[ https://issues.apache.org/jira/browse/HADOOP-15999?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Gabor Bota reassigned HADOOP-15999: ----------------------------------- Assignee: Gabor Bota > [s3a] Better support for out-of-band operations > ----------------------------------------------- > > Key: HADOOP-15999 > URL: https://issues.apache.org/jira/browse/HADOOP-15999 > Project: Hadoop Common > Issue Type: New Feature > Components: fs/s3 > Affects Versions: 3.1.0 > Reporter: Sean Mackrory > Assignee: Gabor Bota > Priority: Major > Attachments: out-of-band-operations.patch > > > S3Guard was initially done on the premise that a new MetadataStore would be > the source of truth, and that it wouldn't provide guarantees if updates were > done without using S3Guard. > I've been seeing increased demand for better support for scenarios where > operations are done on the data that can't reasonably be done with S3Guard > involved. For example: > * A file is deleted using S3Guard, and replaced by some other tool. S3Guard > can't tell the difference between the new file and delete / list > inconsistency and continues to treat the file as deleted. > * An S3Guard-ed file is overwritten by a longer file by some other tool. When > reading the file, only the length of the original file is read. > We could possibly have smarter behavior here by querying both S3 and the > MetadataStore (even in cases where we may currently only query the > MetadataStore in getFileStatus) and use whichever one has the higher modified > time. > This kills the performance boost we currently get in some workloads with the > short-circuited getFileStatus, but we could keep it with authoritative mode > which should give a larger performance boost. At least we'd get more > correctness without authoritative mode and a clear declaration of when we can > make the assumptions required to short-circuit the process. If we can't > consider S3Guard the source of truth, we need to defer to S3 more. > We'd need to be extra sure of any locality / time zone issues if we start > relying on mod_time more directly, but currently we're tracking the > modification time as returned by S3 anyway. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org