Eugene 🔒 trace report of examples/E10/good/1.sql

Statement number 1 for 10ms

SQL

-- 1.sql
create table prices (
    id integer generated always as identity
        primary key,
    price int not null
)

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

create table authors (
    id integer generated always as identity
        primary key,
    name text not null
)

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 of examples/E10/good/2.sql

Statement number 1 for 10ms

SQL

-- 2.sql
set local 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
    add column meta jsonb

Locks at start

No locks held at the start of this statement.

New locks taken

SchemaObjectModeRelkindOIDSafeDuration held (ms)
publicauthorsAccessExclusiveLockTable110

Eugene 🔒 trace report of examples/E10/good/3.sql

Statement number 1 for 10ms

SQL

-- 3.sql
set local 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

-- eugene: ignore E5, E4
-- causes table rewrite, but this example isnt't about that
alter table prices
    alter price set data type bigint

Locks at start

No locks held at the start of this statement.

New locks taken

SchemaObjectModeRelkindOIDSafeDuration held (ms)
publicpricesAccessExclusiveLockTable110
publicpricesShareLockTable110
publicprices_pkeyAccessExclusiveLockIndex110

Hints

Creating a new index on an existing table

ID: E6

A new index was created on an existing table without the CONCURRENTLY keyword. This blocks all writes to the table while the index is being created. A safer way is: Run CREATE INDEX CONCURRENTLY instead of CREATE INDEX.

A new index was created on the table public.prices. The index was created non-concurrently, which blocks all writes to the table. Use CREATE INDEX CONCURRENTLY to avoid blocking writes.

Rewrote table or index while holding dangerous lock

ID: E10

A table or index was rewritten while holding a lock that blocks many operations. This blocks many operations on the table or index while the rewrite is in progress. A safer way is: Build a new table or index, write to both, then swap them.

The Table public.prices was rewritten while holding AccessExclusiveLock on the Table public.prices. This blocks SELECT, FOR UPDATE, FOR NO KEY UPDATE, FOR SHARE, FOR KEY SHARE, UPDATE, DELETE, INSERT, MERGE while the rewrite is in progress.