Function to reset sequence.....

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Function to reset sequence.....
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* Function to reset sequence.....
@ 2006-10-27 16:28  Doug Hyde <doug.hyde@e-cocreate.com>
  0 siblings, 1 reply; 2+ messages in thread

From: Doug Hyde @ 2006-10-27 16:28 UTC (permalink / raw)
  To: pgsql-sql

I am a real newbie with PL/pgSQL, and with postgres, but here goes. 

The problem: when you import data into postgresql, there is no way to set
the proper sequence on the primary key. For example, I could have a table
with 2000 rows, some of which have been added/deleted in time, so the
nextval for the sequence should be 3301. When you set the table up with sql
as:

CREATE TABLE "public"."tblcompany"(
"intcompany" SERIAL PRIMARY KEY,
"txtcompanyname_1" varchar(255) ,
...
);

The nextval is set by default to 1. 

To overcome this, and avoid manually resetting the key (which is error
prone), my strategy is (1) create the structure, (2) import the data, and
then (3) reset the primary key. I have written sql to accomplish the first
two which I have working well; the third is more complicated. What I would
like to try is pasted below, after messing around - I haven't really got it
even close to working:

CREATE OR REPLACE FUNCTION fixsequence() returns void AS $$

BEGIN

  x RECORD; 
  temp int;

-- set up a loop for the tables in the database

  FOR x IN
	SELECT table_name, column_name
	FROM information_schema.key_column_usage
	NATURAL JOIN information_schema.table_constraints
	WHERE constraint_type = 'PRIMARY KEY'
	AND ordinal_position = 1
	ORDER BY 1;

-- begin loop 

  LOOP
	-- get the max value of the primary key and add 1
	select max(x.column_name)+1 as temp from x.tablename;

	-- get the seqence name for the table, sequence name always includes
the table name of the pimary key
	select relname as seq_name  from pg_class where relkind = 'S' and
relname like x.table_name'%';

	-- now reset the sequence for that table
	SELECT setval(seq_name, temp);

  END LOOP;

END;
$LANGUAGE 'plpgsql';

Before I mess up my data, will this (or something like it work) as I have
little confidence? I am having trouble with combining variables with
wildcards (middle of the loop).  

Thanks for any support. 

Doug

^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: Function to reset sequence.....
@ 2006-11-03 23:52  Anonymous <anonymous.nospam@hotmail.com>
  parent: Doug Hyde <doug.hyde@e-cocreate.com>
  0 siblings, 0 replies; 2+ messages in thread

From: Anonymous @ 2006-11-03 23:52 UTC (permalink / raw)
  To: pgsql-sql

It is not the answer to your question, but please note that the NATURAL
JOIN may cause problems if the underlaying database structure changes
(for example after a version upgrade). See the following thread for
more information:
http://forums.oracle.com/forums/thread.jspa?threadID=440287

^ permalink  raw  reply  [nested|flat] 2+ messages in thread

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2006-10-27 16:28 Function to reset sequence..... Doug Hyde <doug.hyde@e-cocreate.com>
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