diff options
Diffstat (limited to 'src/bin/pgaccess/lib/help/create_language.hlp')
-rw-r--r-- | src/bin/pgaccess/lib/help/create_language.hlp | 130 |
1 files changed, 0 insertions, 130 deletions
diff --git a/src/bin/pgaccess/lib/help/create_language.hlp b/src/bin/pgaccess/lib/help/create_language.hlp deleted file mode 100644 index e68fe6f190e..00000000000 --- a/src/bin/pgaccess/lib/help/create_language.hlp +++ /dev/null @@ -1,130 +0,0 @@ -.pgaw:Help.f.t insert end "CREATE LANGUAGE" {bold} ". Using CREATE LANGUAGE, a Postgres user can register a new language with Postgres. Subsequently, functions and trigger procedures can be defined in this new language. The user must \ -have the Postgres superuser privilege to register a new language. - -Writing PL handlers - - The call handler for a procedural language must be written in a compiler language such as 'C' and registered with Postgres as a function taking no arguments and returning the opaque type, a \ -placeholder for unspecified or undefined types.. This prevents the call handler from being called directly as a function from queries. -However, arguments must be supplied on the actual call when a PL function or trigger procedure in the language offered by the handler is to be executed. \ - When called from the trigger manager, the only argument is the object ID from the procedure's pg_proc entry. All other information from the trigger manager is found in the global \ - CurrentTriggerData pointer. - When called from the function manager, the arguments are the object ID of the procedure's pg_proc entry, the number of arguments given to the PL function, the arguments in a \ - FmgrValues structure and a pointer to a boolean where the function tells the caller if the return value is the SQL NULL value. - - It's up to the call handler to fetch the pg_proc entry and to analyze the argument and return types of the called procedure. The AS clause from the CREATE FUNCTION of the procedure will \ -be found in the prosrc attribute of the pg_proc table entry. This may be the source text in the procedural language itself (like for PL/Tcl), a pathname to a file or anything else that tells the call \ -handler what to do in detail. - -" {} "Synopsis" {bold} " - -CREATE \[ TRUSTED \] PROCEDURAL LANGUAGE 'langname' - HANDLER call_handler - LANCOMPILER 'comment' - -" {code} "Inputs" {bold} " - -" {} "TRUSTED" {italic} " - TRUSTED specifies that the call handler for the language is safe; that is, it offers an unprivileged user no functionality to bypass access restrictions. If this keyword is omitted when - registering the language, only users with the Postgres superuser privilege can use this language to create new functions (like the 'C' language). - -" {} "langname" {italic} " - The name of the new procedural language. The language name is case insensitive. A procedural language cannot override one of the built-in languages of Postgres. - -" {} "HANDLER call_handler" {italic} " - call_handler is the name of a previously registered function that will be called to execute the PL procedures. - -" {} "comment" {italic} " - The LANCOMPILER argument is the string that will be inserted in the LANCOMPILER attribute of the new pg_language entry. At present, Postgres does not use this attribute in any way. - -" {} "Outputs" {bold} " - -" {} "CREATE" {italic} " - This message is returned if the language is successfully created. - -" {} "ERROR: PL handler function funcname\(\) doesn't exist" {italic} " - This error is returned if the function funcname() is not found. - -" {} "Usage" {bold} " - -This is a template for a PL handler written in 'C': -" {} " - #include \"executor/spi.h\" - #include \"commands/trigger.h\" - #include \"utils/elog.h\" - #include \"fmgr.h\" /* for FmgrValues struct */ - #include \"access/heapam.h\" - #include \"utils/syscache.h\" - #include \"catalog/pg_proc.h\" - #include \"catalog/pg_type.h\" - - Datum - plsample_call_handler\( - Oid prooid, - int pronargs, - FmgrValues *proargs, - bool *isNull\) - \{ - Datum retval; - TriggerData *trigdata; - - if \(CurrentTriggerData == NULL\) \{ - /* - * Called as a function - */ - - retval = ... - \} else \{ - /* - * Called as a trigger procedure - */ - trigdata = CurrentTriggerData; - CurrentTriggerData = NULL; - - retval = ... - \} - - *isNull = false; - return retval; - \} -" {code} " -Only a few thousand lines of code have to be added instead of the dots to complete the PL call handler. See CREATE FUNCTION for information on how to compile it into a loadable module . - -The following commands then register the sample procedural language: -" {} " - CREATE FUNCTION plsample_call_handler () RETURNS opaque - AS '/usr/local/pgsql/lib/plsample.so' - LANGUAGE 'C'; - - CREATE PROCEDURAL LANGUAGE 'plsample' - HANDLER plsample_call_handler - LANCOMPILER 'PL/Sample'; - -" {code} "Notes" {bold} " - -Use " {} "CREATE FUNCTION" {bold} " to create a function. - -Use DROP LANGUAGE to drop procedural languages. - -Refer to the table pg_language for further information: - -Table = pg_language -" {} " -+-----------------+----------+-------+ -| Field | Type | Length| -+-----------------+----------+-------+ -| lanname | name | 32 | -| lancompiler | text | var | -+-----------------+----------+-------+ - -lanname |lancompiler ---------+-------------- -internal|n/a -lisp |/usr/ucb/liszt -C |/bin/cc -sql |postgres -" {code} " - -" {} "Restrictions" {bold} " - -Since the call handler for a procedural language must be registered with Postgres in the 'C' language, it inherits all the capabilities and restrictions of 'C' functions. -" |