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Amazon Redshift
Database Developer Guide (API Version 2012-12-01)

Examples of Catalog Queries

The following queries show a few of the ways in which you can query the catalog tables to get useful information about an Amazon Redshift database.

View Table ID, Database, Schema, and Table Name

The following view definition joins the STV_TBL_PERM system table with the PG_CLASS, PG_NAMESPACE, and PG_DATABASE system catalog tables to return the table ID, database name, schema name, and table name.

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create view tables_vw as select distinct(id) table_id ,trim(datname) db_name ,trim(nspname) schema_name ,trim(relname) table_name from stv_tbl_perm join pg_class on pg_class.oid = stv_tbl_perm.id join pg_namespace on pg_namespace.oid = relnamespace join pg_database on pg_database.oid = stv_tbl_perm.db_id;

The following example returns the information for table ID 117855.

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select * from tables_vw where table_id = 117855;
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table_id | db_name | schema_name | table_name ---------+-----------+-------------+----------- 117855 | dev | public | customer

List the Number of Columns per Amazon Redshift Table

The following query joins some catalog tables to find out how many columns each Amazon Redshift table contains. Amazon Redshift table names are stored in both PG_TABLES and STV_TBL_PERM; where possible, use PG_TABLES to return Amazon Redshift table names.

This query does not involve any Amazon Redshift tables.

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select nspname, relname, max(attnum) as num_cols from pg_attribute a, pg_namespace n, pg_class c where n.oid = c.relnamespace and a.attrelid = c.oid and c.relname not like '%pkey' and n.nspname not like 'pg%' and n.nspname not like 'information%' group by 1, 2 order by 1, 2; nspname | relname | num_cols --------+----------+---------- public | category | 4 public | date | 8 public | event | 6 public | listing | 8 public | sales | 10 public | users | 18 public | venue | 5 (7 rows)

List the Schemas and Tables in a Database

The following query joins STV_TBL_PERM to some PG tables to return a list of tables in the TICKIT database and their schema names (NSPNAME column). The query also returns the total number of rows in each table. (This query is helpful when multiple schemas in your system have the same table names.)

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select datname, nspname, relname, sum(rows) as rows from pg_class, pg_namespace, pg_database, stv_tbl_perm where pg_namespace.oid = relnamespace and pg_class.oid = stv_tbl_perm.id and pg_database.oid = stv_tbl_perm.db_id and datname ='tickit' group by datname, nspname, relname order by datname, nspname, relname; datname | nspname | relname | rows --------+---------+----------+-------- tickit | public | category | 11 tickit | public | date | 365 tickit | public | event | 8798 tickit | public | listing | 192497 tickit | public | sales | 172456 tickit | public | users | 49990 tickit | public | venue | 202 (7 rows)

List Table IDs, Data Types, Column Names, and Table Names

The following query lists some information about each user table and its columns: the table ID, the table name, its column names, and the data type of each column:

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select distinct attrelid, rtrim(name), attname, typname from pg_attribute a, pg_type t, stv_tbl_perm p where t.oid=a.atttypid and a.attrelid=p.id and a.attrelid between 100100 and 110000 and typname not in('oid','xid','tid','cid') order by a.attrelid asc, typname, attname; attrelid | rtrim | attname | typname ---------+----------+----------------+----------- 100133 | users | likebroadway | bool 100133 | users | likeclassical | bool 100133 | users | likeconcerts | bool ... 100137 | venue | venuestate | bpchar 100137 | venue | venueid | int2 100137 | venue | venueseats | int4 100137 | venue | venuecity | varchar ...

Count the Number of Data Blocks for Each Column in a Table

The following query joins the STV_BLOCKLIST table to PG_CLASS to return storage information for the columns in the SALES table.

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select col, count(*) from stv_blocklist s, pg_class p where s.tbl=p.oid and relname='sales' group by col order by col; col | count ----+------- 0 | 4 1 | 4 2 | 4 3 | 4 4 | 4 5 | 4 6 | 4 7 | 4 8 | 4 9 | 8 10 | 4 12 | 4 13 | 8 (13 rows)