Cassandra with C#

1. Using Microsoft Visual Studio, Create New Project for Console Application   

2. Configure the project 

3. My target Framework using NET 5.0 

4. Add Client Driver for Cassandra, click Tools menu ->NuGet Package Manager-> Manage NuGet Packages for Solution, then type CassandraCSharpDriver

so CassandraCSharpDriver package get installed

5. Create program 

using System;
using System.Collections;
using System.Collections.Generic;
using Cassandra;
using Cassandra.Mapping;

namespace Cassandra_con
{

    public class KeyspacesMain
    {
        public string Keyspace_name { get; set; }
        public bool Durable_writes { get; set; }
        public SortedDictionary<string string=""> Replication { get; set; }
    }

    class Program
    {
       const string MyDC = "datacenter1";
       const string MyIP = "localhost";
       const int MyPortNo = 9042;
       const string MyUID = "username";
       const string MyPass = "password";
       
        static void Main(string[] args)
        {
            Console.WriteLine("Hello Cassandra!");

            var cluster = Cluster.Builder()
                .AddContactPoints(MyIP)
                .WithPort(MyPortNo)
//              .WithLoadBalancingPolicy(new DCAwareRoundRobinPolicy(MyDC))
//              .WithAuthProvider(new PlainTextAuthProvider(MyUID, MyPass))
                .Build();

            var session = cluster.Connect();
            Console.WriteLine("Connected to cluster: " + cluster.Metadata.ClusterName);

            IMapper mapper = new Mapper(session);
            IEnumerable<keyspacesmain> datax = mapper.Fetch<keyspacesmain>("SELECT keyspace_name, durable_writes, replication FROM system_schema.keyspaces");
            Console.WriteLine("Keyspace Name      Durable Writes  Replication Factor"); 

            foreach (var row in datax)
            {
                Console.Write("{0}", row.Keyspace_name.PadRight(19));
                Console.Write("{0}     ", row.Durable_writes);
                

SortedDictionary<string string=""> obj = (SortedDictionary<string string="">)row.Replication;
                

                IDictionaryEnumerator dictEnum = obj.GetEnumerator();
                int spaces = 12;
                while (dictEnum.MoveNext())
                {
                    Console.WriteLine("Key= ".PadLeft(spaces) + dictEnum.Key + ", Value= " + dictEnum.Value);
                    spaces += 28;
                }
            }
        }
     }
 }

5. Output

Hello Cassandra!

Connected to cluster: Test Cluster

Keyspace Name      Durable Writes  Replication Factor

system_auth          True                     Key= class, Value= org.apache.cassandra.locator.SimpleStrategy

                                                          Key= replication_factor, Value= 1

system_schema     True                    Key= class, Value= org.apache.cassandra.locator.LocalStrategy

system_distributed True                    Key= class, Value= org.apache.cassandra.locator.SimpleStrategy

                                                          Key= replication_factor, Value= 3

system                    True                    Key= class, Value= org.apache.cassandra.locator.LocalStrategy

system_traces        True                     Key= class, Value= org.apache.cassandra.locator.SimpleStrategy

                                                          Key= replication_factor, Value= 2

So simple!

Cassandra Installation Using Docker On Windows

1. Make sure you have installed Docker Desktop for Windows.

2. Open Windows PowerShell

3. Download Cassandra image from the Docker Hub registry. 
Let’s pull Cassandra 4.01 image by type this command: docker pull cassandra:4.0.1

4. Start Cassandra

To start Cassandra, use docker run command that first creates a writeable container layer over the specified image, and then starts it using the specified command in a new container 

docker run --rm --name fercassandra -dp 9042:9042 cassandra:4.0.1

The --rm flag automatically removes the container (fercassandra) when it exits,

--name flag assign a name to the container
--detach , -d flag run container in background and print container ID
--publish , -p flag publish a container's port(s) to the host

5. Cassandra is running

6. CQL Shell

a.  Click CLI button to open window for interacting with Cassandra using CQL,

 then type this query: 

SELECT cluster_name, listen_address, listen_port, data_center, rpc_address, rpc_port FROM system.local;

b. Use docker exec command to run CQL Shell in a running container, then type the query:

c. Use docker exec command to run CQL shell cqlsh for interacting with Cassandra using CQL (the Cassandra Query Language). It is shipped with every Cassandra package, and can be found in the bin/ directory alongside the cassandra executable.

7.  Show more..

a. Use docker ps command to shows running containers:

b. Use docker port command to list port mappings or a specific mapping for the container:

That's enough for now, hope it helps someone.

How to fix 404 Not Found Nginx - PHP

I'm working on moving applications from the old server to the new server and have to re-install. At this stage I configure PHP-based applications with related frameworks using Nginx as a web server. The problem that arises is the message Not Found with code 404, when the application runs the index.php file which then calls another file to run the actual process.

 

Next I created a test.php file to detect errors in the application and the tes.php file can run normally (code 200).

Information from curl shows the index.php file Found (302), but controller and action Not Found (404).

Status code HTTP/1.1 302 Found, indicates the requested resource resides temporarily under a different URI

The 404 Not Found message states that the server has not found anything matching the Request-URI.

The results of sudo tail -f /var/log/nginx/error.log and sudo tail -f /var/log/nginx/access.log don't show anything odd. The php files have been processed correctly, but the problem lies most likely in my Nginx configuration which is not suitable for processing php files.

I changed the configuration in the file /etc/nginx/sites-available/myweb.domain.com, which is from

location / {

try_files $uri $uri/ =404;

}

to 

location / {

try_files $uri $uri/ /index.php?$args;

}

Then do sudo service nginx restart and check the result:

As a result, my applications can run as they should and the status becomes HTTP/1.1 200 OK  or request has succeeded.

Oracle orasso

How to find lost ORASSO password

Login as orcladmin through Directory Manager and navigate to:

--> Entry Management

--> cn=OracleContext

--> cn=Products

--> cn=IAS

--> cn=IAS Infrastructure Databases

--> orclReferenceName=(yoursid.domain)

--> orclResourceName=ORASSO find the password in orclpasswords atribute on Properties tab.

also see --> orclResourceName=PORTAL

If you forget orcladmin, use this command from $ORACLE_HOME/bin directory

oidpasswd connect=yourDBconn unlock_su_acct=true enter new password...

OID DB user password: mynewpass

Shrinking the SQL Server log

To backup a database, we could instruct SQL Server to truncate of the transaction log, using T-SQL command: BACKUP LOG db_name WITH TRUNCATE_ONLY. Log truncation remove transactions from the log file and the space remains allocated to the file. Sometimes as in my case below, you need to shrink the log file to reclaim the space.

In my case, I receive a backup file from SQL Server 2008, probably a full backup. After restoring the file and create a new database on my laptop, the used space is 160MB for the data and 52GB for the log file. My local disk free space 18 GB left, I need to shrinking the log file.

1. Check the database size property:
Select name, filename, convert(decimal(12,2), round(a.size/128.000,2)) as SizeMB,
convert(decimal(12,2), round(fileproperty(a.name,'SpaceUsed')/128.000,2)) as SpcUsedMB, 
convert(decimal(12,2), round((a.size-fileproperty(a.name,'SpaceUsed'))/128.000,2)) as FreeSpcMB
from dbo.sysfiles a

name        filename            SizeMB    SpcUsedMB  FreeSpcMB 
-----------------------------------------------------------------
Student     D:\DATA\STUDENT.mdf 155.69    149.50     6.19
Student_log D:\DATA\STUDENT.ldf 50861.94  362.09     50499.84

The FreeSpcMB shows 51GB and I try to reclaim the space of the log file to OS.

2. Change the database recover mode to simple
   ALTER DATABASE Student SET RECOVERY SIMPLE;
   GO

3. Do the Shrink the log file to 1 MB
   DBCC SHRINKFILE (Student_log, 1);
   GO

3. Reset the database recovery model.
   ALTER DATABASE Student SET RECOVERY FULL;
   GO
   SELECT name, recovery_model_desc FROM sys.databases;
   GO


Now, the OS has 70GB free space.

Eclipse: Cannot create a server using the selected type

I just install Tomcat version 7.0.37 to replace the old 7 version, but the new server could not be add to Eclipse with error message "Cannot create a server using the selected type".

To solve the problem, I've remove these files: org.eclipse.jst.server.tomcat.core.prefs  and org.eclipse.wst.server.core.prefs from /workspace/.metadata/.plugins/org.eclipse.core.runtime/.settings
and delete the old server.

After restarting Eclipse, "Define a New Server", now Tomcat works.

Hierarchical Data

Recursive queries are typically used to deal with hierarchical or tree-structured data, such as chart of accounts (COA). COA is a listing all the accounts in the general ledger in such a way that forms a hierarchical structure, for example the following:


acc_
acc_id parid acc_code     acc_name                    acc_level
-----------------------------------------------------------------
1           10.0000.0000 AKTIVA                         0
2 1 11.0000.0000 AKTIVA LANCAR                   1
3 2 11.1000.0000 Kas dan Setara Kas                2
4  3 11.1100.0000 Kas                            3
5  4 11.1110.0000 Kas - Program Kemitraan          4
6  4 11.1120.0000 Kas - Bina Lingkungan             4
7  3 11.1200.0000 Bank                            3
8  7 11.1210.0000 Bank - Program Kemitraan        4
....
....
116  97 22.0000.0000 KEWAJIBAN JANGKA PANJANG 1
117  116 22.2000.0000 Hutang Kepada BUMN Pembina Lain  2
119  116 22.9000.0000 Hutang Jangka Panjang Lainnya     2
122          30.0000.0000 AKTIVA BERSIH                   0
123  122 33.0000.0000 PENYISIHAN                      1



The list is generated by running the following SQL command:


WITH RECURSIVE tree AS (SELECT acc_id,acc_code, acc_parid, acc_name ,0 AS acc_level 
FROM tova.coa WHERE acc_parid IS NULL
UNION ALL
SELECT c.acc_id, c.acc_code, c.acc_parid, c.acc_name, acc_level+1 AS acc_level 
FROM tova.coa c JOIN tree t ON t.acc_id  = c.acc_parid)
SELECT acc_id, acc_parid, tova.getakunttk(acc_code), acc_name, acc_level 
FROM tree b order by 3;


I save the transaction only at the lowest level account, of course user still can see reports for each account in a hierarchy. The stored function below will display accounts hierarchy.

CREATE OR REPLACE FUNCTION tova.getcoa_allchildofparentrec(IN pacc_parid integer) 
RETURNS TABLE (acc_id integer,acc_code character varying, acc_name character varying) AS
$$
BEGIN
    RETURN QUERY WITH RECURSIVE tree AS (
            SELECT a.acc_id, a.acc_code as acc_code,a.acc_name 
               FROM tova.coa a WHERE acc_parid = $1
            UNION ALL
            SELECT a.acc_id, a.acc_code as acc_code,a.acc_name 
               FROM tova.coa a, tree t WHERE t.acc_id = a.acc_parid)
    SELECT h.acc_id,h.acc_code, h.acc_name FROM tree h;
END;
$$ LANGUAGE plpgsql;


To display the coa's tree, just call this:
select acc_code, acc_name from ferry.getcoa_allchildofparentrec(34) order by 1;


acc_code acc_name
---------------------------------------------------------------------
11.3610.0000 Piutang Pinjaman Mitra Binaan - Sektor Industri
11.3610.6108 PPMB Sektor Industri - Kab. Landak
11.3610.6103 PPMB Sektor Industri - Kab. Sanggau
11.3610.6301 PPMB Sektor Industri - Kab. Tanah Laut
11.3610.6309 PPMB Sektor Industri - Kab. Tabalong
11.3610.6105 PPMB Sektor Industri - Kab. Sintang
11.3610.6303 PPMB Sektor Industri - Kab. Banjar
11.3610.6100 PPMB Sektor Industri Prov. Kalimantan Barat
11.3610.6171 PPMB Sektor Industri - Kota Pontianak
11.3620.0000 Piutang Pinjaman Mitra Binaan - Sektor Perdagangan
11.3630.0000 Piutang Pinjaman Mitra Binaan - Sektor Pertanian
11.3640.0000 Piutang Pinjaman Mitra Binaan - Sektor Peternakan
11.3650.0000 Piutang Pinjaman Mitra Binaan - Sektor Perkebunan
11.3660.0000 Piutang Pinjaman Mitra Binaan - Sektor Perikanan
11.3670.0000 Piutang Pinjaman Mitra Binaan - Sektor Jasa
11.3680.0000 Piutang Pinjaman Mitra Binaan - Sektor Lain
11.3610.6300 Sektor Industri Prov. Kalimantan Selatan
11.3610.6310 PPMB - Sektor Industri - Kab. Tanah Bumbu
...
...
11.3670.6171 Piutang Pinjaman Mitra Binaan - Sektor Jasa - Kota Pontianak
11.3660.6171 Piutang Pinjaman Mitra Binaan - Sektor Perikanan - Kota Pontianak
11.3680.6171 Piutang Pinjaman Mitra Binaan - Sektor Lain - Kota Pontianak