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stack commented on HBASE-20952: ------------------------------- Deferred would be good to support again; i.e. fire the edit but client doesn't wait on it. In background we sync edits on a configurable periodiciit. We used to have this but distruptor messed it up. Don't forget read/recovery API. Currently WALs are grouped by server and/or by multiwal policy/count. You might want to add metadata on WALs to support queries by server or wal-group. Cool would be an API that allowed adding arbitrary metadata about a WAL on the fly. Imagine being able to mark regions seen as WAL metadata and then being able to query before replay, what regions have edits in a particular WAL. Other metadata might be oldest/newest sequenceid and/or timestamp. > Re-visit the WAL API > -------------------- > > Key: HBASE-20952 > URL: https://issues.apache.org/jira/browse/HBASE-20952 > Project: HBase > Issue Type: Sub-task > Components: wal > Reporter: Josh Elser > Priority: Major > > Take a step back from the current WAL implementations and think about what an > HBase WAL API should look like. What are the primitive calls that we require > to guarantee durability of writes with a high degree of performance? > The API needs to take the current implementations into consideration. We > should also have a mind for what is happening in the Ratis LogService (but > the LogService should not dictate what HBase's WAL API looks like RATIS-272). > Other "systems" inside of HBase that use WALs are replication and > backup&restore. Replication has the use-case for "tail"'ing the WAL which we > should provide via our new API. B&R doesn't do anything fancy (IIRC). We > should make sure all consumers are generally going to be OK with the API we > create. > The API may be "OK" (or OK in a part). We need to also consider other methods > which were "bolted" on such as {{AbstractFSWAL}} and > {{WALFileLengthProvider}}. Other corners of "WAL use" (like the > {{WALSplitter}} should also be looked at to use WAL-APIs only). > We also need to make sure that adequate interface audience and stability > annotations are chosen. -- This message was sent by Atlassian JIRA (v7.6.3#76005)