Is it good to have toast table for information schema table?

On 04/22/2014 04:58 PM, AI Rumman wrote:

Hi,

Is it good to have toast table for information schema table? I am using
Postgresql 8.4 and current state is:

*select datname, datfrozenxid from pg_database; *
datname | datfrozenxid
-----------+--------------
template1 | 1462730397
template0 | 1462741467
postgres | 1562754912
jangles | 1459615432
(4 rows)
*
*
*
*
*select * from pg_class where relfrozenxid = 1459615432;*
relname | reltoastidxid | relhasindex | relfrozenxid
----------------+---------------+-------------+--------------
pg_toast_11447 | 11451 | t | 1459615432
(1 row)
*
*
*
*
*select 11447::regclass; *
regclass
---------------------------------
information_schema.sql_features
(1 row)

Please advice.

A TOAST table is used whenever the actual table has variable length
fields that meet certain criteria:

http://www.postgresql.org/docs/9.3/static/storage-toast.html

information_schema.sql_features schema is:

test=# \d information_schema.sql_features
Table "information_schema.sql_features"
Column | Type | Modifiers
------------------+-----------------------------------+-----------
feature_id | information_schema.character_data |
feature_name | information_schema.character_data |
sub_feature_id | information_schema.character_data |
sub_feature_name | information_schema.character_data |
is_supported | information_schema.yes_or_no |
is_verified_by | information_schema.character_data |
comments | information_schema.character_data |

From here you see character_data is not fixed length:

http://www.postgresql.org/docs/9.3/static/infoschema-datatypes.html

so a TOAST table is not out of order.

I see it on my database also.

Thanks.

--
Adrian Klaver
adrian.klaver@aklaver.com

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