eugene 0.8.3

Careful with That Lock, Eugene
Documentation 
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## ✅ Eugene trace report

Script name: `examples/W12/bad/1.sql`


### ✅ Statement number 1 for 10ms

```sql
-- 1.sql
create table authors(
    id integer generated always as identity
        primary key,
    name text,
    email text
)
```

#### Locks at start

No locks held at the start of this statement.

#### New locks taken

No new locks taken by this statement.


## ❌ Eugene trace report

Script name: `examples/W12/bad/2.sql`


### ✅ Statement number 1 for 10ms

```sql
-- 2.sql
set lock_timeout = '2s'
```

#### Locks at start

No locks held at the start of this statement.

#### New locks taken

No new locks taken by this statement.


### ❌ Statement number 2 for 10ms

```sql
alter table authors
    alter column name set not null
```

#### Locks at start

No locks held at the start of this statement.

#### New locks taken

| Schema | Object | Mode | Relkind | OID | Safe | Duration held (ms) |
|--------|--------|------|---------|-----|------|--------------------|
| `public` | `authors` | `AccessExclusiveLock` | Table | 1 | ❌ | 10 |

#### Triggered rules

##### `E2`: [Validating table with a new `NOT NULL` column](https://kaveland.no/eugene/hints/E2/)

The column `name` in the table `public.authors` was changed to `NOT NULL`. If there is a `CHECK (name IS NOT NULL)` constraint on `public.authors`, this is safe. Splitting this kind of change into 3 steps can make it safe:

1. Add a `CHECK (name IS NOT NULL) NOT VALID;` constraint on `public.authors`.
2. Validate the constraint in a later transaction, with `ALTER TABLE public.authors VALIDATE CONSTRAINT ...`.
3. Make the column `NOT NULL`


### ✅ Statement number 3 for 10ms

```sql
-- eugene: ignore E2, E4
alter table authors
    alter column email set not null
```

#### Locks at start

| Schema | Object | Mode | Relkind | OID | Safe | Duration held (ms) |
|--------|--------|------|---------|-----|------|--------------------|
| `public` | `authors` | `AccessExclusiveLock` | Table | 1 | ❌ | 10 |

#### New locks taken

No new locks taken by this statement.