Trait parquet::file::writer::RowGroupWriter [−][src]
pub trait RowGroupWriter { fn next_column(&mut self) -> Result<Option<ColumnWriter>>; fn close_column(&mut self, column_writer: ColumnWriter) -> Result<()>; fn close(&mut self) -> Result<RowGroupMetaDataPtr>; }
Expand description
Parquet row group writer API. Provides methods to access column writers in an iterator-like fashion, order is guaranteed to match the order of schema leaves (column descriptors).
All columns should be written sequentially; the main workflow is:
- Request the next column using
next_column
method - this will returnNone
if no more columns are available to write. - Once done writing a column, close column writer with
close_column
method - this will finalise column chunk metadata and update row group metrics. - Once all columns have been written, close row group writer with
close
method - it will return row group metadata and is no-op on already closed row group.
Required methods
fn next_column(&mut self) -> Result<Option<ColumnWriter>>
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fn next_column(&mut self) -> Result<Option<ColumnWriter>>
[src]Returns the next column writer, if available; otherwise returns None
.
In case of any IO error or Thrift error, or if row group writer has already been
closed returns Err
.
To request the next column writer, the previous one must be finalised and closed
using close_column
.
fn close_column(&mut self, column_writer: ColumnWriter) -> Result<()>
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fn close_column(&mut self, column_writer: ColumnWriter) -> Result<()>
[src]Closes column writer that was created using next_column
method.
This should be called before requesting the next column writer.
fn close(&mut self) -> Result<RowGroupMetaDataPtr>
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fn close(&mut self) -> Result<RowGroupMetaDataPtr>
[src]Closes this row group writer and returns row group metadata. After calling this method row group writer must not be used.
It is recommended to call this method before requesting another row group, but it will be closed automatically before returning a new row group.
Can be called multiple times. In subsequent calls will result in no-op and return already created row group metadata.
Implementors
impl<W: 'static + ParquetWriter> RowGroupWriter for SerializedRowGroupWriter<W>
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impl<W: 'static + ParquetWriter> RowGroupWriter for SerializedRowGroupWriter<W>
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