First, the database cluster information
1、gp_segment_configration
2、pg_filespace_entry
These two tables are in pg_global table space below, it is a global table.
Cluster segment to view information such as the number of segment.
Second, common data dictionary table
1、pg_class
Save all the tables, views, sequences, indexes the metadata information for each DDL / DML operations have a relationship with this table.
2、pg_attribute
Content record fields
3、gp_distribution_policy
Distribution of key records table
4, pg_statistic and pg_stats
Statistical information is stored in the database table in pg_statistic
pg_stats can easily help us to view the contents of pg_statistic
5、pg_partition
Record partition table information
6、pg_partition_rule
Partition Table partitioning rules
7、pg_partitions
Third, the application dictionary tables
1, to obtain field information
select a.attname,pg_catalog.format_type(a.atttypid,a.atttypmod) as data_type
from pg_catalog.pg_attribute a,
(
select c.oid
from pg_catalog.pg_class c
left join pg_catalog.pg_namespace n
on n.oid = c.relnamespace
where c.relname = 'pg_class'
and n.nspname='pg_catalog'
) b
where a.attrelid=b.oid
and a.attnum>0
and not a.attisdropped order by a.attnum;