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LWLock optimization

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Hi.

I was asked to bring up this topic on maling lists after asking question on IRC. 

The issue is the following.
On one of our servers (10.5), I see a lot of queries with wait_event_type='LWLock', wait_event='lock_manager' 

This is a stat gathering/analyzing application with tables which have > 100 partitions.
The queries itself are mostly simple (select by pkey, update by primary key and so on).

 select count(*) from pg_locks shows about 40K  records (all granted) and 

 select count(*) from (select distinct locktype,database,relation,page,tuple,virtualxid,transactionid,classid,objid,objsubid from pg_locks) 

is varying from about 1K to 25K (I haven't stored this value in monitoring system, just observed manually).

Currently I was adviced to increase LOG2_NUM_LOCK_PARTITIONS at compile time. If it bothers us enough, we would likely do it, but I have a question,  if this  (or NUM_LOCK_PARTITIONS) value should be increased by default  or set tunable?


С уважением,
Александр Пыхалов,
программист отдела телекоммуникационной инфраструктуры
управления информационно-коммуникационной инфраструктуры ЮФУ







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