Category Archives: Uncategorized

Configure Reverse Proxy – CentOS 7 – httpd

By default mod_proxy is included in http package. Had created a new VM – So installing httpd yum clean all yum -y update yum -y install httpd firewall-cmd –permanent –add-port=80/tcp firewall-cmd –permanent –add-port=8080/tcp systemctl start httpd systemctl enable httpd systemctl … Continue reading

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MySQL – Disable Full Group By

Encountered the exception : java.sql.SQLSyntaxErrorException: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column ‘IAM_DB.this_.ID’ which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by. Fix was to … Continue reading

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MySQL 5.6/7 on Debian 7.x

Debian 7.6 was installed on the VM.  Default mysql-server which was getting installed using apt-get was 5.5.  One of the updates in mysql 5.6 was to support more than one current_timestamp column with default value of current time stamp. So … Continue reading

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Neo4J – Linux – Configurations

After installing the community edition of Neo4J on Debian VM  understood from manuals about the need to increase the number of files limit for Neo4J. cat /proc/sys/fs/file-max The output was 3273723 – So no issues.  In case if it is less … Continue reading

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Multiple Tomcat instances

Had to start two instances of Tomcat on the same VM (Linux) – Did the following without even knowing whether the steps were correct or not – will check later – but it worked. Unzipped the tomcat zip file into … Continue reading

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Oracle Java 8 – Debian

Wanted to install Oracle Java on a new Wheezy system – On searching the net got the following information which worked for me apt-get install software-properties-common python-software-properties add-apt-repository ppa:webupd8team/java Edit /etc/apt/sources.list.d/webupd8team-java-wheezy.list and replace “wheezy” with “trusty” apt-get install oracle-java8-installer and that’s … Continue reading

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Neo4J – Indexes, Constraints

Cypher allows the creation of indexes over a property for all nodes that have a given label.   Neo4j CQL has provided “CREATE INDEX” command to create indexes on NODE’s or Relationship’s properties. CREATE INDEX ON :Person(name) CREATE INDEX ON :Customer … Continue reading

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Neo4J – Functions

[table id=4 /]

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Neo4J – Delete and Remove

Main Difference between Neo4j CQL DELETE and REMOVE commands – DELETE operation is used to delete Nodes and associated Relationships. REMOVE operation is used to remove labels and properties. Similarity between Neo4j CQL DELETE and REMOVE commands – Both commands … Continue reading

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Ne04J – Labels / WHERE

A label is a named graph construct that is used to group nodes into sets; all nodes labeled with the same label belongs to the same set. Many database queries can work with these sets instead of the whole graph, … Continue reading

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