cvilsmeier/sqinn-go

Sqinn-Go is a Go (Golang) library for accessing SQLite databases without cgo. It uses Sqinn https://github.com/cvilsmeier/sqinn under the hood. It starts Sqinn as a child process (os/exec) and communicates with Sqinn over stdin/stdout/stderr. The Sqinn child process then does the SQLite work.

If you want SQLite but do not want cgo, Sqinn-Go can be a solution.

$ go get -u github.com/cvilsmeier/sqinn-go/sqinn

import "github.com/cvilsmeier/sqinn-go/sqinn"

// Simple sqinn-go usage. Error handling is left out for brevity.
func main() {

	// Launch sqinn. Terminate at program exit.
	sq := sqinn.MustLaunch(sqinn.Options{})
	defer sq.Terminate()

	// Open database. Close when we're done.
	sq.MustOpen("./users.db")
	defer sq.Close()

	// Create a table.
	sq.MustExecOne("CREATE TABLE users (id INTEGER PRIMARY KEY NOT NULL, name VARCHAR)")

	// Insert users.
	sq.MustExecOne("INSERT INTO users (id, name) VALUES (1, 'Alice')")
	sq.MustExecOne("INSERT INTO users (id, name) VALUES (2, 'Bob')")

	// Query users.
	rows := sq.MustQuery("SELECT id, name FROM users ORDER BY id", nil, []byte{sqinn.ValInt, sqinn.ValText})
	for _, row := range rows {
		fmt.Printf("id=%d, name=%s\n", row.Values[0].AsInt(), row.Values[1].AsString())
	}

	// Output:
	// id=1, name=Alice
	// id=2, name=Bob
}

Before running that program, Sqinn must be installed on your system. The most convenient way is to download a pre-built binary from https://github.com/cvilsmeier/sqinn/releases and put it somewhere on your $PATH, or %PATH% on Windows.

If you want to store the Sqinn binary in a non-PATH folder, you must specify it when opening a Sqinn connection:

    // take from environment...
    sq := sqinn.MustLaunch(sqinn.Options{
        SqinnPath: os.Getenv("SQINN_PATH"),
    })

    // ...or set path directly
    sq := sqinn.MustLaunch(sqinn.Options{
        SqinnPath: "/path/to/sqinn",
    })

If you do not want to use a pre-built Sqinn binary, you can compile Sqinn yourself. See https://github.com/cvilsmeier/sqinn for instructions.

For more usage examples, see file sqinn/sqinn_examples_test.go.

• No need to have gcc installed on development machines.
• Go cross compilation works.
• Faster build speed than cgo (1s vs 3s for sample program).
• Smaller binary size than cgo (2MB vs 10MB for sample program).

• No built-in connection pooling.
• Sqinn-Go is not a Golang database/sql Driver.
• Sqinn covers only a subset of SQLite's C APIs.

Performance tests show that Sqinn-Go performance is comparable to cgo solutions, depending on the use case.

For benchmarks I used github.com/mattn/go-sqlite3 and crawshaw.io/sqlite. Numbers are given in milliseconds, lower numbers are better.

                   mattn  crawshaw     sqinn
simple/insert       2901      2140      1563
simple/query        2239      1287      1390
complex/insert      2066      1817      1683
complex/query       1458      1129      1338
many/N=10             97        78       134
many/N=100           246       194       276
many/N=1000         1797      1240      1436
large/N=2000         119        87       341
large/N=4000         361       322       760
large/N=8000         701       650      1531
concurrent/N=2      1332       865       951    
concurrent/N=4      1505       989      1207    
concurrent/N=8      2347      1557      2044     

See https://github.com/cvilsmeier/sqinn-go-bench for details.

Sqinn-Go comes with a large set of automated unit tests. Follow these steps to execute all tests on linux_amd64:

Download and Install Sqinn

$ cd /tmp
$ curl -sL https://github.com/cvilsmeier/sqinn/releases/download/v1.1.27/dist-linux.zip >> dist-linux.zip && unzip dist-linux.zip
$ export SQINN_PATH=/tmp/sqinn

Get and test Sqinn-Go

$ go get -v -u github.com/cvilsmeier/sqinn-go/sqinn
$ go test github.com/cvilsmeier/sqinn-go/sqinn

Check test coverage

$ go test github.com/cvilsmeier/sqinn-go/sqinn -coverprofile=./cover.out
$ go tool cover -func=./cover.out
$ go tool cover -html=./cover.out

Test coverage is ~85% (as of 2021-03-27)

Sqinn-Go is Go without cgo, as it does not use cgo, nor does it depend on third-party cgo packages. However, Sqinn-Go has a runtime dependency on Sqinn, which is a program written in C. Sqinn has to be installed separately on each machine where a Sqinn-Go application is executing. For this to work, Sqinn has to be compiled for every target platform. As an alternative, pre-built Sqinn binaries for common platforms can be downloaded from the Sqinn releases page https://github.com/cvilsmeier/sqinn/releases.

Database/sql is Go's default abstraction layer for SQL databases. It is widely used and there are many third-party packages built on top of it. Sqinn-Go does not implement the database/sql interfaces. The reason is that the sql package provides low-level function calls to prepare statements, bind parameters, fetch column values, and so on. Sqinn could do that, too. But, since for every function call, Sqinn-Go has to make a inter-process communication request/response roundtrip to a sqinn child process, this would be very slow. Instead, Sqinn-Go provides higher-level Exec/Query interfaces that should be used in favor of low-level fine-grained functions.

Sqinn/Sqinn-Go performs well in non-concurrent as well as concurrent settings, as shown in the Performance section. However, a single Sqinn instance should only be called from one goroutine. Exceptions are the Exec and Query methods, these are mutex'ed and goroutine safe. But, since Sqinn is inherently single-threaded, Exec and Query requests are served one-after-another.

If you want true concurrency at the database level, you can spin up multiple Sqinn instances. You may even implement a connection pool. But be aware that when accessing a SQLite database concurrently, the dreaded SQLITE_BUSY error might occur. The PRAGMA busy_timeout might help to avoid SQLITE_BUSY errors.

We recommend the following: Have one Sqinn instance. You may call Exec/Query on that single Sqinn instance from as many goroutines as you want. For long-running tasks (VACUUM, BACKUP, etc), spin up a second Sqinn instance on demand, and terminate it once the long-running work is done. Use PRAGMA busy_timeout to avoid SQLITE_BUSY.

A Sqinn instance allows only one active statement at a time. A statement is active from the time it is prepared until it is finalized. Before preparing a new statement, you have to finalize the current statement first, otherwise Sqinn will respond with an error.

This is why we recommend using Exec/Query: These methods do a complete prepare-finalize cycle and the caller can be sure that, once Exec/Query returns, no active statements are hanging around.

• Added marshalling benchmark
• Removed 'pure Go' claim
• Removed travis build
• Added github workflow with sqinn v1.1.27
• Updated min. go version 1.19
• Updated samples

• Fixed negative int32 marshalling

• Added more docs for Values
• Added example for handling NULL values
• Added example for sqlite specialties

• Use IEEE 745 encoding for float64 values, needs sqinn v1.1.0 or higher.

• First version.

This is free and unencumbered software released into the public domain.

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