github.com/dolthub/go-mysql-server@v0.18.0/sql/rowexec/limit_test.go (about)

     1  // Copyright 2020-2021 Dolthub, 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  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package rowexec
    16  
    17  import (
    18  	"fmt"
    19  	"io"
    20  	"reflect"
    21  	"testing"
    22  
    23  	"github.com/stretchr/testify/require"
    24  
    25  	"github.com/dolthub/go-mysql-server/memory"
    26  	"github.com/dolthub/go-mysql-server/sql"
    27  	"github.com/dolthub/go-mysql-server/sql/expression"
    28  	"github.com/dolthub/go-mysql-server/sql/plan"
    29  	"github.com/dolthub/go-mysql-server/sql/types"
    30  )
    31  
    32  var testingTable *memory.Table
    33  var testingTableSize int
    34  
    35  func TestLimitPlan(t *testing.T) {
    36  	require := require.New(t)
    37  	_, table, _ := getTestingTable(t)
    38  
    39  	limitPlan := plan.NewLimit(expression.NewLiteral(0, types.Int8), plan.NewResolvedTable(table, nil, nil))
    40  	require.Equal(1, len(limitPlan.Children()))
    41  
    42  	iterator, err := getLimitedIterator(t, 1)
    43  	require.NoError(err)
    44  	require.NotNil(iterator)
    45  }
    46  
    47  func TestLimitImplementsNode(t *testing.T) {
    48  	require := require.New(t)
    49  	_, table, _ := getTestingTable(t)
    50  
    51  	limitPlan := plan.NewLimit(expression.NewLiteral(0, types.Int8), plan.NewResolvedTable(table, nil, nil))
    52  	childSchema := table.Schema()
    53  	nodeSchema := limitPlan.Schema()
    54  	require.True(reflect.DeepEqual(childSchema, nodeSchema))
    55  	require.True(receivesNode(limitPlan))
    56  	require.True(limitPlan.Resolved())
    57  }
    58  
    59  func TestLimit0(t *testing.T) {
    60  	db, _, size := getTestingTable(t)
    61  	pro := memory.NewDBProvider(db)
    62  	ctx := newContext(pro)
    63  
    64  	testingLimit := 0
    65  	iterator, _ := getLimitedIterator(t, int64(testingLimit))
    66  	testLimitOverflow(t, ctx, iterator, testingLimit, size)
    67  }
    68  
    69  func TestLimitLessThanTotal(t *testing.T) {
    70  	db, _, size := getTestingTable(t)
    71  	pro := memory.NewDBProvider(db)
    72  	ctx := newContext(pro)
    73  
    74  	testingLimit := size - 1
    75  	iterator, _ := getLimitedIterator(t, int64(testingLimit))
    76  	testLimitOverflow(t, ctx, iterator, testingLimit, size)
    77  }
    78  
    79  func TestLimitEqualThanTotal(t *testing.T) {
    80  	db, _, size := getTestingTable(t)
    81  	pro := memory.NewDBProvider(db)
    82  	ctx := newContext(pro)
    83  
    84  	testingLimit := size
    85  	iterator, _ := getLimitedIterator(t, int64(testingLimit))
    86  	testLimitOverflow(t, ctx, iterator, testingLimit, size)
    87  }
    88  
    89  func TestLimitGreaterThanTotal(t *testing.T) {
    90  	db, _, size := getTestingTable(t)
    91  	pro := memory.NewDBProvider(db)
    92  	ctx := newContext(pro)
    93  
    94  	testingLimit := size + 1
    95  	iterator, _ := getLimitedIterator(t, int64(testingLimit))
    96  	testLimitOverflow(t, ctx, iterator, testingLimit, size)
    97  }
    98  
    99  func testLimitOverflow(t *testing.T, ctx *sql.Context, iter sql.RowIter, limit int, dataSize int) {
   100  	require := require.New(t)
   101  	for i := 0; i < limit+1; i++ {
   102  		row, err := iter.Next(ctx)
   103  		hint := fmt.Sprintf("Iter#%d : size.%d : limit.%d", i, dataSize, limit)
   104  		if i >= limit || i >= dataSize {
   105  			require.Nil(row, hint)
   106  			require.Equal(io.EOF, err, hint)
   107  		} else {
   108  			require.NotNil(row, hint)
   109  			require.Nil(err, hint)
   110  		}
   111  	}
   112  }
   113  
   114  func getTestingTable(t *testing.T) (*memory.Database, *memory.Table, int) {
   115  	t.Helper()
   116  	if &testingTable == nil {
   117  		return nil, testingTable, testingTableSize
   118  	}
   119  
   120  	db := memory.NewDatabase("test")
   121  	childSchema := sql.NewPrimaryKeySchema(sql.Schema{
   122  		{Name: "col1", Type: types.Text},
   123  	})
   124  	testingTable = memory.NewTable(db, "test", childSchema, nil)
   125  
   126  	rows := []sql.Row{
   127  		sql.NewRow("11a"),
   128  		sql.NewRow("22a"),
   129  		sql.NewRow("33a"),
   130  	}
   131  
   132  	pro := memory.NewDBProvider(db)
   133  	ctx := newContext(pro)
   134  
   135  	for _, r := range rows {
   136  		require.NoError(t, testingTable.Insert(ctx, r))
   137  	}
   138  
   139  	return db, testingTable, len(rows)
   140  }
   141  
   142  func getLimitedIterator(t *testing.T, limitSize int64) (sql.RowIter, error) {
   143  	t.Helper()
   144  
   145  	db, table, _ := getTestingTable(t)
   146  	pro := memory.NewDBProvider(db)
   147  	ctx := newContext(pro)
   148  
   149  	limitPlan := plan.NewLimit(expression.NewLiteral(limitSize, types.Int64), plan.NewResolvedTable(table, nil, nil))
   150  	return DefaultBuilder.Build(ctx, limitPlan, nil)
   151  }
   152  
   153  func receivesNode(n sql.Node) bool {
   154  	return true
   155  }