Re:What Write Skew Looks Like
by drkp on Thursday May 24, 2018 @08:16PM
(#17149637)
I have some experience with that specific question, although it was a few years ago...
Do you remember what conflict was causing things to fall over?
In general, the usual important parameters to tweak are:
- max_pred_locks_per_transaction may need to be increased; otherwise locks will switch to coarse granularity to save room in the lock table
- for tables that fit in memory, the planner may choose a sequential scan even when an index scan is available, which can be faster but creates more conflicts on a serializable workload. Increasing cpu_tuple_cost should avoid that (or even just enable_seqscan=off to force indexes whenever available)
Do you remember what conflict was causing things to fall over?
In general, the usual important parameters to tweak are:
- max_pred_locks_per_transaction may need to be increased; otherwise locks will switch to coarse granularity to save room in the lock table
- for tables that fit in memory, the planner may choose a sequential scan even when an index scan is available, which can be faster but creates more conflicts on a serializable workload. Increasing cpu_tuple_cost should avoid that (or even just enable_seqscan=off to force indexes whenever available)