Flow PHP

FileListingExtractor implements BatchableExtractor, Extractor, FileExtractor

FinalYes

Interfaces

BatchableExtractor: A source that decides how many rows it puts in one Rows: withBatchSize() bounds what the source builds.
Extractor
FileExtractor

Methods

__construct() : mixed
batchSize() : int<1, max>
extract() : Generator<Signal|null, void>: Yields rows in batches. When the source is a BatchableExtractor a batch holds between 0 and that extractor's own batchSize() rows; the size is chosen by the extractor and MAY vary between batches. Consumers must not assume a minimum size, a constant size, or a non-empty batch.
isRepeatable() : bool: True when extract() can run more than once and yield the same rows each time, so a build-time pass may read the source before the run without consuming it. A one-shot stream returns false; a wrapper answers for what it reads.
partitionSchema() : Schema
prunes() : bool
refresh() : void: Drops the listing and everything derived from it, so the next run lists the source again. A run calls it when it ends; a plan that does not run (explain(), schema()) keeps what it listed for the run that follows.
schema() : Schema: Answers before extract() runs, so every batch it yields carries this shape. Takes no FlowContext: a source that needs the pipeline's context to describe itself has not moved the answer to bind time.
source() : Path
statistics() : Statistics: What the source knows about the data before a single row is read: how many rows, how many bytes. A source that knows nothing returns `new Statistics()`. Describes the source with NO pushdown applied - a limit or a partition filter the plan pushed is the plan's to account for.
withBatchSize() : static: Mutates and returns the same instance, so one extractor shared across from_all() children shares its size.
withSchema() : static: Declares the shape every yielded batch must carry. A source that describes itself uses this instead of its own description, and values are cast to fit.

__construct()


    public
                    __construct(Path $path, ListedFileRow $row[, Filesystem $filesystem = new NativeLocalFilesystem() ]) : mixed

Parameters

$path : Path
$row : ListedFileRow
$filesystem : Filesystem = new NativeLocalFilesystem()

batchSize()


    public
                    batchSize() : int<1, max>

Return values

int<1, max>

extract()

Yields rows in batches. When the source is a BatchableExtractor a batch holds between 0 and that extractor's own batchSize() rows; the size is chosen by the extractor and MAY vary between batches. Consumers must not assume a minimum size, a constant size, or a non-empty batch.


    public
                    extract(Backend $backend, Criteria $criteria) : Generator<Signal|null, void>

Parameters

$backend : Backend
$criteria : Criteria

Return values

Generator<Signal|null, void>

isRepeatable()

True when extract() can run more than once and yield the same rows each time, so a build-time pass may read the source before the run without consuming it. A one-shot stream returns false; a wrapper answers for what it reads.


    public
                    isRepeatable() : bool

Return values

bool

partitionSchema()


    public
                    partitionSchema() : Schema

Return values

Schema

prunes()


    public
                    prunes(ScalarFunction $conjunct) : bool

Parameters

$conjunct : ScalarFunction

Return values

bool

refresh()

Drops the listing and everything derived from it, so the next run lists the source again. A run calls it when it ends; a plan that does not run (explain(), schema()) keeps what it listed for the run that follows.


    public
                    refresh() : void

schema()

Answers before extract() runs, so every batch it yields carries this shape. Takes no FlowContext: a source that needs the pipeline's context to describe itself has not moved the answer to bind time.


    public
                    schema() : Schema

Called once per RUN - every run plans afresh - so it MUST be idempotent and cheap on repeat: memoise what it sniffs, as CSVExtractor and ArrayExtractor do.

Return values

Schema

source()


    public
                    source() : Path

Return values

Path

statistics()

What the source knows about the data before a single row is read: how many rows, how many bytes. A source that knows nothing returns `new Statistics()`. Describes the source with NO pushdown applied - a limit or a partition filter the plan pushed is the plan's to account for.


    public
                    statistics() : Statistics

Called AT MOST ONCE per run, and only when something needs the answer - so it must be lazy, never computed in the constructor - and it MUST be idempotent and cheap on repeat: memoise what it reads, the way schema() does.

A file source may only spend what the run already spends: it may complete a listing it must produce anyway and read metadata from the files schema() already opens, and it may extrapolate from those. It must not open an extra file or make an extra remote call. A database source may ask the planner for an estimate (EXPLAIN without ANALYZE), never run the query.

Return values

Statistics

withBatchSize()

Mutates and returns the same instance, so one extractor shared across from_all() children shares its size.


    public
                    withBatchSize(int $batchSize) : static

Parameters

$batchSize : int

Return values

static

withSchema()

Declares the shape every yielded batch must carry. A source that describes itself uses this instead of its own description, and values are cast to fit.


    public
                    withSchema(Schema $schema) : static

Parameters

$schema : Schema

Return values

static