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https://github.com/araddon/qlbridge

A golang expression evaluator & Library to build SQL query engine based functionality.
https://github.com/araddon/qlbridge

expressionengine go golang query-engine sql sql-runtime

Last synced: 4 days ago
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A golang expression evaluator & Library to build SQL query engine based functionality.

Host: GitHub
URL: https://github.com/araddon/qlbridge
Owner: araddon
License: mit
Created: 2014-10-26T01:58:25.000Z (about 10 years ago)
Default Branch: master
Last Pushed: 2023-08-29T10:59:30.000Z (over 1 year ago)
Last Synced: 2024-11-28T17:47:49.075Z (14 days ago)
Topics: expressionengine, go, golang, query-engine, sql, sql-runtime
Language: Go
Homepage:
Size: 7.65 MB
Stars: 862
Watchers: 18
Forks: 78
Open Issues: 36
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE

Awesome Lists containing this project

awesome-ccamel - araddon/qlbridge - A golang expression evaluator & Library to build SQL query engine based functionality. (Go)
go-awesome - QLBridge - Go to the SQL runtime engine (Open source library / Interpreter)
awesome-golang-repositories - qlbridge

README

        QLBridge - Go SQL Runtime Engine

=====================================================

A SQL execution engine for embedded use as a library for SQL or SQL-Like functionality.

Hackable, add datasources ("Storage" can be rest apis, or anything), and add functions.  See usage in https://github.com/dataux/dataux

a federated Sql Engine mysql-compatible with backends (Elasticsearch, Google-Datastore, Mongo, Cassandra, Files).

[![Code Coverage](https://codecov.io/gh/araddon/qlbridge/branch/master/graph/badge.svg)](https://codecov.io/gh/araddon/qlbridge)

[![GoDoc](https://godoc.org/github.com/araddon/qlbridge?status.svg)](http://godoc.org/github.com/araddon/qlbridge)

[![Build Status](https://travis-ci.org/araddon/qlbridge.svg?branch=master)](https://travis-ci.org/araddon/qlbridge)

[![Go ReportCard](https://goreportcard.com/badge/araddon/qlbridge)](https://goreportcard.com/report/araddon/qlbridge)

### QLBridge Features and Goals

* expression engine for evaluation of single expressions

* execution of sql queries against your data, embedable, not coupled to storage layer

* extend VM with custom go functions, provide rich basic library of functions

* provide example backends (csv, elasticsearch, etc)

### Dialects

* SQL [see examples](https://github.com/araddon/qlbridge/blob/master/exec/exec_test.go)

* FilterQL (just Where clause) with more of a DSL for filter [see examples](https://github.com/araddon/qlbridge/blob/master/vm/filterqlvm_test.go#L75)

* Simple Expressions [see examples](https://github.com/araddon/qlbridge/blob/master/vm/vm_test.go#L59)

### Example of Expression Evaluation Engine

These expressions can be used stand-alone embedded usage in your app.  But, 

are the same expressions which might be columns, where, group-by clauses in SQL.

[see example](examples/expressions/main.go)

```go

func main() {

	// Add a custom function to the VM to make available to expression language

	expr.FuncAdd("email_is_valid", &EmailIsValid{})

	// This is the evaluation context which will be the data-source

	// to be evaluated against the expressions.  There is a very simple

	// interface you can use to create your own.

	evalContext := datasource.NewContextSimpleNative(map[string]interface{}{

		"int5":     5,

		"str5":     "5",

		"created":  dateparse.MustParse("12/18/2015"),

		"bvalt":    true,

		"bvalf":    false,

		"user_id":  "abc",

		"urls":     []string{"http://google.com", "http://nytimes.com"},

		"hits":     map[string]int64{"google.com": 5, "bing.com": 1},

		"email":    "[email protected]",

		"emailbad": "bob",

		"mt": map[string]time.Time{

			"event0": dateparse.MustParse("12/18/2015"),

			"event1": dateparse.MustParse("12/22/2015"),

		},

	})

	// Example list of expressions

	exprs := []string{

		"int5 == 5",

		`6 > 5`,

		`6 > 5.5`,

		`(4 + 5) / 2`,

		`6 == (5 + 1)`,

		`2 * (3 + 5)`,

		`todate("12/12/2012")`,

		`created > "now-1M"`, // Date math

		`created > "now-10y"`,

		`user_id == "abc"`,

		`email_is_valid(email)`,

		`email_is_valid(emailbad)`,

		`email_is_valid("not_an_email")`,

		`EXISTS int5`,

		`!exists(user_id)`,

		`mt.event0 > now()`, // step into child of maps

		`["portland"] LIKE "*land"`,

		`email contains "bob"`,

		`email NOT contains "bob"`,

		`[1,2,3] contains int5`,

		`[1,2,3,5] NOT contains int5`,

		`urls contains "http://google.com"`,

		`split("chicago,portland",",") LIKE "*land"`,

		`10 BETWEEN 1 AND 50`,

		`15.5 BETWEEN 1 AND "55.5"`,

		`created BETWEEN "now-50w" AND "12/18/2020"`,

		`toint(not_a_field) NOT IN ("a","b" 4.5)`,

		`

		OR (

			email != "[email protected]"

			AND (

				NOT EXISTS not_a_field

				int5 == 5 

			)

		)`,

	}

	for _, expression := range exprs {

		// Same ast can be re-used safely concurrently

		exprAst := expr.MustParse(expression)

		// Evaluate AST in the vm

		val, _ := vm.Eval(evalContext, exprAst)

		v := val.Value()

		u.Debugf("Output: %-35v T:%-15T expr:  %s", v, v, expression)

	}

}

// Example of a custom Function, that we are making available in the Expression VM

type EmailIsValid struct{}

func (m *EmailIsValid) Validate(n *expr.FuncNode) (expr.EvaluatorFunc, error) {

	if len(n.Args) != 1 {

		return nil, fmt.Errorf("Expected 1 arg for EmailIsValid(arg) but got %s", n)

	}

	return func(ctx expr.EvalContext, args []value.Value) (value.Value, bool) {

		if args[0] == nil || args[0].Err() || args[0].Nil() {

			return value.BoolValueFalse, true

		}

		if _, err := mail.ParseAddress(args[0].ToString()); err == nil {

			return value.BoolValueTrue, true

		}

		return value.BoolValueFalse, true

	}, nil

}

func (m *EmailIsValid) Type() value.ValueType { return value.BoolType }

```

### Example SQL Runtime for Reading a Csv via Stdio, File

See example in [qlcsv](https://github.com/araddon/qlbridge/tree/master/examples/qlcsv)

folder for a CSV reader, parser, evaluation engine.

```sh

./qlcsv -sql 'select 

		user_id, email, item_count * 2, yy(reg_date) > 10 

	FROM stdin where email_is_valid(email);' < users.csv

```

```go

func main() {

	if sqlText == "" {

		u.Errorf("You must provide a valid select query in argument:    --sql=\"select ...\"")

		return

	}

	// load all of our built-in functions

	builtins.LoadAllBuiltins()

	// Add a custom function to the VM to make available to SQL language

	expr.FuncAdd("email_is_valid", &EmailIsValid{})

	// We are registering the "csv" datasource, to show that

	// the backend/sources can be easily created/added.  This csv

	// reader is an example datasource that is very, very simple.

	exit := make(chan bool)

	src, _ := datasource.NewCsvSource("stdin", 0, bytes.NewReader([]byte("##")), exit)

	schema.RegisterSourceAsSchema("example_csv", src)

	db, err := sql.Open("qlbridge", "example_csv")

	if err != nil {

		panic(err.Error())

	}

	defer db.Close()

	rows, err := db.Query(sqlText)

	if err != nil {

		u.Errorf("could not execute query: %v", err)

		return

	}

	defer rows.Close()

	cols, _ := rows.Columns()

	// this is just stupid hijinx for getting pointers for unknown len columns

	readCols := make([]interface{}, len(cols))

	writeCols := make([]string, len(cols))

	for i := range writeCols {

		readCols[i] = &writeCols[i]

	}

	fmt.Printf("\n\nScanning through CSV: (%v)\n\n", strings.Join(cols, ","))

	for rows.Next() {

		rows.Scan(readCols...)

		fmt.Println(strings.Join(writeCols, ", "))

	}

	fmt.Println("")

}

// Example of a custom Function, that we are adding into the Expression VM

//

//         select

//              user_id AS theuserid, email, item_count * 2, reg_date

//         FROM stdin

//         WHERE email_is_valid(email)

type EmailIsValid struct{}

func (m *EmailIsValid) Validate(n *expr.FuncNode) (expr.EvaluatorFunc, error) {

	if len(n.Args) != 1 {

		return nil, fmt.Errorf("Expected 1 arg for EmailIsValid(arg) but got %s", n)

	}

	return func(ctx expr.EvalContext, args []value.Value) (value.Value, bool) {

		if args[0] == nil || args[0].Err() || args[0].Nil() {

			return value.BoolValueFalse, true

		}

		if _, err := mail.ParseAddress(args[0].ToString()); err == nil {

			return value.BoolValueTrue, true

		}

		return value.BoolValueFalse, true

	}, nil

}

func (m *EmailIsValid) Type() value.ValueType { return value.BoolType }

```

[x]QL languages are making a comeback.   It is still an easy, approachable

way of working with data.   Also, we see more and more ql's that are xql'ish but

un-apologetically non-standard.  This matches our observation that

data is stored in more and more formats in more tools, services that aren't

traditional db's but querying that data should still be easy.  Examples

[Influx](http://influxdb.com/docs/v0.8/api/query_language.html), 

[GitQL](https://github.com/cloudson/gitql), 

[Presto](http://prestosql.io/), 

[Hive](https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Select), 

[CQL](http://www.datastax.com/documentation/cql/3.1/cql/cql_intro_c.html),

[yql](https://developer.yahoo.com/yql/),

[ql.io](http://ql.io/), etc

Projects that access non-sql data via [x]ql

----------------------------------------------------

* http://prestosql.io/

* https://crate.io/docs/current/sql/index.html

* http://senseidb.com/

* http://influxdb.com/docs/v0.8/api/query_language.html

* https://github.com/crosbymichael/dockersql

* http://harelba.github.io/q/

* https://github.com/dinedal/textql

* https://github.com/cloudson/gitql

* https://github.com/brendandburns/ksql 

Go Script/VM interpreters

---------------------------------------

* https://github.com/robpike/ivy

* https://github.com/yuin/gopher-lua

* https://github.com/SteelSeries/golisp

* [Complete List](https://github.com/golang/go/wiki/Projects#virtual-machines-and-languages)