github.com/hasnat/dolt/go@v0.0.0-20210628190320-9eb5d843fbb7/libraries/doltcore/diff/sql_diff.go (about)

     1  // Copyright 2019 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 diff
    16  
    17  import (
    18  	"errors"
    19  	"io"
    20  
    21  	"github.com/dolthub/dolt/go/libraries/doltcore/row"
    22  	"github.com/dolthub/dolt/go/libraries/doltcore/schema"
    23  	"github.com/dolthub/dolt/go/libraries/doltcore/sqle/sqlfmt"
    24  	"github.com/dolthub/dolt/go/libraries/doltcore/table/pipeline"
    25  	"github.com/dolthub/dolt/go/libraries/utils/iohelp"
    26  	"github.com/dolthub/dolt/go/store/types"
    27  )
    28  
    29  type SQLDiffSink struct {
    30  	wr        io.WriteCloser
    31  	sch       schema.Schema
    32  	tableName string
    33  }
    34  
    35  // NewSQLDiffSink creates a SQLDiffSink for a diff pipeline.
    36  func NewSQLDiffSink(wr io.WriteCloser, sch schema.Schema, tableName string) (*SQLDiffSink, error) {
    37  	return &SQLDiffSink{wr, sch, tableName}, nil
    38  }
    39  
    40  // GetSchema gets the schema that the SQLDiffSink was created with.
    41  func (sds *SQLDiffSink) GetSchema() schema.Schema {
    42  	return sds.sch
    43  }
    44  
    45  // ProcRowWithProps satisfies pipeline.SinkFunc; it writes SQL diff statements to output.
    46  func (sds *SQLDiffSink) ProcRowWithProps(r row.Row, props pipeline.ReadableMap) error {
    47  
    48  	taggedVals := make(row.TaggedValues)
    49  	allCols := sds.sch.GetAllCols()
    50  	colDiffs := make(map[string]DiffChType)
    51  
    52  	if prop, ok := props.Get(CollChangesProp); ok {
    53  		if convertedVal, convertedOK := prop.(map[string]DiffChType); convertedOK {
    54  			colDiffs = convertedVal
    55  		}
    56  	}
    57  
    58  	err := allCols.Iter(func(tag uint64, col schema.Column) (stop bool, err error) {
    59  		if val, ok := r.GetColVal(tag); ok {
    60  			taggedVals[tag] = val
    61  		}
    62  		return false, nil
    63  	})
    64  
    65  	if err != nil {
    66  		return err
    67  	}
    68  
    69  	r, err = row.New(r.Format(), sds.sch, taggedVals)
    70  
    71  	if err != nil {
    72  		return err
    73  	}
    74  
    75  	taggedVals[diffColTag] = types.String("   ")
    76  	if prop, ok := props.Get(DiffTypeProp); ok {
    77  		if dt, convertedOK := prop.(DiffChType); convertedOK {
    78  			switch dt {
    79  			case DiffAdded:
    80  				stmt, err := sqlfmt.RowAsInsertStmt(r, sds.tableName, sds.sch)
    81  
    82  				if err != nil {
    83  					return err
    84  				}
    85  
    86  				return iohelp.WriteLine(sds.wr, stmt)
    87  			case DiffRemoved:
    88  				stmt, err := sqlfmt.RowAsDeleteStmt(r, sds.tableName, sds.sch)
    89  
    90  				if err != nil {
    91  					return err
    92  				}
    93  
    94  				return iohelp.WriteLine(sds.wr, stmt)
    95  			case DiffModifiedOld:
    96  				return nil
    97  			case DiffModifiedNew:
    98  				// TODO: minimize update statement to modified rows
    99  				stmt, err := sqlfmt.RowAsUpdateStmt(r, sds.tableName, sds.sch)
   100  
   101  				if err != nil {
   102  					return err
   103  				}
   104  
   105  				return iohelp.WriteLine(sds.wr, stmt)
   106  			}
   107  			// Treat the diff indicator string as a diff of the same type
   108  			colDiffs[diffColName] = dt
   109  		}
   110  	}
   111  
   112  	return err
   113  }
   114  
   115  // ProcRowWithProps satisfies pipeline.SinkFunc; it writes rows as SQL statements.
   116  func (sds *SQLDiffSink) ProcRowForExport(r row.Row, _ pipeline.ReadableMap) error {
   117  	stmt, err := sqlfmt.RowAsInsertStmt(r, sds.tableName, sds.sch)
   118  
   119  	if err != nil {
   120  		return err
   121  	}
   122  
   123  	return iohelp.WriteLine(sds.wr, stmt)
   124  }
   125  
   126  // Close should release resources being held
   127  func (sds *SQLDiffSink) Close() error {
   128  	if sds.wr != nil {
   129  		err := sds.wr.Close()
   130  		if err != nil {
   131  			return err
   132  		}
   133  		sds.wr = nil
   134  		return nil
   135  	} else {
   136  		return errors.New("Already closed.")
   137  	}
   138  }