Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Is parquet using delta encoding for positions? #1552

Closed
jpdna opened this issue May 30, 2017 · 2 comments
Closed

Is parquet using delta encoding for positions? #1552

jpdna opened this issue May 30, 2017 · 2 comments
Labels
Milestone

Comments

@jpdna
Copy link
Member

@jpdna jpdna commented May 30, 2017

I'm having trouble confirming as parquet-tools is not building for me right now, but I wanted to check if we think that our long genomic positions are being encoded in the most efficient way possible (probably delta for sorted data) in parquet. See discussion here: https://issues.apache.org/jira/browse/PARQUET-225

@fnothaft
Copy link
Member

@fnothaft fnothaft commented May 30, 2017

To get delta encoding, you need to set disableDictionaryEncoding to true. This effectively enables the Parquet 2 format, which supports delta encoding. There was a discussion recently on the Spark lists that the vectorized Spark SQL reader only supports Parquet 1, so you may see worse performance with delta encoding from Spark SQL. Truth be told, I looked at file sizes a while back and moving to delta encoding didn't seem to make a huge difference.

@fnothaft
Copy link
Member

@fnothaft fnothaft commented Jun 22, 2017

I don't think there's anything actionable here for right now, so I'll close this. Please reopen if you have a question @jpdna.

@fnothaft fnothaft closed this Jun 22, 2017
@heuermh heuermh modified the milestone: 0.23.0 Jul 22, 2017
@heuermh heuermh added this to Completed in Release 0.23.0 Jan 4, 2018
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
Linked pull requests

Successfully merging a pull request may close this issue.

None yet
3 participants
You can’t perform that action at this time.