[TRAFODION-52] LP Blueprint: cmp-trafodion-to-hbase-mapping - Make the mapping of Trafodion tables to HBase tables and column families more flexible

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Component/s: sql-cmp
• External issue URL: https://blueprints.launchpad.net/trafodion/+spec/cmp-trafodion-to-hbase-mapping
• Assignee: Hans Zeller
• Reporter: Hans Zeller
• Created: 22/Jul/15 18:13
• Updated: 25/Apr/18 17:03
• Resolved: 01/Mar/17 21:15

Description

Right now, each Trafodion table is mapped to an HBase table with one column family. This could be a problem in the future, if a user creates very many Trafodion tables. It is known that HBase is not designed to have a very high number of tables and/or regions, due to the high memory footprint that is caused by every region.

One solution could be to allow multiple Trafodion tables to share a single HBase table, and to use a 2 byte table id as the key prefix to identify the table. This would work only for small tables that don't need to be split into regions and for tables that wouldn't create a hot spot.

One the other side, it may be desirable to separate frequently used columns in large tables from those that are less frequently used. That could be achieved by using more than one column family.

Both features - sharing common HBase tables and utilizing multiple column families - would require new Trafodion SQL syntax. Given the complexity of the DDL code, it would be a significant effort to implement these features.

Issue Links

• duplicates: TRAFODION-1419 Add support for multiple column families in a trafodion table
• relates to: TRAFODION-2953 support multiple small size table map to a single or a few hbase table