Mastering PostgreSQL 11 - Second Edition

Running queries

To show you how the JIT works, we shall compile a simple example. Let's begin by creating a big table – one that contains a lot of data. Remember, JIT compilation is only useful if the operation is sufficiently large. For beginners, 50 million rows should suffice. The following example shows how to populate the table:

jit=# CREATE TABLE t_jit AS          SELECT (random()*10000)::int AS x, (random()*100000)::int AS y, (random()*1000000)::int AS z          FROM generate_series(1, 50000000) AS id;SELECT 50000000jit=# VACUUM ANALYZE t_jit;VACUUM

In this case, we will use the random function to generate some data. To show you how JIT works and to make execution plans easier to read, you can turn off parallel queries. JIT works fine with parallel ...