Database Technologies

Anonymous Block Support: Now, user would be able to create anonymous block using plpgsql as given below: do $$ declare id1 varchar; begin select id into id1 from test_sort limit 1; raise notice '%',id1; end; $$ language plpgsql; Output: NOTICE: 1.1 DO Column Trigger: PG9.0 is also supports the column level and When Triggers. Following is an example: create or replace function test_col_trigger() returns trigger as $$ BEGIN RAISE NOTICE 'INSERTED VALUE in Column a %',new.id; RETURN null; END; $$ language plpgsql; create trigger col_trigger after update of "a" on test_def FOR EACH ROW EXECUTE procedure test_col_trigger(); Output: postgres=# update test_def set a='Second'; NOTICE: INSERTED VALUE in Column a 1 UPDATE 1 When Triggers in PG9.0: PG9.0 has "When trigger" which allowed user to create trigger to execute procedure for a particular condition. create or replace function test_col_trigger() returns t

Till Advanced Server 8.3, there was a function pg_get_tabledef, which some people were using to get the definition of table. This function is no more part of new versions of Advanced Server 8.3 (8.3R2AS and 8.4AS). So, they would be missing this function by default. However, they can get the same functionality using following function, which provides similar result as of pg_get_tabledef. Function code is given below: CREATE OR REPLACE Function pg_get_tabledef(text) RETURNS text AS $$ DECLARE tabledef TEXT; dotpos integer; tablename text; schemaname text; prevcol text; coltype text; notnull1 boolean; rec record; oidcheck boolean; BEGIN dotpos:=strpos($1,'.'); if dotpos = 0 then schemaname:='public'; tablename:=substr($1,dotpos+1); else schemaname:=substr($1,1,dotpos-1); tablename:=substr($1,dotpos+1); end if; select relhasoids into oidcheck from pg_class,pg_namespace where pg_class.r

vmstat command: vmstat is a command which can be use to display system statistics. Syntax is given below: vmstat <# second> < #number of times> Example vmstat 1 10 Above Command is to display the system statistics every second, 10 times. Sample Output of the command: vmstat procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 1 0 0 950888 57536 512868 0 0 559 45 479 671 9 2 73 15 Lets understand the column definition: Procs Column would be having three subcolumns r: count (processes waiting for run time) b: count( Processes in uninterruptible sleep) w: Count (Process which are swapped out and runnable) (on RHEL) If any process in b and w column then DBA/System admin has to check the system. Memory Column would be having following subcolumns: swap: swap space currently available.(in kBs) free: Amount of idle memory(kBs) buff: Memory

Some New Security Features in PG9.0 1. New Grant and Revoke in PG9.0 In Previous version of PG (7.x,8.x), all the DBAs and Users used to miss the GRANT and REVOKE command which can be use to give permissions on all the tables inside the Schema. Now, they don;t have to. From PG9.0, user can execute single GRANT and REVOKE command to give the permission on all the tables in a SCHEMA. GRANT SELECT ON ALL TABLES in SCHEMA TEST to test_user; Here is output of query which shows that above command has given SELECT privileges on all the tables in SCHEMA Test. postgres=# select * from information_schema.table_privileges where grantee ='test_user';; grantor | grantee | table_catalog | table_schema | table_name | privilege_type | is_grantable | with_hierarchy ----------+-----------+---------------+--------------+------------+----------------+--------------+---------------- postgres | test_user | postgres | test | test | SELECT | NO | NO

With all the Processes of Stand-alone Oracle Database, Real Application Cluster provides some other processes which plays important role. These Processes are: 1. LMON: Globa Enqueue Service Monitor Responsibilities Assigned: This Process is responsible for monitoring the entire cluster global enqueues and the resources. It also manages the instances failure and process failures and the associated recovery for Global Cache service and Global Enqueue Service. Main responsibility of this process is recovery of Global Resources. Services provided by this process is also known as Cluster Group Services. View:: So, we have one watcher and recovery agent for Global Resources. 2. LMDx: Global Enqueue Service Daemon (Lock Agent) Responsibility Assigned: This process controls the access of Global Enqueue and resources. It also handles the Deadlock detection and remote enqueue requests (i.e requests from instances). View: Hmm, we have one recorder agent and resource informa

Since, edb-replication which comes with advanced Server is more compactly build with one particular version, therefore some times user does not able to replicate the data between two different version of Advanced Servers. For replicating data between two advanced Server versions, it is important to have same version of Slony on Source and target database. I did research around the slony source code and tried to make it compatible with Advanced Server. If user plainly comile the slony source code against the Advanced Server database, then user will start to get messages like : version/ while configuring the Replication. Reason for such messages is that slony did not able to parse the Advanced Server version, therefore it would not be able to continue further for replication. I did some research and gone through the slony source code. Slony uses a program called dbutil*.c for finding the version of PostgreSQL or checking the compatibility of PostgreSQL version with Slony. F

Users always look for a Backup utility which can give some Good options and a utility can be use with all the instances of PG to take the backup. I have thought in same way and created a pg_hotbackup script. pg_hotbackup utility which I worked on is now a server side utility which takes backup on server side and keep the backups in Backup directory. Options which I have included in it, are following: Compulsory Options: -H (This is for Bin Directory location, utility will use psql command of PG Instance ) -b (Directory where user wants to keep the backup) -p (Port number of PG Instance) -U username (Username) -P passwd (Password). Some other options: -a: Archive Only Option [1|0] -r: Retention Policy [ in days ] -l: List Backups -n: Backup File Name -v: Validate Only [1|0] -R: Retention Only [|0] \?: Help So, I have all the options with me. Now, lets understand what do we need: 1. We need a catalog file, in which utility can keep the backups information and validate the