sqlexec

Documentation

Index

• type Failer
• type RestrictedSQLExecutor
• type SQLExecutor
• type SQLParser

Types

type Failer

type Failer interface {
	Fail() error
}

Failer is temporary interface to use Fail method TODO: remove this after we remove TxnState.fail.

type RestrictedSQLExecutor

type RestrictedSQLExecutor interface {
	// ExecRestrictedSQL run sql statement in ctx with some restriction.
	ExecRestrictedSQL(ctx sessionctx.Context, sql string) ([]types.Row, []*ast.ResultField, error)
}

RestrictedSQLExecutor is an interface provides executing restricted sql statement. Why we need this interface? When we execute some management statements, we need to operate system tables. For example when executing create user statement, we need to check if the user already exists in the mysql.User table and insert a new row if not exists. In this case, we need a convenience way to manipulate system tables. The most simple way is executing sql statement. In order to execute sql statement in stmts package, we add this interface to solve dependence problem. And in the same time, we do not want this interface becomes a general way to run sql statement. We hope this could be used with some restrictions such as only allowing system tables as target, do not allowing recursion call. For more information please refer to the comments in session.ExecRestrictedSQL(). This is implemented in session.go.

type SQLExecutor

type SQLExecutor interface {
	Execute(ctx context.Context, sql string) ([]ast.RecordSet, error)
}

SQLExecutor is an interface provides executing normal sql statement. Why we need this interface? To break circle dependence of packages. For example, privilege/privileges package need execute SQL, if it use session.Session.Execute, then privilege/privileges and tidb would become a circle.

type SQLParser

type SQLParser interface {
	ParseSQL(sql, charset, collation string) ([]ast.StmtNode, error)
}

SQLParser is an interface provides parsing sql statement. To parse a sql statement, we could run parser.New() to get a parser object, and then run Parse method on it. But a session already has a parser bind in it, so we define this interface and use session as its implementation, thus avoid allocating new parser. See session.SQLParser for more information.