Package oracle.nosql.driver

Interface NoSQLHandle

  • All Superinterfaces:
    AutoCloseable
    public interface NoSQLHandle
extends AutoCloseable
    NoSQLHandle is a handle that can be used to access Oracle NoSQL tables. To create a connection represented by NoSQLHandle, request an instance using NoSQLHandleFactory.createNoSQLHandle(oracle.nosql.driver.NoSQLHandleConfig) and NoSQLHandleConfig, which allows an application to specify default values and other configuration information to be used by the handle.

    The same interface is available to both users of the Oracle NoSQL Database Cloud Service and the on-premises Oracle NoSQL Database; however, some methods and/or parameters are specific to each environment. The documentation has notes about whether a class, method, or parameter is environment-specific. Unless otherwise noted they are applicable to both environments.

    A handle has memory and network resources associated with it. Consequently, the close() method must be invoked to free up the resources when the application is done using the handle.

    To minimize network activity as well as resource allocation and deallocation overheads, it's best to avoid repeated creation and closing of handles. For example, creating and closing a handle around each operation, would incur large resource allocation overheads resulting in poor application performance.

    A handle permits concurrent operations, so a single handle is sufficient to access tables in a multi-threaded application. The creation of multiple handles incurs additional resource overheads without providing any performance benefit.

    With the exception of close() the operations on this interface follow a similar pattern. They accept a Request object containing parameters, both required and optional. They return a Result object containing results. Operation failures throw exceptions. Unique subclasses of Request and Result exist for most operations, containing information specific to the operation. All of these operations result in remote calls across a network.

    All Request instances support specification of parameters for the operation as well as the ability to override default parameters which may have been specified in NoSQLHandleConfig, such as request timeouts, Consistency, etc.

    Objects returned by methods of this interface can only be used safely by one thread at a time unless synchronized externally. Request objects are not copied and must not be modified by the application while a method on this interface is using them.

    Error and Exception Handling

    On success all methods in this interface return Result objects. Errors are thrown as exceptions. Some Java exceptions, such as IllegalArgumentException and NullPointerException are thrown directly. All other exceptions are instances of NoSQLException, which serves as a base class for NoSQL Database exceptions.

    NoSQLException instances are split into 2 broad categories:

    1. Exceptions that may be retried with the expectation that they may succeed on retry. These are instances of RetryableException
    2. Exceptions that may not be retried and if retried, will fail again

    Exceptions that may be retried return true for NoSQLException.okToRetry() while those that may not will return false. Examples of retryable exceptions are those which indicate resource consumption violations such as ThrottlingException. Examples of exceptions that should not be retried are IllegalArgumentException, TableNotFoundException, and any other exception indicating a syntactic or semantic error.

    Instances of NoSQLHandle are thread-safe and expected to be shared among threads.

    • Method Detail

      • put

        PutResult put​(PutRequest request)
        Puts a row into a table. This method creates a new row or overwrites an existing row entirely. The value used for the put is in the PutRequest object and must contain a complete primary key and all required fields.

        It is not possible to put part of a row. Any fields that are not provided will be defaulted, overwriting any existing value. Fields that are not nullable or defaulted must be provided or an exception will be thrown.

        By default a put operation is unconditional, but put operations can be conditional based on existence, or not, of a previous value as well as conditional on the Version of the existing value.

        It is also possible, on failure, to return information about the existing row. The row, including it's Version can be optionally returned if a put operation fails because of a Version mismatch or if the operation fails because the row already exists. The existing row information will only be returned if PutRequest.setReturnRow(boolean) is true and one of the following occurs:

        Use of PutRequest.setReturnRow(boolean) may result in additional consumed read capacity. If the operation is successful there will be no information returned about the previous row.

        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • writeMultiple

        WriteMultipleResult writeMultiple​(WriteMultipleRequest request)
        Executes a sequence of operations associated with a table that share the same shard key portion of their primary keys, all the specified operations are executed within the scope of a single transaction. WriteMultipleRequest.

        There are some size-based limitations on this operation:

        • The max number of individual operations (put, delete) in a single WriteMultiple request is 50.
        • The total request size is limited to 25MB.

        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        RowSizeLimitException - if data size in an operation exceeds the limit.
        BatchOperationNumberLimitException - if the number of operations exceeds this limit.
        NoSQLException - if the operation cannot be performed for any other reason

      • multiDelete

        MultiDeleteResult multiDelete​(MultiDeleteRequest request)
        Deletes multiple rows from a table in an atomic operation. The key used may be partial but must contain all of the fields that are in the shard key. A range may be specified to delete a range of keys.
        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • query

        QueryResult query​(QueryRequest request)
        Queries a table based on the query statement specified in the QueryRequest.

        Queries that include a full shard key will execute much more efficiently than more distributed queries that must go to multiple shards.

        Table- and system-style queries such as "CREATE TABLE ..." or "DROP TABLE .." are not supported by this interface. Those operations must be performed using tableRequest(oracle.nosql.driver.ops.TableRequest) or systemRequest(oracle.nosql.driver.ops.SystemRequest) as appropriate.

        The amount of data read by a single query request is limited by a system default and can be further limited using QueryRequest.setMaxReadKB(int). This limits the amount of data read and not the amount of data returned, which means that a query can return zero results but still have more data to read. This situation is detected by checking if the QueryResult has a continuation key, using QueryResult.getContinuationKey(). For this reason queries should always operate in a loop, acquiring more results, until the continuation key is null, indicating that the query is done. Inside the loop the continuation key is applied to the QueryRequest using QueryRequest.setContinuationKey(byte[]).

        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • queryIterable

        QueryIterableResult queryIterable​(QueryRequest request)
        Queries a table based on the query statement specified in the QueryRequest while returning an iterable result.

        Queries that include a full shard key will execute much more efficiently than more distributed queries that must go to multiple shards.

        Remote calls, including preparation of a query statement, will not occur until the iteration starts. This means that errors such as an invalid statement or network issue will be thrown from the iterator and not this method.

        Table- and system-style queries such as "CREATE TABLE ..." or "DROP TABLE .." are not supported by this interface. Those operations must be performed using tableRequest(oracle.nosql.driver.ops.TableRequest) or systemRequest(oracle.nosql.driver.ops.SystemRequest) as appropriate.

        The results are returned through an iterator, if connected to the cloud, the SDK uses the read/write rate limits set in the NoSQLHandleConfig or they can be overwritten using the Request.setReadRateLimiter(RateLimiter) and Request.setWriteRateLimiter(RateLimiter).

        Note: Since iterators might use resources until they reach the end, it is necessary to close the QueryIterableResult or use the try-with-resources statement: 

            try (
        QueryRequest qreq = new QueryRequest()
            .setStatement("select * from MyTable");
        QueryIterableResult qir = handle.queryIterable(qreq)) {
        for( MapValue row : qir) {
            // do something with row
        }
    }

        Parameters:
        request - the input parameters for the operation
        Returns:
        the iterable result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • prepare

        PrepareResult prepare​(PrepareRequest request)
        Prepares a query for execution and reuse. See query(oracle.nosql.driver.ops.QueryRequest) for general information and restrictions. It is recommended that prepared queries are used when the same query will run multiple times as execution is much more efficient than starting with a query string every time. The query language and API support query variables to assist with re-use.
        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • tableRequest

        TableResult tableRequest​(TableRequest request)
        Performs an operation on a table. This method is used for creating and dropping tables and indexes as well as altering tables. Only one operation is allowed on a table at any one time.

        This operation is implicitly asynchronous. The caller must poll using methods on TableResult to determine when it has completed.

        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • getTable

        TableResult getTable​(GetTableRequest request)
        Gets static information about the specified table including its state, provisioned throughput and capacity and schema. Dynamic information such as usage is obtained using getTableUsage(oracle.nosql.driver.ops.TableUsageRequest). Throughput, capacity and usage information is only available when using the Cloud Service and will be null or not defined on-premises.
        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        TableNotFoundException - if the specified table does not exist
        NoSQLException - if the operation cannot be performed for any other reason

      • getTableUsage

        TableUsageResult getTableUsage​(TableUsageRequest request)
        Cloud service only.

        Gets dynamic information about the specified table such as the current throughput usage. Usage information is collected in time slices and returned in individual usage records. It is possible to specify a time-based range of usage records using input parameters.

        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        TableNotFoundException - if the specified table does not exist
        NoSQLException - if the operation cannot be performed for any other reason

      • listTables

        ListTablesResult listTables​(ListTablesRequest request)
        Lists tables, returning table names. If further information about a specific table is desired the getTable(oracle.nosql.driver.ops.GetTableRequest) interface may be used. If a given identity has access to a large number of tables the list may be paged using input parameters.
        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • getIndexes

        GetIndexesResult getIndexes​(GetIndexesRequest request)
        Returns information about and index, or indexes on a table. If no index name is specified in the GetIndexesRequest, then information on all indexes is returned.
        Parameters:
        request - the input parameters for the operation
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        NoSQLException - if the operation cannot be performed for any other reason

      • listNamespaces

        String[] listNamespaces()
        On-premises only.

        Returns the namespaces in a store as an array of String.

        Returns:
        the namespaces or null if none are found

      • listRoles

        String[] listRoles()
        On-premises only.

        Returns the roles in a store as an array of String.

        Returns:
        the list of roles or null if none are found

      • listUsers

        UserInfo[] listUsers()
        On-premises only.

        Returns the users in a store as an array of UserInfo.

        Returns:
        the users or null if none are found

      • doSystemRequest

        SystemResult doSystemRequest​(String statement,
                             int timeoutMs,
                             int pollIntervalMs)
        On-premises only.

        A convenience method that performs a SystemRequest and waits for completion of the operation. This is the same as calling systemRequest(oracle.nosql.driver.ops.SystemRequest) then calling SystemResult.waitForCompletion(oracle.nosql.driver.NoSQLHandle, int, int). If the operation fails an exception is thrown. All parameters are required.

        System requests are those related to namespaces and security and are generally independent of specific tables. Examples of statements include:

        • CREATE NAMESPACE mynamespace
        • CREATE USER some_user IDENTIFIED BY password
        • CREATE ROLE some_role
        • GRANT ROLE some_role TO USER some_user

        Parameters:
        statement - the system statement for the operation.
        timeoutMs - the amount of time to wait for completion, in milliseconds.
        pollIntervalMs - the polling interval for the wait operation.
        Returns:
        the result of the operation
        Throws:
        IllegalArgumentException - if any of the parameters are invalid or required parameters are missing
        RequestTimeoutException - if the operation times out.
        NoSQLException - if the operation cannot be performed for any other reason

      • getStatsControl

        StatsControl getStatsControl()
        Returns an object that allows control over how statistics are collected.
        Returns:
        the StatsControl object
        Since:
        5.2.30

      • close

        void close()
        Closes the handle, releasing its memory and network resources. Once this method is closed the handle is no longer usable. Any attempt to use a closed handle will throw IllegalArgumentException.
        Specified by:
        close in interface AutoCloseable