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Rows back from INSERT, UPDATE and DELETE: TimescaleDB and SQLite

Every file of the TimescaleDB and SQLite versions side by side, with the lines that differ marked.

Compare TimescaleDB withSQLitePostgreSQLCockroachDBMariaDBDuckDB

Configuration

sgl.yamldiffers
TimescaleDB
SQLite
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: orders
4 - name: orders
5 dialect: postgres
5 dialect: sqlite
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 migrate:
13 dsn: ${env:DATABASE_URL}

Migrations

db/migrations/0001_orders.up.sqldiffers
TimescaleDB
SQLite
1CREATE TABLE orders (
1CREATE TABLE orders (
2 id BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
2 id INTEGER PRIMARY KEY,
3 item TEXT NOT NULL,
3 item TEXT NOT NULL,
4 quantity BIGINT NOT NULL DEFAULT 1,
4 quantity INTEGER NOT NULL DEFAULT 1,
5 status TEXT NOT NULL DEFAULT 'waiting'
5 status TEXT NOT NULL DEFAULT 'waiting'
6);
6);
db/migrations/0001_orders.down.sqlidentical
TimescaleDB
SQLite
1DROP TABLE orders;
1DROP TABLE orders;

Queries

PlaceOrderdiffers
TimescaleDB · db/queries/orders.sql
SQLite · db/queries/orders.sql
1-- sgl.query(PlaceOrder, one)
1-- sgl.query(PlaceOrder, one)
2INSERT INTO orders (item, quantity) VALUES ($1, $2)
2INSERT INTO orders (item, quantity) VALUES (?, ?)
3RETURNING id, status, quantity * 250 AS price_pence;
3RETURNING id, status, quantity * 250 AS price_pence;
ServeWaitingOrdersdiffers
TimescaleDB · db/queries/orders.sql
SQLite · db/queries/orders.sql
1-- sgl.query(ServeWaitingOrders, many, row: OrderLine)
1-- sgl.query(ServeWaitingOrders, many)
2UPDATE orders SET status = 'served' WHERE status = 'waiting'
2UPDATE orders SET status = 'served' WHERE status = 'waiting'
3RETURNING id, item, quantity;
3RETURNING id, item, quantity;
CancelOrderdiffers
TimescaleDB · db/queries/orders.sql
SQLite · db/queries/orders.sql
1-- sgl.query(CancelOrder, one, row: OrderLine)
1-- sgl.query(CancelOrder, one)
2DELETE FROM orders WHERE id = $1 AND status = 'waiting'
2DELETE FROM orders WHERE id = ? AND status = 'waiting'
3RETURNING id, item, quantity;
3RETURNING item, quantity;
ReopenOrderonly TimescaleDB
TimescaleDB · db/queries/orders.sql
SQLite · not in this version
1-- sgl.query(ReopenOrder, one, model: orders)
2UPDATE orders SET status = 'waiting' WHERE id = $1
3RETURNING *;

What sgl generates

PlaceOrderidentical
TimescaleDB
SQLite
1func (queries *Queries) PlaceOrder(ctx context.Context, params PlaceOrderParams) (PlaceOrderRow, error)
1func (queries *Queries) PlaceOrder(ctx context.Context, params PlaceOrderParams) (PlaceOrderRow, error)
2
2
3type PlaceOrderParams struct {
3type PlaceOrderParams struct {
4 Item string
4 Item string
5 Quantity int64
5 Quantity int64
6}
6}
7
7
8type PlaceOrderRow struct {
8type PlaceOrderRow struct {
9 ID int64 `json:"id"`
9 ID int64 `json:"id"`
10 Status string `json:"status"`
10 Status string `json:"status"`
11 PricePence int64 `json:"price_pence"`
11 PricePence int64 `json:"price_pence"`
12}
12}
ServeWaitingOrdersdiffers
TimescaleDB
SQLite
1func (queries *Queries) ServeWaitingOrders(ctx context.Context) ([]OrderLine, error)
1func (queries *Queries) ServeWaitingOrders(ctx context.Context) ([]ServeWaitingOrdersRow, error)
2
2
3type OrderLine struct {
3type ServeWaitingOrdersRow struct {
4 ID int64 `json:"id"`
4 ID int64 `json:"id"`
5 Item string `json:"item"`
5 Item string `json:"item"`
6 Quantity int64 `json:"quantity"`
6 Quantity int64 `json:"quantity"`
7}
7}
CancelOrderdiffers
TimescaleDB
SQLite
1func (queries *Queries) CancelOrder(ctx context.Context, id int64) (OrderLine, error)
1func (queries *Queries) CancelOrder(ctx context.Context, id int64) (CancelOrderRow, error)
2
2
3type OrderLine struct {
3type CancelOrderRow struct {
4 ID int64 `json:"id"`
5 Item string `json:"item"`
4 Item string `json:"item"`
6 Quantity int64 `json:"quantity"`
5 Quantity int64 `json:"quantity"`
7}
6}
ReopenOrderonly TimescaleDB
TimescaleDB
SQLite · not in this version
1func (queries *Queries) ReopenOrder(ctx context.Context, id int64) (Orders, error)
2
3type Orders struct {
4 ID int64 `json:"id"`
5 Item string `json:"item"`
6 Quantity int64 `json:"quantity"`
7 Status string `json:"status"`
8}

The program

example.godiffers
TimescaleDB
SQLite
1package main
1package main
2
2
3import (
3import (
4 "cmp"
4 "cmp"
5 "context"
5 "context"
6 "database/sql"
6 "database/sql"
7 "errors"
7 "errors"
8 "fmt"
8 "fmt"
9 "io"
9 "io"
10 "slices"
10 "slices"
11
11
12 "seagull.sh/seagull/examples/postgres/020_returning/internal/store"
12 "seagull.sh/seagull/examples/sqlite/020_returning/internal/store"
13)
13)
14
14
15// run places three orders, cancels one, serves the rest, tries to cancel an order that
15// run places three orders, cancels one, serves the rest and then tries to cancel an order
16// has already been served and reopens one. Every write uses RETURNING, so the rows it
16// that has already been served. Every write uses RETURNING, so the rows it touched come
17// touched come back from the same statement.
17// back from the same statement.
18//
19// A query reads its rows into a struct of its own, such as PlaceOrderRow, unless its
20// header names another. ServeWaitingOrders and CancelOrder return the same three columns,
21// so both name the row type OrderLine with row: OrderLine, and the generated code
22// declares that struct once for the two. ReopenOrder returns the whole order with
23// RETURNING *, so model: orders reads it into Orders, the table's model in models.go,
24// rather than a ReopenOrderRow with the same fields.
25//
18//
26// Takes database (*sql.DB) which is a migrated database.
19// Takes database (*sql.DB) which is a migrated database.
27// Takes output (io.Writer) which receives what each write returned.
20// Takes output (io.Writer) which receives what each write returned.
28//
21//
29// Returns error when a query fails.
22// Returns error when a query fails.
30func run(ctx context.Context, database *sql.DB, output io.Writer) error {
23func run(ctx context.Context, database *sql.DB, output io.Writer) error {
31 queries := store.New(database)
24 queries := store.New(database)
32
25
33 // PlaceOrder is an INSERT declared as one: the id the identity column assigned, the
26 // PlaceOrder is an INSERT declared as one: the id SQLite assigned, the default status
34 // default status and a computed price all come back in a PlaceOrderRow.
27 // and a computed price all come back in a PlaceOrderRow.
35 orders := []store.PlaceOrderParams{
28 orders := []store.PlaceOrderParams{
36 {Item: "chips", Quantity: 2},
29 {Item: "chips", Quantity: 2},
37 {Item: "battered cod", Quantity: 1},
30 {Item: "battered cod", Quantity: 1},
38 {Item: "mushy peas", Quantity: 1},
31 {Item: "mushy peas", Quantity: 1},
39 }
32 }
40 for _, order := range orders {
33 for _, order := range orders {
41 placed, err := queries.PlaceOrder(ctx, order)
34 placed, err := queries.PlaceOrder(ctx, order)
42 if err != nil {
35 if err != nil {
43 return fmt.Errorf("placing an order for %s: %w", order.Item, err)
36 return fmt.Errorf("placing an order for %s: %w", order.Item, err)
44 }
37 }
45 fmt.Fprintf(output, "placed #%d %-12s %s, %dp\n", placed.ID, order.Item, placed.Status, placed.PricePence)
38 fmt.Fprintf(output, "placed #%d %-12s %s, %dp\n", placed.ID, order.Item, placed.Status, placed.PricePence)
46 }
39 }
47
40
48 // CancelOrder is a DELETE declared as one, so it returns the row it removed.
41 // CancelOrder is a DELETE declared as one, so it returns the row it removed.
49 cancelled, err := queries.CancelOrder(ctx, 2)
42 cancelled, err := queries.CancelOrder(ctx, 2)
50 if err != nil {
43 if err != nil {
51 return fmt.Errorf("cancelling order 2: %w", err)
44 return fmt.Errorf("cancelling order 2: %w", err)
52 }
45 }
53 fmt.Fprintf(output, "cancelled #2 %-12s x%d\n", cancelled.Item, cancelled.Quantity)
46 fmt.Fprintf(output, "cancelled #2 %-12s x%d\n", cancelled.Item, cancelled.Quantity)
54
47
55 // ServeWaitingOrders is an UPDATE declared as many: one row for every order it changed.
48 // ServeWaitingOrders is an UPDATE declared as many: one row for every order it changed.
56 // PostgreSQL does not promise an order for RETURNING rows, so sort them.
49 // SQLite does not promise an order for RETURNING rows, so sort them.
57 served, err := queries.ServeWaitingOrders(ctx)
50 served, err := queries.ServeWaitingOrders(ctx)
58 if err != nil {
51 if err != nil {
59 return fmt.Errorf("serving orders: %w", err)
52 return fmt.Errorf("serving orders: %w", err)
60 }
53 }
61 slices.SortFunc(served, func(a, b store.OrderLine) int { return cmp.Compare(a.ID, b.ID) })
54 slices.SortFunc(served, func(a, b store.ServeWaitingOrdersRow) int { return cmp.Compare(a.ID, b.ID) })
62 for _, order := range served {
55 for _, order := range served {
63 fmt.Fprintf(output, "served #%d %-12s x%d\n", order.ID, order.Item, order.Quantity)
56 fmt.Fprintf(output, "served #%d %-12s x%d\n", order.ID, order.Item, order.Quantity)
64 }
57 }
65
58
66 // A one query that matches no row returns sql.ErrNoRows, writes included: order 1 has
59 // A one query that matches no row returns sql.ErrNoRows, writes included: order 1 has
67 // been served, so the DELETE's WHERE clause no longer matches it.
60 // been served, so the DELETE's WHERE clause no longer matches it.
68 _, err = queries.CancelOrder(ctx, 1)
61 _, err = queries.CancelOrder(ctx, 1)
69 switch {
62 if errors.Is(err, sql.ErrNoRows) {
70 case errors.Is(err, sql.ErrNoRows):
71 fmt.Fprintln(output, "cannot cancel #1: it is no longer waiting")
63 fmt.Fprintln(output, "cannot cancel #1: it is no longer waiting")
72 case err != nil:
64 return nil
73 return fmt.Errorf("cancelling order 1: %w", err)
74 default:
75 return errors.New("cancelled an order that had already been served")
76 }
65 }
77
78 reopened, err := queries.ReopenOrder(ctx, 3)
79 if err != nil {
66 if err != nil {
80 return fmt.Errorf("reopening order 3: %w", err)
67 return fmt.Errorf("cancelling order 1: %w", err)
81 }
68 }
82 fmt.Fprintf(output, "reopened #%d %-12s x%d, %s\n", reopened.ID, reopened.Item, reopened.Quantity, reopened.Status)
69 return errors.New("cancelled an order that had already been served")
83 return nil
84}
70}