file and open it for reading.

Configuration & diagnostics

calibrate	Measure and select a near-optimal gather thread cap for this machine.
ensure_calibrated	Apply a cached cap if present, otherwise calibrate once and cache it.
set_max_workers	Set the package-wide thread count for multi-column reads.
get_max_workers	Return the package-wide default thread count for multi-column reads.
set_gather_thread_cap	Set the per-call gather thread cap (>= 1).
get_gather_thread_cap	Return the maximum OpenMP threads a single gather kernel call may use.
set_default_backend	Set the default gather backend ("cpp" or "numpy").
get_default_backend	Return the default gather backend for new ColStoreReader opens.
set_default_madvise	Set the package-wide default madvise hint for new ColStoreReader opens.
get_default_madvise	Return the default madvise hint applied to new ColStoreReader opens.
max_threads	Return the gather kernel's max thread count (1 without OpenMP).
cpp_available	Return whether the compiled C++ gather extension is importable.
use_passive_openmp_wait	Opt into OMP_WAIT_POLICY=passive so idle OpenMP threads sleep.

Exceptions

FormatError	Raised when a file does not match the expected colstore format.
QueryError	A query string or column expression is malformed or unsupported.