ddlreverser

Documentation

Index

• func ReverseAlterWithCompares(compares *ast.CreateTableStmt, alter *ast.AlterTableStmt) (string, bool, error)
• func ReverseCreateTableStmt(in *ast.CreateTableStmt) string
• func ReverseCreateTableStmts(ddlNodes interface{ ... }) string
• func ReverseDDLWithSnapshot(tx *gorm.DB, ddl ast.DDLNode) (reversing string, ok bool, err error)
• func ReverseDropIndexStmtWithCompares(compares *ast.CreateTableStmt, drop *ast.DropIndexStmt) (string, bool, error)
• func ShowCreateTable(tx *gorm.DB, tableName string) (create string, err error)

Functions

func ReverseAlterWithCompares

func ReverseAlterWithCompares(compares *ast.CreateTableStmt, alter *ast.AlterTableStmt) (string, bool, error)

ReverseAlterWithCompares for giving compares, returns the reversed SQL of AlterTableStmt

func ReverseCreateTableStmt

func ReverseCreateTableStmt(in *ast.CreateTableStmt) string

func ReverseCreateTableStmts

func ReverseCreateTableStmts(ddlNodes interface{ DDLNodes() []ast.DDLNode }) string

ReverseCreateTableStmts reverses DDLs without snapshot. Generally, this function is used to process the baseline, because when processing the baseline, it only needs to Drop all the newly created tables.

func ReverseDDLWithSnapshot

func ReverseDDLWithSnapshot(tx *gorm.DB, ddl ast.DDLNode) (reversing string, ok bool, err error)

ReverseDDLWithSnapshot reverses a DDL. e.g.

CreateTableStmt ==reverse-to==> DropTableStmt
RenameTableStmt a to b ==reverse-to==> RenameTableStmt b to a
AlterTableAddColumns ==reverse-to==> AlterTableDropColumn
AlterTableOption to new ==reverse-to==> AlterTableOption to old
... ....

How to do this ? First, to snapshot the table definition from database, then generate the reversed DDL.

tx *gorm.DB is used to connect to database for getting table's snapshot; ddl ast.DDLNode is is the stmt node for revering.

reversing is the reversed DDL text; ok is whether reversing is success, if not ok, reversing is ""; err is whether an error has occurred, if err is not nil, ok is false, reversing is "".

If the ddl is not allowed (e.g. DropDatabaseStmt, DropTableStmt, AlterTableDropColumnSpec), the function will not process it, and returned err is nil, ok is false, reversing is "".

func ReverseDropIndexStmtWithCompares

func ReverseDropIndexStmtWithCompares(compares *ast.CreateTableStmt, drop *ast.DropIndexStmt) (string, bool, error)

func ShowCreateTable

func ShowCreateTable(tx *gorm.DB, tableName string) (create string, err error)

ShowCreateTable gets create table stmt by executing SHOW CREATE TABLE .