*: add information_schema db with files and column_statistics tables

engine_test.go

@@ -341,7 +341,7 @@ var queries = []struct {
 	},
 	{
 		`SHOW DATABASES`,
-		[]sql.Row{{"mydb"}, {"foo"}},
+		[]sql.Row{{"mydb"}, {"foo"}, {"information_schema"}},
 	},
 	{
 		`SELECT s FROM mytable WHERE s LIKE '%d row'`,
@@ -465,6 +465,47 @@ var queries = []struct {
 		`SELECT CONNECTION_ID()`,
 		[]sql.Row{{uint32(1)}},
 	},
+	{
+		`
+		SELECT DISTINCT
+			tablespace_name, file_name, logfile_group_name, extent_size, initial_size, engine
+		FROM
+			information_schema.files
+		WHERE
+			file_type = 'DATAFILE'
+		ORDER BY tablespace_name, logfile_group_name
+		`,
+		[]sql.Row{},
+	},
+	{
+		`
+		SELECT
+			logfile_group_name, file_name, total_extents, initial_size, engine, extra
+		FROM
+			information_schema.files
+		WHERE
+			file_type = 'UNDO LOG' AND
+			file_name IS NOT NULL AND
+			logfile_group_name IS NOT NULL
+		GROUP BY
+			logfile_group_name, file_name, engine, total_extents, initial_size
+		ORDER BY
+			logfile_group_name
+		`,
+		[]sql.Row{},
+	},
+	{
+		`
+		SELECT
+			column_name
+		FROM
+			information_schema.column_statistics
+		WHERE
+			schema_name = 'foo' AND
+			table_name = 'bar';
+		`,
+		[]sql.Row{},
+	},
 }
 
 func TestQueries(t *testing.T) {
@@ -937,6 +978,7 @@ func newEngineWithParallelism(t *testing.T, parallelism int) *sqle.Engine {
 	catalog := sql.NewCatalog()
 	catalog.AddDatabase(db)
 	catalog.AddDatabase(db2)
+	catalog.AddDatabase(sqle.NewInformationSchemaDB())
 
 	var a *analyzer.Analyzer
 	if parallelism > 1 {

information_schema.go

@@ -0,0 +1,150 @@
+package sqle // import "gopkg.in/src-d/go-mysql-server.v0"
+
+import (
+	"fmt"
+	"io"
+
+	"gopkg.in/src-d/go-mysql-server.v0/sql"
+)
+
+const (
+	InformationSchemaDBName   = "information_schema"
+	FilesTableName            = "files"
+	ColumnStatisticsTableName = "column_statistics"
+)
+
+type informationSchemaDB struct {
+	name   string
+	tables map[string]sql.Table
+}
+
+var _ sql.Database = (*informationSchemaDB)(nil)
+
+// NewInformationSchemaDB creates a new INFORMATION_SCHEMA Database.
+func NewInformationSchemaDB() sql.Database {
+	return &informationSchemaDB{
+		name: InformationSchemaDBName,
+		tables: map[string]sql.Table{
+			FilesTableName:            newFilesTable(),
+			ColumnStatisticsTableName: newColumnStatisticsTable(),
+		},
+	}
+}
+
+// Name implements the sql.Database interface.
+func (i *informationSchemaDB) Name() string { return i.name }
+
+// Tables implements the sql.Database interface.
+func (i *informationSchemaDB) Tables() map[string]sql.Table { return i.tables }
+
+func newFilesTable() sql.Table {
+	return &emptyTable{
+		name:   FilesTableName,
+		schema: filesSchema,
+	}
+}
+
+var filesSchema = sql.Schema{
+	&sql.Column{Name: "file_id", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "file_name", Type: sql.Text, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "file_type", Type: sql.Text, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "tablespace_name", Type: sql.Text, Source: FilesTableName},
+	&sql.Column{Name: "table_catalog", Type: sql.Text, Source: FilesTableName},
+	&sql.Column{Name: "table_schema", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "table_name", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "logfile_group_name", Type: sql.Text, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "logfile_group_number", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "engine", Type: sql.Text, Source: FilesTableName},
+	&sql.Column{Name: "fulltext_keys", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "deleted_rows", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "update_count", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "free_extents", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "total_extents", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "extent_size", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "initial_size", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "maximum_size", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "autoextend_size", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "creation_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "last_update_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "last_access_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "recover_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "transaction_counter", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "version", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "row_format", Type: sql.Text, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "table_rows", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "avg_row_length", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "data_length", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "max_data_length", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "index_length", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "data_free", Type: sql.Int64, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "create_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "update_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "check_time", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "checksum", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "status", Type: sql.Text, Source: FilesTableName, Nullable: true},
+	&sql.Column{Name: "extra", Type: sql.Blob, Source: FilesTableName, Nullable: true},
+}
+
+func newColumnStatisticsTable() sql.Table {
+	return &emptyTable{
+		name:   ColumnStatisticsTableName,
+		schema: columnStatisticsSchema,
+	}
+}
+
+var columnStatisticsSchema = sql.Schema{
+	&sql.Column{Name: "schema_name", Type: sql.Text, Source: ColumnStatisticsTableName},
+	&sql.Column{Name: "table_name", Type: sql.Text, Source: ColumnStatisticsTableName},
+	&sql.Column{Name: "column_name", Type: sql.Text, Source: ColumnStatisticsTableName},
+	&sql.Column{Name: "histogram", Type: sql.JSON, Source: ColumnStatisticsTableName},
+}
+
+type emptyTable struct {
+	name   string
+	schema sql.Schema
+}
+
+var _ sql.Table = (*emptyTable)(nil)
+
+// Name implements the sql.Table interface.
+func (t *emptyTable) Name() string { return t.name }
+
+// String implements the sql.Table interface.
+func (t *emptyTable) String() string { return printTable(t.name, t.schema) }
+
+// Schema implements the sql.Table interface.
+func (t *emptyTable) Schema() sql.Schema { return t.schema }
+
+// Partitions implements the sql.Table interface.
+func (t *emptyTable) Partitions(_ *sql.Context) (sql.PartitionIter, error) {
+	return new(partitionIter), nil
+}
+
+// PartitionRows implements the sql.Table interface.
+func (t *emptyTable) PartitionRows(_ *sql.Context, _ sql.Partition) (sql.RowIter, error) {
+	return sql.RowsToRowIter(), nil
+}
+
+func printTable(name string, tableSchema sql.Schema) string {
+	p := sql.NewTreePrinter()
+	_ = p.WriteNode("Table(%s)", name)
+	var schema = make([]string, len(tableSchema))
+	for i, col := range tableSchema {
+		schema[i] = fmt.Sprintf(
+			"Column(%s, %s, nullable=%v)",
+			col.Name,
+			col.Type.Type().String(),
+			col.Nullable,
+		)
+	}
+	_ = p.WriteChildren(schema...)
+	return p.String()
+}
+
+type partitionIter struct{}
+
+var _ sql.PartitionIter = (*partitionIter)(nil)
+
+func (p *partitionIter) Next() (sql.Partition, error) { return nil, io.EOF }
+
+func (p *partitionIter) Close() error { return nil }