Compare · 023

Transactions: DuckDB and SQLite

Every file of the DuckDB and SQLite versions side by side, with the lines that differ marked. 4 parameter or column types differ in Go.

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Configuration

sgl.yamldiffers

DuckDB
SQLite
1version: 1
1version: 1
2
2
3databases:
3databases:
4  - name: bank
4  - name: bank
5    dialect: duckdb
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

Migrations

db/migrations/0001_accounts.up.sqldiffers

DuckDB
SQLite
1CREATE SEQUENCE account_ids;
2
3CREATE TABLE accounts (
1CREATE TABLE accounts (
4    id      BIGINT  PRIMARY KEY DEFAULT nextval('account_ids'),
2    id      INTEGER PRIMARY KEY,
5    owner   VARCHAR NOT NULL,
3    owner   TEXT    NOT NULL,
6    balance INTEGER NOT NULL CHECK (balance >= 0)
4    balance INTEGER NOT NULL CHECK (balance >= 0)
7);
5);

db/migrations/0001_accounts.down.sqldiffers

DuckDB
SQLite
1DROP TABLE accounts;
1DROP TABLE accounts;
2DROP SEQUENCE account_ids;

Queries

OpenAccountdiffers

DuckDB · db/queries/accounts.sql
SQLite · db/queries/accounts.sql
1-- sgl.query(OpenAccount, one)
1-- sgl.query(OpenAccount, one)
2INSERT INTO accounts (owner, balance) VALUES ($1, $2) RETURNING id;
2INSERT INTO accounts (owner, balance) VALUES (?, ?) RETURNING id;

Depositidentical

DuckDB · db/queries/accounts.sql
SQLite · db/queries/accounts.sql
1-- sgl.query(Deposit, exec)
1-- sgl.query(Deposit, exec)
2UPDATE accounts SET balance = balance + :amount WHERE id = :id;
2UPDATE accounts SET balance = balance + :amount WHERE id = :id;

Withdrawidentical

DuckDB · db/queries/accounts.sql
SQLite · db/queries/accounts.sql
1-- sgl.query(Withdraw, exec)
1-- sgl.query(Withdraw, exec)
2UPDATE accounts SET balance = balance - :amount WHERE id = :id;
2UPDATE accounts SET balance = balance - :amount WHERE id = :id;

ListAccountsidentical

DuckDB · db/queries/accounts.sql
SQLite · db/queries/accounts.sql
1-- sgl.query(ListAccounts, many)
1-- sgl.query(ListAccounts, many)
2SELECT id, owner, balance FROM accounts ORDER BY id;
2SELECT id, owner, balance FROM accounts ORDER BY id;

What sgl generates

OpenAccountdiffers

DuckDB
SQLite
1func (queries *Queries) OpenAccount(ctx context.Context, params OpenAccountParams) (OpenAccountRow, error)
1func (queries *Queries) OpenAccount(ctx context.Context, params OpenAccountParams) (OpenAccountRow, error)
2
2
3type OpenAccountParams struct {
3type OpenAccountParams struct {
4	Owner   string
4	Owner   string
5	Balance int32
5	Balance int64
6}
6}
7
7
8type OpenAccountRow struct {
8type OpenAccountRow struct {
9	ID int64 `json:"id"`
9	ID int64 `json:"id"`
10}
10}

Depositdiffers

DuckDB
SQLite
1func (queries *Queries) Deposit(ctx context.Context, params DepositParams) error
1func (queries *Queries) Deposit(ctx context.Context, params DepositParams) error
2
2
3type DepositParams struct {
3type DepositParams struct {
4	Amount int32
4	Amount int64
5	ID     int64
5	ID     int64
6}
6}

Withdrawdiffers

DuckDB
SQLite
1func (queries *Queries) Withdraw(ctx context.Context, params WithdrawParams) error
1func (queries *Queries) Withdraw(ctx context.Context, params WithdrawParams) error
2
2
3type WithdrawParams struct {
3type WithdrawParams struct {
4	Amount int32
4	Amount int64
5	ID     int64
5	ID     int64
6}
6}

ListAccountsdiffers

DuckDB
SQLite
1func (queries *Queries) ListAccounts(ctx context.Context) ([]ListAccountsRow, error)
1func (queries *Queries) ListAccounts(ctx context.Context) ([]ListAccountsRow, error)
2
2
3type ListAccountsRow struct {
3type ListAccountsRow struct {
4	ID      int64  `json:"id"`
4	ID      int64  `json:"id"`
5	Owner   string `json:"owner"`
5	Owner   string `json:"owner"`
6	Balance int32  `json:"balance"`
6	Balance int64  `json:"balance"`
7}
7}

The program

example.godiffers

DuckDB
SQLite
1package main
1package main
2
2
3import (
3import (
4	"context"
4	"context"
5	"database/sql"
5	"database/sql"
6	"errors"
6	"errors"
7	"fmt"
7	"fmt"
8	"io"
8	"io"
9
9
10	"seagull.sh/seagull/examples/duckdb/023_transactions/internal/store"
10	"seagull.sh/seagull/examples/sqlite/023_transactions/internal/store"
11)
11)
12
12
13// run opens two accounts in a transaction it manages itself, then makes two transfers
13// run opens two accounts in a transaction it manages itself, then makes two transfers
14// with RunInTx: one commits, and one breaks the balance check part-way and rolls back.
14// with RunInTx: one commits, and one breaks the balance check part-way and rolls back.
15//
15//
16// Takes database (*sql.DB) which is a migrated database.
16// Takes database (*sql.DB) which is a migrated database.
17// Takes output (io.Writer) which receives each step and the balances.
17// Takes output (io.Writer) which receives each step and the balances.
18//
18//
19// Returns error when a query fails other than as the example expects.
19// Returns error when a query fails other than as the example expects.
20func run(ctx context.Context, database *sql.DB, output io.Writer) error {
20func run(ctx context.Context, database *sql.DB, output io.Writer) error {
21	queries := store.New(database)
21	queries := store.New(database)
22
22
23	pip, gull, err := openAccounts(ctx, database, queries)
23	pip, gull, err := openAccounts(ctx, database, queries)
24	if err != nil {
24	if err != nil {
25		return fmt.Errorf("opening accounts: %w", err)
25		return fmt.Errorf("opening accounts: %w", err)
26	}
26	}
27	fmt.Fprintln(output, "opened accounts for Pip and Gull: committed")
27	fmt.Fprintln(output, "opened accounts for Pip and Gull: committed")
28	if err := printBalances(ctx, queries, output); err != nil {
28	if err := printBalances(ctx, queries, output); err != nil {
29		return err
29		return err
30	}
30	}
31
31
32	if err := transfer(ctx, database, queries, pip, gull, 1500); err != nil {
32	if err := transfer(ctx, database, queries, pip, gull, 1500); err != nil {
33		return fmt.Errorf("first transfer: %w", err)
33		return fmt.Errorf("first transfer: %w", err)
34	}
34	}
35	fmt.Fprintln(output, "transferred 1500 from Pip to Gull: committed")
35	fmt.Fprintln(output, "transferred 1500 from Pip to Gull: committed")
36	if err := printBalances(ctx, queries, output); err != nil {
36	if err := printBalances(ctx, queries, output); err != nil {
37		return err
37		return err
38	}
38	}
39
39
40	// Gull holds 3500, so this transfer credits Pip and then fails the CHECK constraint when
40	// Gull holds 3500, so this transfer credits Pip and then fails the CHECK constraint when
41	// it debits Gull. RunInTx rolls back, and the credit to Pip that had already run is
41	// it debits Gull. RunInTx rolls back, and the credit to Pip that had already run is
42	// undone with it.
42	// undone with it.
43	err = transfer(ctx, database, queries, gull, pip, 9000)
43	err = transfer(ctx, database, queries, gull, pip, 9000)
44	if err == nil {
44	if err == nil {
45		return errors.New("an overdrawing transfer committed")
45		return errors.New("an overdrawing transfer committed")
46	}
46	}
47	fmt.Fprintf(output, "transferred 9000 from Gull to Pip: rolled back (%v)\n", err)
47	fmt.Fprintf(output, "transferred 9000 from Gull to Pip: rolled back (%v)\n", err)
48	return printBalances(ctx, queries, output)
48	return printBalances(ctx, queries, output)
49}
49}
50
50
51// openAccounts opens both accounts in one transaction that it begins and commits itself.
51// openAccounts opens both accounts in one transaction that it begins and commits itself.
52// WithTx returns a copy of queries bound to that transaction, which suits a transaction
52// WithTx returns a copy of queries bound to that transaction, which suits a transaction
53// begun with options or shared with code that does not use Seagull.
53// begun with options or shared with code that does not use Seagull.
54//
54//
55// Takes database (*sql.DB) which begins the transaction.
55// Takes database (*sql.DB) which begins the transaction.
56// Takes queries (*store.Queries) which are bound to it.
56// Takes queries (*store.Queries) which are bound to it.
57//
57//
58// Returns pipID (int64) which is Pip's account ID.
58// Returns pipID (int64) which is Pip's account ID.
59// Returns gullID (int64) which is Gull's account ID.
59// Returns gullID (int64) which is Gull's account ID.
60// Returns err (error) when an account cannot be opened or the commit fails.
60// Returns err (error) when an account cannot be opened or the commit fails.
61func openAccounts(ctx context.Context, database *sql.DB, queries *store.Queries) (pipID, gullID int64, err error) {
61func openAccounts(ctx context.Context, database *sql.DB, queries *store.Queries) (pipID, gullID int64, err error) {
62	transaction, err := database.BeginTx(ctx, nil)
62	transaction, err := database.BeginTx(ctx, nil)
63	if err != nil {
63	if err != nil {
64		return 0, 0, err
64		return 0, 0, err
65	}
65	}
66	// Rollback after a successful Commit does nothing, so deferring it covers every early
66	// Rollback after a successful Commit does nothing, so deferring it covers every early
67	// return.
67	// return.
68	defer func() { _ = transaction.Rollback() }()
68	defer func() { _ = transaction.Rollback() }()
69
69
70	inTransaction := queries.WithTx(transaction)
70	inTransaction := queries.WithTx(transaction)
71	pip, err := inTransaction.OpenAccount(ctx, store.OpenAccountParams{Owner: "Pip", Balance: 5000})
71	pip, err := inTransaction.OpenAccount(ctx, store.OpenAccountParams{Owner: "Pip", Balance: 5000})
72	if err != nil {
72	if err != nil {
73		return 0, 0, err
73		return 0, 0, err
74	}
74	}
75	gull, err := inTransaction.OpenAccount(ctx, store.OpenAccountParams{Owner: "Gull", Balance: 2000})
75	gull, err := inTransaction.OpenAccount(ctx, store.OpenAccountParams{Owner: "Gull", Balance: 2000})
76	if err != nil {
76	if err != nil {
77		return 0, 0, err
77		return 0, 0, err
78	}
78	}
79	return pip.ID, gull.ID, transaction.Commit()
79	return pip.ID, gull.ID, transaction.Commit()
80}
80}
81
81
82// transfer moves an amount between two accounts with RunInTx, which begins a transaction,
82// transfer moves an amount between two accounts with RunInTx, which begins a transaction,
83// passes fn a Queries bound to it, and commits when fn returns nil or rolls back when it
83// passes fn a Queries bound to it, and commits when fn returns nil or rolls back when it
84// returns an error.
84// returns an error.
85//
85//
86// Takes database (*sql.DB) which begins the transaction.
86// Takes database (*sql.DB) which begins the transaction.
87// Takes queries (*store.Queries) which run the transfer.
87// Takes queries (*store.Queries) which run the transfer.
88// Takes from (int64) which is the account to debit.
88// Takes from (int64) which is the account to debit.
89// Takes to (int64) which is the account to credit.
89// Takes to (int64) which is the account to credit.
90// Takes amount (int32) which is the sum to move, in pence.
90// Takes amount (int64) which is the sum to move, in pence.
91//
91//
92// Returns error when either update fails; the transaction is then rolled back.
92// Returns error when either update fails; the transaction is then rolled back.
93func transfer(ctx context.Context, database *sql.DB, queries *store.Queries, from, to int64, amount int32) error {
93func transfer(ctx context.Context, database *sql.DB, queries *store.Queries, from, to, amount int64) error {
94	return queries.RunInTx(ctx, database, func(inTransaction *store.Queries) error {
94	return queries.RunInTx(ctx, database, func(inTransaction *store.Queries) error {
95		if err := inTransaction.Deposit(ctx, store.DepositParams{Amount: amount, ID: to}); err != nil {
95		if err := inTransaction.Deposit(ctx, store.DepositParams{Amount: amount, ID: to}); err != nil {
96			return err
96			return err
97		}
97		}
98		return inTransaction.Withdraw(ctx, store.WithdrawParams{Amount: amount, ID: from})
98		return inTransaction.Withdraw(ctx, store.WithdrawParams{Amount: amount, ID: from})
99	})
99	})
100}
100}
101
101
102// printBalances writes every account's balance on one line.
102// printBalances writes every account's balance on one line.
103//
103//
104// Takes queries (*store.Queries) which read the accounts.
104// Takes queries (*store.Queries) which read the accounts.
105// Takes output (io.Writer) which receives the line.
105// Takes output (io.Writer) which receives the line.
106//
106//
107// Returns error when the accounts cannot be listed.
107// Returns error when the accounts cannot be listed.
108func printBalances(ctx context.Context, queries *store.Queries, output io.Writer) error {
108func printBalances(ctx context.Context, queries *store.Queries, output io.Writer) error {
109	accounts, err := queries.ListAccounts(ctx)
109	accounts, err := queries.ListAccounts(ctx)
110	if err != nil {
110	if err != nil {
111		return fmt.Errorf("listing accounts: %w", err)
111		return fmt.Errorf("listing accounts: %w", err)
112	}
112	}
113	fmt.Fprint(output, "  balances:")
113	fmt.Fprint(output, "  balances:")
114	for _, account := range accounts {
114	for _, account := range accounts {
115		fmt.Fprintf(output, " %s %d", account.Owner, account.Balance)
115		fmt.Fprintf(output, " %s %d", account.Owner, account.Balance)
116	}
116	}
117	fmt.Fprintln(output)
117	fmt.Fprintln(output)
118	return nil
118	return nil
119}
119}

Go type differences

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

Query	Field	DuckDB	SQLite
OpenAccount	parameter `balance`	`int32`	`int64`
Deposit	parameter `amount`	`int32`	`int64`
Withdraw	parameter `amount`	`int32`	`int64`
ListAccounts	column `balance`	`int32`	`int64`