73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
package influxql
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import (
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"fmt"
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"github.com/influxdata/flux"
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"github.com/influxdata/flux/functions"
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"github.com/influxdata/influxql"
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)
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type joinCursor struct {
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id flux.OperationID
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m map[influxql.Expr]string
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exprs []influxql.Expr
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}
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func Join(t *transpilerState, cursors []cursor, on []string) cursor {
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if len(cursors) == 1 {
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return cursors[0]
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}
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// Iterate through each cursor and each expression within each cursor to assign them an id.
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var exprs []influxql.Expr
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m := make(map[influxql.Expr]string)
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tables := make(map[flux.OperationID]string)
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for i, cur := range cursors {
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// Record this incoming cursor within the table.
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tableName := fmt.Sprintf("t%d", i)
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tables[cur.ID()] = tableName
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for _, k := range cur.Keys() {
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// Combine the table name with the name to access this attribute so we can know
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// what it will be mapped to.
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varName, _ := cur.Value(k)
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name := fmt.Sprintf("%s_%s", tableName, varName)
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exprs = append(exprs, k)
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m[k] = name
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}
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}
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// Retrieve the parent ids from the cursors.
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parents := make([]flux.OperationID, 0, len(tables))
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for _, cur := range cursors {
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parents = append(parents, cur.ID())
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}
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id := t.op("join", &functions.JoinOpSpec{
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TableNames: tables,
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On: on,
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}, parents...)
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return &joinCursor{
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id: id,
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m: m,
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exprs: exprs,
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}
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}
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func (c *joinCursor) ID() flux.OperationID {
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return c.id
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}
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func (c *joinCursor) Keys() []influxql.Expr {
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keys := make([]influxql.Expr, 0, len(c.m))
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for k := range c.m {
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keys = append(keys, k)
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}
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return keys
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}
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func (c *joinCursor) Value(expr influxql.Expr) (string, bool) {
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value, ok := c.m[expr]
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return value, ok
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}
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