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https://issues.apache.org/jira/browse/PARQUET-1559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17171434#comment-17171434
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wxmimperio commented on PARQUET-1559:
-------------------------------------
[~gszadovszky]
Hi, If I need to write multiple files, and each file is very large, such as
flink to hdfs.
There is not enough memory to buffer all the data, resulting in serious gc.
I don’t need the files to be readable, just flush the memory to disk.
And I did not find a place to call PositionOutputStream.flush(), I think this
is the main reason.
columnStore.flush、columnStore.flush, just flush to PositionOutputStream, but
not to disk.
{code:java}
//代码占位符
private void flushRowGroupToStore()
throws IOException {
recordConsumer.flush();
LOG.debug("Flushing mem columnStore to file. allocated memory: {}",
columnStore.getAllocatedSize());
if (columnStore.getAllocatedSize() > (3 * rowGroupSizeThreshold)) {
LOG.warn("Too much memory used: {}", columnStore.memUsageString());
}
if (recordCount > 0) {
parquetFileWriter.startBlock(recordCount);
columnStore.flush();
pageStore.flushToFileWriter(parquetFileWriter);
recordCount = 0;
parquetFileWriter.endBlock();
this.nextRowGroupSize = Math.min(
parquetFileWriter.getNextRowGroupSize(),
rowGroupSizeThreshold);
}
columnStore = null;
pageStore = null;
}
{code}
> Add way to manually commit already written data to disk
> -------------------------------------------------------
>
> Key: PARQUET-1559
> URL: https://issues.apache.org/jira/browse/PARQUET-1559
> Project: Parquet
> Issue Type: Improvement
> Components: parquet-mr
> Affects Versions: 1.10.1
> Reporter: Victor
> Priority: Major
>
> I'm not exactly sure this is compliant with the way parquet works, but I have
> the following need:
> * I'm using parquet-avro to write to a parquet file during a long running
> process
> * I would like to be able from time to time to access the already written
> data
> So I was expecting to be able to flush manually the file to ensure the data
> is on disk and then copy the file for preliminary analysis.
> If it's contradictory to the way parquet works (for example there is
> something about metadata being at the footer of the file), what would then be
> the alternative?
> Closing the file and opening a new one to continue writing?
> Could this be supported directly by parquet-mr maybe? It would then write
> multiple files in that case.
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