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UPSERT/MERGE using Writable CTE in PostgreSQL 9.1

There is always discussion of having UPSERT/MERGE in postgresql. Since, oracle and other RDBMS has this feature, therefore people ask about this feature in PostgeSQL. In previous version of PostgreSQL, we used to implement it using functions. Now in PostgreSQL 9.1, user can implement this feature using Writable CTE. PostgreSQL 9.1, now has Writable CTE using WTH. WITH provides a way to write auxiliary statements for use in a larger query. These statements, which are often referred to as Common Table Expressions or CTEs, can be thought of as defining temporary tables that exist just for one query. Each auxiliary statement in a WITH clause can be a SELECT, INSERT, UPDATE, or DELETE; and the WITH clause itself is attached to a primary statement that can also be a SELECT, INSERT, UPDATE, or DELETE. Lets see how we can use Writable CTE for UPSERT. Following are SQL Code which can be use in Oracle and PostgreSQL for creating sample data: For oracle: create table myTable (pid ...
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Remote Log Reading in PostgreSQL 8.4 and 9.0.

I was going through the one of the important feature (SQL/MED) which is coming feature of PostgreSQL 9.1. This feature enables user to access any external file, using SQL, from PostgreSQL Terminal. Magnus hagander's has also blogged about this feature and he has shown "How to access the PostgreSQL logfile using SQL/Med" . After going through his blog, I thought to do same with PostgreSQL 8.4/9.0 using plperl program. Following are the steps, which can be use to access the postgreSQL csv log file: 1. Change the log_destination parameter in postgresql.conf file of PG Instance Directory, to create csvlog of postgreSQL log. As given below. log_destination = 'stderr,csvlog' 2. Reload the changes in PostgreSQL, using following command: postgres=# select pg_reload_conf(); pg_reload_conf ---------------- t (1 row) 3. Connect to PostgreSQL database using psql command and Create following data type CREATE type pg_log_type as ( log_time timestamp(3) with ti...
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Creating user probe and alert in PEM 2.1

This is also one type of thing in which people are very interested. How to create probes other than PEM inbuilt probe? And how to create alert based on probe? Well answer is simple. Understand what probe is in PEM and then understand PEM Data detail. Probe in PEM requires following: 1. SQL Code which can be use to gathering data by pemagent. 2. Table in pemdata schema, which will be use for storing Current status/data of SQL. 3. History table (specially in pemhistory schema) where all history data will reside. Suppose user wants to monitor the Slony Replication using PEM (since, PEM doesn't have slony replication moniotring), so user can do following: 1. SQL Code which can be use for slony replication monitoring. We know that slony replication monitoring can be done using view sl_status of slony. So, user can create a SQL Code as given below for replication. select '_test_slony' as schema_name, st_origin,st_received, st_lag_num_events , st_lag_time from _test_slony...
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