Compare · 022

Batch and copyfrom: MariaDB and DuckDB

Every file of the MariaDB and DuckDB versions side by side, with the lines that differ marked.

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Configuration

sgl.yamldiffers
MariaDB
DuckDB
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: tides
4 - name: tides
5 dialect: mysql
5 dialect: duckdb
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_readings.up.sqldiffers
MariaDB
DuckDB
1CREATE SEQUENCE reading_ids;
2
1CREATE TABLE readings (
3CREATE TABLE readings (
2 id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
4 id BIGINT PRIMARY KEY DEFAULT nextval('reading_ids'),
3 station VARCHAR(20) NOT NULL,
5 station VARCHAR NOT NULL,
4 minute INT NOT NULL,
6 minute INTEGER NOT NULL,
5 height_cm INT NOT NULL,
7 height_cm INTEGER NOT NULL,
6 note VARCHAR(50)
8 note VARCHAR
7);
9);
db/migrations/0001_readings.down.sqldiffers
MariaDB
DuckDB
1DROP TABLE readings;
1DROP TABLE readings;
2DROP SEQUENCE reading_ids;

Queries

RecordReadingsdiffers
MariaDB · db/queries/readings.sql
DuckDB · db/queries/readings.sql
1-- sgl.query(RecordReadings, batch)
1-- sgl.query(RecordReadings, batch)
2INSERT INTO readings (station, minute, height_cm, note) VALUES (?, ?, ?, ?);
2INSERT INTO readings (station, minute, height_cm, note) VALUES ($1, $2, $3, $4);
SummariseReadingsidentical
MariaDB · db/queries/readings.sql
DuckDB · db/queries/readings.sql
1-- sgl.query(SummariseReadings, many)
1-- sgl.query(SummariseReadings, many)
2SELECT station, COUNT(*) AS readings, COUNT(note) AS noted
2SELECT station, COUNT(*) AS readings, COUNT(note) AS noted
3FROM readings
3FROM readings
4GROUP BY station
4GROUP BY station
5ORDER BY station;
5ORDER BY station;

What sgl generates

RecordReadingsidentical
MariaDB
DuckDB
1func (queries *Queries) RecordReadings(ctx context.Context, params []RecordReadingsParams) error
1func (queries *Queries) RecordReadings(ctx context.Context, params []RecordReadingsParams) error
2
2
3type RecordReadingsParams struct {
3type RecordReadingsParams struct {
4 Station string
4 Station string
5 Minute int32
5 Minute int32
6 HeightCm int32
6 HeightCm int32
7 Note *string
7 Note *string
8}
8}
SummariseReadingsidentical
MariaDB
DuckDB
1func (queries *Queries) SummariseReadings(ctx context.Context) ([]SummariseReadingsRow, error)
1func (queries *Queries) SummariseReadings(ctx context.Context) ([]SummariseReadingsRow, error)
2
2
3type SummariseReadingsRow struct {
3type SummariseReadingsRow struct {
4 Station string `json:"station"`
4 Station string `json:"station"`
5 Readings int64 `json:"readings"`
5 Readings int64 `json:"readings"`
6 Noted int64 `json:"noted"`
6 Noted int64 `json:"noted"`
7}
7}

The program

example.godiffers
MariaDB
DuckDB
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/mysql/022_bulk_writes/internal/store"
9 "seagull.sh/seagull/examples/duckdb/022_bulk_writes/internal/store"
10)
10)
11
11
12const (
12const (
13 // minutesPerWeek is how many readings each tide gauge takes in a week.
13 // minutesPerWeek is how many readings each tide gauge takes in a week, one a minute.
14 minutesPerWeek = 7 * 24 * 60
14 minutesPerWeek = 7 * 24 * 60
15)
15)
16
16
17// statementCounter is a store.DBTX that counts the statements sent through ExecContext.
17// statementCounter is a store.DBTX that counts the statements sent through ExecContext.
18// QueryContext and QueryRowContext come from the embedded *sql.DB.
18// QueryContext and QueryRowContext come from the embedded *sql.DB.
19type statementCounter struct {
19type statementCounter struct {
20 *sql.DB
20 *sql.DB
21
21
22 // statements is how many times ExecContext has been called.
22 // statements is how many times ExecContext has been called.
23 statements int
23 statements int
24}
24}
25
25
26// ExecContext counts the statement, then runs it on the database.
26// ExecContext counts the statement, then runs it on the database.
27//
27//
28// Takes query (string) which is the SQL to run.
28// Takes query (string) which is the SQL to run.
29// Takes arguments (...any) which are its bind values.
29// Takes arguments (...any) which are its bind values.
30//
30//
31// Returns sql.Result which is the database's result.
31// Returns sql.Result which is the database's result.
32// Returns error when the statement fails.
32// Returns error when the statement fails.
33func (counter *statementCounter) ExecContext(ctx context.Context, query string, arguments ...any) (sql.Result, error) {
33func (counter *statementCounter) ExecContext(ctx context.Context, query string, arguments ...any) (sql.Result, error) {
34 counter.statements++
34 counter.statements++
35 return counter.DB.ExecContext(ctx, query, arguments...)
35 return counter.DB.ExecContext(ctx, query, arguments...)
36}
36}
37
37
38// run records a week of readings from two tide gauges in one batch call, shows how many
38// run records a week of readings from two tide gauges in one batch call, shows how many
39// INSERT statements that took, and summarises what landed in the table.
39// INSERT statements that took, and summarises what landed in the table.
40//
40//
41// Takes database (*sql.DB) which is a migrated database.
41// Takes database (*sql.DB) which is a migrated database.
42// Takes output (io.Writer) which receives the statement counts and the summary.
42// Takes output (io.Writer) which receives the statement counts and the summary.
43//
43//
44// Returns error when a query fails.
44// Returns error when a query fails.
45func run(ctx context.Context, database *sql.DB, output io.Writer) error {
45func run(ctx context.Context, database *sql.DB, output io.Writer) error {
46 counter := &statementCounter{DB: database}
46 counter := &statementCounter{DB: database}
47 queries := store.New(counter)
47 queries := store.New(counter)
48
48
49 // An empty batch is a no-op: nothing is sent to the database.
49 // An empty batch is a no-op: nothing is sent to the database.
50 if err := queries.RecordReadings(ctx, nil); err != nil {
50 if err := queries.RecordReadings(ctx, nil); err != nil {
51 return fmt.Errorf("recording no readings: %w", err)
51 return fmt.Errorf("recording no readings: %w", err)
52 }
52 }
53 fmt.Fprintf(output, "0 readings sent in %d statements\n", counter.statements)
53 fmt.Fprintf(output, "0 readings sent in %d statements\n", counter.statements)
54
54
55 readings := tideReadings("harbour", "pier")
55 readings := tideReadings("harbour", "pier")
56
56
57 // A batch query takes a slice of Params, one per row. On database/sql the generated
57 // A batch query takes a slice of Params, one per row. On database/sql the generated
58 // method writes them as multi-row INSERTs, chunked so that no statement binds more than
58 // method writes them as multi-row INSERTs, chunked so that no statement binds more than
59 // 65,535 variables, the most a MySQL prepared statement can hold: four columns a row
59 // 65535 variables, the limit declared by Seagull's DuckDB dialect: four columns a row
60 // allows 16,383 rows a statement. copyfrom generates the same code on database/sql.
60 // allows 16383 rows a statement, so a week's 20160 rows take two. copyfrom generates the
61 // same code on database/sql.
61 //
62 //
62 // Each chunk is its own statement, so run the call inside RunInTx (concept 23) when
63 // Each chunk is its own statement, so run the call inside RunInTx (concept 23) when
63 // every row must land or none.
64 // every row must land or none.
64 if err := queries.RecordReadings(ctx, readings); err != nil {
65 if err := queries.RecordReadings(ctx, readings); err != nil {
65 return fmt.Errorf("recording readings: %w", err)
66 return fmt.Errorf("recording readings: %w", err)
66 }
67 }
67 fmt.Fprintf(output, "%d readings sent in %d statements\n", len(readings), counter.statements)
68 fmt.Fprintf(output, "%d readings sent in %d statements\n", len(readings), counter.statements)
68
69
69 summary, err := queries.SummariseReadings(ctx)
70 summary, err := queries.SummariseReadings(ctx)
70 if err != nil {
71 if err != nil {
71 return fmt.Errorf("summarising readings: %w", err)
72 return fmt.Errorf("summarising readings: %w", err)
72 }
73 }
73 for _, row := range summary {
74 for _, row := range summary {
74 fmt.Fprintf(output, "%-8s %d readings, %d with a note\n", row.Station, row.Readings, row.Noted)
75 fmt.Fprintf(output, "%-8s %d readings, %d with a note\n", row.Station, row.Readings, row.Noted)
75 }
76 }
76 return nil
77 return nil
77}
78}
78
79
79// tideReadings makes one reading a minute for a week at each station. The height rises
80// tideReadings makes one reading a minute for a week at each station. The height rises
80// and falls in a simple saw-tooth, and the reading on the hour carries a note.
81// and falls in a simple saw-tooth, and the reading on the hour carries a note.
81//
82//
82// Takes stations (...string) which name the gauges.
83// Takes stations (...string) which name the gauges.
83//
84//
84// Returns []store.RecordReadingsParams which holds every reading, ready for the batch.
85// Returns []store.RecordReadingsParams which holds every reading, ready for the batch.
85func tideReadings(stations ...string) []store.RecordReadingsParams {
86func tideReadings(stations ...string) []store.RecordReadingsParams {
86 readings := make([]store.RecordReadingsParams, 0, len(stations)*minutesPerWeek)
87 readings := make([]store.RecordReadingsParams, 0, len(stations)*minutesPerWeek)
87 for _, station := range stations {
88 for _, station := range stations {
88 for minute := range int32(minutesPerWeek) {
89 for minute := range int32(minutesPerWeek) {
89 var note *string
90 var note *string
90 if minute%60 == 0 {
91 if minute%60 == 0 {
91 note = new(fmt.Sprintf("hour %d check", minute/60))
92 note = new(fmt.Sprintf("hour %d check", minute/60))
92 }
93 }
93 readings = append(readings, store.RecordReadingsParams{
94 readings = append(readings, store.RecordReadingsParams{
94 Station: station,
95 Station: station,
95 Minute: minute,
96 Minute: minute,
96 HeightCm: 200 + minute%360,
97 HeightCm: 200 + minute%360,
97 Note: note,
98 Note: note,
98 })
99 })
99 }
100 }
100 }
101 }
101 return readings
102 return readings
102}
103}