Hello
2011/11/22 J.V.<jvsrvcs@xxxxxxxxx>:
I cannot find a way to programatically:
1. Given a table name, find all foreign key fields in the given table by
field name (column name)
2. Given a single foreign key field name, programatically look up the
corresponding reference table name and the reference primary key field
so have thought of simply hard coding this (for 100 tables).
What Kind of data structure could I use that is available to me that would
hold as the key the table name and from there be able to iterate through and
get all foreign keys by field name and from there another inner loop that
would give me another key/value pair of the table name (key) and the primary
key (value) that corresponds to that foreign key?
I want to hard code all of this information into a data structure and
iterate through at some point in another function.
Instead of discovering this programatically, I can manually look at each
table / schema diagram and hard code it, but I really need one super
structure that will hold as keys every table in the schema and be able to
drill down that that tables foreign keys and from there further drill down
to get the table name, primary key field in that table.
I have seen a number of structures that might work, but cannot find an
example on how to actually use for what I need to do. If you do have an
idea of a structure, it would be great and awesome if I could be pointed to
an actual working example that I could test in a sandbox first to understand
how it works.
psql has a nice featute, that can help with orientation in system catalog
if I need a query, that describe a some database object, I need to
know a adequate psql meta statement. You have to run psql with -E
param, and then psql shows a queries that was necessary for processing
a statement
[pavel@nemesis ~]$ psql -E postgres
psql (9.2devel)
Type "help" for help.
postgres=# \d a1
********* QUERY **********
SELECT c.oid,
n.nspname,
c.relname
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relname ~ '^(a1)$'
AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 2, 3;
**************************
********* QUERY **********
SELECT c.relchecks, c.relkind, c.relhasindex, c.relhasrules,
c.relhastriggers, c.relhasoids, '', c.reltablespace, CASE WHEN
c.reloftype = 0 THEN '' ELSE
c.reloftype::pg_catalog.regtype::pg_catalog.text END, c.relpersistence
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_class tc ON (c.reltoastrelid = tc.oid)
WHERE c.oid = '146989';
**************************
********* QUERY **********
SELECT a.attname,
pg_catalog.format_type(a.atttypid, a.atttypmod),
(SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)
FROM pg_catalog.pg_attrdef d
WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef),
a.attnotnull, a.attnum,
(SELECT c.collname FROM pg_catalog.pg_collation c, pg_catalog.pg_type t
WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND
a.attcollation<> t.typcollation) AS attcollation,
NULL AS indexdef,
NULL AS attfdwoptions
FROM pg_catalog.pg_attribute a
WHERE a.attrelid = '146989' AND a.attnum> 0 AND NOT a.attisdropped
ORDER BY a.attnum;
**************************
********* QUERY **********
SELECT c2.relname, i.indisprimary, i.indisunique, i.indisclustered,
i.indisvalid, pg_catalog.pg_get_indexdef(i.indexrelid, 0, true),
pg_catalog.pg_get_constraintdef(con.oid, true), contype,
condeferrable, condeferred, c2.reltablespace
FROM pg_catalog.pg_class c, pg_catalog.pg_class c2, pg_catalog.pg_index i
LEFT JOIN pg_catalog.pg_constraint con ON (conrelid = i.indrelid AND
conindid = i.indexrelid AND contype IN ('p','u','x'))
WHERE c.oid = '146989' AND c.oid = i.indrelid AND i.indexrelid = c2.oid
ORDER BY i.indisprimary DESC, i.indisunique DESC, c2.relname;
**************************
********* QUERY **********
SELECT conname,
pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '146989' AND r.contype = 'f' ORDER BY 1;
**************************
********* QUERY **********
SELECT conname, conrelid::pg_catalog.regclass,
pg_catalog.pg_get_constraintdef(c.oid, true) as condef
FROM pg_catalog.pg_constraint c
WHERE c.confrelid = '146989' AND c.contype = 'f' ORDER BY 1;
**************************
********* QUERY **********
SELECT t.tgname, pg_catalog.pg_get_triggerdef(t.oid, true), t.tgenabled
FROM pg_catalog.pg_trigger t
WHERE t.tgrelid = '146989' AND NOT t.tgisinternal
ORDER BY 1;
**************************
********* QUERY **********
SELECT c.oid::pg_catalog.regclass FROM pg_catalog.pg_class c,
pg_catalog.pg_inherits i WHERE c.oid=i.inhparent AND i.inhrelid =
'146989' ORDER BY inhseqno;
**************************
********* QUERY **********
SELECT c.oid::pg_catalog.regclass FROM pg_catalog.pg_class c,
pg_catalog.pg_inherits i WHERE c.oid=i.inhrelid AND i.inhparent =
'146989' ORDER BY c.oid::pg_catalog.regclass::pg_catalog.text;
**************************
Table "public.a1"
Column │ Type │ Modifiers
────────┼─────────┼───────────
id │ integer │ not null
v │ integer │
Indexes:
"a1_pkey" PRIMARY KEY, btree (id)
Referenced by:
TABLE "a2" CONSTRAINT "a2_id_fkey" FOREIGN KEY (id) REFERENCES a1(id)
postgres=# \d a2
********* QUERY **********
SELECT c.oid,
n.nspname,
c.relname
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relname ~ '^(a2)$'
AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 2, 3;
**************************
********* QUERY **********
SELECT c.relchecks, c.relkind, c.relhasindex, c.relhasrules,
c.relhastriggers, c.relhasoids, '', c.reltablespace, CASE WHEN
c.reloftype = 0 THEN '' ELSE
c.reloftype::pg_catalog.regtype::pg_catalog.text END, c.relpersistence
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_class tc ON (c.reltoastrelid = tc.oid)
WHERE c.oid = '146994';
**************************
********* QUERY **********
SELECT a.attname,
pg_catalog.format_type(a.atttypid, a.atttypmod),
(SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)
FROM pg_catalog.pg_attrdef d
WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef),
a.attnotnull, a.attnum,
(SELECT c.collname FROM pg_catalog.pg_collation c, pg_catalog.pg_type t
WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND
a.attcollation<> t.typcollation) AS attcollation,
NULL AS indexdef,
NULL AS attfdwoptions
FROM pg_catalog.pg_attribute a
WHERE a.attrelid = '146994' AND a.attnum> 0 AND NOT a.attisdropped
ORDER BY a.attnum;
**************************
********* QUERY **********
SELECT conname,
pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '146994' AND r.contype = 'f' ORDER BY 1;
**************************
********* QUERY **********
SELECT conname, conrelid::pg_catalog.regclass,
pg_catalog.pg_get_constraintdef(c.oid, true) as condef
FROM pg_catalog.pg_constraint c
WHERE c.confrelid = '146994' AND c.contype = 'f' ORDER BY 1;
**************************
********* QUERY **********
SELECT t.tgname, pg_catalog.pg_get_triggerdef(t.oid, true), t.tgenabled
FROM pg_catalog.pg_trigger t
WHERE t.tgrelid = '146994' AND NOT t.tgisinternal
ORDER BY 1;
**************************
********* QUERY **********
SELECT c.oid::pg_catalog.regclass FROM pg_catalog.pg_class c,
pg_catalog.pg_inherits i WHERE c.oid=i.inhparent AND i.inhrelid =
'146994' ORDER BY inhseqno;
**************************
********* QUERY **********
SELECT c.oid::pg_catalog.regclass FROM pg_catalog.pg_class c,
pg_catalog.pg_inherits i WHERE c.oid=i.inhrelid AND i.inhparent =
'146994' ORDER BY c.oid::pg_catalog.regclass::pg_catalog.text;
**************************
Table "public.a2"
Column │ Type │ Modifiers
────────┼─────────┼───────────
id │ integer │
v │ integer │
Foreign-key constraints:
"a2_id_fkey" FOREIGN KEY (id) REFERENCES a1(id)
Regards
Pavel Stehule
thanks
J.V.
--
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
