On Mon, 2 Dec 2002, Henner Zeller wrote:
Hi,
Just compiled the 7.3 branch from source and made some tests using the
JDBC driver coming with it. I did some tests with the henplus
JDBC-shell and noticed some problems quering the database meta data:
o the foreign key name is 'wierd'
---
DatabaseMetaData meta = conn.getMetaData();
ResultSet rset = meta.getImportedKeys(null, null, 'bar');
rset.next();
String foreignKeyName=rset.getString(12);
---
results in names that seemingly contains the internal representation:
fk_foo_id\000bar\000foo\000UNSPECIFIED\000fooref\000id\000
(see below for an example)
In September, I proposed a patch to change this to the foreign key name.
This was rejected because = 7.2 servers don't enforce unique constraint
names per table, so it was decided to keep the above behavior to
guaranteee a unique name. I think this should be changed. See the
original discussion at...
http://archives.postgresql.org/pgsql-patches/2002-09/msg00150.php
o It takes _ages_ to retrieve the meta data. While doing a 'describe',
the postmaster process runs on 100% CPU. And: it takes extremly
different amounts of time. Executing the describe-command below, it
took (56.285 sec, 12.799 sec, 5 min 13.468, 12.203 sec) to execute
the same command. This look very like a missing or
random break-condition somewhere in a loop ?
The query to generate the ResultSet is a monster and has enough tables
involved to enable the genetic query optimizer which is neither consistent
nor particularly good. I was able to solve this using an ANALYZE, but the
long term solution is to state the desired join order explicitly in the
query using JOIN statements. I will submit a patch to this effect later
this week.
o this might be a minor point, but annoying as well: the columns are
not ordered in the sequence the're created in the table.
I have already submitted a patch to fix this because of a previous
complaint.
http://fts.postgresql.org/db/mw/msg.html?mid=1359758
If this cannot be reproduced, I'll try to track this down, but probably
this seems simple to you (BTW: doing this with the current 7.4development
CVS on my machine, this results in a segmentation fault on the postmaster
side - this indicates, that there indeed is a problem ..)
Will investigate as well.
===8==
pg create table foo (id int4 constraint pk_foo primary key);
pg create table bar ( id int4 constraint pk_bar primary key,
fooref int4 constraint fk_foo_id references foo(id)
);
pg describe bar
catalog: postgres
'-' : referencing
+-+--+-+++
column | type | null | default | pk | fk
|
+-+--+-+++
fooref | int4(4) | YES | [NULL] ||
fk_foo_id\000bar\000foo\000UNSPECIFIED\000fooref\000id\000 |
| | | || - foo(id)
|
id | int4(4) | NO | [NULL] | pk_bar |
|
+-+--+-+++
56.285 sec
===
ciao,
-hen
BTW:
henplus JDBC-Shell can be found
http://henplus.sourceforge.net/
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