github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/sql/sequence_select.go (about)

     1  // Copyright 2018 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package sql
    12  
    13  import (
    14  	"context"
    15  
    16  	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
    17  	"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
    18  	"github.com/cockroachdb/errors"
    19  )
    20  
    21  type sequenceSelectNode struct {
    22  	optColumnsSlot
    23  
    24  	desc *sqlbase.ImmutableTableDescriptor
    25  
    26  	val  int64
    27  	done bool
    28  }
    29  
    30  var _ planNode = &sequenceSelectNode{}
    31  
    32  func (p *planner) SequenceSelectNode(desc *sqlbase.ImmutableTableDescriptor) (planNode, error) {
    33  	if desc.SequenceOpts == nil {
    34  		return nil, errors.New("descriptor is not a sequence")
    35  	}
    36  	return &sequenceSelectNode{
    37  		desc: desc,
    38  	}, nil
    39  }
    40  
    41  func (ss *sequenceSelectNode) startExec(runParams) error {
    42  	return nil
    43  }
    44  
    45  func (ss *sequenceSelectNode) Next(params runParams) (bool, error) {
    46  	if ss.done {
    47  		return false, nil
    48  	}
    49  	val, err := params.p.GetSequenceValue(params.ctx, params.ExecCfg().Codec, ss.desc)
    50  	if err != nil {
    51  		return false, err
    52  	}
    53  	ss.val = val
    54  	ss.done = true
    55  	return true, nil
    56  }
    57  
    58  func (ss *sequenceSelectNode) Values() tree.Datums {
    59  	valDatum := tree.DInt(ss.val)
    60  	cntDatum := tree.DInt(0)
    61  	calledDatum := tree.DBoolTrue
    62  	return []tree.Datum{
    63  		&valDatum,
    64  		&cntDatum,
    65  		calledDatum,
    66  	}
    67  }
    68  
    69  func (ss *sequenceSelectNode) Close(ctx context.Context) {}