Class DatabaseConnection

java.lang.Object
com.mckoi.database.DatabaseConnection
All Implemented Interfaces:
TriggerListener

public class DatabaseConnection extends Object implements TriggerListener
An object that represents a connection to a Database. This object handles all transactional queries and modifications to the database.
Author:
Tobias Downer
  • Method Details

    • getJDBCConnection

      public 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.
    • getSystem

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

      public Database getDatabase()
      Returns the Database object for this connection.
    • 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(String name)
      Sets the transaction isolation level from a string.
    • setVar

      public void setVar(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.

    • 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 String getTransactionIsolationAsString()
      Returns the transaction isolation level of this connection as a string.
    • getCurrentSchema

      public 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(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.
    • 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(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 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(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(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(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.
    • 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(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(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(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(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(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(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(String table_name)
      Returns the next unique identifier for the given table in the connection schema.
    • 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(String trigger_name, 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(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(String schema_name)
      Changes the default schema to the given schema.
    • createSchema

      public void createSchema(String name, String type)
      Same as the Transaction.createSchema method.
    • dropSchema

      public void dropSchema(String name)
      Same as the Transaction.dropSchema method.
    • schemaExists

      public boolean schemaExists(String name)
      Same as the Transaction.schemaExists method.
    • resolveSchemaCase

      public SchemaDef resolveSchemaCase(String name, boolean ignore_case)
      Same as the Transaction.resolveSchemaCase method.
    • resolveSchemaName

      public SchemaDef resolveSchemaName(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(String variable, String value)
      Same as the Transaction.setPersistentVar method.
    • getPersistentVar

      public String getPersistentVar(String variable)
      Same as the Transaction.getPersistentVar method.
    • addUniqueConstraint

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

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

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

      public void addCheckConstraint(TableName table_name, Expression expression, short deferred, 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, String constraint_name)
      Same as the Transaction.dropNamedConstraint method.
    • dropPrimaryKeyConstraintForTable

      public boolean dropPrimaryKeyConstraintForTable(TableName table_name, 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.
    • queryTableCheckExpressions

      public Transaction.CheckExpression[] queryTableCheckExpressions(TableName table_name)
      Same as the Transaction.queryTableCheckExpression method.
    • queryTableForeignKeyReferences

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

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

      public void fireTrigger(DatabaseConnection database, 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.
    • 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 Throwable
      Overrides:
      finalize in class Object
      Throws:
      Throwable