Documentation
¶
Index ¶
- Constants
- Variables
- func NewMongoDataSource() schema.Source
- type MongoDataSource
- func (m *MongoDataSource) Close() error
- func (m *MongoDataSource) DataSource() schema.Source
- func (m *MongoDataSource) Open(collectionName string) (schema.Conn, error)
- func (m *MongoDataSource) Setup(ss *schema.SchemaSource) error
- func (m *MongoDataSource) Table(table string) (*schema.Table, error)
- func (m *MongoDataSource) Tables() []string
- type ResultReader
- type ResultReaderNext
- type SqlToMgo
- func (m *SqlToMgo) Columns() []string
- func (m *SqlToMgo) WalkAggs(cur expr.Node) (q bson.M, _ error)
- func (m *SqlToMgo) WalkExecSource(p *plan.Source) (exec.Task, error)
- func (m *SqlToMgo) WalkGroupBy() error
- func (m *SqlToMgo) WalkNode(cur expr.Node, q *bson.M) (value.Value, error)
- func (m *SqlToMgo) WalkSelectList() error
- func (m *SqlToMgo) WalkSourceSelect(planner plan.Planner, p *plan.Source) (plan.Task, error)
Constants ¶
View Source
const (
ListenerType = "mongo"
)
Variables ¶
View Source
var (
DefaultLimit = 20
)
Functions ¶
func NewMongoDataSource ¶
Types ¶
type MongoDataSource ¶
type MongoDataSource struct {
// contains filtered or unexported fields
}
Mongo Data Source implements qlbridge DataSource interfaces to mongo server
- singleton shared across all sessions/connections
- creates connections by mgo.Session.Clone()
func (*MongoDataSource) Close ¶
func (m *MongoDataSource) Close() error
func (*MongoDataSource) DataSource ¶
func (m *MongoDataSource) DataSource() schema.Source
func (*MongoDataSource) Open ¶
func (m *MongoDataSource) Open(collectionName string) (schema.Conn, error)
func (*MongoDataSource) Setup ¶
func (m *MongoDataSource) Setup(ss *schema.SchemaSource) error
func (*MongoDataSource) Table ¶
func (m *MongoDataSource) Table(table string) (*schema.Table, error)
func (*MongoDataSource) Tables ¶
func (m *MongoDataSource) Tables() []string
type ResultReader ¶
type ResultReader struct {
*exec.TaskBase
Docs []u.JsonHelper
Vals [][]driver.Value
Total int
Aggs u.JsonHelper
ScrollId string
// contains filtered or unexported fields
}
Mongo ResultReader implements result paging, reading - driver.Rows
func NewResultReader ¶
func NewResultReader(req *SqlToMgo, q *mgo.Query, limit int) *ResultReader
func (*ResultReader) Close ¶
func (m *ResultReader) Close() error
func (*ResultReader) Run ¶
func (m *ResultReader) Run() error
type ResultReaderNext ¶
type ResultReaderNext struct {
*ResultReader
}
A wrapper, allowing us to implement sql/driver Next() interface
which is different than qlbridge/datasource Next()
type SqlToMgo ¶
SqlToMgo Rewrite a Sql AST statement to a Mongo request
- Walk the AST and see what can be pushed down and what can't
- try to poly-fill the missing pieces.
func NewSqlToMgo ¶
func (*SqlToMgo) WalkAggs ¶
WalkAggs() aggregate expressions when used ast part of <select_list>
- For Aggregates (functions) it builds appropriate underlying mongo aggregation/map-reduce
- For Projections (non-functions) it does nothing, that will be done later during projection
func (*SqlToMgo) WalkExecSource ¶
func (*SqlToMgo) WalkGroupBy ¶
Group By Clause: Mongo is a little weird where they move the
group by expressions INTO the aggregation clause
operation(field) FROM x GROUP BY x,y,z
db.article.aggregate([{"$group":{_id: "$author", count: {"$sum":1}}}]);
func (*SqlToMgo) WalkNode ¶
Walk() an expression, and its logic to create an appropriately
nested bson document for mongo queries if possible.
- if can't express logic we need to allow qlbridge to poly-fill
func (*SqlToMgo) WalkSelectList ¶
Aggregations from the <select_list>
SELECT <select_list> FROM ... WHERE
Source Files
Click to show internal directories.
Click to hide internal directories.