Re: [SQL] abusing an aggregate funct

On Sat, 14 Nov 1998, Thomas Good wrote:

> Due to the sheer girth of the table the following query, called from
> a data entry script,  takes a bit of time to finish:
>
> SELECT max(rec_num) FROM crtrd1;
>
> I use this to setup `rec_num + 1' for my query number (p_key)...any
> way I can speed this up a bit?  I've run vacuum analyze but the
> table size is doing me in...
>
Use a sequence to generate rec_num.  See man create_sequence.

You can then use curval('sequence_name') to get the last
sequence number generated, or if you are performing an insert:
  insert into crtrd1 (p_key,otherdata) values (nextval('sequence_name',moredata);

You could also create the table using nextval as the default
value of p_key.  You may wish to create a unique_index on
p_key, but nextval is guaranteed not to generate duplicates
unless you allow it to rollover.





Marc Zuckman
marc@fallon.classyad.com

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