原 PostgreSQL的系统函数分析记录

CATALOG(pg_proc,1255) BKI_BOOTSTRAP BKI_ROWTYPE_OID(81) BKI_SCHEMA_MACRO
   37 {
   38     NameData    proname;        /* procedure name */
   39     Oid         pronamespace;   /* OID of namespace containing this proc */
   40     Oid         proowner;       /* procedure owner */
   41     Oid         prolang;        /* OID of pg_language entry */
   42     float4      procost;        /* estimated execution cost */
   43     float4      prorows;        /* estimated # of rows out (if proretset) */
   44     Oid         provariadic;    /* element type of variadic array, or 0 */
   45     regproc     protransform;   /* transforms calls to it during planning */
   46     bool        proisagg;       /* is it an aggregate? */
   47     bool        proiswindow;    /* is it a window function? */
   48     bool        prosecdef;      /* security definer */
   49     bool        proleakproof;   /* is it a leak-proof function? */
   50     bool        proisstrict;    /* strict with respect to NULLs? */
   51     bool        proretset;      /* returns a set? */
   52     char        provolatile;    /* see PROVOLATILE_ categories below */
   53     int16       pronargs;       /* number of arguments */
   54     int16       pronargdefaults;    /* number of arguments with defaults */
   55     Oid         prorettype;     /* OID of result type */
   56 
   57     /*
   58      * variable-length fields start here, but we allow direct access to
   59      * proargtypes
   60      */
   61     oidvector   proargtypes;    /* parameter types (excludes OUT params) */
   62 
   63 #ifdef CATALOG_VARLEN
   64     Oid         proallargtypes[1];      /* all param types (NULL if IN only) */
   65     char        proargmodes[1]; /* parameter modes (NULL if IN only) */
   66     text        proargnames[1]; /* parameter names (NULL if no names) */
   67     pg_node_tree proargdefaults;/* list of expression trees for argument
   68                                  * defaults (NULL if none) */
   69     text        prosrc;         /* procedure source text */
   70     text        probin;         /* secondary procedure info (can be NULL) */
   71     text        proconfig[1];   /* procedure-local GUC settings */
   72     aclitem     proacl[1];      /* access permissions */
   73 #endif
   74 } FormData_pg_proc;

CREATE OR REPLACE FUNCTION date_part(text, time with time zone)
  RETURNS double precision AS
'timetz_part'
  LANGUAGE internal IMMUTABLE STRICT
  COST 1;

CREATE OR REPLACE FUNCTION date_part(text, abstime)
  RETURNS double precision AS
'select pg_catalog.date_part($1, cast($2 as timestamp with time zone))'
  LANGUAGE sql STABLE STRICT
  COST 1;
ALTER FUNCTION date_part(text, abstime) OWNER TO highgo;
COMMENT ON FUNCTION date_part(text, abstime) IS 'extract field from abstime';

CREATE OR REPLACE FUNCTION concat(VARIADIC "any")
  RETURNS text AS
'text_concat'
  LANGUAGE internal STABLE
  COST 1;
ALTER FUNCTION concat("any")
  OWNER TO postgres;
COMMENT ON FUNCTION concat("any") IS 'concatenate values';

CREATE OR REPLACE FUNCTION varbit(bit varying, integer, boolean)
  RETURNS bit varying AS
'varbit'
  LANGUAGE internal IMMUTABLE STRICT
  COST 1;

#define PG_FUNCTION_ARGS    FunctionCallInfo fcinfo
typedef struct FunctionCallInfoData *FunctionCallInfo;
typedef Datum (*PGFunction) (FunctionCallInfo fcinfo);
typedef struct Node *fmNodePtr; typedef uintptr_t Datum;
typedef struct Node
{
 NodeTag		type; //NodeTag 这是一个枚举类型
} Node;

  
 typedef struct FmgrInfo
{
         PGFunction	fn_addr;		/* pointer to function or handler to be called */
         Oid		fn_oid;			/* OID of function (NOT of handler, if any) */
         short		fn_nargs;		/* number of input args (0..FUNC_MAX_ARGS) */
         bool		fn_strict;		/* function is "strict" (NULL in => NULL out) */
         bool		fn_retset;		/* function returns a set */
         unsigned char fn_stats;		/* collect stats if track_functions > this */
         void	   *fn_extra;		/* extra space for use by handler */
         MemoryContext fn_mcxt;		/* memory context to store fn_extra in */
         fmNodePtr	fn_expr;		/* expression parse tree for call, or NULL */
} FmgrInfo;

typedef struct FunctionCallInfoData
{
	FmgrInfo   *flinfo;			/* ptr to lookup info used for this call */
	fmNodePtr	context;		/* pass info about context of call */
	fmNodePtr	resultinfo;		/* pass or return extra info about result */
	Oid			fncollation;	/* collation for function to use */
	bool		isnull;			/* function must set true if result is NULL */
	short		nargs;			/* # arguments actually passed */
	Datum		arg[FUNC_MAX_ARGS];		/* Arguments passed to function */
	bool		argnull[FUNC_MAX_ARGS]; /* T if arg[i] is actually NULL */
} FunctionCallInfoData; 

postgres=# select concat('su','re');

typedef struct FuncCall
{
	NodeTag		type;
	List	   *funcname;		/* qualified name of function */
	List	   *args;			/* the arguments (list of exprs) */
	List	   *agg_order;		/* ORDER BY (list of SortBy) */
	Node	   *agg_filter;		/* FILTER clause, if any */
	bool		agg_star;		/* argument was really '*' */
	bool		agg_distinct;	/* arguments were labeled DISTINCT */
	bool		func_variadic;	/* last argument was labeled VARIADIC */
	struct WindowDef *over;		/* OVER clause, if any */
	int			location;		/* token location, or -1 if unknown */
} FuncCall;

typedef struct PortalData *Portal;

typedef struct PortalData
{
	/* Bookkeeping data */
	const char *name;			/* portal's name */
	const char *prepStmtName;	/* source prepared statement (NULL if none) */
	MemoryContext heap;			/* subsidiary memory for portal */
	ResourceOwner resowner;		/* resources owned by portal */
	void		(*cleanup) (Portal portal);		/* cleanup hook */
	SubTransactionId createSubid;		/* the ID of the creating subxact */

	/*
	 * if createSubid is InvalidSubTransactionId, the portal is held over from
	 * a previous transaction
	 */

	/* The query or queries the portal will execute */
	const char *sourceText;		/* text of query (as of 8.4, never NULL) */
	const char *commandTag;		/* command tag for original query */
	List	   *stmts;			/* PlannedStmts and/or utility statements */
	CachedPlan *cplan;			/* CachedPlan, if stmts are from one */

	ParamListInfo portalParams; /* params to pass to query */

	/* Features/options */
	PortalStrategy strategy;	/* see above */
	int			cursorOptions;	/* DECLARE CURSOR option bits */

	/* Status data */
	PortalStatus status;		/* see above */
	bool		portalPinned;	/* a pinned portal can't be dropped */

	/* If not NULL, Executor is active; call ExecutorEnd eventually: */
	QueryDesc  *queryDesc;		/* info needed for executor invocation */

	/* If portal returns tuples, this is their tupdesc: */
	TupleDesc	tupDesc;		/* descriptor for result tuples */
	/* and these are the format codes to use for the columns: */
	int16	   *formats;		/* a format code for each column */

	/*
	 * Where we store tuples for a held cursor or a PORTAL_ONE_RETURNING or
	 * PORTAL_UTIL_SELECT query.  (A cursor held past the end of its
	 * transaction no longer has any active executor state.)
	 */
	Tuplestorestate *holdStore; /* store for holdable cursors */
	MemoryContext holdContext;	/* memory containing holdStore */

	/*
	 * atStart, atEnd and portalPos indicate the current cursor position.
	 * portalPos is zero before the first row, N after fetching N'th row of
	 * query.  After we run off the end, portalPos = # of rows in query, and
	 * atEnd is true.  If portalPos overflows, set posOverflow (this causes us
	 * to stop relying on its value for navigation).  Note that atStart
	 * implies portalPos == 0, but not the reverse (portalPos could have
	 * overflowed).
	 */
	bool		atStart;
	bool		atEnd;
	bool		posOverflow;
	long		portalPos;

	/* Presentation data, primarily used by the pg_cursors system view */
	TimestampTz creation_time;	/* time at which this portal was defined */
	bool		visible;		/* include this portal in pg_cursors? */
}	PortalData;