Golang SelectStatement.NamesInSelect方法代码示例

// SelectTags returns a list of non-field tags in the SELECT section of stmt.
func (m *Measurement) SelectTags(stmt *influxql.SelectStatement) []string {
	set := newStringSet()
	for _, name := range stmt.NamesInSelect() {
		if !m.HasField(name) && m.HasTagKey(name) {
			set.add(name)
		}
	}
	return set.list()
}

// SelectFields returns a list of fields in the SELECT section of stmt.
func (m *Measurement) SelectFields(stmt *influxql.SelectStatement) []string {
	set := newStringSet()
	for _, name := range stmt.NamesInSelect() {
		if m.HasField(name) {
			set.add(name)
			continue
		}
	}
	return set.list()
}

// createTagSetsAndFields returns the tagsets and various fields given a measurement and
// SELECT statement.
func createTagSetsAndFields(m *Measurement, stmt *influxql.SelectStatement) (*tagSetsAndFields, error) {
	_, tagKeys, err := stmt.Dimensions.Normalize()
	if err != nil {
		return nil, err
	}

	sfs := newStringSet()
	sts := newStringSet()
	wfs := newStringSet()

	// Validate the fields and tags asked for exist and keep track of which are in the select vs the where
	for _, n := range stmt.NamesInSelect() {
		if m.HasField(n) {
			sfs.add(n)
			continue
		}
		if m.HasTagKey(n) {
			sts.add(n)
		}
	}

	for _, n := range stmt.NamesInDimension() {
		if m.HasTagKey(n) {
			tagKeys = append(tagKeys, n)
		}
	}

	for _, n := range stmt.NamesInWhere() {
		if n == "time" {
			continue
		}
		if m.HasField(n) {
			wfs.add(n)
			continue
		}
	}

	// Get the sorted unique tag sets for this statement.
	tagSets, err := m.TagSets(stmt, tagKeys)
	if err != nil {
		return nil, err
	}

	return &tagSetsAndFields{
		tagSets:      tagSets,
		selectFields: sfs.list(),
		selectTags:   sts.list(),
		whereFields:  wfs.list(),
	}, nil
}

// CreateMappers will create a set of mappers that need to be run to execute the map phase of a MapReduceJob.
func (tx *tx) CreateMapReduceJobs(stmt *influxql.SelectStatement, tagKeys []string) ([]*influxql.MapReduceJob, error) {
	jobs := []*influxql.MapReduceJob{}
	for _, src := range stmt.Sources {
		mm, ok := src.(*influxql.Measurement)
		if !ok {
			return nil, fmt.Errorf("invalid source type: %#v", src)
		}

		// get the index and the retention policy
		rp, err := tx.meta.RetentionPolicy(mm.Database, mm.RetentionPolicy)
		if err != nil {
			return nil, err
		}
		m := tx.store.Measurement(mm.Database, mm.Name)
		if m == nil {
			return nil, ErrMeasurementNotFound(influxql.QuoteIdent([]string{mm.Database, "", mm.Name}...))
		}

		tx.measurement = m

		// Validate the fields and tags asked for exist and keep track of which are in the select vs the where
		var selectFields []string
		var whereFields []string
		var selectTags []string

		for _, n := range stmt.NamesInSelect() {
			if m.HasField(n) {
				selectFields = append(selectFields, n)
				continue
			}
			if !m.HasTagKey(n) {
				return nil, fmt.Errorf("unknown field or tag name in select clause: %s", n)
			}
			selectTags = append(selectTags, n)
			tagKeys = append(tagKeys, n)
		}
		for _, n := range stmt.NamesInWhere() {
			if n == "time" {
				continue
			}
			if m.HasField(n) {
				whereFields = append(whereFields, n)
				continue
			}
			if !m.HasTagKey(n) {
				return nil, fmt.Errorf("unknown field or tag name in where clause: %s", n)
			}
		}

		if len(selectFields) == 0 && len(stmt.FunctionCalls()) == 0 {
			return nil, fmt.Errorf("select statement must include at least one field or function call")
		}

		// Validate that group by is not a field
		for _, d := range stmt.Dimensions {
			switch e := d.Expr.(type) {
			case *influxql.VarRef:
				if !m.HasTagKey(e.Val) {
					return nil, fmt.Errorf("can not use field in group by clause: %s", e.Val)
				}
			}
		}

		// Grab time range from statement.
		tmin, tmax := influxql.TimeRange(stmt.Condition)
		if tmax.IsZero() {
			tmax = tx.now
		}
		if tmin.IsZero() {
			tmin = time.Unix(0, 0)
		}

		// Find shard groups within time range.
		var shardGroups []*meta.ShardGroupInfo
		for _, group := range rp.ShardGroups {
			if group.Overlaps(tmin, tmax) {
				g := group
				shardGroups = append(shardGroups, &g)
			}
		}
		if len(shardGroups) == 0 {
			return nil, nil
		}

		// get the group by interval, if there is one
		var interval int64
		if d, err := stmt.GroupByInterval(); err != nil {
			return nil, err
		} else {
			interval = d.Nanoseconds()
		}

		// get the sorted unique tag sets for this query.
		tagSets, err := m.TagSets(stmt, tagKeys)
		if err != nil {
			return nil, err
		}

		for _, t := range tagSets {
//.........这里部分代码省略.........

// CreateMappers will create a set of mappers that need to be run to execute the map phase of a MapReduceJob.
func (tx *tx) CreateMapReduceJobs(stmt *influxql.SelectStatement, tagKeys []string) ([]*influxql.MapReduceJob, error) {
	// Parse the source segments.
	database, policyName, measurement, err := splitIdent(stmt.Source.(*influxql.Measurement).Name)
	if err != nil {
		return nil, err
	}

	// Find database and retention policy.
	db := tx.server.databases[database]
	if db == nil {
		return nil, ErrDatabaseNotFound
	}
	rp := db.policies[policyName]
	if rp == nil {
		return nil, ErrRetentionPolicyNotFound
	}

	// Find measurement.
	m, err := tx.server.measurement(database, measurement)
	if err != nil {
		return nil, err
	}
	if m == nil {
		return nil, ErrMeasurementNotFound
	}

	tx.measurement = m
	tx.decoder = NewFieldCodec(m)

	// Validate the fields and tags asked for exist and keep track of which are in the select vs the where
	var selectFields []*Field
	var whereFields []*Field
	var selectTags []string

	for _, n := range stmt.NamesInSelect() {
		f := m.FieldByName(n)
		if f != nil {
			selectFields = append(selectFields, f)
			continue
		}
		if !m.HasTagKey(n) {
			return nil, fmt.Errorf("unknown field or tag name in select clause: %s", n)
		}
		selectTags = append(selectTags, n)
	}
	for _, n := range stmt.NamesInWhere() {
		if n == "time" {
			continue
		}
		f := m.FieldByName(n)
		if f != nil {
			whereFields = append(whereFields, f)
			continue
		}
		if !m.HasTagKey(n) {
			return nil, fmt.Errorf("unknown field or tag name in where clause: %s", n)
		}
	}

	// Grab time range from statement.
	tmin, tmax := influxql.TimeRange(stmt.Condition)
	if tmax.IsZero() {
		tmax = tx.now
	}
	if tmin.IsZero() {
		tmin = time.Unix(0, 0)
	}

	// Find shard groups within time range.
	var shardGroups []*ShardGroup
	for _, group := range rp.shardGroups {
		if group.Contains(tmin, tmax) {
			shardGroups = append(shardGroups, group)
		}
	}
	if len(shardGroups) == 0 {
		return nil, nil
	}

	// get the sorted unique tag sets for this query.
	tagSets := m.tagSets(stmt, tagKeys)

	jobs := make([]*influxql.MapReduceJob, 0, len(tagSets))
	for _, t := range tagSets {
		// make a job for each tagset
		job := &influxql.MapReduceJob{
			MeasurementName: m.Name,
			TagSet:          t,
			TMin:            tmin.UnixNano(),
			TMax:            tmax.UnixNano(),
		}

		// make a mapper for each shard that must be hit. We may need to hit multiple shards within a shard group
		mappers := make([]influxql.Mapper, 0)

		// create mappers for each shard we need to hit
		for _, sg := range shardGroups {
			if len(sg.Shards) != 1 { // we'll only have more than 1 shard in a group when RF < # servers in cluster
				// TODO: implement distributed queries.
//.........这里部分代码省略.........