Oracle NoSQL Database Table C Driver Quick Start

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8-Dec-2016


Table of Contents

Introduction
Installation
Using the Proxy Server
Compiling and Running C Clients
Connecting to the Store
Automatically Starting the Proxy Server
Creating Table and Index Definitions
Writing to a Table Row
Deleting a Table Row
Reading a Single Table Row
Reading Multiple Table Rows
Reading Using Indexes
Sequence Execution
Setting Consistency Guarantees
Setting Durability Guarantees
Proxy Server Reference
Securing Oracle NoSQL Database Proxy Server
Trouble Shooting the Proxy Server

Introduction

This article provides a quick introduction to the Oracle NoSQL Database C driver. This driver provides native C client access to data stored in Oracle NoSQL Database tables. (There is a C JNI driver which provides a Key/Value API for access to Oracle NoSQL Database data. That driver relies on a JNI layer and is not described by this article.)

The C driver is available as a separate download from the Oracle NoSQL Database server package. You can obtain both the server and the driver download packages from:

http://www.oracle.com/technetwork/database/database-technologies/nosqldb/downloads/index.html

To work, the C driver requires use of a proxy server which translates network activity between the C client and the Oracle NoSQL Database store. The proxy is written in Java, and can run on any machine that is network accessible by both your C client code and the Oracle NoSQL Database store. However, for performance and security reasons, Oracle recommends that you run the proxy on the same local host as your driver, and that the proxy be used in a 1:1 configuration with your drivers (that is, each instance of the proxy should be used with just a single driver instance).

This quick start assumes that you have read and understood the concepts described in the Oracle NoSQL Database Getting Started with the Table API guide. You can find that guide in your Oracle NoSQL Database server installation package, or find it here:

The entirety of the API used by the C driver is described in the C API Reference Guide. This document can be accessed in the C driver package by pointing your browser to .../kv-c-driver-X.Y.Z/c/doc/html/index.html.

Installation

Both the C driver and the proxy are available in a common download package. The proxy server resides in the kvproxy directory, and is provided as a Java jar file (kvproxy.jar). To use the proxy, you must also have a Oracle NoSQL Database server installation. Specifically, the kvclient.jar file from that installation must be available to the proxy.

The C driver library must be compiled before it can be used by your client code. The source code for this library is available in the c directory of the driver package. Library dependencies and compile instructions are available in the BUILDING.html which is found in the c directory.

The C driver is also available as a pre-compiled binary. To access this binary, download and install the relevant rpm or deb file. If you use the rpm or deb, the required Java jar files are also installed on your system. In this case, the relevant library and jar files are installed into /usr/local/lib. To use them, you might need to adjust your CLASSPATH and LD_LIBRARY_PATH environment variables to include that directory.

Using the Proxy Server

The proxy server is a Java application that accepts network traffic from the Table C API, translates it into requests that the Oracle NoSQL Database store can understand, and then forwards the translated request to the store. The proxy also provides the reverse translation service by interpreting store responses and forwarding them to the client.

The proxy server can run on any network-accessible machine. It has minimal resource requirements and, in many cases, can run on the same machine as the client code is running.

Before your C client can access the store, the proxy server must be running. It requires the following jar files to be in its class path, either by using the java -cp command line option, or by using the CLASSPATH environment variable:

  • KVHOME/lib/kvclient.jar

  • .../kv-c-driver-X.Y.Z/kvproxy/lib/kvproxy.jar

Note

If you installed using rpm or deb, then these files are located in /usr/local/lib.

The proxy server itself is started using the oracle.kv.proxy.KVProxy command. At a minimum, the following information is required when you start the proxy server:

  • -helper-hosts

    This is a list of one or more host:port pairs representing Oracle NoSQL Database storage nodes that the proxy server can use to connect to the store.

  • -port

    The port where your client code can connect to this instance of the proxy server.

  • -store

    The name of the store to which the proxy server is connecting.

A range of other command line options are available. In particular, if you are using the proxy server with a secure store, you must provide authentication information to the proxy server. In addition, you will probably have to identify a store name to the proxy server. For a complete description of the proxy server and its command line options, see Proxy Server Reference.

The simple examples provided in this quick start guide were written to work with an proxy server that is connected to a kvlite instance which was started with default values. The location of the kvclient.jar and kvproxy.jar files were provided using a CLASSPATH environment variable. The command line call used to start the proxy server was:

nohup java oracle.kv.proxy.KVProxy -port 7010 \
-helper-hosts localhost:5000 -store kvstore

Compiling and Running C Clients

To compile your C clients, link either libkvstore.so or libkvstore-static.a. They can be found in the lib directory contained in the installation location that you provided to cmake.

If you use the .so file, make sure to add its installation directory to your LD_LIBRARY_PATH environment variable so that the library can be found at run time.

The kvstore.h header file is located in the include directory contained in the installation location that you provided to cmake.

Connecting to the Store

To perform any store operations, you must establish a network connection between your client code and the store. There are two pieces of information that you must provide:

  1. Identify the store's name, host and port using a kv_config_t structure. The host and port that you provide to this structure is for any machine hosting a node in the store. (Because the store is comprised of many hosts, there should be multiple host/port pairs for you to choose from.)

    You create the kv_config_t structure using kv_create_config(). You can release the structure using kv_release_config().

  2. Identify the host and port where the proxy is running. You do this using kv_open_store(). This function creates an kv_store_t structure, which is what you will use for all subsequent store operations. You release this structure using kv_close_store().

For example, suppose you have a Oracle NoSQL Database store named "MyNoSQLStore" and it has a node running on n1.example.org at port 5000. Further, suppose you are running your proxy on the localhost using port 7010. Then you would open and close a connection to the store in the following way:

#include <stdlib.h>
#include <stdio.h>
#include "kvstore.h"

void open_store(kv_store_t **);
void do_store_ops(kv_store_t *);

int main(void) {
    kv_store_t *store = NULL;

    open_store(&store);
    if (!store) {
        goto ERROR;
    }

    do_store_ops(store);


ERROR:
    /* Close the store handle. */
    if (store) {
        kv_close_store(&store);
    }
    return 0;
}

void do_store_ops(kv_store_t *store)
{
    printf("Do store operations here.\n");
}

void
open_store(kv_store_t **store)
{
    kv_config_t *config = NULL;
    kv_error_t ret;

    ret = kv_create_config("kvstore",   // store name
                           "localhost", // host name
                           5000,        // host port
                           &config);

    if (ret != KV_SUCCESS) {
        return;
    }

    /* Connect to a proxy server */
    ret = kv_open_store(store, "localhost", 7010, config);
    if (ret != KV_SUCCESS) {
        printf("could not connect to the store.\n");
        // Release the configuration structure
        kv_release_config(&config);
    }
} 

If you are using a secure store then the configuration of your store handle must also include the user name. Use kv_config_set_auth_user() for this purpose.

Automatically Starting the Proxy Server

Your client code can start the proxy server on the local host when it opens the store using kv_open_store_with_proxy(). This function requires everything that kv_open_store() requires, plus a kv_proxy_config_t structure populated with the on-disk location of the kvclient.jar and kvproxy.jar files.

You populate the kv_proxy_config_t structure using kv_create_proxy_config(). You can release this structure (only necessary if some error occurs when opening the store) using kv_release_proxy_config(). When your code is done with the proxy server, shut it down using kv_shutdown_proxy().

For example:

int main(void) {
    kv_store_t *store = NULL;

    open_store(&store);
    if (!store) {
        goto ERROR;
    }

    do_store_ops(store);


ERROR:
    /* Close the store handle. */
    if (store) {
        kv_shutdown_proxy(store);
        kv_close_store(&store);
    }
    return 0;
}

// do_store_ops() not implemented in this example

void
open_store(kv_store_t **store)
{
    kv_config_t *config = NULL;
    kv_proxy_config_t *proxy_config = NULL;
    kv_error_t ret;

    const char *path2kvclient = "/export/kvstore/lib/kvclient.jar";
    const char *path2kvproxy = 
                        "/export/c_driver/kvproxy/lib/kvproxy.jar";

    ret = kv_create_config("kvstore",   // store name
                           "localhost", // host name
                           5000,        // host port
                           &config);
            // All configs are correct for kvlite
    if (ret != KV_SUCCESS) {
        return;
    }

    // Create the proxy configuration structure.
    // This must identify where the two relevant jar
    // files reside on disk.
    ret = kv_create_proxy_config(path2kvclient,
                                 path2kvproxy,
                                 &proxy_config);
    if (ret != KV_SUCCESS) {
        printf("could not create proxy config.\n");
        return;
    }

    ret = kv_open_store_with_proxy(store,
                                   "localhost",
                                   7010,
                                   config,
                                   proxy_config);
    if (ret != KV_SUCCESS) {
        printf("could not connect to the store.\n");
        // Release the configuration structure
        if (config) {
            kv_release_config(&config);
        }

        if (proxy_config) {
            kv_release_proxy_config(&proxy_config);
        }
        store = NULL;
    }
} 

Creating Table and Index Definitions

Before you can write data to tables in your store, you must define your tables using table DDL statements. You also use DDL statements to define indexes. The table DDL is described in detail in the Oracle NoSQL Database Getting Started with the Table API guide.

If you want to submit table DDL statements to the store from your C client code, use either kv_table_execute_sync() or kv_table_execute(). The latter function submits DDL statements to the store asynchronously, which you may want to do when creating indexes or dropping tables because these operations can take a long time.

For example, to create a table synchronously:

void do_store_ops(kv_store_t *store)
{
    kv_error_t ret;

    /* ... Data operations ... */
    kv_statement_result_t *result = NULL;

    const char *statement = "CREATE TABLE Users2 (\
        id INTEGER, \
        firstName STRING, \
        lastName STRING, \
        description STRING, \
        PRIMARY KEY (SHARD(id, firstName), lastName)\
    )";

    ret = kv_table_execute_sync(store, statement, &result);
    if (ret != KV_SUCCESS) {
        printf("Table creation failed.\n");
        printf("Error message is %s\n", 
            kv_statement_result_get_error_message(result));
    } else {
        printf("Table create succeeded.\n");
    }   
} 

Writing to a Table Row

Once you have defined a table in the store, use kv_create_row() to create an empty table row. Then use the appropriate kv_row_put_xxx() function (where xxx is the data type for the field that you are writing) to populate each field with data. Finally, use kv_table_put() to actually write the table row to the store. For example, for a table designed like this:

"CREATE TABLE myTable (item STRING, \
                       description STRING, \
                       count INTEGER, \
                       percentage FLOAT, \
                       PRIMARY KEY (item))" 

You can write a row of table data in the following fashion (the store open and close is skipped for brevity):

void 
do_store_ops(kv_store_t *store)
{
    kv_error_t ret;
    kv_row_t *row = NULL;

    row = kv_create_row();
    if (!row) {
       printf("row creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(row, "item", "Bolts");
    if (ret != KV_SUCCESS) {
        printf("row put 'item' failed.\n");
        goto cleanup;
    }
    ret = kv_row_put_string(row, "description", 
                            "Hex head, stainless");
    if (ret != KV_SUCCESS) {
        printf("row put 'description' failed.\n");
        goto cleanup;
    }
    ret = kv_row_put_int(row, "count", 5);
    if (ret != KV_SUCCESS) {
        printf("row put 'count' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_float(row, "percentage", 0.2173913);
    if (ret != KV_SUCCESS) {
        printf("row put 'percentage' failed.\n");
        goto cleanup;
    }

    ret = kv_table_put(store, "myTable", row,
                        NULL); // new version 
    if (ret != KV_SUCCESS) {
        printf("Store put failed.\n");
        goto cleanup;
    } else {
        printf("Store put succeeded.\n");
    }

cleanup:
    if (row) {
        kv_release_row(&row);
    }
} 

Other versions of kv_table_put() exist which allow you to provide options and version information, and so forth. See the API C documentation for details.

Deleting a Table Row

Use kv_table_delete() to delete a table row. Notice that this function does not return KV_ERROR_T, but instead returns an integer.

void
do_store_ops(kv_store_t *store)
{
    kv_error_t ret;
    kv_row_t *key = NULL;

    key = kv_create_row();
    if (!key) {
       printf("key creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(key, "item", "Bolts");
    if (ret != KV_SUCCESS) {
        printf("row put 'item' failed.\n");
        goto cleanup;
    }

    ret = kv_table_delete(store, "myTable", key);
    // ret is 1 if a row was deleted
    //        0 if no row with the provided key was found
    //        < 0 if an error occurred. 
    if (ret < 0) {
        printf("Row deletion failed. %i\n", ret);
        goto cleanup;
    } else {
        printf("Row deletion succeeded.\n");
    }

cleanup:
    if (key) {
        kv_release_row(&key);
    }
} 

Other versions of kv_table_delete() exist which allow you to provide options and version information, and so forth. See the API C documentation for details.

Reading a Single Table Row

To read a single table row, create a kv_row_t structure set with the field names and field values contained by the row that you want to retrieve. Then create a second kv_row_t structure that you will use to hold the retrieved row. The row is retrieved using kv_table_get(). You can then examine the various fields in the retrieved row using the proper version of kv_row_get_xxxx(), where xxxx is the datatype of the field that you are examining.

For example, to retrieve the table row created in Writing to a Table Row:

void
do_store_ops(kv_store_t *store)
{
    kv_error_t ret;
    kv_row_t *key = NULL;

    key = kv_create_row();
    if (!key) {
       printf("key creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(key, "item", "Bolts");
    if (ret != KV_SUCCESS) {
        printf("row put 'item' failed.\n");
        goto cleanup;
    }

    kv_row_t *retRow = NULL;
    retRow = kv_create_row();
    if (!retRow) {
       printf("retRow creation failed.\n");
       goto cleanup;
    }
    ret = kv_table_get(store, "myTable", key, &retRow);
    if (!retRow) {
        printf("Row retrieval failed.\n");
        goto cleanup;
    }

    const char *retItem = NULL, *retDescription = NULL;
    int retCount = 0;
    float retPercentage = 0.0;

    kv_row_get_string(retRow, "item", &retItem);
    kv_row_get_string(retRow, "description", &retDescription);
    kv_row_get_int(retRow, "count", &retCount);
    kv_row_get_float(retRow, "percentage", &retPercentage);

    printf("Item: %s. Desc: %s. Count is %i. Percent is %f\n",          
            retItem, retDescription, retCount, retPercentage);

cleanup:
    if (key) {
        kv_release_row(&key);
    } 

    if (retRow) {
        kv_release_row(&retRow);
    }
} 

Reading Multiple Table Rows

Use kv_table_multi_get() or kv_table_iterator() to read multiple rows from a table at a time. These functions require you to provide a kv_row_t structure that serves as the lookup key. Different restrictions apply to the key you provide, depending on the function that you use. The example provided here uses kv_table_multi_get() which requires that the provided key at least contains all the table's shard keys. If all of the shard keys are not present, then the function will return without error, but without any results.

kv_table_multi_get() populates a kv_iterator_t structure, which you iterate over using kv_iterator_next(). Use kv_iterator_get_result() and kv_result_get_row() to retrieve the row available for each position in the result set.

For example, suppose you design a table like this:

CREATE TABLE myTable (
    itemType STRING,
    itemCategory STRING,
    itemClass STRING,
    itemColor STRING,
    itemSize STRING,
    price FLOAT,
    inventoryCount INTEGER,
    PRIMARY KEY (SHARD(itemType, itemCategory, itemClass), itemColor,
    itemSize)
) 

And you populate it with data like this:

int main(void) {
    kv_store_t *store = NULL;

    open_store(&store);
    if (!store) {
        goto ERROR;
    }

    do_store_ops(store, "Hats", "baseball", "longbill",
                 "red", "small", 12.07, 127);

    do_store_ops(store, "Hats", "baseball", "longbill",
                 "red", "medium", 13.07, 201);

    do_store_ops(store, "Hats", "baseball", "longbill",
                 "red", "large", 14.07, 309);

    retrieve_table_rows(store);

ERROR:
    /* Close the store handle. */
    if (store) {
        kv_close_store(&store);
    }
    return 0;
}

void
do_store_ops(kv_store_t *store,
             const char *itemType, const char *itemCategory,
             const char *itemClass, const char *itemColor,
             const char *itemSize, float price, int inventoryCount)
{
    kv_error_t ret;
    kv_row_t *row = NULL;

    row = kv_create_row();
    if (!row) {
       printf("row creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(row, "itemType", itemType);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemType' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "itemCategory", itemCategory);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemCategory' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "itemClass", itemClass);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemClass' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "itemColor", itemColor);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemColor' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "itemSize", itemSize);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemSize' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_float(row, "price", price);
    if (ret != KV_SUCCESS) {
        printf("row put 'price' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_int(row, "inventoryCount", inventoryCount);
    if (ret != KV_SUCCESS) {
        printf("row put 'inventoryCount' failed.\n");
        goto cleanup;
    }

    ret = kv_table_put(store, "myTable", row,
                        NULL); // new version 
    if (ret != KV_SUCCESS) {
        printf("Store put failed.\n");
        goto cleanup;
    } else {
        printf("Store put succeeded.\n");
    }

cleanup:
    if (row) {
        kv_release_row(&row);
    }
} 

Then you can retrieve all of the rows in the table by providing just the shard key because, in this example, the shard key is identical for all the rows in the table. (Normally, if you wanted to display all the rows in a table, you would use kv_table_iterator with an empty row for the key parameter.)

 void
retrieve_table_rows(kv_store_t *store)
{
    kv_error_t ret;
    kv_iterator_t *iter = NULL;
    kv_row_t *key = NULL;

    key = kv_create_row();
    if (!key) {
       printf("key creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(key, "itemType", "Hats");
    if (ret != KV_SUCCESS) {
        printf("row put 'itemType' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(key, "itemCategory", "baseball");
    if (ret != KV_SUCCESS) {
        printf("row put 'itemCategory' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(key, "itemClass", "longbill");
    if (ret != KV_SUCCESS) {
        printf("row put 'itemClass' failed.\n");
        goto cleanup;
    }

    ret = kv_table_multi_get(store,
                             "myTable",
                             key,
                             KV_FALSE /* Keyonly*/,
                             NULL /* Field range */,
                             NULL /* Included tables */,
                             NULL /* Read options */,
                             &iter);

    int nRows = 0;
    while (kv_iterator_next(iter) == KV_SUCCESS) {
        const kv_result_t *result;
        kv_row_t *retRow;
        const char *itemType = NULL;
        const char *itemCategory = NULL;
        const char *itemClass = NULL;
        const char *itemColor = NULL;
        const char *itemSize = NULL;
        float price = 0.0;
        int inventoryCount = 0;

        result = kv_iterator_get_result(iter);
        retRow = kv_result_get_row(result);

        nRows++;

        kv_row_get_string(retRow, "itemType", &itemType);
        kv_row_get_string(retRow, "itemCategory", &itemCategory);
        kv_row_get_string(retRow, "itemClass", &itemClass);
        kv_row_get_string(retRow, "itemSize", &itemSize);
        kv_row_get_string(retRow, "itemColor", &itemColor);
        kv_row_get_float(retRow, "price", &price);
        kv_row_get_int(retRow, "inventoryCount", &inventoryCount);

        printf("Row %d:\n", nRows);
        printf("\t%s, %s, %s:\n", itemType, itemCategory, itemClass);
        printf("\t\tColor: %s    itemSize: %s\n", itemColor, 
                itemSize);
        printf("\t\tprice: %f    inventory: %d\n", price, 
                inventoryCount);
    }

cleanup:
    if (key) {
        kv_release_row(&key);
    }

    if (iter) {
        kv_release_iterator(&iter);
    }
} 

Reading Using Indexes

Use kv_index_iterator() to read table rows based on a specified index. To use this function, the index must first be created using the CREATE INDEX statement.

There are two ways to identify the index values you want the results set based on. The first way is to provide a kv_row_t structure that represents the indexed field(s) and value(s) that you want retrieved. The second way is to provide a kv_field_range_t structure that identifies starting and ending index values that you want returned. The kv_field_range_t and kv_row_t structures can be used together to restrict the return set values.

If both the kv_row_t and kv_field_range_t values are NULL, then every row in the table matching the specified index is contained in the return set.

For example, suppose you have a table defined like this:

CREATE TABLE myTable ( 
    surname STRING, 
    familiarName STRING, 
    userID STRING, 
    phonenumber STRING, 
    address STRING, 
    email STRING, 
    dateOfBirth STRING, 
    PRIMARY KEY (SHARD(surname, familiarName), userID)) 

With this index:

CREATE INDEX DoB ON myTable (dateOfBirth)

And you populate the table with data like this:

int main(void) {
    kv_store_t *store = NULL;

    open_store(&store);
    if (!store) {
        goto ERROR;
    }


    do_store_ops(store, "Anderson", "Pete", "panderson",
                 "555-555-5555", "1122 Somewhere Court",
                 "panderson@example.com", "1994-05-01");

    do_store_ops(store, "Andrews", "Veronica", "vandrews",
                 "666-666-6666", "5522 Nowhere Court",
                 "vandrews@example.com", "1973-08-21");

    do_store_ops(store, "Bates", "Pat", "pbates",
                 "777-777-7777", "12 Overhere Lane",
                 "pbates@example.com", "1988-02-20");

    do_store_ops(store, "Macar", "Tarik", "tmacar",
                 "888-888-8888", "100 Overthere Street",
                 "tmacar@example.com", "1990-05-17");

    read_index(store);


ERROR:
    /* Close the store handle. */
    if (store) {
        kv_close_store(&store);
    }
    return 0;
} 

void
do_store_ops(kv_store_t *store,
             const char *surname, const char *familiarName,
             const char *userID, const char *phone,
             const char *address, const char *email,
             const char *birthdate)
{
    kv_error_t ret;
    kv_row_t *row = NULL;

    row = kv_create_row();
    if (!row) {
       printf("row creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(row, "surname", surname);
    if (ret != KV_SUCCESS) {
        printf("row put 'surname' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "familiarName", familiarName);
    if (ret != KV_SUCCESS) {
        printf("row put 'familiarName' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "userID", userID);
    if (ret != KV_SUCCESS) {
        printf("row put 'userID' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "phonenumber", phone);
    if (ret != KV_SUCCESS) {
        printf("row put 'phonenumber' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "address", address);
    if (ret != KV_SUCCESS) {
        printf("row put 'address' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "email", email);
    if (ret != KV_SUCCESS) {
        printf("row put 'email' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_string(row, "dateOfBirth", birthdate);
    if (ret != KV_SUCCESS) {
        printf("row put 'birthdate' failed.\n");
        goto cleanup;
    }



    ret = kv_table_put(store, "myTable", row,
                        NULL); // new version 
    if (ret != KV_SUCCESS) {
        printf("Store put failed.\n");
        goto cleanup;
    } else {
        printf("Store put succeeded.\n");
    }

cleanup:
    if (row) {
        kv_release_row(&row);
    }
} 

Then you can read using the DoB index using the following function. In the following example, BLOCK 1 (see the comments in the code) is commented out, because its usage with BLOCK 2 causes the result set to be empty. Comment both BLOCK 1 and BLOCK 2 in order to print the entire table.

void
read_index(kv_store_t *store)
{
    kv_error_t ret;
    kv_iterator_t *iter = NULL;
    kv_row_t *key = NULL;
    kv_field_range_t *rangep = NULL;

    key = kv_create_row();
    if (!key) {
       printf("key creation failed.\n");
       goto cleanup;
    }

    // BLOCK 1:
    // Uncomment this block to look up only table rows with a 
    // dateOfBirth field set to "1988-02-20". If this
    // block and BLOCK 2 are both used, then the result set 
    // will be empty.
    //
    //ret = kv_row_put_string(key, "dateOfBirth", "1988-02-20");
    //if (ret != KV_SUCCESS) {
    //    printf("row put 'dateOfBirth' failed.\n");
    //    goto cleanup;
    //}

    // BLOCK 2:
    // This field range restricts the results set to only
    // those rows with a dateOfBirth field value between
    // "1990-01-01" and "2000-01-01", inclusive. 
    ret = kv_create_field_range("dateOfBirth", // Field
                                "1990-01-01",  // Start value 
                                KV_TRUE,       // Inclusive?
                                "2000-01-01",  // End value
                                KV_TRUE,       // Inclusive? 
                                &rangep);
    if (ret != KV_SUCCESS) {
        printf("field range creation failed.\n");
        goto cleanup;
    }

    ret = kv_index_iterator(store, "myTable", "DoB",
                            key, // Key to use for the lookup
                            KV_FALSE, // Whether only primary keys 
                                      // are returned
                            rangep, // Field range
                            NULL,  // Included tables
                            KV_DIRECTION_UNORDERED,
                            NULL,  // Read options 
                            0, // max iterator results, 0 - use default
                            &iter);
    int nRows = 0;
    while (kv_iterator_next(iter) == KV_SUCCESS) {
        const kv_result_t *result;
        kv_row_t *retRow;
        const char *surname = NULL;
        const char *familiarName = NULL; 
        const char *userID = NULL;   
        const char *phonenumber = NULL;
        const char *address = NULL;
        const char *email = NULL;
        const char *dateOfBirth = NULL;

        result = kv_iterator_get_result(iter);
        retRow = kv_result_get_row(result);

        nRows++;

        kv_row_get_string(retRow, "surname", &surname);
        kv_row_get_string(retRow, "familiarName", &familiarName);
        kv_row_get_string(retRow, "userID", &userID);
        kv_row_get_string(retRow, "phonenumber", &phonenumber);
        kv_row_get_string(retRow, "address", &address);
        kv_row_get_string(retRow, "email", &email);
        kv_row_get_string(retRow, "dateOfBirth", &dateOfBirth);

        printf("Row %d:\n", nRows);
        printf("\t%s, %s (%s):\n", familiarName, surname, userID);
        printf("\t\tPhone: %s\n", phonenumber);
        printf("\t\tEmail: %s\n", email);
        printf("\t\tAddress: %s\n", address);
        printf("\t\tDoB: %s\n", dateOfBirth);
    }

cleanup:
    if (key) {
        kv_release_row(&key);
    }

    if (rangep) {
        kv_release_field_range(&rangep);
    }

    if (iter) {
        kv_release_iterator(&iter);
    }
} 

Sequence Execution

Use kv_create_operations() to create a kv_operations_t structure to hold a sequence of write operations. All the write operations will execute as a single atomic structure so long as all the operations share the same shard key.

You populate operations to the kv_operations_t structure using a series of one or more kv_create_table_xxxx_op() functions, where xxxx indicates the type of operation to insert into the operations list. For example, kv_create_table_delete_op() inserts a row deletion operation into the sequence.

The operations sequence is executed using kv_table_execute_operations().

For example, if you had a table populated with data such as is described in Reading Multiple Table Rows, then you could update the price and inventory values for each row of the table in an atomic operation like this:

int main(void) {
    kv_error_t ret;
    kv_store_t *store = NULL;
    kv_operations_t *op = NULL;
    kv_operation_results_t *resultp = NULL;

    open_store(&store);
    if (!store) {
        goto ERROR;
    }


    op = kv_create_operations();

    // Causes all rows to be released when op is released.
    kv_operations_set_donate(op);

    ret = add_op_list(op, "Hats", "baseball", "longbill",
                 "red", "small", 13.07, 107);
    if (ret != KV_SUCCESS) {
        printf("adding to op list failed.\n");
        return -1;
    } 

    ret = add_op_list(op, "Hats", "baseball", "longbill",
                 "red", "medium", 14.07, 198);
    if (ret != KV_SUCCESS) {
        printf("adding to op list failed.\n");
        return -1;
    }

    ret = add_op_list(op, "Hats", "baseball", "longbill",
                 "red", "large", 15.07, 140);
    if (ret != KV_SUCCESS) {
        printf("adding to op list failed.\n");
        return -1;
    }

    ret = kv_table_execute_operations(store, op, NULL, &resultp);
    if (ret != KV_SUCCESS) {
        printf("operation execution failed.\n");
    } else {
        printf("operation execution succeeded.\n");
    }

ERROR:
    /* Close the store handle. */
    if (store) {
        kv_close_store(&store);
    }

    if (resultp) {
        kv_release_operation_results(&resultp);
    }
    
    if (op) {
        kv_release_operations(&op);
    }

    return 0;
}

int
add_op_list(kv_operations_t *op, 
            const char *itemType, const char *itemCategory, 
            const char *itemClass, const char *itemColor,
            const char *itemSize, float price, int inventoryCount)
{
    kv_error_t ret;
    kv_row_t *row = NULL;

    row = kv_create_row();
    if (!row) {
        printf("row creation failed.\n");
        return -1;
    }

    ret = kv_row_put_string(row, "itemType", itemType);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemType' failed.\n");
        return -1;
    }

    ret = kv_row_put_string(row, "itemCategory", itemCategory);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemCategory' failed.\n");
        return -1;
    }

    ret = kv_row_put_string(row, "itemClass", itemClass);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemClass' failed.\n");
        return -1;
    }

    ret = kv_row_put_string(row, "itemColor", itemColor);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemColor' failed.\n");
        return -1;
    }

    ret = kv_row_put_string(row, "itemSize", itemSize);
    if (ret != KV_SUCCESS) {
        printf("row put 'itemSize' failed.\n");
        return -1;
    }

    ret = kv_row_put_float(row, "price", price);
    if (ret != KV_SUCCESS) {
        printf("row put 'price' failed.\n");
        return -1;
    }

    ret = kv_row_put_int(row, "inventoryCount", inventoryCount);
    if (ret != KV_SUCCESS) {
        printf("row put 'inventoryCount' failed.\n");
        return -1;
    }

    ret = kv_create_table_put_op(op, "myTable", row,
                  KV_RETURN_ROW_NONE, // kv_return_row_version_enum
                  0); // Abort on failure?
    if (ret != KV_SUCCESS) {
        printf("Store put op failed.\n");
        return -1;
    } else {
        printf("Store put op succeeded.\n");
    }

    // Do not release the row at the end of this, as doing so will 
    // cause the operation execution to core dump. The row must be 
    // saved for the future operation.
    //
    return KV_SUCCESS;
} 

Setting Consistency Guarantees

By default, read operations are performed with a consistency of guarantee of KV_CONSISTENCY_NONE. Use one of the following functions to create a consistency guarantee that overrides this default:

  1. kv_create_simple_consistency()

  2. kv_create_time_consistency()

  3. kv_create_version_consistency()

These allocate and populate a kv_consistency_t structure that must be released using kv_release_consistency().

You then use the kv_consistency_t structure with kv_create_read_options() to create allocate and populate a kv_read_options_t structure. Use kv_release_read_options() to release this structure.

Finally, use the kv_read_options_t structure when performing a read operation from the store.

For example, the code fragment shown in Reading a Single Table Row can be rewritten to use a default consistency policy in the following way:

void
do_store_ops(kv_store_t *store)
{
    kv_consistency_t *consis = NULL;
    kv_error_t ret;
    kv_read_options_t *readopts = NULL;
    kv_result_t *results = NULL;
    kv_row_t *key = NULL;

    ret = kv_create_simple_consistency(KV_CONSISTENCY_ABSOLUTE, 
                                       &consis);
    if (ret != KV_SUCCESS) {
        printf("consistency creation failed\n");
        goto cleanup;
    }
    
    ret = kv_create_read_options(consis,  // consistency
                                 0,       // timeout value. 
                                          // 0 means use the default.
                                 &readopts);
    if (ret != KV_SUCCESS) {
        printf("readoptions creation failed\n");
        return;
    }

    key = kv_create_row();
    if (!key) {
       printf("key creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(key, "item", "Bolts");
    if (ret != KV_SUCCESS) {
        printf("row put 'item' failed.\n");
        goto cleanup;
    }

    ret = kv_table_get_with_options(store, 
                                    "myTable", 
                                    key, 
                                    readopts,
                                    &results);
    if (ret != KV_SUCCESS) {
        printf("Retrieval failed.\n");
        goto cleanup;
    }
    
    kv_row_t *retRow = kv_result_get_row(results);

    const char *retItem = NULL, *retDescription = NULL;
    int retCount = 0;
    float retPercentage = 0.0;

    kv_row_get_string(retRow, "item", &retItem);
    kv_row_get_string(retRow, "description", &retDescription);
    kv_row_get_int(retRow, "count", &retCount);
    kv_row_get_float(retRow, "percentage", &retPercentage);

    printf("Item: %s. Desc: %s. Count is %i. Percent is %f\n",
            retItem, retDescription, retCount, retPercentage);

cleanup:
    if (key) {
        kv_release_row(&key);
    }

    if (retRow) {
        kv_release_row(&retRow);
    }

    // kv_release_read_options also releases the 
    // kv_consistency_t structure.
    if (readopts) {
        kv_release_read_options(&readopts);
    }
} 

Setting Durability Guarantees

By default, write operations are performed with a durability guarantee of KV_DURABILITY_COMMIT_NO_SYNC. You can override this by creating and using a durability guarantee.

Use kv_create_durability() to initialize a kv_durability_t structure. You then use the kv_durability_t structure with kv_create_write_options() to allocate and populate a kv_write_options_t structure. Use kv_release_write_options() to release this structure.

Finally, use the kv_write_options_t structure when performing a write operation in the store.

For example, the code fragment shown in Writing to a Table Row can be rewritten to use a durability policy in the following way:

void
do_store_ops(kv_store_t *store)
{
    kv_error_t ret;
    kv_row_t *row = NULL;
    kv_durability_t durability;
    kv_write_options_t *writeopts;
    kv_result_t *results;

    row = kv_create_row();
    if (!row) {
       printf("row creation failed.\n");
       goto cleanup;
    }

    ret = kv_row_put_string(row, "item", "Bolts");
    if (ret != KV_SUCCESS) {
        printf("row put 'item' failed.\n");
        goto cleanup;
    }
    ret = kv_row_put_string(row, "description", "Hex head, stainless");
    if (ret != KV_SUCCESS) {
        printf("row put 'description' failed.\n");
        goto cleanup;
    }
    ret = kv_row_put_int(row, "count", 5);
    if (ret != KV_SUCCESS) {
        printf("row put 'count' failed.\n");
        goto cleanup;
    }

    ret = kv_row_put_float(row, "percentage", 0.2173913);
    if (ret != KV_SUCCESS) {
        printf("row put 'percentage' failed.\n");
        goto cleanup;
    }

    durability = kv_create_durability(
                    KV_SYNC_FLUSH, // Master sync
                    KV_SYNC_NONE,  // Replica sync
                    KV_ACK_MAJORITY); // Ack policy

    ret = kv_create_write_options(durability,
                                  0, // 0 is default timeout
                                  &writeopts);
    if (ret != KV_SUCCESS) {
        printf("Write options creation failed.\n");
        return;
    }   


    ret = kv_table_put_with_options(store, 
                                    "myTable", 
                                    row,
                                    writeopts,
                                    // Whether the new row should be
                                    // returned in the results 
                                    // parameter.
                                    KV_RETURN_ROW_NONE, 
                                    &results);

    if (ret != KV_SUCCESS) {
        printf("Store put failed.\n");
        goto cleanup;
    } else {
        printf("Store put succeeded.\n");
    }

cleanup:
    if (row) {
        kv_release_row(&row);
    }

    if (writeopts) {
        kv_release_write_options(&writeopts);
    }
    
    if (results) {
        kv_release_result(&results);
        }
} 

Proxy Server Reference

The proxy server command line options are:

nohup java -cp KVHOME/lib/kvclient.jar:kvproxy/lib/kvproxy.jar 
oracle.kv.proxy.KVProxy -help
 -port <port-number> Port number of the proxy server. Default: 5010
 -store <store-name> Required KVStore name. No default.
 -helper-hosts <host:port,host:port,...>   Required list of KVStore 
        hosts and ports (comma separated).
 -security <security-file-path>  Identifies the security file used 
        to specify properties for login. Required for connecting to 
        a secure store.
  -username <user>  Identifies the name of the user to login to the 
        secured store. Required for connecting to a secure store.
  -read-zones <zone,zone,...>  List of read zone names.
  -max-active-requests <int> Maximum number of active requests towards
        the store.
  -node-limit-percent <int> Limit on the number of requests, as a 
        percentage of the requested maximum active requests.
  -request-threshold-percent <int> Threshold for activating request 
        limiting, as a percentage of the requested maximum active 
        requests.
  -request-timeout <long> Configures the default request timeout in
        milliseconds.
  -socket-open-timeout <long> Configures the open timeout in 
        milliseconds used when establishing sockets to the store.
  -socket-read-timeout <long> Configures the read timeout in 
        milliseconds associated with the underlying sockets to the 
        store.
  -max-iterator-results <long> A long representing the maximum 
        number of results returned in one single iterator call. 
        Default: 100
  -iterator-expiration <long>  Iterator expiration interval in 
        milliseconds.
  -max-open-iterators <int>    Maximum concurrent opened iterators.
        Default: 10000
  -num-pool-threads <int>      Number of proxy threads. Default: 20
  -max-concurrent-requests <int>      The maximum number of 
        concurrent requests per iterator. Default: <num_cpus * 2>
  -max-results-batches <int>      The maximum number of results 
        batches that can be held in the proxy per iterator. 
        Default: 0
  -help  Usage instructions.
  -version  Print KVProxy server version number.
  -verbose  Turn verbose flag on.  

Always start the Oracle NoSQL Database store before starting the proxy server.

When connecting to a non-secured store, the following parameters are required:

  • -helper-hosts

  • -port

  • -store

When connecting to a secured store, the following parameters are also required:

  • -security

  • -username

Note

Drivers are able to start and stop the proxy server on the local host if properly configured. See Automatically Starting the Proxy Server for details.

Securing Oracle NoSQL Database Proxy Server

If configured properly, the proxy can access a secure installation of Oracle NoSQL Database. To do this, the -username and -security proxy options must be specified.

The following example describes how to add security to an Oracle NoSQL Database single node deployment. The example also shows how to initiate a connection to the Oracle NoSQL Database replication nodes.

To install Oracle NoSQL Database securely:

java -Xmx256m -Xms256m \
-jar KVHOME/lib/kvstore.jar makebootconfig \
-root KVROOT -port 5000 \
-runadmin -host node01 -harange 5890,5900 \
-store-security configure -pwdmgr pwdfile -capacity 1 
  1. Run the makebootconfig utility with the required -store-security option to set up the basic store configuration with security:

  2. In this example, -store-security configure is used, so the security configuration utility is run as part of the makebootconfig process and you are prompted for a password to use for your keystore file:

    Enter a password for the Java KeyStore: 
  3. Enter a password for your store and then reenter it for verification. In this case, the password file is used, and the securityconfig tool will automatically generate the following security related files:

    Enter a password for the Java KeyStore: ***********
    Re-enter the KeyStore password for verification: ***********
    Created files:
    security/client.trust
    security/client.security 
    security/store.keys
    security/store.trust
    security/store.passwd
    security/security.xml 

    Note

    In a multi-host store environment, the security directory and all files contained in it should be copied to each server that will host a Storage Node. For more information on multiple node deployments see the Oracle NoSQL Database Security Guide.

  4. Start the Storage Node Agent (SNA):

    nohup java -Xmx256m -Xms256m \
    -jar KVHOME/lib/kvstore.jar start -root KVROOT&

    When a newly created store with a secure configuration is first started, there are no user definitions available against which to authenticate access. To reduce risk of unauthorized access, an admin will only allow you to connect to it from the host on which it is running. This security measure is not a complete safeguard against unauthorized access. It is important that you do not provide local access to machines running KVStore. In addition, you should perform steps 5, 6 and 7 soon after this step to minimize the time period in which the admin might be accessible without full authentication. For more information on maintaining a secure store see the Oracle NoSQL Database Security Guide.

  5. Start runadmin in security mode on the KVStore server host (node01). To do this, use the following command:

    java -Xmx256m -Xms256m \
    -jar KVHOME/lib/kvstore.jar \
    runadmin -port 5000 -host node01 \
    -security KVROOT/security/client.security
    Logged in admin as anonymous 
  6. Use the configure -name command to specify the name of the KVStore that you want to configure:

    kv-> configure -name mystore
    Store configured: mystore 
  7. Configure the KVStore by deploying a Zone, a Storage Node, and an Admin Node. Then, create a Storage Node Pool. Finally, create and deploy a topology.

    kv-> plan deploy-zone -name mydc -rf 1 -wait
    Executed plan 2, waiting for completion...
    Plan 2 ended successfully
    kv-> plan deploy-sn -zn zn1 -port 5000 -host node01 -wait
    Executed plan 3, waiting for completion...
    Plan 3 ended successfully
    kv-> plan deploy-admin -sn sn1 -port 0 -wait
    Executed plan 4, waiting for completion...
    Plan 4 ended successfully
    kv-> pool create -name mypool
    kv-> pool join -name mypool -sn sn1
    Added Storage Node(s) [sn1] to pool mypool
    kv-> topology create -name mytopo -pool mypool -partitions 30
    Created: mytopo
    kv-> plan deploy-topology -name mytopo -wait
    Executed plan 5, waiting for completion...
    Plan 5 ended successfully 
  8. Create an admin user. In this case, user root is defined:

    kv-> plan create-user -name root -admin -wait
    Enter the new password: ********
    Re-enter the new password: ********
    Executed plan 6, waiting for completion...
    Plan 6 ended successfully  
  9. Create a new password file to store the credentials needed to allow clients to login as the admin user (root):

    java -Xmx256m -Xms256m \
    -jar KVHOME/lib/kvstore.jar securityconfig \
    pwdfile create -file KVROOT/security/login.passwd
    java -Xmx256m -Xms256m \
    -jar KVHOME/lib/kvstore.jar securityconfig pwdfile secret \
    -file KVROOT/security/login.passwd -set -alias root 
    Enter the secret value to store: ********
    Re-enter the secret value for verification: ********
    Secret created
    OK

    Note

    The password must match the one set for the admin in the previous step.

  10. At this point, it is possible to connect to the store as the root user. To login, you can use either the -username <user> runadmin argument or specify the "oracle.kv.auth.username" property in the security file.

    In this example, a security file (mylogin.txt) is used. To login, use the following command:

    java -Xmx256m -Xms256m \
    -jar KVHOME/lib/kvstore.jar runadmin -port 5000 \
    -host localhost -security mylogin
    Logged in admin as root 

    The file mylogin.txt should be a copy of the client.security file with additional properties settings for authentication. The file would then contain content like this:

    oracle.kv.auth.username=root
    oracle.kv.auth.pwdfile.file=KVROOT/security/login.passwd
    oracle.kv.transport=ssl
    oracle.kv.ssl.trustStore=KVROOT/security/client.trust
    oracle.kv.ssl.protocols=TLSv1.2,TLSv1.1,TLSv1
    oracle.kv.ssl.hostnameVerifier=dnmatch(CN\=NoSQL) 

Then, to run KVProxy and access the secure Oracle NoSQL Database deployment:

java -cp KVHOME/lib/kvclient.jar:KVPROXY/lib/kvproxy.jar 
oracle.kv.proxy.KVProxy -helper-hosts node01:5000 -port 5010 
-store mystore -username root -security mylogin 
Nov 21, 2014 12:59:12 AM oracle.kv.proxy.KVProxy <init>
INFO: PS: Starting KVProxy server
Nov 21, 2014 12:59:12 AM oracle.kv.proxy.KVProxy <init>
INFO: PS: Connect to Oracle NoSQL Database mystore nodes : localhost:5000
Nov 21, 2014 12:59:13 AM oracle.kv.proxy.KVProxy <init>
INFO: PS:   ... connected successfully
Nov 21, 2014 12:59:13 AM oracle.kv.proxy.KVProxy startServer
INFO: PS: Starting listener ( Half-Sync/Half-Async server - 20
no of threads on port 5010) 

Note

Because this proxy server is being used with a secure store, you should limit the proxy server's listening port (port 5010 in the previous example) to only those hosts running authorized clients.

Trouble Shooting the Proxy Server

If your client is having trouble connecting to the store, then the problem can possibly be with your client code, with the proxy and its configuration, or with the store. To help determine what might be going wrong, it is useful to have a high level understanding of what happens when your client code is connecting to a store.

  1. First, your client code tries to connect to the ip:port pair given for the proxy.

  2. If the connection attempt is not successful, and your client code indicates that the proxy should be automatically started, then:

    1. The client driver will prepare a command line that starts the proxy on the local host. This command line includes the path to the java command, the classpath to the two jar files required to start the proxy, and the parameters required to start the proxy and connect to the store (these include the local port for the proxy to listen on, and the store's connection information).

    2. The driver executes the command line. If there is a problem, the driver might be able to provide some relevant error information, depending on the exact nature of the problem.

    3. Upon command execution, the driver waits for a few seconds for the connection to complete. During this time, the proxy will attempt to start. At this point it might indicate a problem with the classpath.

      Next, it will check the version of kvclient.jar and indicate if it is not suited.

      After that, it will check the connection parameters, and indicate problems with those, if any.

      Then the proxy will actually connect to the store, using the helper-hosts parameter. At this time, it could report connection errors such as the store is not available, security credentials are not available, or security credentials are incorrect.

      Finally, the proxy tries to listen to the indicated port. If there's an error listening to the port (it is already in use by another process, for example), the proxy reports that.

    4. If any errors occur in the previous step, the driver will automatically repeat the entire process again. It will continue to repeat this process until it either successfully obtains a connection, or it runs out of retry attempts.

      Ultimately, if the driver cannot successfully create a connection, the driver will return with an error.

  3. If the driver successfully connects to the proxy, it sends a verify message to the proxy. This verify message includes the helper-host list, the store name, the username (if using a secure store), and the readzones if they are being used in the store.

    If there is anything wrong with the information in the verify message, the proxy will return an error message. This causes the proxy to check the verify parameters so as to ensure that the driver is connected to the right store.

  4. If there are no errors seen in the verify message, then the connection is established and store operations can be performed.

To obtain the best error information possible when attempting to troubleshoot a connection problem, start the proxy with the -verbose command line option. Also, you can enable assertions in the proxy Java code by using the java -ea command line option.

Between these two mechanisms, the proxy will provide a great deal of information. To help you analyze it, you can enable logging to a file. To do this:

Start the proxy with the following parameter:

java -cp KVHOME/lib/kvclient.jar:KVPROXY/lib/kvproxy.jar  
-Djava.util.logging.config.file=logger.properties 
oracle.kv.proxy.KVProxy -helper-hosts node01:5000 -port 5010 
-store mystore -verbose 

The file logger.properties would then contain content like this:

# Log to file and console
handlers = java.util.logging.FileHandler, java.util.logging.ConsoleHandler
## ConsoleHandler ##
java.util.logging.ConsoleHandler.level = FINE
java.util.logging.ConsoleHandler.formatter = 
                                       java.util.logging.SimpleFormatter
## FileHandler ##
java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter
# Limit the size of the file to x bytes
java.util.logging.FileHandler.limit = 100000
# Number of log files to rotate
java.util.logging.FileHandler.count = 1
# Location and log file name
# %g is the generation number to distinguish rotated logs
java.util.logging.FileHandler.pattern = ./kvproxy.%g.log

Configuration parameters control the size and number of rotating log files used (similar to java logging, see java.util.logging.FileHandler). For a rotating set of files, as each file reaches a given size limit, it is closed, rotated out, and a new file is opened. Successively older files are named by adding "0", "1", "2", etc. into the file name.