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Your first query: PostgreSQL and ClickHouse

Every file of the PostgreSQL and ClickHouse versions side by side, with the lines that differ marked. 3 parameter or column types differ in Go.

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Configuration

sgl.yamldiffers
PostgreSQL
ClickHouse
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: tasks
4 - name: tasks
5 dialect: postgres
5 dialect: clickhouse
6 migrations: db/migrations
6 migrations: db/migrations
7 queries: db/queries
7 queries: db/queries
8 go:
8 go:
9 package: store
9 package: store
10 out: internal/store
10 out: internal/store
11 driver: database/sql
12 doc_comments: true
13 migrate:
14 dsn: ${env:DATABASE_URL}

Migrations

db/migrations/0001_init.up.sqldiffers
PostgreSQL
ClickHouse
1CREATE TABLE tasks (
1CREATE TABLE tasks (
2 id BIGSERIAL PRIMARY KEY,
2 id UInt64,
3 title TEXT NOT NULL,
3 title String,
4 completed BOOLEAN NOT NULL DEFAULT false,
4 completed UInt8 DEFAULT 0,
5 created_at TIMESTAMPTZ NOT NULL DEFAULT now()
5 created_at DateTime DEFAULT now()
6);
6) ENGINE = MergeTree() ORDER BY id;
7
8COMMENT ON TABLE tasks IS 'Jobs to do around the harbour.';
9COMMENT ON COLUMN tasks.completed IS 'Whether the job is done.';
db/migrations/0001_init.down.sqlidentical
PostgreSQL
ClickHouse
1DROP TABLE tasks;
1DROP TABLE tasks;

Queries

CreateTaskdiffers
PostgreSQL · db/queries/tasks.sql
ClickHouse · db/queries/tasks.sql
1-- CreateTask adds a task and returns it with the id and creation time the database
1-- sgl.query(CreateTask, exec)
2-- gave it.
2INSERT INTO tasks (id, title) VALUES ({id:UInt64}, {title:String});
3-- sgl.query(CreateTask, one)
4INSERT INTO tasks (title) VALUES ($1) RETURNING id, title, completed, created_at;
ListTasksdiffers
PostgreSQL · db/queries/tasks.sql
ClickHouse · db/queries/tasks.sql
1-- ListTasks returns every task, oldest first.
2-- sgl.query(ListTasks, many)
1-- sgl.query(ListTasks, many)
3SELECT id, title, completed, created_at FROM tasks ORDER BY id;
2SELECT id, title, completed, created_at FROM tasks ORDER BY id;
CompleteTaskdiffers
PostgreSQL · db/queries/tasks.sql
ClickHouse · db/queries/tasks.sql
1-- CompleteTask marks a task done and returns how many tasks it changed.
1-- sgl.query(CompleteTask, asyncexec)
2-- sgl.query(CompleteTask, execrows)
2ALTER TABLE tasks UPDATE completed = 1 WHERE id = {id:UInt64};
3UPDATE tasks SET completed = true WHERE id = $1;
GetTaskonly ClickHouse
PostgreSQL · not in this version
ClickHouse · db/queries/tasks.sql
1-- sgl.query(GetTask, one)
2SELECT id, title, completed, created_at FROM tasks WHERE id = {id:UInt64};

What sgl generates

CreateTaskdiffers
PostgreSQL
ClickHouse
1func (queries *Queries) CreateTask(ctx context.Context, title string) (CreateTaskRow, error)
1func (queries *Queries) CreateTask(ctx context.Context, params CreateTaskParams) error
2
2
3type CreateTaskRow struct {
3type CreateTaskParams struct {
4 ID int64 `json:"id"`
4 ID uint64
5 Title string `json:"title"`
5 Title string
6 Completed bool `json:"completed"`
7 CreatedAt time.Time `json:"created_at"`
8}
6}
ListTasksdiffers
PostgreSQL
ClickHouse
1func (queries *Queries) ListTasks(ctx context.Context) ([]ListTasksRow, error)
1func (queries *Queries) ListTasks(ctx context.Context) ([]ListTasksRow, error)
2
2
3type ListTasksRow struct {
3type ListTasksRow struct {
4 ID int64 `json:"id"`
4 ID uint64 `json:"id"`
5 Title string `json:"title"`
5 Title string `json:"title"`
6 Completed bool `json:"completed"`
6 Completed uint8 `json:"completed"`
7 CreatedAt time.Time `json:"created_at"`
7 CreatedAt time.Time `json:"created_at"`
8}
8}
CompleteTaskdiffers
PostgreSQL
ClickHouse
1func (queries *Queries) CompleteTask(ctx context.Context, id int64) (int64, error)
1func (queries *Queries) CompleteTask(ctx context.Context, id uint64) error
GetTaskonly ClickHouse
PostgreSQL · not in this version
ClickHouse
1func (queries *Queries) GetTask(ctx context.Context, id uint64) (GetTaskRow, error)
2
3type GetTaskRow struct {
4 ID uint64 `json:"id"`
5 Title string `json:"title"`
6 Completed uint8 `json:"completed"`
7 CreatedAt time.Time `json:"created_at"`
8}

The program

example.godiffers
PostgreSQL
ClickHouse
1package main
1package main
2
2
3import (
3import (
4 "context"
4 "context"
5 "database/sql"
5 "database/sql"
6 "fmt"
6 "fmt"
7 "io"
7 "io"
8
8
9 "seagull.sh/seagull/examples/postgres/001_first_query/internal/store"
9 "seagull.sh/seagull/examples/clickhouse/001_first_query/internal/store"
10)
10)
11
11
12// run adds two tasks, completes the first and lists them all, through the methods sgl
12// run adds two tasks, completes the first and lists them all, through the methods sgl
13// generated from db/queries/tasks.sql. The id column is BIGSERIAL, so ID is int64, and
13// generated from db/queries/tasks.sql.
14// created_at is TIMESTAMPTZ, so CreatedAt is a time.Time; the example leaves it out of
15// the output, as it changes on every run.
16//
14//
17// sgl.yaml sets go.doc_comments, so the comment above each query in tasks.sql becomes its
15// ClickHouse has no auto-increment and no RETURNING, so the caller chooses each task's id
18// method's doc comment, and the migration's COMMENT ON TABLE and COMMENT ON COLUMN become
16// and reads a task back with GetTask. CompleteTask uses ALTER TABLE ... UPDATE, which
19// the doc comments of the Tasks model and its Completed field: open internal/store to see
17// queues a mutation that the server applies in the background, so the query is declared
20// them, or hover over queries.CreateTask in an editor.
18// asyncexec and returns only an error (concept 36 explains why). The connection sets
19// mutations_sync=2, which makes the server finish the mutation before it replies, so the
20// list below already shows the task completed.
21//
21//
22// Takes database (*sql.DB) which is a migrated database, opened with pgx's database/sql
22// Takes database (*sql.DB) which is a migrated database.
23// driver.
24// Takes output (io.Writer) which receives the task list.
23// Takes output (io.Writer) which receives the task list.
25//
24//
26// Returns error when a query fails.
25// Returns error when a query fails.
27func run(ctx context.Context, database *sql.DB, output io.Writer) error {
26func run(ctx context.Context, database *sql.DB, output io.Writer) error {
28 queries := store.New(database)
27 queries := store.New(database)
29
28
30 feed, err := queries.CreateTask(ctx, "Feed the seagulls")
29 tasks := []store.CreateTaskParams{
31 if err != nil {
30 {ID: 1, Title: "Feed the seagulls"},
32 return fmt.Errorf("creating a task: %w", err)
31 {ID: 2, Title: "Count the chips"},
33 }
32 }
34 if _, err := queries.CreateTask(ctx, "Count the chips"); err != nil {
33 for _, task := range tasks {
35 return fmt.Errorf("creating a task: %w", err)
34 if err := queries.CreateTask(ctx, task); err != nil {
35 return fmt.Errorf("creating task %d: %w", task.ID, err)
36 }
36 }
37 }
37
38
38 completed, err := queries.CompleteTask(ctx, feed.ID)
39 feed, err := queries.GetTask(ctx, 1)
39 if err != nil {
40 if err != nil {
41 return fmt.Errorf("getting task 1: %w", err)
42 }
43 fmt.Fprintf(output, "created task %d, %s\n", feed.ID, feed.Title)
44
45 if err := queries.CompleteTask(ctx, feed.ID); err != nil {
40 return fmt.Errorf("completing task %d: %w", feed.ID, err)
46 return fmt.Errorf("completing task %d: %w", feed.ID, err)
41 }
47 }
42 fmt.Fprintf(output, "completed %d task\n", completed)
48 fmt.Fprintf(output, "completed task %d\n", feed.ID)
43
49
44 tasks, err := queries.ListTasks(ctx)
50 listed, err := queries.ListTasks(ctx)
45 if err != nil {
51 if err != nil {
46 return fmt.Errorf("listing tasks: %w", err)
52 return fmt.Errorf("listing tasks: %w", err)
47 }
53 }
48 for _, task := range tasks {
54 for _, task := range listed {
49 fmt.Fprintf(output, "%d\t%-18s completed=%t\n", task.ID, task.Title, task.Completed)
55 fmt.Fprintf(output, "%d\t%-18s completed=%d\n", task.ID, task.Title, task.Completed)
50 }
56 }
51 return nil
57 return nil
52}
58}

Go type differences

The same SQL types map to different Go types, because each database reports them differently.

QueryFieldPostgreSQLClickHouse
ListTaskscolumn idint64uint64
ListTaskscolumn completedbooluint8
CompleteTaskparameter idint64uint64