On 08/15/13 17:27, Adrian Klaver napisa:
On 08/15/2013 08:07 AM, Ivan Radovanovic wrote:
On 08/15/13 16:59, Adrian Klaver napisa:
On 08/15/2013 07:53 AM, Ivan Radovanovic wrote:
Now I just need to find out which types can be indexed (and which
types
can be part of PK)
http://www.postgresql.org/docs/9.2/interactive/indexes.html
doesn't list which types can be indexed and which can't?
Postgres can handle a variety of indexes including indexing on
expressions, which is why I pointed you to that link.
To cut to the chase, in the above link at:
http://www.postgresql.org/docs/9.2/interactive/indexes-opclass.html
there is this:
SELECT am.amname AS index_method,
opf.opfname AS opfamily_name,
amop.amopopr::regoperator AS opfamily_operator
FROM pg_am am, pg_opfamily opf, pg_amop amop
WHERE opf.opfmethod = am.oid AND
amop.amopfamily = opf.oid
ORDER BY index_method, opfamily_name, opfamily_operator;
Thanks Adrian, but question was how to decide which types are indexable
- query which you sent returns list of operators defined for some types
- for example it returns operators for bytea too, and you can't index by
bytea,
Actually you can:
CREATE TABLE bytea_test(id int, fld_1 bytea);
test=# \d bytea_test
Table "public.bytea_test"
Column | Type | Modifiers
--------+---------+-----------
id | integer |
fld_1 | bytea |
test=# CREATE INDEX i ON bytea_test (fld_1);
test=# \d bytea_test
Table "public.bytea_test"
Column | Type | Modifiers
--------+---------+-----------
id | integer |
fld_1 | bytea |
Indexes:
"i" btree (fld_1)
Didn't know that - I just tried on one existing table and it failed on
account of index row too short
ERROR: index row requires 14616 bytes, maximum size is 8191
SQL state: 54000
Although it looked suspicious like it could be solved by defining custom
tablespace (never did that on Postgres so I am not sure if it would
work), I assumed that it is because bytea can't be indexed.
Obviously I learned one more new thing today :-)
Thanks,
Ivan
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