github.com/insionng/yougam@v0.0.0-20170714101924-2bc18d833463/libraries/pingcap/tidb/kv/key_test.go (about)

     1  // Copyright 2015 PingCAP, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package kv
    15  
    16  import (
    17  	"bytes"
    18  
    19  	. "github.com/insionng/yougam/libraries/pingcap/check"
    20  	"github.com/insionng/yougam/libraries/pingcap/tidb/util/codec"
    21  	"github.com/insionng/yougam/libraries/pingcap/tidb/util/testleak"
    22  	"github.com/insionng/yougam/libraries/pingcap/tidb/util/types"
    23  )
    24  
    25  var _ = Suite(&testKeySuite{})
    26  
    27  type testKeySuite struct {
    28  }
    29  
    30  func (s *testKeySuite) TestPartialNext(c *C) {
    31  	defer testleak.AfterTest(c)()
    32  	// keyA represents a multi column index.
    33  	keyA, err := codec.EncodeValue(nil, types.NewDatum("abc"), types.NewDatum("def"))
    34  	c.Check(err, IsNil)
    35  	keyB, err := codec.EncodeValue(nil, types.NewDatum("abca"), types.NewDatum("def"))
    36  
    37  	// We only use first column value to seek.
    38  	seekKey, err := codec.EncodeValue(nil, types.NewDatum("abc"))
    39  	c.Check(err, IsNil)
    40  
    41  	nextKey := Key(seekKey).Next()
    42  	cmp := bytes.Compare(nextKey, keyA)
    43  	c.Assert(cmp, Equals, -1)
    44  
    45  	// Use next partial key, we can skip all index keys with first column value equal to "abc".
    46  	nextPartialKey := Key(seekKey).PrefixNext()
    47  	cmp = bytes.Compare(nextPartialKey, keyA)
    48  	c.Assert(cmp, Equals, 1)
    49  
    50  	cmp = bytes.Compare(nextPartialKey, keyB)
    51  	c.Assert(cmp, Equals, -1)
    52  }