Enhanced SQL and Other Miscellaneous Features v11
Advanced Server includes enhanced SQL functionality and various other features that provide additional flexibility and convenience. This chapter discusses some of these additions.
COMMENT
In addition to commenting on objects supported by the PostgreSQL COMMENT command, Advanced Server supports comments on additional object types. The complete supported syntax is:
COMMENT ON
{
AGGREGATE <aggregate_name> ( <aggregate_signature> ) |
CAST (<source_type> AS <target_type>) |
COLLATION <object_name> |
COLUMN <relation_name>.<column_name> |
CONSTRAINT <constraint_name> ON <table_name> |
CONSTRAINT <constraint_name> ON DOMAIN <domain_name> |
CONVERSION <object_name> |
DATABASE <object_name> |
DOMAIN <object_name> |
EXTENSION <object_name> |
EVENT TRIGGER <object_name> |
FOREIGN DATA WRAPPER <object_name> |
FOREIGN TABLE <object_name> |
FUNCTION <func_name> ([[<argmode>] [<argname>] <argtype> [,...]])|
INDEX <object_name> |
LARGE OBJECT <large_object_oid> |
MATERIALIZED VIEW <object_name> |
OPERATOR <operator_name> (left_type, right_type) |
OPERATOR CLASS <object_name> USING <index_method> |
OPERATOR FAMILY <object_name> USING <index_method> |
PACKAGE <object_name>
POLICY <policy_name> ON <table_name> |
[ PROCEDURAL ] LANGUAGE <object_name> |
PROCEDURE <proc_name> [([[<argmode>] [<argname>] <argtype> [, ...]])]
PUBLIC SYNONYM <object_name>
ROLE <object_name> |
RULE <rule_name> ON <table_name> |
SCHEMA <object_name> |
SEQUENCE <object_name> |
SERVER <object_name> |
TABLE <object_name> |
TABLESPACE <object_name> |
TEXT SEARCH CONFIGURATION <object_name> |
TEXT SEARCH DICTIONARY <object_name> |
TEXT SEARCH PARSER <object_name> |
TEXT SEARCH TEMPLATE <object_name> |
TRANSFORM FOR <type_name> LANGUAGE <lang_name> |
TRIGGER <trigger_name> ON <table_name> |
TYPE <object_name> |
VIEW <object_name>
} IS <'text'>where aggregate_signature is:
* | [ <argmode> ] [ <argname> ] <argtype> [ , ... ] | [ [ <argmode> ] [ <argname> ] <argtype> [ , ... ] ] ORDER BY [ <argmode> ] [ <argname> ] <argtype> [ , ... ]
Parameters
object_name
The name of the object on which you are commenting.
AGGREGATE aggregate_name (aggregate_signature)
Include the AGGREGATE clause to create a comment about an aggregate. aggregate_name specifies the name of an aggregate, and aggregate_signature specifies the associated signature in one of the following forms:
* | [ <argmode> ] [ <argname> ] <argtype> [ , ... ] | [ [ <argmode> ] [ <argname> ] <argtype> [ , ... ] ] ORDER BY [ <argmode> ] [ <argname> ] <argtype> [ , ... ]
Where argmode is the mode of a function, procedure, or aggregate argument, argmode may be IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN.
argname is the name of an aggregate argument.
argtype is the data type of an aggregate argument.
CAST (source_type AS target_type)
Include the CAST clause to create a comment about a cast. When creating a comment about a cast, source_type specifies the source data type of the cast, and target_type specifies the target data type of the cast.
COLUMN relation_name.column_name
Include the COLUMN clause to create a comment about a column. column_name specifies name of the column to which the comment applies. relation_name is the table, view, composite type, or foreign table in which a column resides.
CONSTRAINT constraint_name ON table_name
CONSTRAINT constraint_name ON DOMAIN domain_name
Include the CONSTRAINT clause to add a comment about a constraint. When creating a comment about a constraint, constraint_name specifies the name of the constraint. table_name or domain_name specifies the name of the table or domain on which the constraint is defined.
FUNCTION func_name ([[argmode] [argname] argtype [, ...]])
Include the FUNCTION clause to add a comment about a function. func_name specifies the name of the function. argmode specifies the mode of the function. argmode may be IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN.
argname specifies the name of a function, procedure, or aggregate argument. argtype specifies the data type of a function, procedure, or aggregate argument.
large_object_oid
large_object_oid is the system-assigned OID of the large object about which you are commenting.
OPERATOR operator_name (left_type, right_type)
Include the OPERATOR clause to add a comment about an operator. operator_name specifies the (optionally schema-qualified) name of an operator on which you are commenting. left_type and right_type are the (optionally schema-qualified) data type(s) of the operator's arguments.
OPERATOR CLASS object_name USING index_method
Include the OPERATOR CLASS clause to add a comment about an operator class. object_name specifies the (optionally schema-qualified) name of an operator on which you are commenting. index_method specifies the associated index method of the operator class.
OPERATOR FAMILY object_name USING index_method
Include the OPERATOR FAMILY clause to add a comment about an operator family. object_name specifies the (optionally schema-qualified) name of an operator family on which you are commenting. index_method specifies the associated index method of the operator family.
POLICY policy_name ON table_name
Include the POLICY clause to add a comment about a policy. policy_name specifies the name of the policy, and table_name specifies the table that the policy is associated with.
PROCEDURE proc_name [([[argmode] [argname] argtype [, ...]])]
Include the PROCEDURE clause to add a comment about a procedure. proc_name specifies the name of the procedure. argmode specifies the mode of the procedure. argmode may be IN, OUT, INOUT, or VARIADIC. If omitted, the default is IN.
argname specifies the name of a function, procedure, or aggregate argument. argtype specifies the data type of a function, procedure, or aggregate argument.
RULE rule_name ON table_name
Include the RULE clause to specify a COMMENT on a rule. rule_name specifies the name of the rule, and table_name specifies the name of the table on which the rule is defined.
TRANSFORM FOR type_name LANGUAGE lang_name
Include the TRANSFORM FOR clause to specify a COMMENT on a TRANSFORM.
type_name specifies the name of the data type of the transform and lang_name specifies the name of the language of the transform.
TRIGGER trigger_name ON table_name
Include the TRIGGER clause to specify a COMMENT on a trigger. trigger_name specifies the name of the trigger, and table_name specifies the name of the table on which the trigger is defined.
text
The comment, written as a string literal or NULL to drop the comment.
Notes:
Names of tables, aggregates, collations, conversions, domains, foreign tables, functions, indexes, operators, operator classes, operator families, packages, procedures, sequences, text search objects, types, and views can be schema-qualified.
Example:
The following example adds a comment to a table named new_emp:
COMMENT ON TABLE new_emp IS 'This table contains information about new employees.';
For more information about using the COMMENT command, see the PostgreSQL core documentation at:
https://www.postgresql.org/docs/11/static/sql-comment.html
Output of Function version()
The text string output of the version() function displays the name of the product, its version, and the host system on which it has been installed.
For Advanced Server, the version() output is in a format similar to the PostgreSQL community version in that the first text word is PostgreSQL instead of EnterpriseDB as in Advanced Server version 10 and earlier.
The general format of the version() output is the following:
PostgreSQL $PG_VERSION_EXT (EnterpriseDB Advanced Server $PG_VERSION) on $host
So for the current Advanced Server the version string appears as follows:
edb@45032=#select version(); version ------------------------------------------------------------------------------------------------ ----------------------------------------------- PostgreSQL 11.0 (EnterpriseDB Advanced Server 11.0.0) on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11), 64-bit (1 row)
In contrast, for Advanced Server 10, the version string was the following:
edb=# select version();
version
--------------------------------------------------------------------------------------------
-----------------
EnterpriseDB 10.4.9 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.4.7 20120313 (Red Hat
4.4.7-18), 64-bit
(1 row)SQL Server dbo schema
Prior to Advanced Server 11, a system catalog named dbo was available. The dbo system catalog contained views of database objects for similarity with Microsoft SQL Server.
Now, for Advanced Server neither the dbo system catalog nor a schema named dbo exist in any database.
If it is desired to have such a schema with its SQL Server compatible views, use the CREATE EXTENSION edb_dbo command to create the dbo schema and its content.
The following example shows the creation of the dbo schema and its views:
edb=# CREATE EXTENSION edb_dbo;
CREATE EXTENSION
edb=# \dn
List of Schemas
Name | Owner
-------+--------------
dbo | enterprisedb
public | enterprisedb
edb=# SET search_path TO dbo;
SET
edb=# \dv
List of relations
Schema | Name | Type | Owner
---------+-------------+------+-------------
dbo | sysinedexes | view | enterprisedb
dbo | sysobjects | view | enterprisedb
dbo | systables | view | enterprisedb
dbo | systypes | view | enterprisedb
dbo | sysusers | view | enterprisedb
(5 rows)