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08f8d478eb
parse analysis phase, rather than at execution time. This makes parameter handling work the same as it does in ordinary plannable queries, and in particular fixes the incompatibility that Pavel pointed out with plpgsql's new handling of variable references. plancache.c gets a little bit grottier, but the alternatives seem worse.
107 lines
3.7 KiB
C
107 lines
3.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* params.h
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* Support for finding the values associated with Param nodes.
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*
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*
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/nodes/params.h,v 1.41 2010/01/15 22:36:35 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PARAMS_H
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#define PARAMS_H
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/* To avoid including a pile of parser headers, reference ParseState thus: */
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struct ParseState;
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/* ----------------
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* ParamListInfo
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*
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* ParamListInfo arrays are used to pass parameters into the executor
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* for parameterized plans. Each entry in the array defines the value
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* to be substituted for a PARAM_EXTERN parameter. The "paramid"
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* of a PARAM_EXTERN Param can range from 1 to numParams.
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*
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* Although parameter numbers are normally consecutive, we allow
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* ptype == InvalidOid to signal an unused array entry.
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*
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* pflags is a flags field. Currently the only used bit is:
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* PARAM_FLAG_CONST signals the planner that it may treat this parameter
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* as a constant (i.e., generate a plan that works only for this value
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* of the parameter).
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*
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* There are two hook functions that can be associated with a ParamListInfo
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* array to support dynamic parameter handling. First, if paramFetch
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* isn't null and the executor requires a value for an invalid parameter
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* (one with ptype == InvalidOid), the paramFetch hook is called to give
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* it a chance to fill in the parameter value. Second, a parserSetup
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* hook can be supplied to re-instantiate the original parsing hooks if
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* a query needs to be re-parsed/planned (as a substitute for supposing
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* that the current ptype values represent a fixed set of parameter types).
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* Although the data structure is really an array, not a list, we keep
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* the old typedef name to avoid unnecessary code changes.
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* ----------------
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*/
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#define PARAM_FLAG_CONST 0x0001 /* parameter is constant */
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typedef struct ParamExternData
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{
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Datum value; /* parameter value */
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bool isnull; /* is it NULL? */
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uint16 pflags; /* flag bits, see above */
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Oid ptype; /* parameter's datatype, or 0 */
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} ParamExternData;
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typedef struct ParamListInfoData *ParamListInfo;
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typedef void (*ParamFetchHook) (ParamListInfo params, int paramid);
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typedef void (*ParserSetupHook) (struct ParseState *pstate, void *arg);
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typedef struct ParamListInfoData
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{
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ParamFetchHook paramFetch; /* parameter fetch hook */
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void *paramFetchArg;
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ParserSetupHook parserSetup; /* parser setup hook */
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void *parserSetupArg;
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int numParams; /* number of ParamExternDatas following */
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ParamExternData params[1]; /* VARIABLE LENGTH ARRAY */
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} ParamListInfoData;
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/* ----------------
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* ParamExecData
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*
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* ParamExecData entries are used for executor internal parameters
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* (that is, values being passed into or out of a sub-query). The
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* paramid of a PARAM_EXEC Param is a (zero-based) index into an
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* array of ParamExecData records, which is referenced through
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* es_param_exec_vals or ecxt_param_exec_vals.
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*
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* If execPlan is not NULL, it points to a SubPlanState node that needs
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* to be executed to produce the value. (This is done so that we can have
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* lazy evaluation of InitPlans: they aren't executed until/unless a
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* result value is needed.) Otherwise the value is assumed to be valid
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* when needed.
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* ----------------
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*/
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typedef struct ParamExecData
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{
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void *execPlan; /* should be "SubPlanState *" */
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Datum value;
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bool isnull;
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} ParamExecData;
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/* Functions found in src/backend/nodes/params.c */
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extern ParamListInfo copyParamList(ParamListInfo from);
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#endif /* PARAMS_H */
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