Revive ability to read dolt_schema table which predates 0.19.0

go/libraries/doltcore/sqle/database.go

@@ -525,7 +525,7 @@ func (db Database) getTableInsensitive(ctx *sql.Context, head *doltdb.Commit, ds
 			dt = NewEmptySchemaTable()
 		} else {
 			writeTable := backingTable.(*WritableDoltTable)
-			dt, err = NewSchemaTable(ctx, db, writeTable)
+			dt, err = NewSchemaTable(writeTable)
 			if err != nil {
 				return nil, false, err
 			}

go/libraries/doltcore/sqle/schema_table.go

@@ -57,10 +57,15 @@ func (st *SchemaTable) String() string {
 
 func (st *SchemaTable) Schema() sql.Schema {
 	if st.backingTable == nil {
-		// No backing table; return an current schema.
+		// No backing table; return a current schema.
 		return SchemaTableSqlSchema().Schema
 	}
 
+	if !st.backingTable.Schema().Contains(doltdb.SchemasTablesExtraCol, doltdb.SchemasTableName) {
+		// No Extra column; return an ancient schema.
+		return SchemaTableAncientSqlSchema()
+	}
+
 	if !st.backingTable.Schema().Contains(doltdb.SchemasTablesSqlModeCol, doltdb.SchemasTableName) {
 		// No SQL_MODE column; return an old schema.
 		return SchemaTableV1SqlSchema()
@@ -163,6 +168,22 @@ func SchemaTableV1SqlSchema() sql.Schema {
 	return sqlSchema.Schema
 }
 
+// dolt_schemas columns, for dolt_schemas <= 0.19.0.
+func SchemaTableAncientSqlSchema() sql.Schema {
+	var schemasTableCols = schema.NewColCollection(
+		mustNewColWithTypeInfo(doltdb.SchemasTablesTypeCol, schema.DoltSchemasTypeTag, typeinfo.CreateVarStringTypeFromSqlType(mustCreateStringType(query.Type_VARCHAR, 64, sql.Collation_utf8mb4_0900_ai_ci)), true, "", false, ""),
+		mustNewColWithTypeInfo(doltdb.SchemasTablesNameCol, schema.DoltSchemasNameTag, typeinfo.CreateVarStringTypeFromSqlType(mustCreateStringType(query.Type_VARCHAR, 64, sql.Collation_utf8mb4_0900_ai_ci)), true, "", false, ""),
+		mustNewColWithTypeInfo(doltdb.SchemasTablesFragmentCol, schema.DoltSchemasFragmentTag, typeinfo.CreateVarStringTypeFromSqlType(gmstypes.LongText), false, "", false, ""),
+	)
+
+	legacy := schema.MustSchemaFromCols(schemasTableCols)
+	sqlSchema, err := sqlutil.FromDoltSchema("", doltdb.SchemasTableName, legacy)
+	if err != nil {
+		panic(err) // should never happen
+	}
+	return sqlSchema.Schema
+}
+
 // dolt_schemas columns
 func SchemaTableSchema() schema.Schema {
 	var schemasTableCols = schema.NewColCollection(
@@ -180,11 +201,7 @@ func NewEmptySchemaTable() sql.Table {
 	return &SchemaTable{}
 }
 
-func NewSchemaTable(ctx *sql.Context, db Database, backingTable *WritableDoltTable) (sql.Table, error) {
-	if !backingTable.Schema().Contains(doltdb.SchemasTablesExtraCol, doltdb.SchemasTableName) {
-		return nil, fmt.Errorf("cannot migrate dolt_schemas table from v0.19.1 or earlier")
-	}
-
+func NewSchemaTable(backingTable *WritableDoltTable) (sql.Table, error) {
 	return &SchemaTable{backingTable: backingTable}, nil
 }
 
@@ -221,10 +238,9 @@ func getOrCreateDoltSchemasTable(ctx *sql.Context, db Database) (retTbl *Writabl
 
 	if wrapper.backingTable != nil {
 		schemasTable := wrapper.backingTable
-		// Old schemas are missing the `extra` column. Very ancient. Provide error message and bail.
-		if !schemasTable.Schema().Contains(doltdb.SchemasTablesExtraCol, doltdb.SchemasTableName) {
-			return nil, fmt.Errorf("cannot migrate dolt_schemas table from v0.19.1 or earlier")
-		} else if !schemasTable.Schema().Contains(doltdb.SchemasTablesSqlModeCol, doltdb.SchemasTableName) {
+
+		if !schemasTable.Schema().Contains(doltdb.SchemasTablesExtraCol, doltdb.SchemasTableName) ||
+			!schemasTable.Schema().Contains(doltdb.SchemasTablesSqlModeCol, doltdb.SchemasTableName) {
 			return migrateOldSchemasTableToNew(ctx, db, schemasTable)
 		} else {
 			return schemasTable, nil
@@ -288,8 +304,9 @@ func migrateOldSchemasTableToNew(ctx *sql.Context, db Database, schemasTable *Wr
 		newRow[0] = sqlRow[typeIdx]
 		newRow[1] = sqlRow[nameIdx]
 		newRow[2] = sqlRow[fragmentIdx]
-		newRow[3] = sqlRow[extraIdx]
-
+		if extraIdx >= 0 {
+			newRow[3] = sqlRow[extraIdx]
+		}
 		if sqlModeIdx >= 0 {
 			newRow[4] = sqlRow[sqlModeIdx]
 		}

go/libraries/doltcore/sqle/schema_table_test.go

@@ -16,10 +16,12 @@ package sqle
 
 import (
 	"context"
+	"io"
 	"testing"
 
 	"github.com/dolthub/go-mysql-server/sql"
 	gmstypes "github.com/dolthub/go-mysql-server/sql/types"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
@@ -45,10 +47,47 @@ func TestAncientSchemaTableError(t *testing.T) {
 	}), sql.Collation_Default, "")
 	require.NoError(t, err)
 
-	_, _, err = db.GetTableInsensitive(ctx, doltdb.SchemasTableName)
-	require.Error(t, err)
-	require.Contains(t, err.Error(), "cannot migrate dolt_schemas table from v0.19.1 or earlier")
+	sqlTbl, found, err := db.GetTableInsensitive(ctx, doltdb.SchemasTableName)
+	require.NoError(t, err)
+	require.True(t, found)
+
+	wrapper, ok := sqlTbl.(*SchemaTable)
+	require.True(t, ok)
+	require.NotNil(t, wrapper.backingTable)
+	// unmodified dolt_schemas table.
+	require.Equal(t, 3, len(wrapper.backingTable.Schema()))
+
+	inserter := wrapper.backingTable.Inserter(ctx)
+	err = inserter.Insert(ctx, sql.Row{"view", "view1", "SELECT v1 FROM test;"})
+	require.NoError(t, err)
+	err = inserter.Insert(ctx, sql.Row{"view", "view2", "SELECT v2 FROM test;"})
+	require.NoError(t, err)
+	err = inserter.Close(ctx)
+	require.NoError(t, err)
+
+	tbl, err := getOrCreateDoltSchemasTable(ctx, db) // removes the old table and recreates it with the new schema
+	require.NoError(t, err)
+
+	iter, err := SqlTableToRowIter(ctx, tbl.DoltTable, nil)
+	require.NoError(t, err)
 
+	var rows []sql.Row
+	for {
+		row, err := iter.Next(ctx)
+		if err == io.EOF {
+			break
+		}
+
+		require.NoError(t, err)
+		rows = append(rows, row)
+	}
+
+	require.NoError(t, iter.Close(ctx))
+	expectedRows := []sql.Row{
+		{"view", "view1", "SELECT v1 FROM test;", nil, nil},
+		{"view", "view2", "SELECT v2 FROM test;", nil, nil},
+	}
+	assert.Equal(t, expectedRows, rows)
 }
 
 func TestV1SchemasTable(t *testing.T) {

integration-tests/bats/triggers.bats

@@ -184,3 +184,22 @@ SQL
     [ "$status" -eq "0" ]
     [[ "$output" =~ "type,name,fragment,extra,sql_mode" ]] || false
 }
+
+@test "triggers: Upgrade oldest dolt_schemas" {
+    rm -rf .dolt
+
+    # old_old_dolt_schemas was created using v0.19.0, which is pre-extra column.
+    cp -a $BATS_TEST_DIRNAME/helper/old_old_dolt_schemas/. ./.dolt/
+
+    run dolt sql -q "SELECT * FROM dolt_schemas" -r=csv
+    [ "$status" -eq "0" ]
+
+    [[ "$output" =~ "type,name,fragment" ]] || false
+    [[ "$output" =~ "view,view1,SELECT 2+2 FROM dual" ]] || false
+
+    dolt sql -q "CREATE VIEW another_view AS SELECT 3+3"
+
+    run dolt sql -q "SELECT * FROM dolt_schemas" -r=csv
+    [ "$status" -eq "0" ]
+    [[ "$output" =~ "type,name,fragment,extra,sql_mode" ]] || false
+}