[SQL] Simultaneous Connection Problem

[Webb Sprague]

I have a table that is sequence_number (my PK), session_start_time, and
session_stop_stime.  I would like to query it to determine the max number
of simultaneous sessions.  Has anyone conquered a problem like this?  It
seems like it should be in a book somewhere, but I haven't found it yet.

Thanks,
-- 
Webb Sprague
Programmer
O1 Communications

[SQL] Convert from Seconds-Since-Epoch to Timestamp

[Webb Sprague]

Hi all,

How do I convert from seconds (an integer) to
timestamp?  

I am sure it is easy, but I can't find it in the docs,
so far.

Thanks
Webb

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Re: [SQL] Optimizing huge inserts/copy's

[Webb Sprague]

I am experimenting with this too.  If I have any
indexes at all, the copy's get VERY SLOW as the table
gets big.  Delete ALL your indexes, do your copy's,
and then create your indexes again.

Good luck.
--- Jie Liang [EMAIL PROTECTED] wrote:
 Hi, there,
 
 I tried different  ways,  include vaccum table , 
 ensure index works, it
 still is as slow as ~100rows per minute.
 
 
 Stephan Szabo wrote:
 
  On Tue, 29 Aug 2000, Jie Liang wrote:
 
   Hi, there,
  
   1. use copy ... from '.';
   2. write a PL/pgSQL function and pass multiple
 records as an array.
  
   However, if your table have a foreign key
 constraint, it cannot be speed
   up,
  
   I have same question as you, my table invloving
 9-13 million rows, I
   don't
   know how can I add a foreign key them also?
 
  I haven't tried it on really large tables, but
 does it turn out faster to
  use ALTER TABLE ADD CONSTRAINT to add the foreign
 key constraint after the
  data is loaded and the indexes are created?
 
 --
 Jie LIANG
 
 Internet Products Inc.
 
 10350 Science Center Drive
 Suite 100, San Diego, CA 92121
 Office:(858)320-4873
 
 [EMAIL PROTECTED]
 www.ipinc.com
 
 
 


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[SQL] Optimizing huge inserts/copy's

[Webb Sprague]

Hi all,

Does anybody have any thoughts on optimizing a huge
insert, involving something like 3 million records all
at once?  Should I drop my indices before doing the
copy, and then create them after?  I keep a
tab-delimited file as a buffer, copy it, then do it
again about 400 times.  Each separate buffer is a few
thousand records. 

We do this at night, so it's not the end of the world
if it takes 8 hours, but I would be very grateful for
some good ideas...

Thanks
W

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Re: [SQL] Create Primary Key + Massive Copy's?

[Webb Sprague]

This is my next approach--I got rid of all indexes and
PK's, and then created an index with unique after
everything is added.  Wish me luck.

W
--- Stephan Szabo [EMAIL PROTECTED]
wrote:
 
 We don't currently support the SQL syntax for adding
 a PK to a table.  However, if you have the columns
 as NOT NULL already, adding a unique index to the
 columns in question has the same general effect.
 
 Stephan Szabo
 [EMAIL PROTECTED]
 
 On Tue, 29 Aug 2000, Webb Sprague wrote:
 
  Apropos of my last question:
  
  Is there syntax to create a primary key after the
  table has been defined and populated?  I think I
 could
  speed things up quite a bit by not having any
 indexes
  at all when I do my mass copies.
 


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Re: [SQL] \copy...

[Webb Sprague]

Finally--a question I think I can answer!

You need to specify what delimiters you use in your
.dat file;  the default for COPY is tab, but you can
change that to | with

   copy tablename from '/home/ed/import.dat' 
   delimiters '|'

Hope this works...(oops--I mean 'helps')

--- Ed [EMAIL PROTECTED] wrote:
 Hi,
 
 I have a file that look like this :
 
 firstname|lastname|[EMAIL PROTECTED]
 firstname2|lastname2|[EMAIL PROTECTED]
 
 and a table foo like :
 
 firstname  varchar(30),
 lastname   varchar(30),
 emailvarchar(50)
 
 and I would like to do a :
 
 copy tablename from '/home/ed/import.dat';
 
 But then, everything goes in the first field... what
 does i'm doing
 wrong?!?!
 
 Frédéric Boucher
 [EMAIL PROTECTED]
 Programmation, Support technique
 Jetumele Communications inc.
 
 


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