[PIG-5323] Implement LastInputStreamingOptimizer in Tez

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 0.18.0
• Assignee: Rohini Palaniswamy
• Reporter: Rohini Palaniswamy
• Created: 26/Dec/17 19:39
• Updated: 28/Dec/17 20:42

Description

http://pig.apache.org/docs/r0.17.0/perf.html#join-optimizations

Optimization for regular joins ensures that the last table in the join is not brought into memory but streamed through instead. Optimization reduces the amount of memory used which means you can avoid spilling the data and also should be able to scale your query to larger data volumes.

To take advantage of this optimization, make sure that the table with the largest number of tuples per key is the last table in your query. In some of our tests we saw 10x performance improvement as the result of this optimization.

We are not doing that in Tez and both the tables are materialized as InternalCachedBag.

Issue Links

• is related to: PIG-5324 Stream the first input in Tez for skewed, bloom and replicate joins
• links to: Review board