Package edu.caltech.nanodb.commands

This package contains the classes that represent the commands that the NanoSQL database recognizes. All of the commands are represented as subclasses of the Command abstract base-class. Commands are grouped into the following categories:

Data Definition Language (DDL) Commands

These commands manipulate the contents of the data-dictionary. The supported commands are as follows:

• CREATE TABLE - CreateTableCommand class
• DROP TABLE - DropTableCommand class

Data Manipulation Language (DML) Commands

These commands retrieve and modify the database tables themselves. Note that these commands all derive from the QueryCommand abstract class. The supported commands are as follows:

• DELETE ... - DeleteCommand class
• INSERT ... - InsertCommand class
• SELECT ... - SelectCommand class
• UPDATE ... - UpdateCommand class

Transaction-Demarcation Commands

These commands provide control over when a transaction is started or ended:

• BEGIN [WORK] | START TRANSACTION - BeginTransactionCommand class
• COMMIT [WORK] - CommitTransactionCommand class
• ROLLBACK [WORK] - RollbackTransactionCommand class

Utility Commands

These commands perform various utility operations:

• ANALYZE ... - AnalyzeCommand class
• EXPLAIN ... - ExplainCommand class
• EXIT | QUIT - ExitCommand class

Class Summary

Class	Description
AnalyzeCommand	This Command class represents the ANALYZE SQL command, which analyzes a table's internal data and updates its cached statistics to be as up-to-date as possible.
BeginTransactionCommand	This class represents a command that starts a transaction, such as BEGIN, BEGIN WORK, or START TRANSACTION.
Command	Abstract base-class for all commands that NanoDB supports.
CommandProperties	This class holds properties that might contain additional details for a command.
CommitTransactionCommand	This class represents a command that commits a transaction, such as COMMIT or COMMIT WORK.
ConstraintDecl	Constraints may be specified at the table level, or they may be specified on individual columns.
CrashCommand	This command "crashes" the database by shutting it down immediately without any proper cleanup or flushing of caches.
CreateIndexCommand	This command-class represents the CREATE INDEX DDL command.
CreateTableCommand	This command handles the CREATE TABLE DDL operation.
CreateViewCommand	This command-class represents the CREATE VIEW DDL command.
DDLUtils	This helper class provides some useful functions for constructing keys and indexes and other details for tables that are being initialized.
DeleteCommand	This command object represents a top-level DELETE command issued against the database.
DeleteCommand.TupleRemover	An implementation of the tuple processor interface used by the DeleteCommand to delete each tuple.
DropIndexCommand	This command-class represents the DROP INDEX DDL command.
DropTableCommand	This Command class represents the DROP TABLE SQL command.
DumpCommand	An abstract base-class that holds the common implementation of the various kinds of dump commands.
DumpCommand.TupleExporter	A tuple processor implementation used to dump each tuple.
DumpIndexCommand	This command object represents a DUMP INDEX command issued against the database.
DumpTableCommand	This command object represents a DUMP TABLE command issued against the database.
ExitCommand	This Command class represents the EXIT or QUIT SQL commands.
ExplainCommand	This Command class represents the EXPLAIN SQL command, which prints out details of how SQL DML statements will be evaluated.
FlushCommand	This command flushes all unwritten data from the buffer manager to disk.
InsertCommand	This command object represents a top-level INSERT command issued against the database.
InsertCommand.TupleInserter	An implementation of the tuple processor interface used by the InsertCommand to insert tuples into a table, when the command is of the form INSERT ...
OptimizeCommand	This Command class represents the OPTIMIZE SQL command, which optimizes a table's representation (along with any indexes) to improve access performance and space utilization.
QueryCommand	This class represents all SQL query commands, including SELECT, INSERT, UPDATE, and DELETE.
RollbackTransactionCommand	This class represents a command that rolls back a transaction, such as ROLLBACK or ROLLBACK WORK.
SelectCommand	This command object represents a top-level SELECT command issued against the database.
SetPropertyCommand	Implements the "SET VARIABLE ..." command.
ShowPropertiesCommand	Implements the "SHOW VARIABLES" command.
ShowSystemStatsCommand	Implements the "SHOW [system] STATS" command.
ShowTablesCommand	Implements the "SHOW TABLES" command.
ShowTableStatsCommand	Implements the "SHOW TABLE t STATS" command.
TableColumnDecl	This class represents a single column declaration within a CREATE TABLE command.
UpdateCommand	This command object represents a top-level UPDATE command issued against the database.
UpdateCommand.TupleUpdater	An implementation of the tuple processor interface used by the UpdateCommand to update each tuple.
UpdateValue	This class represents a single column-name/expression pair in an UPDATE statement's SET clause.
VerifyCommand	This Command class represents the VERIFY SQL command, which verifies a table's representation (along with any indexes) to ensure that all structural details are valid.

Enum Summary

Enum	Description
Command.Type	Commands are either Data-Definition Language (DDL), Data-Manipulation Language (DML), or utility commands.
QueryCommand.Type	Typesafe enumeration of query-command types.

Exception Summary

Exception	Description
ExecutionException	This exception is thrown when a fatal error occurs during command execution.