src/include/nodes/params.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * params.h
   4  *        Support for finding the values associated with Param nodes.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef PARAMS_H
  15 #define PARAMS_H
  16
  17
  18 /* ----------------
  19  *        ParamListInfo
  20  *
  21  *        ParamListInfo arrays are used to pass parameters into the executor
  22  *        for parameterized plans.      Each entry in the array defines the value
  23  *        to be substituted for a PARAM_EXTERN parameter.  The "paramid"
  24  *        of a PARAM_EXTERN Param can range from 1 to numParams.
  25  *
  26  *        Although parameter numbers are normally consecutive, we allow
  27  *        ptype == InvalidOid to signal an unused array entry.
  28  *
  29  *        PARAM_FLAG_CONST signals the planner that it may treat this parameter
  30  *        as a constant (i.e., generate a plan that works only for this value
  31  *        of the parameter).
  32  *
  33  *        Although the data structure is really an array, not a list, we keep
  34  *        the old typedef name to avoid unnecessary code changes.
  35  * ----------------
  36  */
  37
  38 #define PARAM_FLAG_CONST        0x0001          /* parameter is constant */
  39
  40 typedef struct ParamExternData
  41 {
  42         Datum           value;                  /* parameter value */
  43         bool            isnull;                 /* is it NULL? */
  44         uint16          pflags;                 /* flag bits, see above */
  45         Oid                     ptype;                  /* parameter's datatype, or 0 */
  46 } ParamExternData;
  47
  48 typedef struct ParamListInfoData
  49 {
  50         int                     numParams;              /* number of ParamExternDatas following */
  51         ParamExternData params[1];      /* VARIABLE LENGTH ARRAY */
  52 } ParamListInfoData;
  53
  54 typedef ParamListInfoData *ParamListInfo;
  55
  56
  57 /* ----------------
  58  *        ParamExecData
  59  *
  60  *        ParamExecData entries are used for executor internal parameters
  61  *        (that is, values being passed into or out of a sub-query).  The
  62  *        paramid of a PARAM_EXEC Param is a (zero-based) index into an
  63  *        array of ParamExecData records, which is referenced through
  64  *        es_param_exec_vals or ecxt_param_exec_vals.
  65  *
  66  *        If execPlan is not NULL, it points to a SubPlanState node that needs
  67  *        to be executed to produce the value.  (This is done so that we can have
  68  *        lazy evaluation of InitPlans: they aren't executed until/unless a
  69  *        result value is needed.)      Otherwise the value is assumed to be valid
  70  *        when needed.
  71  * ----------------
  72  */
  73
  74 typedef struct ParamExecData
  75 {
  76         void       *execPlan;           /* should be "SubPlanState *" */
  77         Datum           value;
  78         bool            isnull;
  79 } ParamExecData;
  80
  81
  82 /* Functions found in src/backend/nodes/params.c */
  83 extern ParamListInfo copyParamList(ParamListInfo from);
  84
  85 extern void getParamListTypes(ParamListInfo params,
  86                                   Oid **param_types, int *num_params);
  87
  88 #endif   /* PARAMS_H */