PostgreSQL limitations question

[Bartosz Dmytrak <bdmytrak@xxxxxxxxx>]

Hi All

I found PG limitations (http://www.postgresql.org/about/):

• Maximum Rows per Table - Unlimited
• Maximum Table Size - 32 TB

My question is:

how is it possible to *reach* unlimited rows in table?

I did a test:

1. Create Table:

CREATE TABLE test.limits("RowValue" text) WITH (OIDS=FALSE, FILLFACTOR=100);

2. Fill table (I used pgScript available in pgAdmin);

DECLARE @I;

SET @I = 0;

WHILE @I < 1000

BEGIN

        INSERT INTO test.limits ("RowValue") VALUES (NULL);

SET @I = @I + 1;

END

3. do Vacuum full to be sure free space is removed

VACUUM FULL test.limits;

4. I checked table size:

SELECT * FROM pg_size_pretty(pg_relation_size('test.limits'::regclass));

and I realized table size is 32 kB.

I used pgstattupet extension (http://www.postgresql.org/docs/9.1/static/pgstattuple.html) to check what is going on:

SELECT * FROM pgstattuple('test.limits');

and I got:

table_len	tuple_count	tuple_len	tuple_percent	dead_tuple_count	dead_tuple_len	dead_tuple_percent	free_space	free_percent
32768	1000	24000	73.24	0	0	0	4608	14.06

Did I missed something?

Is there a non storage cost data type?

I know that "storage requirement for a short string (up to 126 bytes) is 1 byte plus the actual string" (http://www.postgresql.org/docs/9.1/static/datatype-character.html).

Regards,

Bartek