codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * params.h4 *	  Support for finding the values associated with Param nodes.5 *6 *7 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group8 * Portions Copyright (c) 1994, Regents of the University of California9 *10 * src/include/nodes/params.h11 *12 *-------------------------------------------------------------------------13 */14#ifndef PARAMS_H15#define PARAMS_H16 17/* Forward declarations, to avoid including other headers */18struct Bitmapset;19struct ExprState;20struct Param;21struct ParseState;22 23 24/*25 *	  ParamListInfo26 *27 *	  ParamListInfo structures are used to pass parameters into the executor28 *	  for parameterized plans.  We support two basic approaches to supplying29 *	  parameter values, the "static" way and the "dynamic" way.30 *31 *	  In the static approach, per-parameter data is stored in an array of32 *	  ParamExternData structs appended to the ParamListInfo struct.33 *	  Each entry in the array defines the value to be substituted for a34 *	  PARAM_EXTERN parameter.  The "paramid" of a PARAM_EXTERN Param35 *	  can range from 1 to numParams.36 *37 *	  Although parameter numbers are normally consecutive, we allow38 *	  ptype == InvalidOid to signal an unused array entry.39 *40 *	  pflags is a flags field.  Currently the only used bit is:41 *	  PARAM_FLAG_CONST signals the planner that it may treat this parameter42 *	  as a constant (i.e., generate a plan that works only for this value43 *	  of the parameter).44 *45 *	  In the dynamic approach, all access to parameter values is done through46 *	  hook functions found in the ParamListInfo struct.  In this case,47 *	  the ParamExternData array is typically unused and not allocated;48 *	  but the legal range of paramid is still 1 to numParams.49 *50 *	  Although the data structure is really an array, not a list, we keep51 *	  the old typedef name to avoid unnecessary code changes.52 *53 *	  There are 3 hook functions that can be associated with a ParamListInfo54 *	  structure:55 *56 *	  If paramFetch isn't null, it is called to fetch the ParamExternData57 *	  for a particular param ID, rather than accessing the relevant element58 *	  of the ParamExternData array.  This supports the case where the array59 *	  isn't there at all, as well as cases where the data in the array60 *	  might be obsolete or lazily evaluated.  paramFetch must return the61 *	  address of a ParamExternData struct describing the specified param ID;62 *	  the convention above about ptype == InvalidOid signaling an invalid63 *	  param ID still applies.  The returned struct can either be placed in64 *	  the "workspace" supplied by the caller, or it can be in storage65 *	  controlled by the paramFetch hook if that's more convenient.66 *	  (In either case, the struct is not expected to be long-lived.)67 *	  If "speculative" is true, the paramFetch hook should not risk errors68 *	  in trying to fetch the parameter value, and should report an invalid69 *	  parameter instead.70 *71 *	  If paramCompile isn't null, then it controls what execExpr.c compiles72 *	  for PARAM_EXTERN Param nodes --- typically, this hook would emit a73 *	  EEOP_PARAM_CALLBACK step.  This allows unnecessary work to be74 *	  optimized away in compiled expressions.75 *76 *	  If parserSetup isn't null, then it is called to re-instantiate the77 *	  original parsing hooks when a query needs to be re-parsed/planned.78 *	  This is especially useful if the types of parameters might change79 *	  from time to time, since it can replace the need to supply a fixed80 *	  list of parameter types to the parser.81 *82 *	  Notice that the paramFetch and paramCompile hooks are actually passed83 *	  the ParamListInfo struct's address; they can therefore access all84 *	  three of the "arg" fields, and the distinction between paramFetchArg85 *	  and paramCompileArg is rather arbitrary.86 */87 88#define PARAM_FLAG_CONST	0x0001	/* parameter is constant */89 90typedef struct ParamExternData91{92	Datum		value;			/* parameter value */93	bool		isnull;			/* is it NULL? */94	uint16		pflags;			/* flag bits, see above */95	Oid			ptype;			/* parameter's datatype, or 0 */96} ParamExternData;97 98typedef struct ParamListInfoData *ParamListInfo;99 100typedef ParamExternData *(*ParamFetchHook) (ParamListInfo params,101											int paramid, bool speculative,102											ParamExternData *workspace);103 104typedef void (*ParamCompileHook) (ParamListInfo params, struct Param *param,105								  struct ExprState *state,106								  Datum *resv, bool *resnull);107 108typedef void (*ParserSetupHook) (struct ParseState *pstate, void *arg);109 110typedef struct ParamListInfoData111{112	ParamFetchHook paramFetch;	/* parameter fetch hook */113	void	   *paramFetchArg;114	ParamCompileHook paramCompile;	/* parameter compile hook */115	void	   *paramCompileArg;116	ParserSetupHook parserSetup;	/* parser setup hook */117	void	   *parserSetupArg;118	char	   *paramValuesStr; /* params as a single string for errors */119	int			numParams;		/* nominal/maximum # of Params represented */120 121	/*122	 * params[] may be of length zero if paramFetch is supplied; otherwise it123	 * must be of length numParams.124	 */125	ParamExternData params[FLEXIBLE_ARRAY_MEMBER];126}			ParamListInfoData;127 128 129/* ----------------130 *	  ParamExecData131 *132 *	  ParamExecData entries are used for executor internal parameters133 *	  (that is, values being passed into or out of a sub-query).  The134 *	  paramid of a PARAM_EXEC Param is a (zero-based) index into an135 *	  array of ParamExecData records, which is referenced through136 *	  es_param_exec_vals or ecxt_param_exec_vals.137 *138 *	  If execPlan is not NULL, it points to a SubPlanState node that needs139 *	  to be executed to produce the value.  (This is done so that we can have140 *	  lazy evaluation of InitPlans: they aren't executed until/unless a141 *	  result value is needed.)	Otherwise the value is assumed to be valid142 *	  when needed.143 * ----------------144 */145 146typedef struct ParamExecData147{148	void	   *execPlan;		/* should be "SubPlanState *" */149	Datum		value;150	bool		isnull;151} ParamExecData;152 153/* type of argument for ParamsErrorCallback */154typedef struct ParamsErrorCbData155{156	const char *portalName;157	ParamListInfo params;158} ParamsErrorCbData;159 160/* Functions found in src/backend/nodes/params.c */161extern ParamListInfo makeParamList(int numParams);162extern ParamListInfo copyParamList(ParamListInfo from);163extern Size EstimateParamListSpace(ParamListInfo paramLI);164extern void SerializeParamList(ParamListInfo paramLI, char **start_address);165extern ParamListInfo RestoreParamList(char **start_address);166extern char *BuildParamLogString(ParamListInfo params, char **knownTextValues,167								 int maxlen);168extern void ParamsErrorCallback(void *arg);169 170#endif							/* PARAMS_H */171