Commit Graph

5 Commits

Author SHA1 Message Date
Tom Lane
1f1c332381 Remove inappropriate double-quoting in connectby() code; adjust
regression test to avoid using VALUE as a name.  From Joe Conway.
2002-11-23 01:54:09 +00:00
Bruce Momjian
620dddf88a > The previous patch fixed an infinite recursion bug in
> contrib/tablefunc/tablefunc.c:connectby. But, other unmanageable error
> seems to occur even if a table has commonplace tree data(see below).
>
> I would think the patch, ancestor check, should be
>
>   if (strstr(branch_delim || branchstr->data || branch_delim,
>                        branch_delim || current_key || branch_delim))
>
> This is my image, not a real code. However, if branchstr->data includes
> branch_delim, my image will not be perfect.

Good point. Thank you Masaru for the suggested fix.

Attached is a patch to fix the bug found by Masaru. His example now
produces:

regression=# SELECT * FROM connectby('connectby_tree', 'keyid',
'parent_keyid', '11', 0, '-') AS t(keyid int, parent_keyid int, level
int,
branch text);
  keyid | parent_keyid | level |  branch

-------+--------------+-------+----------
     11 |              |     0 | 11
     10 |           11 |     1 | 11-10
    111 |           11 |     1 | 11-111
      1 |          111 |     2 | 11-111-1
(4 rows)

While making the patch I also realized that the "no show branch" form of
the  function was not going to work very well for recursion detection.
Therefore  there is now a default branch delimiter ('~') that is used
internally, for  that case, to enable recursion detection to work. If
you need a different  delimiter for your specific data, you will have to
use the "show branch" form  of the function.

Joe Conway
2002-10-03 17:11:12 +00:00
Bruce Momjian
6aa4482f2f Attached is an update to contrib/tablefunc. It introduces a new
function, connectby(), which can serve as a reference implementation for

the changes made in the last few days -- namely the ability of a
function to return an entire tuplestore, and the ability of a function
to make use of the query provided "expected" tuple description.

Description:

   connectby(text relname, text keyid_fld, text parent_keyid_fld,
     text start_with, int max_depth [, text branch_delim])
   - returns keyid, parent_keyid, level, and an optional branch string
   - requires anonymous composite type syntax in the FROM clause. See
     the instructions in the documentation below.

Joe Conway
2002-09-02 05:44:05 +00:00
Bruce Momjian
45e2544584 As discussed on several occasions previously, the new anonymous
composite type capability makes it possible to create a system view
based on a table function in a way that is hopefully palatable to
everyone. The attached patch takes advantage of this, moving
show_all_settings() from contrib/tablefunc into the backend (renamed
all_settings(). It is defined as a builtin returning type RECORD. During
initdb a system view is created to expose the same information presently
available through SHOW ALL. For example:

test=# select * from pg_settings where name like '%debug%';
          name          | setting
-----------------------+---------
  debug_assertions      | on
  debug_pretty_print    | off
  debug_print_parse     | off
  debug_print_plan      | off
  debug_print_query     | off
  debug_print_rewritten | off
  wal_debug             | 0
(7 rows)


Additionally during initdb two rules are created which make it possible
to change settings by updating the system view -- a "virtual table" as
Tom put it. Here's an example:

Joe Conway
2002-08-15 02:51:27 +00:00
Bruce Momjian
41f862ba87 As mentioned above, here is my contrib/tablefunc patch. It includes
three functions which exercise the tablefunc API.

show_all_settings()
   - returns the same information as SHOW ALL, but as a query result

normal_rand(int numvals, float8 mean, float8 stddev, int seed)
   - returns a set of normally distributed float8 values
   - This routine implements Algorithm P (Polar method for normal
     deviates) from Knuth's _The_Art_of_Computer_Programming_, Volume 2,
     3rd ed., pages 122-126. Knuth cites his source as "The polar
     method", G. E. P. Box, M. E. Muller, and G. Marsaglia,
     _Annals_Math,_Stat._ 29 (1958), 610-611.

crosstabN(text sql)
   - returns a set of row_name plus N category value columns
   - crosstab2(), crosstab3(), and crosstab4() are defined for you,
     but you can create additional crosstab functions per directions
     in the README.

Joe Conway
2002-07-30 16:31:11 +00:00