Gbase 8C system table information function (II)

1. pg_get_expr(pg_node_tree, relation_oid)

describe ： Decompile the internal form of the expression , Suppose any of them Vars Both reference the relationship specified by the second parameter .

Return type ：text

1. pg_get_expr(pg_node_tree, relation_oid, pretty_bool)

describe ： Decompile the internal form of the expression , Suppose any of them Vars Both reference the relationship specified by the second parameter .

Return type ：text

remarks ：pg_get_expr Decompile the internal form of an independent expression , For example, the default value of a field . It is very useful when checking the contents of the system table . If the expression may contain keywords , Then specify that they quote the relevant OID As the second parameter ; If there are no keywords , Zero is enough .

1. pg_get_functiondef(func_oid)

describe ： Get the definition of the function .

Return type ：text

Example ：

 gbase=# select * from pg_get_functiondef(598);

headerlines |                     definition

-------------+----------------------------------------------------

           4 | CREATE OR REPLACE FUNCTION pg_catalog.abbrev(inet)+

             |  RETURNS text                                     +

             |  LANGUAGE internal                                +

             |  IMMUTABLE STRICT NOT FENCED NOT SHIPPABLE        +

             | AS $function$inet_abbrev$function$;               +

             |

(1 row)

1. pg_get_function_arguments(func_oid)

describe ： Get the parameter list of the function definition （ With default ）.

Return type ：text

remarks ：pg_get_function_arguments Return the parameter list of a function , Need to be in CREATE FUNCTION This format is used in .

1. pg_get_function_identity_arguments(func_oid)

describe ： Get the parameter list to determine a function （ Without default ）.

Return type ：text

remarks ：pg_get_function_identity_arguments Return the required parameter list to identify the function , This form needs to be in ALTER FUNCTION Use in , And this form omits the default value .