jit
No restart — settable per sessiontuned by pgconfiguratorboolean (on/off)
Just-in-time compilation of expressions for big analytical queries.
What pgconfigurator would set
32 GB · 8 vCPU · NVMe · OLTP
Computing…
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What it does
When enabled, PostgreSQL can JIT-compile expression evaluation and tuple deforming for queries whose estimated cost is high. This speeds up long, CPU-bound analytical queries, but the compilation itself has overhead that can hurt short OLTP queries if their cost is mis-estimated.
How to tune it
It's on by default. For pure OLTP workloads with many fast queries, JIT sometimes adds latency (especially when costs are over-estimated) and is often turned off. For analytics/OLAP it usually helps. The jit_above_cost threshold controls when it kicks in.
FAQ
- Should I turn jit off?
- Consider it for latency-sensitive OLTP if you see JIT time inflating short queries. For analytical workloads it generally helps. Rather than a blanket off, you can also raise jit_above_cost so only genuinely expensive queries compile.