func (isp *InfoSchemaPlan) fetchStatisticsInTable(is infoschema.InfoSchema, schema *model.DBInfo, table *model.TableInfo) {
	if table.PKIsHandle {
		for _, col := range table.Columns {
			if mysql.HasPriKeyFlag(col.Flag) {
				record := []interface{}{
					catalogVal,    // TABLE_CATALOG
					schema.Name.O, // TABLE_SCHEMA
					table.Name.O,  // TABLE_NAME
					"0",           // NON_UNIQUE
					schema.Name.O, // INDEX_SCHEMA
					"PRIMARY",     // INDEX_NAME
					1,             // SEQ_IN_INDEX
					col.Name.O,    // COLUMN_NAME
					"A",           // COLLATION
					0,             // CARDINALITY
					nil,           // SUB_PART
					nil,           // PACKED
					"",            // NULLABLE
					"BTREE",       // INDEX_TYPE
					"",            // COMMENT
					"",            // INDEX_COMMENT
				}
				isp.rows = append(isp.rows, &plan.Row{Data: record})
			}
		}
	}
	for _, index := range table.Indices {
		nonUnique := "1"
		if index.Unique {
			nonUnique = "0"
		}
		for i, key := range index.Columns {
			col, _ := is.ColumnByName(schema.Name, table.Name, key.Name)
			nullable := "YES"
			if mysql.HasNotNullFlag(col.Flag) {
				nullable = ""
			}
			record := []interface{}{
				catalogVal,    // TABLE_CATALOG
				schema.Name.O, // TABLE_SCHEMA
				table.Name.O,  // TABLE_NAME
				nonUnique,     // NON_UNIQUE
				schema.Name.O, // INDEX_SCHEMA
				index.Name.O,  // INDEX_NAME
				i + 1,         // SEQ_IN_INDEX
				key.Name.O,    // COLUMN_NAME
				"A",           // COLLATION
				0,             // CARDINALITY
				nil,           // SUB_PART
				nil,           // PACKED
				nullable,      // NULLABLE
				"BTREE",       // INDEX_TYPE
				"",            // COMMENT
				"",            // INDEX_COMMENT
			}
			isp.rows = append(isp.rows, &plan.Row{Data: record})
		}
	}
}

// GetInfoSchema gets TxnCtx InfoSchema if snapshot schema is not set,
// Otherwise, snapshot schema is returned.
func GetInfoSchema(ctx context.Context) infoschema.InfoSchema {
	sessVar := ctx.GetSessionVars()
	var is infoschema.InfoSchema
	if snap := sessVar.SnapshotInfoschema; snap != nil {
		is = snap.(infoschema.InfoSchema)
		log.Infof("[%d] use snapshot schema %d", sessVar.ConnectionID, is.SchemaMetaVersion())
	} else {
		is = sessVar.TxnCtx.InfoSchema.(infoschema.InfoSchema)
	}
	return is
}

func (isp *InfoSchemaPlan) doStatistics(is infoschema.InfoSchema, schemas []*model.DBInfo, iterFunc plan.RowIterFunc) error {
	for _, schema := range schemas {
		for _, table := range schema.Tables {
			for _, index := range table.Indices {
				nonUnique := "1"
				if index.Unique {
					nonUnique = "0"
				}
				for i, key := range index.Columns {
					col, _ := is.ColumnByName(schema.Name, table.Name, key.Name)
					nullable := "YES"
					if mysql.HasNotNullFlag(col.Flag) {
						nullable = ""
					}
					record := []interface{}{
						catalogVal,    // TABLE_CATALOG
						schema.Name.O, // TABLE_SCHEMA
						table.Name.O,  // TABLE_NAME
						nonUnique,     // NON_UNIQUE
						schema.Name.O, // INDEX_SCHEMA
						index.Name.O,  // INDEX_NAME
						i + 1,         // SEQ_IN_INDEX
						key.Name.O,    // COLUMN_NAME
						"A",           // COLLATION
						0,             // CARDINALITY
						nil,           // SUB_PART
						nil,           // PACKED
						nullable,      // NULLABLE
						"BTREE",       // INDEX_TYPE
						"",            // COMMENT
						"",            // INDEX_COMMENT
					}
					if more, err := iterFunc(0, record); !more || err != nil {
						return err
					}
				}
			}
		}
	}
	return nil
}

// Compile compiles an ast.StmtNode to an ast.Statement.
// After preprocessed and validated, it will be optimized to a plan,
// then wrappped to an adapter *statement as stmt.Statement.
func (c *Compiler) Compile(ctx context.Context, node ast.StmtNode) (ast.Statement, error) {
	stmtNodeCounter.WithLabelValues(statementLabel(node)).Inc()
	if _, ok := node.(*ast.UpdateStmt); ok {
		sVars := variable.GetSessionVars(ctx)
		sVars.InUpdateStmt = true
		defer func() {
			sVars.InUpdateStmt = false
		}()
	}

	var is infoschema.InfoSchema
	if snap := variable.GetSessionVars(ctx).SnapshotInfoschema; snap != nil {
		is = snap.(infoschema.InfoSchema)
		log.Infof("use snapshot schema %d", is.SchemaMetaVersion())
	} else {
		is = sessionctx.GetDomain(ctx).InfoSchema()
		binloginfo.SetSchemaVersion(ctx, is.SchemaMetaVersion())
	}
	if err := plan.Preprocess(node, is, ctx); err != nil {
		return nil, errors.Trace(err)
	}
	// Validate should be after NameResolve.
	if err := plan.Validate(node, false); err != nil {
		return nil, errors.Trace(err)
	}
	p, err := plan.Optimize(ctx, node, is)
	if err != nil {
		return nil, errors.Trace(err)
	}
	_, isDDL := node.(ast.DDLNode)
	sa := &statement{
		is:    is,
		plan:  p,
		text:  node.Text(),
		isDDL: isDDL,
	}
	return sa, nil
}