PGCon2015 - final

PGCon 2015
The PostgreSQL Conference

Amit Kapila
Robert Haas
Day Talks - Day 4 - Friday - 2015-06-19
Room DMS 1120
Start time 13:00
Duration 00:45
ID 785
Event type Lecture
Track Hacking
Language used for presentation English

Parallel Sequential Scan

Unleashing a heard of elephants

Parallel query is close to becoming a reality in PostgreSQL! A year ago, much of the low-level infrastructure needed for parallelism, such as dynamic shared memory and dynamic background workers, had been completed, but no user-visible facilities made use of this infrastructure. Major work on error handling, transaction control, and state sharing has been completed, and further patches, including a patch for parallel sequential scan, are pending.

In this talk, we will talk about parallel sequential scan itself, including performance considerations, the work allocation strategy, and the cost model; and we will also discuss the infrastructure that supports parallel sequential scan, including state sharing for GUCs, transaction state, snapshots, and combo CIDs; error handling and transaction management; and the handling of heavyweight locking. Finally, we'll discuss the future of parallelism in PostgreSQL now that the basic infrastructure is (mostly) complete.