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Correctly map enum values when altering an enum column. #2958

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Merged
merged 2 commits into from
May 6, 2025
Merged

Correctly map enum values when altering an enum column. #2958

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f9c02bf
Correctly map enum values when altering an enum column.
nicktobey Apr 28, 2025
3d54d6c
Update enum test to match MySQL behavior and better reflect intent.
nicktobey May 1, 2025
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24 changes: 22 additions & 2 deletions enginetest/queries/script_queries.go
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,7 @@ CREATE TABLE teams (
},
{
Query: "alter table xy modify y enum('a')",
ExpectedErr: types.ErrConvertingToEnum,
ExpectedErr: types.ErrDataTruncatedForColumn,
},
},
},
Expand Down Expand Up @@ -7625,6 +7625,7 @@ where
Name: "preserve enums through alter statements",
SetUpScript: []string{
"create table t (i int primary key, e enum('a', 'b', 'c'));",
"insert ignore into t values (0, 'error');",
"insert into t values (1, 'a');",
"insert into t values (2, 'b');",
"insert into t values (3, 'c');",
Expand All @@ -7633,6 +7634,7 @@ where
{
Query: "select i, e, e + 0 from t;",
Expected: []sql.Row{
{0, "", float64(0)},
{1, "a", float64(1)},
{2, "b", float64(2)},
{3, "c", float64(3)},
Expand All @@ -7647,6 +7649,7 @@ where
{
Query: "select i, e, e + 0 from t;",
Expected: []sql.Row{
{0, "", float64(0)},
{1, "a", float64(2)},
{2, "b", float64(3)},
{3, "c", float64(1)},
Expand All @@ -7661,6 +7664,7 @@ where
{
Query: "select i, e, e + 0 from t;",
Expected: []sql.Row{
{0, "", float64(0)},
{1, "a", float64(2)},
{2, "b", float64(3)},
{3, "c", float64(4)},
Expand All @@ -7675,14 +7679,30 @@ where
{
Query: "select i, e, e + 0 from t;",
Expected: []sql.Row{
{0, "", float64(0)},
{1, "a", float64(2)},
{2, "b", float64(3)},
{3, "c", float64(4)},
},
},
{
Query: "alter table t modify column e enum('a', 'b', 'c');",
Expected: []sql.Row{
{types.NewOkResult(0)},
},
},
{
Query: "select i, e, e + 0 from t;",
Expected: []sql.Row{
{0, "", float64(0)},
{1, "a", float64(1)},
{2, "b", float64(2)},
{3, "c", float64(3)},
},
},
{
Query: "alter table t modify column e enum('abc');",
ExpectedErr: types.ErrConvertingToEnum,
ExpectedErr: types.ErrDataTruncatedForColumn,
},
},
},
Expand Down
26 changes: 14 additions & 12 deletions sql/rowexec/ddl_iters.go
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Original file line number Diff line number Diff line change
Expand Up @@ -545,7 +545,6 @@ func (i *modifyColumnIter) rewriteTable(ctx *sql.Context, rwt sql.RewritableTabl
return false, err
}

newColIdx := newSch.IndexOf(newCol.Name, newCol.Source)
rowIter := sql.NewTableRowIter(ctx, rwt, partitions)
for {
r, err := rowIter.Next(ctx)
Expand All @@ -557,24 +556,27 @@ func (i *modifyColumnIter) rewriteTable(ctx *sql.Context, rwt sql.RewritableTabl
return false, err
}

// remap old enum values to new enum values
if isOldEnum && isNewEnum && r[oldColIdx] != nil {
oldIdx := int(r[oldColIdx].(uint16))
// 0 values in enums are error values. They are preserved during remapping.
if oldIdx != 0 {
oldStr, _ := oldEnum.At(oldIdx)
newIdx := newEnum.IndexOf(oldStr)
if newIdx == -1 {
return false, types.ErrDataTruncatedForColumn.New(newCol.Name)
}
r[oldColIdx] = uint16(newIdx)
}
}

newRow, err := projectRowWithTypes(ctx, newSch, projections, r)
if err != nil {
_ = inserter.DiscardChanges(ctx, err)
_ = inserter.Close(ctx)
return false, err
}

// remap old enum values to new enum values
if isOldEnum && isNewEnum && newRow[newColIdx] != nil {
oldIdx := int(newRow[newColIdx].(uint16))
oldStr, _ := oldEnum.At(oldIdx)
newIdx := newEnum.IndexOf(oldStr)
if newIdx == -1 {
return false, types.ErrDataTruncatedForColumn.New(newCol.Name)
}
newRow[newColIdx] = uint16(newIdx)
}

err = i.validateNullability(ctx, newSch, newRow)
if err != nil {
_ = inserter.DiscardChanges(ctx, err)
Expand Down