[HBASE-21185] WALPrettyPrinter: Additional useful info to be printed by wal printer tool, for debugability purposes

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha-1, 1.3.3, 1.2.8, 2.2.0, 2.1.1, 2.0.3, 1.4.9
• Component/s: Operability
• Hadoop Flags: Reviewed

Release Note

This adds two extra features to WALPrettyPrinter tool:

1) Output for each cell combined size of cell descriptors, plus the cell value itself, in a given WAL edit. This is printed on the results as "cell total size sum:" info by default;

2) An optional -g/--goto argument, that allows to seek straight to that specific WAL file position, then sequentially reading the WAL from that point towards its end;

• Assignee: Wellington Chevreuil
• Reporter: Wellington Chevreuil
• Created: 11/Sep/18 17:22
• Updated: 12/Oct/18 18:50
• Resolved: 11/Oct/18 21:50

Description

WALPrettyPrinter is very useful for troubleshooting wal issues, such as faulty replication sinks. An useful information one might want to track is the size of a single WAL entry edit, as well as size for each edit cell. Am proposing a patch that adds calculations for these two, as well an option to seek straight to a given position on the WAL file being analysed.