lines

Documentation

Overview

Package lines provides a virtual table to read large files line-by-line.

Example

db, err := driver.Open(":memory:", func(c *sqlite3.Conn) error {
	lines.Register(c)
	return nil
})
if err != nil {
	log.Fatal(err)
}
defer db.Close()

// https://storage.googleapis.com/quickdraw_dataset/full/simplified/calendar.ndjson
f, err := os.Open("calendar.ndjson")
if err != nil {
	log.Fatal(err)
}
defer f.Close()

rows, err := db.Query(`
		SELECT
			line ->> '$.countrycode' as countrycode,
			COUNT(*)
  		FROM lines_read(?)
  		GROUP BY 1
  		ORDER BY 2 DESC
  		LIMIT 5`,
	sqlite3.Pointer(f))
if err != nil {
	log.Fatal(err)
}
defer rows.Close()

var countrycode sql.RawBytes
var count int
for rows.Next() {
	err := rows.Scan(&countrycode, &count)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s: %d\n", countrycode, count)
}
if err := rows.Err(); err != nil {
	log.Fatal(err)
}
// Sample output:
// US: 141001
// GB: 22560
// CA: 11759
// RU: 9250
// DE: 8748

Index

• func Register(db *sqlite3.Conn)

Examples

• Package

Functions

func Register

func Register(db *sqlite3.Conn)

Register registers the lines and lines_read virtual tables. The lines virtual table reads from a database blob or text. The lines_read virtual table reads from a file or an io.ReaderAt.