Package com.mckoi.database

Class DatabaseConnection

  • All Implemented Interfaces:
    TriggerListener
    public class DatabaseConnection
extends java.lang.Object
implements TriggerListener
    An object that represents a connection to a Database. This object handles all transactional queries and modifications to the database.

    • Field Detail

      • user

        private User user
        The User that this connection has been made by.

      • database

        private Database database
        The Database object that this connection is on.

      • logger

        private DebugLogger logger
        The DebugLogger object that we can use to log messages to.

      • call_back

        private DatabaseConnection.CallBack call_back
        A loop-back object that is managing this connection. This typically is the session protocol. This is notified of all connection events, such as triggers.

      • locking_mechanism

        private LockingMechanism locking_mechanism
        The locking mechanism within this connection.

      • conglomerate

        private TableDataConglomerate conglomerate
        The TableDataConglomerate object that is used for transactional access to the data.

      • transaction

        private Transaction transaction
        The current Transaction that this connection is operating within.

      • jdbc_connection

        private java.sql.Connection jdbc_connection
        The current java.sql.Connection object that can be used to access the transaction internally.

      • tables_cache

        private java.util.HashMap tables_cache
        A HashMap of DataTable objects that have been created within this connection.

      • trigger_event_buffer

        private java.util.ArrayList trigger_event_buffer
        A buffer of triggers. This contains triggers that can't fire until the current transaction has closed. These triggers were generated by external actions outside of the context of this transaction.

      • trigger_event_list

        private java.util.ArrayList trigger_event_list
        A list of triggers that are fired by actions taken on tables in this transaction. When the transaction is successfully committed, these trigger events need to be propogated to other connections in the database listening for trigger events on the triggered objects.

      • auto_commit

        private boolean auto_commit
        If this is true then the database connection is in 'auto-commit' mode. This implies a COMMIT instruction is executed after every complete statement in the language grammar. By default this is true.

      • transaction_isolation

        private int transaction_isolation
        The current transaction isolation level this connect is operating under. 1 = READ UNCOMMITTED, 2 = READ COMMITTED, 3 = REPEATABLE READ, 4 = SERIALIZABLE.

      • close_transaction_disabled

        private boolean close_transaction_disabled
        A flag which if set to true, will not allow 'commit' or 'rollback' commands on the transaction to occur and therefore prevent any open transaction from closing. This is useful for restricting the ability of a stored procedure to close.

      • current_schema

        private java.lang.String current_schema
        The name of the schema that this connection is currently in. If the schema is "" then this connection is in the default schema (effectively no schema).

      • grant_manager

        private GrantManager grant_manager
        The GrantManager object for this connection.

      • procedure_manager

        private ProcedureManager procedure_manager
        The procedure manager object for this connection.

      • connection_trigger_manager

        private ConnectionTriggerManager connection_trigger_manager
        The connection trigger manager that handles actions that cause triggers to fire on this connection.

      • view_manager

        private ViewManager view_manager
        The connection view manager that handles view information through this connection.

      • table_backed_cache_list

        private java.util.ArrayList table_backed_cache_list
        The list of all TableBackedCache objects that have been attached to this DatabaseConnection and are to be notified of transaction start/end events.

      • connection_internal_table_info

        private DatabaseConnection.ConnectionInternalTableInfo connection_internal_table_info
        A local member that represents the static list of internal tables that represent connection specific properties such as username, connection, statistics, etc.

      • error_on_dirty_select

        private boolean error_on_dirty_select
        True if transactions through this connection generate an error when there is a dirty select on a table.

      • case_insensitive_identifiers

        private boolean case_insensitive_identifiers
        True if this connection resolves identifiers case insensitive.

      • current_old_new_state

        private DatabaseConnection.OldNewTableState current_old_new_state
        The current state of the OLD and NEW system tables including any cached information about the tables.

      • INTERNAL_DEF_LIST

        private static final DataTableDef[] INTERNAL_DEF_LIST
        A list of DataTableDef system table definitions for tables internal to the database connection.

    • Method Detail

      • init

        void init()
        Initializes this DatabaseConnection (possibly by initializing state from the database).

      • getTransaction

        private Transaction getTransaction()
        Returns the transaction. If 'transaction' is null then it opens a new transaction within the conglomerate.

      • createViewQueryPlanNode

        QueryPlanNode createViewQueryPlanNode​(TableName table_name)
        Returns a freshly deserialized QueryPlanNode object for the given view object.

      • getJDBCConnection

        public java.sql.Connection getJDBCConnection()
        Returns a java.sql.Connection object that can be used as a JDBC interface to access the current transaction of this DatabaseConnection.

        There are a few important considerations when using the JDBC connection;

        • The returned Connection does not allow auto-commit to be set. It is intended to be used to issue commands to this DatabaseConnection from inside a transaction so auto-commit does not make sense.
        • The returned object must only be accessed from the same worker thread that is currently accessing this DatabaseConnection. The returned Connection is NOT multi-thread capable.
        • The java.sql.Connection returned here is invalidated (disposed) when the current transaction is closed (committed or rolled back).
        • This method returns the same java.sql.Connection on multiple calls to this method (while a transaction is open).
        • The DatabaseConnection must be locked in EXCLUSIVE mode or the queries will fail.

      • createProcedureConnection

        ProcedureConnection createProcedureConnection​(User user)
        Creates an object that implements ProcedureConnection that provides access to this connection.

        Note that this connection is set to the user of the privs that the procedure executes under when this method returns.

        There must be a 100% guarentee that after this method is called, a call to 'disposeProcedureConnection' is called which cleans up the state of this object.

      • disposeProcedureConnection

        void disposeProcedureConnection​(ProcedureConnection connection)
        Disposes of the ProcedureConnection that was previously created by the 'createProcedure' method.

      • getSystem

        public DatabaseSystem getSystem()
        Returns the DatabaseSystem object for this connection.

      • getDatabase

        public Database getDatabase()
        Returns the Database object for this connection.

      • setUser

        void setUser​(User user)
        Sets the User object for this connection. This is necessary because we may want to temporarily change the user on this connection to allow top level queries in a different privilege space.

      • getUser

        public User getUser()
        Returns the User object for this connection.

      • Debug

        public final DebugLogger Debug()
        Returns a DebugLogger object that we can use to log debug messages to.

      • getConnectionTriggerManager

        public ConnectionTriggerManager getConnectionTriggerManager()
        Returns the connection trigger manager for this connection.

      • getGrantManager

        public GrantManager getGrantManager()
        Returns the GrantManager object that manages grants for tables in the database for this connection/user.

      • getProcedureManager

        public ProcedureManager getProcedureManager()
        Returns the ProcedureManager object that manages database functions and procedures in the database for this connection/user.

      • setAutoCommit

        public void setAutoCommit​(boolean status)
        Sets the auto-commit mode.

      • setTransactionIsolation

        public void setTransactionIsolation​(java.lang.String name)
        Sets the transaction isolation level from a string.

      • setVar

        public void setVar​(java.lang.String name,
                   Expression exp)
        Assigns a variable to the expression for this connection. This is a generic way of setting properties of the connection. Currently supported variables are;

        ERROR_ON_DIRTY_SELECT - set to Boolean.TRUE for turning this transaction conflict off on this connection. CASE_INSENSITIVE_IDENTIFIERS - Boolean.TRUE means the grammar becomes case insensitive for identifiers resolved by the grammar.

      • toBooleanValue

        private static boolean toBooleanValue​(Expression exp)
        Evaluates the expression to a boolean value (true or false).

      • getAutoCommit

        public boolean getAutoCommit()
        Returns the auto-commit status of this connection. If this is true then the language layer must execute a COMMIT after every statement.

      • getTransactionIsolation

        public int getTransactionIsolation()
        Returns the transaction isolation level of this connection.

      • getTransactionIsolationAsString

        public java.lang.String getTransactionIsolationAsString()
        Returns the transaction isolation level of this connection as a string.

      • getCurrentSchema

        public java.lang.String getCurrentSchema()
        Returns the name of the schema that this connection is within.

      • isInCaseInsensitiveMode

        public boolean isInCaseInsensitiveMode()
        Returns true if the connection is in case insensitive mode. In case insensitive mode the case of identifier strings is not important.

      • setCurrentSchema

        public void setCurrentSchema​(java.lang.String current_schema)
        Sets the schema that this connection is within.

      • getLockingMechanism

        public LockingMechanism getLockingMechanism()
        Returns the LockingMechanism object that is within the context of this database connection. This manages read/write locking within this connection.

      • attachTableBackedCache

        void attachTableBackedCache​(TableBackedCache cache)
        Attaches a TableBackedCache object to this DatabaseConnection which is notified when a transaction is started and stopped, and when the table being backed has changes made to it.

      • getTableList

        public TableName[] getTableList()
        Returns a TableName[] array that contains the list of database tables that are visible by this transaction.

        This returns the list of all objects that represent queriable tables in the database.

      • tableExists

        public boolean tableExists​(java.lang.String table_name)
        Returns true if the table exists within this connection transaction.

      • tableExists

        public boolean tableExists​(TableName table_name)
        Returns true if the table exists within this connection transaction.

      • getTableType

        public java.lang.String getTableType​(TableName table_name)
        Returns the type of the table object. Currently this is either "TABLE" or "VIEW".

      • tryResolveCase

        public TableName tryResolveCase​(TableName table_name)
        Attempts to resolve the given table name to its correct case assuming the table name represents a case insensitive version of the name. For example, "aPP.CuSTOMer" may resolve to "APP.Customer". If the table name can not resolve to a valid identifier it returns the input table name, therefore the actual presence of the table should always be checked by calling 'tableExists' after this method returns.

      • resolveTableName

        public TableName resolveTableName​(java.lang.String name)
        Resolves a TableName string (eg. 'Customer' 'APP.Customer' ) to a TableName object. If the schema part of the table name is not present then it is set to the current schema of the database connection. If the database is ignoring the case then this will correctly resolve the table to the cased version of the table name.

      • resolveToTableName

        public TableName resolveToTableName​(java.lang.String name)
        Resolves the given string to a table name, throwing an exception if the reference is ambiguous. This also generates an exception if the table object is not found.

      • getDataTableDef

        public DataTableDef getDataTableDef​(TableName name)
        Returns the DataTableDef for the table with the given name.

      • getTable

        public DataTable getTable​(TableName name)
        Returns a DataTable that represents the table from the given schema, name in the database.

      • getTable

        public DataTable getTable​(java.lang.String table_name)
        Returns a DataTable that represents the table with the given name in the database from the current connection schema.

      • createTable

        public void createTable​(DataTableDef table_def)
        Create a new table within the context of the current connection transaction.

      • createTable

        public void createTable​(DataTableDef table_def,
                        int data_sector_size,
                        int index_sector_size)
        Create a new table with a starting initial sector size. This should only be used as very fine grain optimization for creating tables. If in the future the underlying table model is changed so that the given 'sector_size' value is unapplicable, then the value will be ignored.

      • createView

        public void createView​(SQLQuery query,
                       ViewDef view)
        Creates a new view. This takes the information in the ViewDef object and adds it to the system view table.

        Note that this is a transactional operation. You need to commit for the view to be visible to other transactions.

      • dropView

        public boolean dropView​(TableName view_name)
        Drops the view with the given name and returns true if the drop succeeded. Returns false if the view was not found.

        Note that this is a transactional operation. You need to commit for the change to be visible to other transactions.

      • updateTable

        public void updateTable​(DataTableDef table_def)
        Updates a given table within the context of the current connection transaction.

      • updateTable

        public void updateTable​(DataTableDef table_def,
                        int data_sector_size,
                        int index_sector_size)
        Updates a given table within the context of the current connection transaction. This should only be used as very fine grain optimization for creating tables.If in the future the underlying table model is changed so that the given 'sector_size' value is unapplicable, then the value will be ignored.

      • alterCreateTable

        public void alterCreateTable​(DataTableDef table_def,
                             int data_sector_size,
                             int index_sector_size)
        Given a DataTableDef, if the table exists then it is updated otherwise if it doesn't exist then it is created.

        This should only be used as very fine grain optimization for creating/ altering tables. If in the future the underlying table model is changed so that the given 'sector_size' value is unapplicable, then the value will be ignored.

      • alterCreateTable

        public void alterCreateTable​(DataTableDef table_def)
        Given a DataTableDef, if the table exists then it is updated otherwise if it doesn't exist then it is created.

      • databaseObjectCreated

        void databaseObjectCreated​(TableName table_name)
        Notifies this transaction that a database object with the given name has successfully been created.

      • databaseObjectDropped

        void databaseObjectDropped​(TableName table_name)
        Notifies this transaction that a database object with the given name has successfully been dropped.

      • checkAllConstraints

        public void checkAllConstraints​(TableName table_name)
        Checks all the rows in the table for immediate constraint violations and when the transaction is next committed check for all deferred constraint violations. This method is used when the constraints on a table changes and we need to determine if any constraint violations occurred. To the constraint checking system, this is like adding all the rows to the given table.

      • dropTable

        public void dropTable​(java.lang.String table_name)
        Drops a table from within the context of the current connection transaction.

      • dropTable

        public void dropTable​(TableName table_name)
        Drops a table from within the context of the current connection transaction.

      • compactTable

        public void compactTable​(java.lang.String table_name)
        Compacts the table with the given name. Throws an exception if the table doesn't exist.

      • compactTable

        public void compactTable​(TableName table_name)
        Compacts the table with the given name. Throws an exception if the table doesn't exist.

      • addSelectedFromTable

        public void addSelectedFromTable​(java.lang.String table_name)
        Adds the given table name to the list of tables that are selected from within the transaction in this connection.

      • addSelectedFromTable

        public void addSelectedFromTable​(TableName name)
        Adds the given table name to the list of tables that are selected from within the transaction in this connection.

      • nextSequenceValue

        public long nextSequenceValue​(java.lang.String name)
        Requests of the sequence generator the next value from the sequence.

        NOTE: This does NOT check that the user owning this connection has the correct privs to perform this operation.

      • lastSequenceValue

        public long lastSequenceValue​(java.lang.String name)
        Returns the current sequence value for the given sequence generator that was last returned by a call to 'nextSequenceValue'. If a value was not last returned by a call to 'nextSequenceValue' then a statement exception is generated.

        NOTE: This does NOT check that the user owning this connection has the correct privs to perform this operation.

      • setSequenceValue

        public void setSequenceValue​(java.lang.String name,
                             long value)
        Sets the sequence value for the given sequence generator. If the generator does not exist or it is not possible to set the value for the generator then an exception is generated.

        NOTE: This does NOT check that the user owning this connection has the correct privs to perform this operation.

      • nextUniqueID

        public long nextUniqueID​(TableName name)
        Returns the next unique identifier for the given table from the schema.

      • nextUniqueID

        public long nextUniqueID​(java.lang.String table_name)
        Returns the next unique identifier for the given table in the connection schema.

      • substituteReservedTableName

        static TableName substituteReservedTableName​(TableName table_name)
        If the given table name is a reserved name, then we must substitute it with its correct form. For example, 'APP.NEW' becomes 'SYS_INFO.NEW', etc.

      • checkAllowCreate

        static void checkAllowCreate​(TableName table_name)
        Generates an exception if the name of the table is reserved and the creation of the table should be prevented. For example, the table names 'OLD' and 'NEW' are reserved.

      • createSequenceGenerator

        public void createSequenceGenerator​(TableName name,
                                    long start_value,
                                    long increment_by,
                                    long min_value,
                                    long max_value,
                                    long cache,
                                    boolean cycle)
        Creates a new sequence generator with the given TableName and initializes it with the given details. This does NOT check if the given name clashes with an existing database object.

      • dropSequenceGenerator

        public void dropSequenceGenerator​(TableName name)
        Drops an existing sequence generator with the given name.

      • createTrigger

        public void createTrigger​(java.lang.String trigger_name,
                          java.lang.String trigger_source,
                          int type)
        Adds a type of trigger for the given trigger source (usually the name of the table).

        Adds a type of trigger to the given Table. When the event is fired, the UserCallBack method is notified of the event.

      • deleteTrigger

        public void deleteTrigger​(java.lang.String trigger_name)
        Removes a type of trigger for the given trigger source (usually the name of the table).

      • notifyTriggerEvent

        public void notifyTriggerEvent​(TriggerEvent evt)
        Informs the underlying transaction that a high level transaction event has occurred and should be dispatched to any listeners occordingly.

      • createNewLargeObject

        public Ref createNewLargeObject​(byte type,
                                long object_size)
        Allocates a new large object in the Blob store of this conglomerate of the given type and size. The blob data must be written through the Ref after the large object is created. Once the data has been written the 'complete' method in Ref is called.

        Once a large object is created and written to, it may be allocated in one or more tables in the conglomerate.

      • flushBlobStore

        public void flushBlobStore()
        Tells the conglomerate to flush the blob store. This should be called after one or more blobs have been created and the data for the blob(s) are set. It is an important step to perform AFTER blobs have been written.

        If this is not called and the database closes (or crashes) before a flush occurs then the blob may not be recoverable.

      • getTableQueryDef

        public TableQueryDef getTableQueryDef​(TableName table_name,
                                      TableName aliased_as)
        Returns a TableQueryDef object that describes the characteristics of a table including the name (TableName), the columns (DataTableDef) and the query plan to produce the table (QueryPlanNode). This object can be used to resolve information about a particular table, and to evaluate the query plan to produce the table itself.

        This produces TableQueryDef objects for all table objects in the database including data tables and views.

        The 'aliased_as' parameter is used to overwrite the default name of the table object.

      • createObjectFetchQueryPlan

        public QueryPlanNode createObjectFetchQueryPlan​(TableName table_name,
                                                TableName aliased_name)
        Creates a QueryPlanNode to fetch the given table object from this connection.

      • setDefaultSchema

        public void setDefaultSchema​(java.lang.String schema_name)
        Changes the default schema to the given schema.

      • checkExclusive

        private void checkExclusive()

      • createSchema

        public void createSchema​(java.lang.String name,
                         java.lang.String type)
        Same as the Transaction.createSchema method.

      • dropSchema

        public void dropSchema​(java.lang.String name)
        Same as the Transaction.dropSchema method.

      • schemaExists

        public boolean schemaExists​(java.lang.String name)
        Same as the Transaction.schemaExists method.

      • resolveSchemaCase

        public SchemaDef resolveSchemaCase​(java.lang.String name,
                                   boolean ignore_case)
        Same as the Transaction.resolveSchemaCase method.

      • resolveSchemaName

        public SchemaDef resolveSchemaName​(java.lang.String name)
        Convenience - returns the SchemaDef object given the name of the schema. If identifiers are case insensitive, we resolve the case of the schema name also.

      • getSchemaList

        public SchemaDef[] getSchemaList()
        Same as the Transaction.getSchemaList method.

      • setPersistentVar

        public void setPersistentVar​(java.lang.String variable,
                             java.lang.String value)
        Same as the Transaction.setPersistentVar method.

      • getPersistentVar

        public java.lang.String getPersistentVar​(java.lang.String variable)
        Same as the Transaction.getPersistentVar method.

      • addUniqueConstraint

        public void addUniqueConstraint​(TableName table_name,
                                java.lang.String[] cols,
                                short deferred,
                                java.lang.String constraint_name)
        Same as the Transaction.addUniqueConstraint method.

      • addForeignKeyConstraint

        public void addForeignKeyConstraint​(TableName table,
                                    java.lang.String[] cols,
                                    TableName ref_table,
                                    java.lang.String[] ref_cols,
                                    java.lang.String delete_rule,
                                    java.lang.String update_rule,
                                    short deferred,
                                    java.lang.String constraint_name)
        Same as the Transaction.addForeignKeyConstraint method.

      • addPrimaryKeyConstraint

        public void addPrimaryKeyConstraint​(TableName table_name,
                                    java.lang.String[] cols,
                                    short deferred,
                                    java.lang.String constraint_name)
        Same as the Transaction.addPrimaryKeyConstraint method.

      • addCheckConstraint

        public void addCheckConstraint​(TableName table_name,
                               Expression expression,
                               short deferred,
                               java.lang.String constraint_name)
        Same as the Transaction.addCheckConstraint method.

      • dropAllConstraintsForTable

        public void dropAllConstraintsForTable​(TableName table_name)
        Same as the Transaction.dropAllConstraintsForTable method.

      • dropNamedConstraint

        public int dropNamedConstraint​(TableName table_name,
                               java.lang.String constraint_name)
        Same as the Transaction.dropNamedConstraint method.

      • dropPrimaryKeyConstraintForTable

        public boolean dropPrimaryKeyConstraintForTable​(TableName table_name,
                                                java.lang.String constraint_name)
        Same as the Transaction.dropPrimaryKeyConstraintForTable method.

      • queryTablesRelationallyLinkedTo

        public TableName[] queryTablesRelationallyLinkedTo​(TableName table)
        Same as the Transaction.queryTablesRelationallyLinkedTo method.

      • queryTableUniqueGroups

        public Transaction.ColumnGroup[] queryTableUniqueGroups​(TableName table_name)
        Same as the Transaction.queryTableUniqueGroups method.

      • queryTablePrimaryKeyGroup

        public Transaction.ColumnGroup queryTablePrimaryKeyGroup​(TableName table_name)
        Same as the Transaction.queryTablePrimaryKeyGroup method.

      • queryTableImportedForeignKeyReferences

        public Transaction.ColumnGroupReference[] queryTableImportedForeignKeyReferences​(TableName table_name)
        Same as the Transaction.queryTableImportedForeignKeyReferences method.

      • setOldNewTableState

        void setOldNewTableState​(DatabaseConnection.OldNewTableState state)
        Sets the current state of the old/new tables. When nesting OLD/NEW tables for nested stored procedures, the current state should be first recorded and reverted back when the nested procedure finishes.

      • fireTableEvent

        void fireTableEvent​(TableModificationEvent evt)
        Notifies this connection that an insert/delete or update operation has occurred on some table of this DatabaseConnection. This should notify the trigger connection manager of this event so that it may perform any action that may have been set up to occur on this event.

      • fireTrigger

        public void fireTrigger​(DatabaseConnection database,
                        java.lang.String trigger_name,
                        TriggerEvent evt)
        Notifies when a trigger has fired for this user. If there are no open transactions on this connection then we do a straight call back trigger notify. If there is a transaction open then trigger events are added to the 'trigger_event_buffer' which fires when the connection transaction is committed or rolled back.
        Specified by:
        fireTrigger in interface TriggerListener
        Parameters:
        database - the DatabaseConnection that this trigger is registered for.
        evt - the trigger event that was fired.

      • firePendingTriggerEvents

        private void firePendingTriggerEvents()
        Fires any triggers that are pending in the trigger buffer.

      • disposeTransaction

        private void disposeTransaction()
        Private method that disposes the current transaction.

      • commit

        public void commit()
            throws TransactionException
        Tries to commit the current transaction. If the transaction can not be committed because there were concurrent changes that interfered with each other then a TransactionError is thrown and the transaction is rolled back.

        NOTE: It's guarenteed that the transaction will be closed even if a transaction exception occurs.

        Synchronization is implied on this method, because the locking mechanism should be exclusive when this is called.

        Throws:
        TransactionException

      • rollback

        public void rollback()
        Rolls back the current transaction operating within this connection.

        NOTE: It's guarenteed that the transaction will be closed even if an exception occurs.

        Synchronization is implied on this method, because the locking mechanism should be exclusive when this is called.

      • close

        public void close()
        Closes this database connection.

      • finalize

        public void finalize()
              throws java.lang.Throwable
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable