maximal length of varchar

prova=> create table a1(a varchar(99999));
ERROR: length for type 'varchar' cannot exceed 8064
prova=> create table a1(a varchar(8064));
CREATE
prova=> drop table a1;
DROP
prova=> create table a1(a varchar(8064),b varchar(8064));
CREATE
prova=> \d a1
Table = a1
+----------------------------------+----------------------------------+-------+

| Field | Type |
Length|
+----------------------------------+----------------------------------+-------+

| a | varchar() |
8064 |
| b | varchar() |
8064 |
+----------------------------------+----------------------------------+-------+

prova=>

guenther mair ha scritto:

i'm interested in knowing how the varchar type is
limited. since there are no references to this it
seems to me, as if there was no postgres-internal
limit.

is this limit posed just by the os/filesystem/memory?

thanks in advance,

guenther mair

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PostgreSQL 6.5.0 on i586-pc-linux-gnu, compiled by gcc 2.7.2.3
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jose'

prova=> create table a1(a varchar(99999));
ERROR: length for type 'varchar' cannot exceed 8064
prova=> create table a1(a varchar(8064));
CREATE

thanks, for this quick answer!

i did the test by myself and found out, that on the my system (freebsd
3.2) where i do actualy my tests, varchar is limited to 4096. this creates
the problem of plattfrom dependence.

what length has the text field?
-> i tried a insert-command with some 10000 signs for one text-field
-> i got a "PQsendQuery() -- query is too long. Maximum length is 8191"

hmpf. so maximum length may not exceed 8191 signs in any case. this causes
textfields to be reduced to a variable length, which depends on the amount
of your table-fields; just think of these two cases:

a table with 50 fields and a realy big textfield

a table with 2 fields where one is a realy big textfield

in the first case the textfield has to be smaller, since i can't exceed
the maximum query length of 8191 signs.....

now what? :)

thanks,

guenther

prova=> create table a1(a varchar(99999));
ERROR: length for type 'varchar' cannot exceed 8064
prova=> create table a1(a varchar(8064));
CREATE

thanks, for this quick answer!

i did the test by myself and found out, that on the my system (freebsd
3.2) where i do actualy my tests, varchar is limited to 4096. this creates
the problem of plattfrom dependence.

I changed This in 6.5 to something near 8k. It may be too large because
I am not sure how a row is going to be updated inside the page. Not
sure if this is an issue.

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