lib_mysqludf_cassandra

Provides UDF commands to access Cassandra from Mysql/MariaDB.

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Table of Contents

• Synopsis
• System Requirements
• Compilation and Install Plugin Library
  • Compilation Argumnets
  • Compilation Variable
• Install and Uninstall UDF
• Usage
• TODO
• Copyright and License
• See Also

Synopsis

figure01 digraph G {

rankdir = "LR";
size ="8,8";
edge [
    fontname = "Consolas"
    fontsize = 10
];
MariaDB [
    label = "MariaDB\n(presistence)"
    shape = "box"
];
Cassandra [
    label = "Cassandra"
    shape = "box"
];
edge [
    fontcolor = "blue"
    color = "blue"
];
writer;
writer:e -> MariaDB [
    label="INSERT\nUPDATE\nDELETE"
];
MariaDB -> Cassandra [
    label = "INSERT\nUPDATE\nDELETE"
];
edge [
    fontcolor = "red"
    color = "red"
];
node [
    fontname = "Consolas"
    fontsize = 10
    penwidth = 0.5
    color    = "gray"
    shape = "record"
    style = "rounded"
];
MariaDB_Data [
  label = <<TABLE border="0" cellspacing="0" cellborder="1"><TR><TD COLSPAN="2">MariaDB data</TD></TR><TR><TD>item</TD><TD>qty</TD></TR><TR><TD>shoes</TD><TD>35</TD></TR><TR><TD>books</TD><TD>158</TD></TR></TABLE>>
];
{
  rank = "same";
  MariaDB:n -> MariaDB_Data:s;
}
Cassandra_Data [
  label = <<TABLE border="0" cellspacing="0" cellborder="1"><TR><TD COLSPAN="2">Cassandra data</TD></TR><TR><TD>item</TD><TD>qty</TD></TR><TR><TD>shoes</TD><TD>35</TD></TR><TR><TD>books</TD><TD>158</TD></TR></TABLE>>
];
{
  rank = "same";
  Cassandra:n -> Cassandra_Data:s;
}

} figure01

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System Requirements

• Architectures: Linux 64-bit(x64)
• Compilers: GCC 4.1.2+
• MariaDB 5.5+
• Cassandra 3.9+
• Dependencies:
  • MariaDB development library 5.5+
  • libuv 1.20.3+
  • datastax/cpp-driver 2.9.0+
  • cJSON 1.6+

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Compilation and Install Plugin Library

Installing compilation tools

CentOS

# install tools
$ yum install -y make wget gcc automake cmake gcc-c++ libtool git

# install dependencies
$ yum install -y openssl openssl-devel

# install mariadb development tool
$ yum install -y mariadb-devel

To compile the plugin library just simply type make and make install.

$ make

# install plugin library to plugin directory
$ make install

# install UDF to Mysql/MariaDB server
$ make installdb

NOTE: If the Mysql/MariaDB is an earlier version or installed from source code, the default include path might be invalid; use make INCLUDE_PATH=`mysql_config --variable=pkgincludedir` to assign INCLUDE_PATH variable for compilation.

Compilation Argumnets

• install

  Install the plugin library to Mysql plugin directory.

• installdb

  Install UDFs to Mysql/MariaDB server.

• uninstalldb

  Uninstall UDFs from Mysql/MariaDB server.

• clean

  Clear the compiled files and resources.

• distclean

  Like the clean and also remove the dependencies resources.

Compilation Variable

The compilation variable can be use in make:

• LIBUV_MODULE_VER

  The libuv version to be compiled. If it is not specified, the default value is 1.20.3.

• CPP_DRIVER_MODULE_VER

  The datastax/cpp-driver version to be compiled. If it is not specified, the default value is 2.9.0.

• CJSON_MODULE_VER

  The cJSON version to be compiled. If it is not specified, the default value is 1.6.0

• INCLUDE_PATH

  The MariaDB or Mysql C header path. If it is not specified, the default will be the Mysql variable pkgincludedir. The value can be displayed by executing the following command:

  $ echo `mysql_config --variable=pkgincludedir`/server

• PLUGIN_PATH

  The MariaDB or Mysql plugin path. The value can be obtained via running the sql statement SHOW VARIABLES LIKE '%plugin_dir%'; in MariaDB/Mysql server. If it is not specified, the default will be Mysql variable plugindir. The value can be displayed by executing the following command:

  $ mysql_config --plugindir

example:

# specify the plugin install path with /opt/mysql/plugin
$ make PLUGIN_PATH=/opt/mysql/plugin
$ make install

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Install and Uninstall UDF

To install UDF from make:

$ make installdb

or executing the following sql statement on Mysql/MariaDB server:

mysql>  CREATE FUNCTION `cassandra` RETURNS STRING SONAME 'lib_mysqludf_cassandra.so';

To uninstall UDF with make uninstalldb -or- executing the following sql statement on Mysql/MariaDB server:

mysql>  DROP FUNCTION IF EXISTS `cassandra`;

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Usage

cassandra($hosts, $query_string)

Call a Cassandra command by specified $hosts, $command, and individual arguments.

• $hosts - represent the Cassandra clusters to be connected, the value is a string, like "127.0.0.1" or "192.168.2.15,192.168.2.17".
• $query_string - the Cassandra cql command. See also http://cassandra.apache.org/doc/latest/cql/index.html for further details.

The function returns a JSON string indicating success or failure of the operation.

the success output:

{
   "result_code": 0
}

the failure output:

{
   "result_code": 16777226,
   "message"    : "No hosts available for the control connection"
}

NOTE: The error code see enum CassError.

The following examples illustrate how to use the function contrast with cqlsh utility.

/*
  the following statement likes:

    cqlsh> INSERT INTO test.t1 (id, value) VALUES (1, 'one');
*/
mysql>  SELECT `cassandra`('192.168.24.29', 'INSERT INTO test.t1 (id, value) VALUES (1, ''one'')')\G
*************************** 1. row ***************************
`cassandra`('192.168.24.29', 'INSERT INTO test.t1 (id, value) VALUES (1, ''one'')'): {
        "result_code":  0
}
1 row in set (0.056 sec)


/*
  the following statement likes:

    cqlsh> INSERT INTO test.t1 (id, unknow_col) VALUES (1, 'one');
    InvalidRequest: Error from server: code=2200 [Invalid query] message="Undefined column name unknow_col"

*/
mysql>  SELECT `cassandra`('192.168.24.29', 'INSERT INTO test.t1 (id, unknow_col) VALUES (1, ''one'')')\G
*************************** 1. row ***************************
`cassandra`('192.168.24.29', 'INSERT INTO test.t1 (id, value) VALUES (1, ''one'')'): {
        "result_code":  33563136,
        "message":      "Undefined column name unknow_col"
}
1 row in set (0.046 sec)

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TODO

• implement Cassandra Authentication

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Copyright and License

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See Also

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