Add Insert A Bunch Of Records With Generate Series as a postgres til

postgres/insert-a-bunch-of-records-with-generate-series.md

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+# Insert A Bunch Of Records With Generate Series
+
+Sometimes you want to quickly insert a bunch of fake (or real) data into a
+Postgres table. This is a great way to populate seed data or set up data
+scenarios for testing things out.
+
+For instance, I recently used the following query to generate a bunch of data
+in a `roles` table to test out a query performance issue.
+
+```sql
+> insert into roles (
+    name,
+    resource_id,
+    resource_type,
+    created_at,
+    updated_at
+  )
+  select
+    'organization_user',
+    g.id,
+    'Organization',
+    now(),
+    now()
+  from generate_series(1,54000) as g(id);
+```
+
+The key part is the [`generate_series()`
+function](https://www.postgresql.org/docs/current/functions-srf.html) which
+will produce a row for every value between the two arguments. In this case, it
+will generate `1`, `2`, `3`, etc. all the way up to `54000` -- so 54k rows in
+total.
+
+The query selects off that generated series with some static values and some
+timestamps to create sufficiently fake data that can be inserted into the
+specified columns of the `roles` table.
+
+This quickly inserts tens of thousands of records that I can now use to test
+out the performance of a SQL query.