sqlexec

Documentation

Index

• type RecordSet
• type RestrictedSQLExecutor
• type SQLExecutor
• type SQLParser
• type Statement

Types

type RecordSet

type RecordSet interface {
	// Fields gets result fields.
	Fields() []*ast.ResultField

	// Next reads records into chunk.
	Next(ctx context.Context, req *chunk.Chunk) error

	//NewChunk create a chunk.
	NewChunk() *chunk.Chunk

	// Close closes the underlying iterator, call Next after Close will
	// restart the iteration.
	Close() error
}

RecordSet is an abstract result set interface to help get data from Plan.

type RestrictedSQLExecutor

type RestrictedSQLExecutor interface {
	// ExecRestrictedSQL run sql statement in ctx with some restriction.
	ExecRestrictedSQL(ctx sessionctx.Context, sql string) ([]chunk.Row, []*ast.ResultField, error)
	// ExecRestrictedSQLWithSnapshot run sql statement in ctx with some restriction and with snapshot.
	// If current session sets the snapshot timestamp, then execute with this snapshot timestamp.
	// Otherwise, execute with the current transaction start timestamp if the transaction is valid.
	ExecRestrictedSQLWithSnapshot(ctx sessionctx.Context, sql string) ([]chunk.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) ([]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.

type Statement

type Statement interface {
	// OriginText gets the origin SQL text.
	OriginText() string

	// Exec executes SQL and gets a Recordset.
	Exec(ctx context.Context) (RecordSet, error)

	// IsPrepared returns whether this statement is prepared statement.
	IsPrepared() bool

	// IsReadOnly returns if the statement is read only. For example: SelectStmt without lock.
	IsReadOnly(vars *variable.SessionVars) bool

	// RebuildPlan rebuilds the plan of the statement.
	RebuildPlan() (schemaVersion int64, err error)
}

Statement is an interface for SQL execution. NOTE: all Statement implementations must be safe for concurrent using by multiple goroutines. If the Exec method requires any Execution domain local data, they must be held out of the implementing instance.