Index Monitoring in Oracle Database

Applies to ONLY Oracle Database 10gR1 through to 12cR1.
In Oracle Database 12cR2, this feature is replaced.  A new blog post of this feature will be posted in due course.

Since Oracle 10g, you can monitor indexes to see if they are being used or not.  Which is very useful as indexes, consume unnecessary CPU and I/O on DML activity if not used.  Therefore, it’s recommended to monitor indexes and any unused (more...)

Which Privileges Are Required to Use the ADWC Service Console?

The Autonomous Data Warehouse Cloud (ADWC) service provides a Service Console that can be used to monitor the service activity and to carry out a small number of administration tasks (e.g. changing some resource management rules).

The documentation specifically says to use the ADMIN user to login. But, actually, any unlocked database user having the CREATE SESSION privilege can be used to login. This is not only useful, but, in my opinion, necessary. In (more...)

Rebuilding Indexes: Danger With Clustering Factor Calculation (Chilly Down)

Let me start by saying if you don’t already following Jonathan Lewis’s excellent Oracle blog, do yourself a favour. In a recent article, Jonathan highlighted a danger with rebuilding indexes (or indeed creating an index) when used in relation to collecting index statistics with the TABLE_CACHED_BLOCKS preference. I’ve discussed the importance of the TABLE_CACHED_BLOCKS statistics […]

MongoDB DataTypes

MongoDB stores documents in BSON, which is the binary encoded format of JSON. Basically, the name BSON itself comes from Binary encoded JSON. The BSON data format provides various types, used when we store the JavaScript objects in the binary form. We can make remote procedure calls in MongoDB by using BSON. All the BSON data-types are supported in MongoDB. Below are the enlisted MongoDB data types. Each MongoDB datatypes corresponds a unique number which (more...)

Where Condition in MongoDB

Below some example of Where condition in MongoDB.
pretty: using for just formatting of data view.
Equal To:
          > db.student.find({“name”: “Mohan” }).pretty()
Less Than:
          > db.student.find({“marks”:{$lt:50}}).pretty()
Less Than Equals:
          > db.student.find({“marks”:{$lte:50}}).pretty()
Greater Than:
          > db.student.find({“marks”:{$gt:50}}).pretty()
Greater Than Equals:

Drop Database Drop Collection

Drop collection from database in mongoDB

db.collection.drop() is used to drop a collection from the database.

Syntax: db.collection.drop()

use TEST

show collections     <——— check the available collections into your database TEST.

db.student.drop()    <——– Check and verify the student collection has been drop from TEST Database.



Drop Database in mongoDB

db.dropDatabase() command is used to drop a existing database.

Syntax: db.dropDatabase()


show (more...)

CRUD Operations

CRUD operations create, read, update, and delete documents as same like in RDBMS (Select and DMLs).


Firstly knows how to create database in mongoDB

MongoDB use DATABASE_NAME is used to create database. The command will create a new database if it doesn’t exist, otherwise it will return the existing database.

Execute simple command : > use TEST

Switch the Database :  > use admin

check your currently selected database : > db

List (more...)

Terminology with MongoDB


Database is a physical container for collections. Each database gets its own set of files on the file system. A single MongoDB server typically has multiple databases.


A grouping of MongoDB documents. A collection is the equivalent of an RDBMS table. A collection exists within a single database. Collections do not enforce a schema.


MongoDB stores data records as BSON documents. BSON is a binary representation of JSON documents, though it (more...)

MongoDB Installation

MongoDB Provide two types of software.

  1. Community Edition :   Its For freeware no mongo support available on this.
  2. Enterprise Edition : Its License Based.

For More Detail about Installation and Packages and Environment Support : Click Here

For any query regarding MongoDB installation/Upgrade feel free contact to Oracle-Help Team.


The post MongoDB Installation appeared first on ORACLE-HELP.

Advantage of mongodb as compare to SQL database

The MongoDB data bases on the JSON (Java Script Object Notation) format. JSON allows for the transfer of data
between web applications and servers using a human readable format.

Before JSON, XML was used for this.
JSON is defined in MongoDB’s BSON (Binary JSON). The binary format of BSON provides reliability and greater efficiency when it comes to speed and storage space.


JSON can only represent a subset of the types (more...)

Overview of MongoDB Collection and Documnets

MongoDB works on concept of collection and document.


Database Database
Table Collection
Tuple/Row Document
column Field
Table Join Embedded Documents
Primary Key Primary Key (Default key _id provided by mongodb itself)


Database Server and Client
Mysqld/Oracle mongod
mysql/sqlplus mongo

The post Overview of MongoDB Collection and Documnets appeared first on ORACLE-HELP.

What is MongoDB ?

MongoDB is open source database system. It’s a document database with the scalability and flexibility that you want with the querying and indexing that you need.

Its support to Dyanmic schema, using a map-reduce, GeoSpatial support the main feature.

  • MongoDB stores data in flexible, JSON-like documents, meaning fields can vary from document to document and data structure can be changed over time
  • The document model maps to the objects in your application code, (more...)

#Exasol Cluster Architecture

This article gives a more detailed view on the Exasol Cluster Architecture. A high level view is provided here.

Exasol Cluster Nodes: Hardware

An Exasol Cluster is built with commodity Intel servers without any particular expensive components. SAS hard drives and Ethernet Cards are sufficient. Especially there is no need for an additional storage layer like a SAN.

See here for a list of Exasol Certified Servers.

Disk layout

As a best practice the hard (more...)

Monitoring java app servers (Tomcat) with Zabbix

This past week we've been trying to enhance our monitoring of java application servers (in our case Tomcat) using zabbix. This actually proved to be a lot more fiddly than we had hoped - and actually this is largely due to two reasons:

1) The documentation is not clear on the architecture
2) The error messages are somewhat misleading

Let me start off by talking about the first point - from the docs I have (more...)

Direct IOT

A recent (automatic ?) tweet from Connor McDonald highlighted an article he’d written a couple of years ago about an enhancement introduced in 12c that allowed for direct path inserts to index organized tables (IOTs). The article included a demonstration seemed to suggest that direct path loads to IOTs were of no benefit, and ended with the comment (which could be applied to any Oracle feature): “Direct mode insert is a very cool facility, but (more...)

New feature in Oracle 11g database to kill session

Now we can kill session after finishing existing transaction to be finished. Means in previous release there was no scope to finish on going transaction. Instead of “alter system kill session” here we can use “alter system disconnect session”. Using syntax “POST_TRANSACTION” we can kill session for active transaction has to be completed first and after that it will be automatically killed. Example of same syntax is given below.

SQL> alter system disconnect session ‘10,251’ (more...)

Quiz Night

Because it’s been a long time since the last quiz night.  Here’s a question prompted by a recent thread on the ODevCom database forum – how many rows will Oracle sorts (assuming you have enough rows to start with in all_objects) for the final query, and how many sort operations will that take ?

drop table t1 purge;

create table t1 nologging as select * from all_objects where rownum < 50000;

select owner, count(distinct object_type),  (more...)

How To Delete Integrated Extract Replicat

Why is this important?

If process is not unregistered from database, they are orphaned.

unregister replicat DATABASE
unregister extract DATABASE

$ ./ggsci 

Oracle GoldenGate Command Interpreter for Oracle
Version OGGCORE_12.
Linux, x64, 64bit (optimized), Oracle 12c on Jul 21 2017 23:31:13
Operating system character set identified as UTF-8.

Copyright (C) 1995, 2017, Oracle and/or its affiliates. All rights reserved.

GGSCI 1> info all

Program      (more...)

pushing predicates

I came across this odd limitation (maybe defect) with pushing predicates (join predicate push down) a few years ago that made a dramatic difference to a client query when fixed but managed to hide itself rather cunningly until you looked closely at what was going on. Searching my library for something completely different I’ve just rediscovered the model I built to demonstrate the issue so I’ve tested it against a couple of newer (more...)

Month Over Month and Newer Schtuff- Power BI

Today’s Post is brought to you by Patrick LeBlanc of Guy in a Cube.  I learn best by doing, so I was working with different features while watching along on Quick Measures:

As a newbie, yes, I had problems with my quick measures just as Patrick said I would, but with a twist-  It wasn’t that I didn’t want to learn DAX, quite the opposite, I could get the expression to work just fine  (more...)