Just-In-Time (JIT) Compilation

Overview

Timeplus can compile SQL expressions into native machine code to significantly improve query performance.
This optimization is especially beneficial for streaming queries, where the compiled expressions are reused throughout the entire query lifetime, reducing runtime overhead.

Example:

SELECT ts, key, value AS v, (a + (b * c)) + 5 AS calc 
FROM stream;

In the above example, the expression (a + (b * c)) + 5 can be executed in two ways:

Interpreted execution: Each operation (+, *) is evaluated separately through an expression tree, adding overhead for each computation step.
JIT-compiled execution: The entire expression is fused into a single machine instruction sequence, eliminating interpretation overhead and enabling much faster execution.

JIT

Settings

The following settings control Just-In-Time (JIT) compilation behavior.
You can override them at query time using:

SET <key> = <value>;

You can also query the current setting values and their descriptions from the system tables.

select * from system.settings where name like '%to_compile%';

`min_count_to_compile_expression`

Specifies the minimum number of times an identical expression must be executed before it becomes eligible for JIT compilation.

Type: uint64
Default: 3

`min_count_to_compile_aggregate_expression`

Specifies the minimum number of identical aggregate expressions required to trigger JIT compilation. This setting takes effect only if compile_aggregate_expressions is enabled.

Type: uint64
Default: 3

`min_count_to_compile_sort_description`

Specifies the number of identical sort descriptions that must appear before they are JIT-compiled.

Type: uint64
Default: 3

Metrics

You can monitor JIT compilation activity by querying the system counters:

select * from system.events where event like 'Compile%';

Overview​

Settings​

min_count_to_compile_expression​

min_count_to_compile_aggregate_expression​

min_count_to_compile_sort_description​

Metrics​