Logo Search packages:      
Sourcecode: postgresql-8.4 version File versions  Download package

funcapi.c
/*-------------------------------------------------------------------------
 *
 * funcapi.c
 *      Utility and convenience functions for fmgr functions that return
 *      sets and/or composite types.
 *
 * Copyright (c) 2002-2009, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/utils/fmgr/funcapi.c,v 1.45 2009/06/11 14:49:05 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "catalog/namespace.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_coerce.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/typcache.h"


static void shutdown_MultiFuncCall(Datum arg);
static TypeFuncClass internal_get_result_type(Oid funcid,
                                     Node *call_expr,
                                     ReturnSetInfo *rsinfo,
                                     Oid *resultTypeId,
                                     TupleDesc *resultTupleDesc);
static bool resolve_polymorphic_tupdesc(TupleDesc tupdesc,
                                          oidvector *declared_args,
                                          Node *call_expr);
static TypeFuncClass get_type_func_class(Oid typid);


/*
 * init_MultiFuncCall
 * Create an empty FuncCallContext data structure
 * and do some other basic Multi-function call setup
 * and error checking
 */
FuncCallContext *
init_MultiFuncCall(PG_FUNCTION_ARGS)
{
      FuncCallContext *retval;

      /*
       * Bail if we're called in the wrong context
       */
      if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("set-valued function called in context that cannot accept a set")));

      if (fcinfo->flinfo->fn_extra == NULL)
      {
            /*
             * First call
             */
            ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
            MemoryContext multi_call_ctx;

            /*
             * Create a suitably long-lived context to hold cross-call data
             */
            multi_call_ctx = AllocSetContextCreate(fcinfo->flinfo->fn_mcxt,
                                                                     "SRF multi-call context",
                                                                     ALLOCSET_SMALL_MINSIZE,
                                                                     ALLOCSET_SMALL_INITSIZE,
                                                                     ALLOCSET_SMALL_MAXSIZE);

            /*
             * Allocate suitably long-lived space and zero it
             */
            retval = (FuncCallContext *)
                  MemoryContextAllocZero(multi_call_ctx,
                                                   sizeof(FuncCallContext));

            /*
             * initialize the elements
             */
            retval->call_cntr = 0;
            retval->max_calls = 0;
            retval->slot = NULL;
            retval->user_fctx = NULL;
            retval->attinmeta = NULL;
            retval->tuple_desc = NULL;
            retval->multi_call_memory_ctx = multi_call_ctx;

            /*
             * save the pointer for cross-call use
             */
            fcinfo->flinfo->fn_extra = retval;

            /*
             * Ensure we will get shut down cleanly if the exprcontext is not run
             * to completion.
             */
            RegisterExprContextCallback(rsi->econtext,
                                                      shutdown_MultiFuncCall,
                                                      PointerGetDatum(fcinfo->flinfo));
      }
      else
      {
            /* second and subsequent calls */
            elog(ERROR, "init_MultiFuncCall cannot be called more than once");

            /* never reached, but keep compiler happy */
            retval = NULL;
      }

      return retval;
}

/*
 * per_MultiFuncCall
 *
 * Do Multi-function per-call setup
 */
FuncCallContext *
per_MultiFuncCall(PG_FUNCTION_ARGS)
{
      FuncCallContext *retval = (FuncCallContext *) fcinfo->flinfo->fn_extra;

      /*
       * Clear the TupleTableSlot, if present.  This is for safety's sake: the
       * Slot will be in a long-lived context (it better be, if the
       * FuncCallContext is pointing to it), but in most usage patterns the
       * tuples stored in it will be in the function's per-tuple context. So at
       * the beginning of each call, the Slot will hold a dangling pointer to an
       * already-recycled tuple.    We clear it out here.
       *
       * Note: use of retval->slot is obsolete as of 8.0, and we expect that it
       * will always be NULL.  This is just here for backwards compatibility in
       * case someone creates a slot anyway.
       */
      if (retval->slot != NULL)
            ExecClearTuple(retval->slot);

      return retval;
}

/*
 * end_MultiFuncCall
 * Clean up after init_MultiFuncCall
 */
void
end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx)
{
      ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;

      /* Deregister the shutdown callback */
      UnregisterExprContextCallback(rsi->econtext,
                                                  shutdown_MultiFuncCall,
                                                  PointerGetDatum(fcinfo->flinfo));

      /* But use it to do the real work */
      shutdown_MultiFuncCall(PointerGetDatum(fcinfo->flinfo));
}

/*
 * shutdown_MultiFuncCall
 * Shutdown function to clean up after init_MultiFuncCall
 */
static void
shutdown_MultiFuncCall(Datum arg)
{
      FmgrInfo   *flinfo = (FmgrInfo *) DatumGetPointer(arg);
      FuncCallContext *funcctx = (FuncCallContext *) flinfo->fn_extra;

      /* unbind from flinfo */
      flinfo->fn_extra = NULL;

      /*
       * Delete context that holds all multi-call data, including the
       * FuncCallContext itself
       */
      MemoryContextDelete(funcctx->multi_call_memory_ctx);
}


/*
 * get_call_result_type
 *          Given a function's call info record, determine the kind of datatype
 *          it is supposed to return.  If resultTypeId isn't NULL, *resultTypeId
 *          receives the actual datatype OID (this is mainly useful for scalar
 *          result types).    If resultTupleDesc isn't NULL, *resultTupleDesc
 *          receives a pointer to a TupleDesc when the result is of a composite
 *          type, or NULL when it's a scalar result.
 *
 * One hard case that this handles is resolution of actual rowtypes for
 * functions returning RECORD (from either the function's OUT parameter
 * list, or a ReturnSetInfo context node).      TYPEFUNC_RECORD is returned
 * only when we couldn't resolve the actual rowtype for lack of information.
 *
 * The other hard case that this handles is resolution of polymorphism.
 * We will never return polymorphic pseudotypes (ANYELEMENT etc), either
 * as a scalar result type or as a component of a rowtype.
 *
 * This function is relatively expensive --- in a function returning set,
 * try to call it only the first time through.
 */
TypeFuncClass
get_call_result_type(FunctionCallInfo fcinfo,
                               Oid *resultTypeId,
                               TupleDesc *resultTupleDesc)
{
      return internal_get_result_type(fcinfo->flinfo->fn_oid,
                                                      fcinfo->flinfo->fn_expr,
                                                      (ReturnSetInfo *) fcinfo->resultinfo,
                                                      resultTypeId,
                                                      resultTupleDesc);
}

/*
 * get_expr_result_type
 *          As above, but work from a calling expression node tree
 */
TypeFuncClass
get_expr_result_type(Node *expr,
                               Oid *resultTypeId,
                               TupleDesc *resultTupleDesc)
{
      TypeFuncClass result;

      if (expr && IsA(expr, FuncExpr))
            result = internal_get_result_type(((FuncExpr *) expr)->funcid,
                                                              expr,
                                                              NULL,
                                                              resultTypeId,
                                                              resultTupleDesc);
      else if (expr && IsA(expr, OpExpr))
            result = internal_get_result_type(get_opcode(((OpExpr *) expr)->opno),
                                                              expr,
                                                              NULL,
                                                              resultTypeId,
                                                              resultTupleDesc);
      else
      {
            /* handle as a generic expression; no chance to resolve RECORD */
            Oid               typid = exprType(expr);

            if (resultTypeId)
                  *resultTypeId = typid;
            if (resultTupleDesc)
                  *resultTupleDesc = NULL;
            result = get_type_func_class(typid);
            if (result == TYPEFUNC_COMPOSITE && resultTupleDesc)
                  *resultTupleDesc = lookup_rowtype_tupdesc_copy(typid, -1);
      }

      return result;
}

/*
 * get_func_result_type
 *          As above, but work from a function's OID only
 *
 * This will not be able to resolve pure-RECORD results nor polymorphism.
 */
TypeFuncClass
get_func_result_type(Oid functionId,
                               Oid *resultTypeId,
                               TupleDesc *resultTupleDesc)
{
      return internal_get_result_type(functionId,
                                                      NULL,
                                                      NULL,
                                                      resultTypeId,
                                                      resultTupleDesc);
}

/*
 * internal_get_result_type -- workhorse code implementing all the above
 *
 * funcid must always be supplied.  call_expr and rsinfo can be NULL if not
 * available.  We will return TYPEFUNC_RECORD, and store NULL into
 * *resultTupleDesc, if we cannot deduce the complete result rowtype from
 * the available information.
 */
static TypeFuncClass
internal_get_result_type(Oid funcid,
                                     Node *call_expr,
                                     ReturnSetInfo *rsinfo,
                                     Oid *resultTypeId,
                                     TupleDesc *resultTupleDesc)
{
      TypeFuncClass result;
      HeapTuple   tp;
      Form_pg_proc procform;
      Oid               rettype;
      TupleDesc   tupdesc;

      /* First fetch the function's pg_proc row to inspect its rettype */
      tp = SearchSysCache(PROCOID,
                                    ObjectIdGetDatum(funcid),
                                    0, 0, 0);
      if (!HeapTupleIsValid(tp))
            elog(ERROR, "cache lookup failed for function %u", funcid);
      procform = (Form_pg_proc) GETSTRUCT(tp);

      rettype = procform->prorettype;

      /* Check for OUT parameters defining a RECORD result */
      tupdesc = build_function_result_tupdesc_t(tp);
      if (tupdesc)
      {
            /*
             * It has OUT parameters, so it's basically like a regular composite
             * type, except we have to be able to resolve any polymorphic OUT
             * parameters.
             */
            if (resultTypeId)
                  *resultTypeId = rettype;

            if (resolve_polymorphic_tupdesc(tupdesc,
                                                            &procform->proargtypes,
                                                            call_expr))
            {
                  if (tupdesc->tdtypeid == RECORDOID &&
                        tupdesc->tdtypmod < 0)
                        assign_record_type_typmod(tupdesc);
                  if (resultTupleDesc)
                        *resultTupleDesc = tupdesc;
                  result = TYPEFUNC_COMPOSITE;
            }
            else
            {
                  if (resultTupleDesc)
                        *resultTupleDesc = NULL;
                  result = TYPEFUNC_RECORD;
            }

            ReleaseSysCache(tp);

            return result;
      }

      /*
       * If scalar polymorphic result, try to resolve it.
       */
      if (IsPolymorphicType(rettype))
      {
            Oid               newrettype = exprType(call_expr);

            if (newrettype == InvalidOid) /* this probably should not happen */
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("could not determine actual result type for function \"%s\" declared to return type %s",
                                          NameStr(procform->proname),
                                          format_type_be(rettype))));
            rettype = newrettype;
      }

      if (resultTypeId)
            *resultTypeId = rettype;
      if (resultTupleDesc)
            *resultTupleDesc = NULL;      /* default result */

      /* Classify the result type */
      result = get_type_func_class(rettype);
      switch (result)
      {
            case TYPEFUNC_COMPOSITE:
                  if (resultTupleDesc)
                        *resultTupleDesc = lookup_rowtype_tupdesc_copy(rettype, -1);
                  /* Named composite types can't have any polymorphic columns */
                  break;
            case TYPEFUNC_SCALAR:
                  break;
            case TYPEFUNC_RECORD:
                  /* We must get the tupledesc from call context */
                  if (rsinfo && IsA(rsinfo, ReturnSetInfo) &&
                        rsinfo->expectedDesc != NULL)
                  {
                        result = TYPEFUNC_COMPOSITE;
                        if (resultTupleDesc)
                              *resultTupleDesc = rsinfo->expectedDesc;
                        /* Assume no polymorphic columns here, either */
                  }
                  break;
            default:
                  break;
      }

      ReleaseSysCache(tp);

      return result;
}

/*
 * Given the result tuple descriptor for a function with OUT parameters,
 * replace any polymorphic columns (ANYELEMENT etc) with correct data types
 * deduced from the input arguments. Returns TRUE if able to deduce all types,
 * FALSE if not.
 */
static bool
resolve_polymorphic_tupdesc(TupleDesc tupdesc, oidvector *declared_args,
                                          Node *call_expr)
{
      int               natts = tupdesc->natts;
      int               nargs = declared_args->dim1;
      bool        have_anyelement_result = false;
      bool        have_anyarray_result = false;
      bool        have_anynonarray = false;
      bool        have_anyenum = false;
      Oid               anyelement_type = InvalidOid;
      Oid               anyarray_type = InvalidOid;
      int               i;

      /* See if there are any polymorphic outputs; quick out if not */
      for (i = 0; i < natts; i++)
      {
            switch (tupdesc->attrs[i]->atttypid)
            {
                  case ANYELEMENTOID:
                        have_anyelement_result = true;
                        break;
                  case ANYARRAYOID:
                        have_anyarray_result = true;
                        break;
                  case ANYNONARRAYOID:
                        have_anyelement_result = true;
                        have_anynonarray = true;
                        break;
                  case ANYENUMOID:
                        have_anyelement_result = true;
                        have_anyenum = true;
                        break;
                  default:
                        break;
            }
      }
      if (!have_anyelement_result && !have_anyarray_result)
            return true;

      /*
       * Otherwise, extract actual datatype(s) from input arguments.    (We assume
       * the parser already validated consistency of the arguments.)
       */
      if (!call_expr)
            return false;                 /* no hope */

      for (i = 0; i < nargs; i++)
      {
            switch (declared_args->values[i])
            {
                  case ANYELEMENTOID:
                  case ANYNONARRAYOID:
                  case ANYENUMOID:
                        if (!OidIsValid(anyelement_type))
                              anyelement_type = get_call_expr_argtype(call_expr, i);
                        break;
                  case ANYARRAYOID:
                        if (!OidIsValid(anyarray_type))
                              anyarray_type = get_call_expr_argtype(call_expr, i);
                        break;
                  default:
                        break;
            }
      }

      /* If nothing found, parser messed up */
      if (!OidIsValid(anyelement_type) && !OidIsValid(anyarray_type))
            return false;

      /* If needed, deduce one polymorphic type from the other */
      if (have_anyelement_result && !OidIsValid(anyelement_type))
            anyelement_type = resolve_generic_type(ANYELEMENTOID,
                                                                     anyarray_type,
                                                                     ANYARRAYOID);
      if (have_anyarray_result && !OidIsValid(anyarray_type))
            anyarray_type = resolve_generic_type(ANYARRAYOID,
                                                                   anyelement_type,
                                                                   ANYELEMENTOID);

      /* Enforce ANYNONARRAY if needed */
      if (have_anynonarray && type_is_array(anyelement_type))
            return false;

      /* Enforce ANYENUM if needed */
      if (have_anyenum && !type_is_enum(anyelement_type))
            return false;

      /* And finally replace the tuple column types as needed */
      for (i = 0; i < natts; i++)
      {
            switch (tupdesc->attrs[i]->atttypid)
            {
                  case ANYELEMENTOID:
                  case ANYNONARRAYOID:
                  case ANYENUMOID:
                        TupleDescInitEntry(tupdesc, i + 1,
                                                   NameStr(tupdesc->attrs[i]->attname),
                                                   anyelement_type,
                                                   -1,
                                                   0);
                        break;
                  case ANYARRAYOID:
                        TupleDescInitEntry(tupdesc, i + 1,
                                                   NameStr(tupdesc->attrs[i]->attname),
                                                   anyarray_type,
                                                   -1,
                                                   0);
                        break;
                  default:
                        break;
            }
      }

      return true;
}

/*
 * Given the declared argument types and modes for a function, replace any
 * polymorphic types (ANYELEMENT etc) with correct data types deduced from the
 * input arguments.  Returns TRUE if able to deduce all types, FALSE if not.
 * This is the same logic as resolve_polymorphic_tupdesc, but with a different
 * argument representation.
 *
 * argmodes may be NULL, in which case all arguments are assumed to be IN mode.
 */
bool
resolve_polymorphic_argtypes(int numargs, Oid *argtypes, char *argmodes,
                                           Node *call_expr)
{
      bool        have_anyelement_result = false;
      bool        have_anyarray_result = false;
      Oid               anyelement_type = InvalidOid;
      Oid               anyarray_type = InvalidOid;
      int               inargno;
      int               i;

      /* First pass: resolve polymorphic inputs, check for outputs */
      inargno = 0;
      for (i = 0; i < numargs; i++)
      {
            char        argmode = argmodes ? argmodes[i] : PROARGMODE_IN;

            switch (argtypes[i])
            {
                  case ANYELEMENTOID:
                  case ANYNONARRAYOID:
                  case ANYENUMOID:
                        if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                              have_anyelement_result = true;
                        else
                        {
                              if (!OidIsValid(anyelement_type))
                              {
                                    anyelement_type = get_call_expr_argtype(call_expr,
                                                                                                inargno);
                                    if (!OidIsValid(anyelement_type))
                                          return false;
                              }
                              argtypes[i] = anyelement_type;
                        }
                        break;
                  case ANYARRAYOID:
                        if (argmode == PROARGMODE_OUT || argmode == PROARGMODE_TABLE)
                              have_anyarray_result = true;
                        else
                        {
                              if (!OidIsValid(anyarray_type))
                              {
                                    anyarray_type = get_call_expr_argtype(call_expr,
                                                                                            inargno);
                                    if (!OidIsValid(anyarray_type))
                                          return false;
                              }
                              argtypes[i] = anyarray_type;
                        }
                        break;
                  default:
                        break;
            }
            if (argmode != PROARGMODE_OUT && argmode != PROARGMODE_TABLE)
                  inargno++;
      }

      /* Done? */
      if (!have_anyelement_result && !have_anyarray_result)
            return true;

      /* If no input polymorphics, parser messed up */
      if (!OidIsValid(anyelement_type) && !OidIsValid(anyarray_type))
            return false;

      /* If needed, deduce one polymorphic type from the other */
      if (have_anyelement_result && !OidIsValid(anyelement_type))
            anyelement_type = resolve_generic_type(ANYELEMENTOID,
                                                                     anyarray_type,
                                                                     ANYARRAYOID);
      if (have_anyarray_result && !OidIsValid(anyarray_type))
            anyarray_type = resolve_generic_type(ANYARRAYOID,
                                                                   anyelement_type,
                                                                   ANYELEMENTOID);

      /* XXX do we need to enforce ANYNONARRAY or ANYENUM here?  I think not */

      /* And finally replace the output column types as needed */
      for (i = 0; i < numargs; i++)
      {
            switch (argtypes[i])
            {
                  case ANYELEMENTOID:
                  case ANYNONARRAYOID:
                  case ANYENUMOID:
                        argtypes[i] = anyelement_type;
                        break;
                  case ANYARRAYOID:
                        argtypes[i] = anyarray_type;
                        break;
                  default:
                        break;
            }
      }

      return true;
}

/*
 * get_type_func_class
 *          Given the type OID, obtain its TYPEFUNC classification.
 *
 * This is intended to centralize a bunch of formerly ad-hoc code for
 * classifying types.  The categories used here are useful for deciding
 * how to handle functions returning the datatype.
 */
static TypeFuncClass
get_type_func_class(Oid typid)
{
      switch (get_typtype(typid))
      {
            case TYPTYPE_COMPOSITE:
                  return TYPEFUNC_COMPOSITE;
            case TYPTYPE_BASE:
            case TYPTYPE_DOMAIN:
            case TYPTYPE_ENUM:
                  return TYPEFUNC_SCALAR;
            case TYPTYPE_PSEUDO:
                  if (typid == RECORDOID)
                        return TYPEFUNC_RECORD;

                  /*
                   * We treat VOID and CSTRING as legitimate scalar datatypes,
                   * mostly for the convenience of the JDBC driver (which wants to
                   * be able to do "SELECT * FROM foo()" for all legitimately
                   * user-callable functions).
                   */
                  if (typid == VOIDOID || typid == CSTRINGOID)
                        return TYPEFUNC_SCALAR;
                  return TYPEFUNC_OTHER;
      }
      /* shouldn't get here, probably */
      return TYPEFUNC_OTHER;
}


/*
 * get_func_arg_info
 *
 * Fetch info about the argument types, names, and IN/OUT modes from the
 * pg_proc tuple.  Return value is the total number of arguments.
 * Other results are palloc'd.  *p_argtypes is always filled in, but
 * *p_argnames and *p_argmodes will be set NULL in the default cases
 * (no names, and all IN arguments, respectively).
 *
 * Note that this function simply fetches what is in the pg_proc tuple;
 * it doesn't do any interpretation of polymorphic types.
 */
int
get_func_arg_info(HeapTuple procTup,
                          Oid **p_argtypes, char ***p_argnames, char **p_argmodes)
{
      Form_pg_proc procStruct = (Form_pg_proc) GETSTRUCT(procTup);
      Datum       proallargtypes;
      Datum       proargmodes;
      Datum       proargnames;
      bool        isNull;
      ArrayType  *arr;
      int               numargs;
      Datum    *elems;
      int               nelems;
      int               i;

      /* First discover the total number of parameters and get their types */
      proallargtypes = SysCacheGetAttr(PROCOID, procTup,
                                                       Anum_pg_proc_proallargtypes,
                                                       &isNull);
      if (!isNull)
      {
            /*
             * We expect the arrays to be 1-D arrays of the right types; verify
             * that.  For the OID and char arrays, we don't need to use
             * deconstruct_array() since the array data is just going to look like
             * a C array of values.
             */
            arr = DatumGetArrayTypeP(proallargtypes);       /* ensure not toasted */
            numargs = ARR_DIMS(arr)[0];
            if (ARR_NDIM(arr) != 1 ||
                  numargs < 0 ||
                  ARR_HASNULL(arr) ||
                  ARR_ELEMTYPE(arr) != OIDOID)
                  elog(ERROR, "proallargtypes is not a 1-D Oid array");
            Assert(numargs >= procStruct->pronargs);
            *p_argtypes = (Oid *) palloc(numargs * sizeof(Oid));
            memcpy(*p_argtypes, ARR_DATA_PTR(arr),
                     numargs * sizeof(Oid));
      }
      else
      {
            /* If no proallargtypes, use proargtypes */
            numargs = procStruct->proargtypes.dim1;
            Assert(numargs == procStruct->pronargs);
            *p_argtypes = (Oid *) palloc(numargs * sizeof(Oid));
            memcpy(*p_argtypes, procStruct->proargtypes.values,
                     numargs * sizeof(Oid));
      }

      /* Get argument names, if available */
      proargnames = SysCacheGetAttr(PROCOID, procTup,
                                                  Anum_pg_proc_proargnames,
                                                  &isNull);
      if (isNull)
            *p_argnames = NULL;
      else
      {
            deconstruct_array(DatumGetArrayTypeP(proargnames),
                                      TEXTOID, -1, false, 'i',
                                      &elems, NULL, &nelems);
            if (nelems != numargs)  /* should not happen */
                  elog(ERROR, "proargnames must have the same number of elements as the function has arguments");
            *p_argnames = (char **) palloc(sizeof(char *) * numargs);
            for (i = 0; i < numargs; i++)
                  (*p_argnames)[i] = TextDatumGetCString(elems[i]);
      }

      /* Get argument modes, if available */
      proargmodes = SysCacheGetAttr(PROCOID, procTup,
                                                  Anum_pg_proc_proargmodes,
                                                  &isNull);
      if (isNull)
            *p_argmodes = NULL;
      else
      {
            arr = DatumGetArrayTypeP(proargmodes);    /* ensure not toasted */
            if (ARR_NDIM(arr) != 1 ||
                  ARR_DIMS(arr)[0] != numargs ||
                  ARR_HASNULL(arr) ||
                  ARR_ELEMTYPE(arr) != CHAROID)
                  elog(ERROR, "proargmodes is not a 1-D char array");
            *p_argmodes = (char *) palloc(numargs * sizeof(char));
            memcpy(*p_argmodes, ARR_DATA_PTR(arr),
                     numargs * sizeof(char));
      }

      return numargs;
}


/*
 * get_func_result_name
 *
 * If the function has exactly one output parameter, and that parameter
 * is named, return the name (as a palloc'd string).  Else return NULL.
 *
 * This is used to determine the default output column name for functions
 * returning scalar types.
 */
char *
get_func_result_name(Oid functionId)
{
      char     *result;
      HeapTuple   procTuple;
      Datum       proargmodes;
      Datum       proargnames;
      bool        isnull;
      ArrayType  *arr;
      int               numargs;
      char     *argmodes;
      Datum    *argnames;
      int               numoutargs;
      int               nargnames;
      int               i;

      /* First fetch the function's pg_proc row */
      procTuple = SearchSysCache(PROCOID,
                                             ObjectIdGetDatum(functionId),
                                             0, 0, 0);
      if (!HeapTupleIsValid(procTuple))
            elog(ERROR, "cache lookup failed for function %u", functionId);

      /* If there are no named OUT parameters, return NULL */
      if (heap_attisnull(procTuple, Anum_pg_proc_proargmodes) ||
            heap_attisnull(procTuple, Anum_pg_proc_proargnames))
            result = NULL;
      else
      {
            /* Get the data out of the tuple */
            proargmodes = SysCacheGetAttr(PROCOID, procTuple,
                                                        Anum_pg_proc_proargmodes,
                                                        &isnull);
            Assert(!isnull);
            proargnames = SysCacheGetAttr(PROCOID, procTuple,
                                                        Anum_pg_proc_proargnames,
                                                        &isnull);
            Assert(!isnull);

            /*
             * We expect the arrays to be 1-D arrays of the right types; verify
             * that.  For the char array, we don't need to use deconstruct_array()
             * since the array data is just going to look like a C array of
             * values.
             */
            arr = DatumGetArrayTypeP(proargmodes);    /* ensure not toasted */
            numargs = ARR_DIMS(arr)[0];
            if (ARR_NDIM(arr) != 1 ||
                  numargs < 0 ||
                  ARR_HASNULL(arr) ||
                  ARR_ELEMTYPE(arr) != CHAROID)
                  elog(ERROR, "proargmodes is not a 1-D char array");
            argmodes = (char *) ARR_DATA_PTR(arr);
            arr = DatumGetArrayTypeP(proargnames);    /* ensure not toasted */
            if (ARR_NDIM(arr) != 1 ||
                  ARR_DIMS(arr)[0] != numargs ||
                  ARR_HASNULL(arr) ||
                  ARR_ELEMTYPE(arr) != TEXTOID)
                  elog(ERROR, "proargnames is not a 1-D text array");
            deconstruct_array(arr, TEXTOID, -1, false, 'i',
                                      &argnames, NULL, &nargnames);
            Assert(nargnames == numargs);

            /* scan for output argument(s) */
            result = NULL;
            numoutargs = 0;
            for (i = 0; i < numargs; i++)
            {
                  if (argmodes[i] == PROARGMODE_IN ||
                        argmodes[i] == PROARGMODE_VARIADIC)
                        continue;
                  Assert(argmodes[i] == PROARGMODE_OUT ||
                           argmodes[i] == PROARGMODE_INOUT ||
                           argmodes[i] == PROARGMODE_TABLE);
                  if (++numoutargs > 1)
                  {
                        /* multiple out args, so forget it */
                        result = NULL;
                        break;
                  }
                  result = TextDatumGetCString(argnames[i]);
                  if (result == NULL || result[0] == '\0')
                  {
                        /* Parameter is not named, so forget it */
                        result = NULL;
                        break;
                  }
            }
      }

      ReleaseSysCache(procTuple);

      return result;
}


/*
 * build_function_result_tupdesc_t
 *
 * Given a pg_proc row for a function, return a tuple descriptor for the
 * result rowtype, or NULL if the function does not have OUT parameters.
 *
 * Note that this does not handle resolution of polymorphic types;
 * that is deliberate.
 */
TupleDesc
build_function_result_tupdesc_t(HeapTuple procTuple)
{
      Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(procTuple);
      Datum       proallargtypes;
      Datum       proargmodes;
      Datum       proargnames;
      bool        isnull;

      /* Return NULL if the function isn't declared to return RECORD */
      if (procform->prorettype != RECORDOID)
            return NULL;

      /* If there are no OUT parameters, return NULL */
      if (heap_attisnull(procTuple, Anum_pg_proc_proallargtypes) ||
            heap_attisnull(procTuple, Anum_pg_proc_proargmodes))
            return NULL;

      /* Get the data out of the tuple */
      proallargtypes = SysCacheGetAttr(PROCOID, procTuple,
                                                       Anum_pg_proc_proallargtypes,
                                                       &isnull);
      Assert(!isnull);
      proargmodes = SysCacheGetAttr(PROCOID, procTuple,
                                                  Anum_pg_proc_proargmodes,
                                                  &isnull);
      Assert(!isnull);
      proargnames = SysCacheGetAttr(PROCOID, procTuple,
                                                  Anum_pg_proc_proargnames,
                                                  &isnull);
      if (isnull)
            proargnames = PointerGetDatum(NULL);      /* just to be sure */

      return build_function_result_tupdesc_d(proallargtypes,
                                                               proargmodes,
                                                               proargnames);
}

/*
 * build_function_result_tupdesc_d
 *
 * Build a RECORD function's tupledesc from the pg_proc proallargtypes,
 * proargmodes, and proargnames arrays.  This is split out for the
 * convenience of ProcedureCreate, which needs to be able to compute the
 * tupledesc before actually creating the function.
 *
 * Returns NULL if there are not at least two OUT or INOUT arguments.
 */
TupleDesc
build_function_result_tupdesc_d(Datum proallargtypes,
                                                Datum proargmodes,
                                                Datum proargnames)
{
      TupleDesc   desc;
      ArrayType  *arr;
      int               numargs;
      Oid            *argtypes;
      char     *argmodes;
      Datum    *argnames = NULL;
      Oid            *outargtypes;
      char    **outargnames;
      int               numoutargs;
      int               nargnames;
      int               i;

      /* Can't have output args if columns are null */
      if (proallargtypes == PointerGetDatum(NULL) ||
            proargmodes == PointerGetDatum(NULL))
            return NULL;

      /*
       * We expect the arrays to be 1-D arrays of the right types; verify that.
       * For the OID and char arrays, we don't need to use deconstruct_array()
       * since the array data is just going to look like a C array of values.
       */
      arr = DatumGetArrayTypeP(proallargtypes); /* ensure not toasted */
      numargs = ARR_DIMS(arr)[0];
      if (ARR_NDIM(arr) != 1 ||
            numargs < 0 ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != OIDOID)
            elog(ERROR, "proallargtypes is not a 1-D Oid array");
      argtypes = (Oid *) ARR_DATA_PTR(arr);
      arr = DatumGetArrayTypeP(proargmodes);          /* ensure not toasted */
      if (ARR_NDIM(arr) != 1 ||
            ARR_DIMS(arr)[0] != numargs ||
            ARR_HASNULL(arr) ||
            ARR_ELEMTYPE(arr) != CHAROID)
            elog(ERROR, "proargmodes is not a 1-D char array");
      argmodes = (char *) ARR_DATA_PTR(arr);
      if (proargnames != PointerGetDatum(NULL))
      {
            arr = DatumGetArrayTypeP(proargnames);    /* ensure not toasted */
            if (ARR_NDIM(arr) != 1 ||
                  ARR_DIMS(arr)[0] != numargs ||
                  ARR_HASNULL(arr) ||
                  ARR_ELEMTYPE(arr) != TEXTOID)
                  elog(ERROR, "proargnames is not a 1-D text array");
            deconstruct_array(arr, TEXTOID, -1, false, 'i',
                                      &argnames, NULL, &nargnames);
            Assert(nargnames == numargs);
      }

      /* zero elements probably shouldn't happen, but handle it gracefully */
      if (numargs <= 0)
            return NULL;

      /* extract output-argument types and names */
      outargtypes = (Oid *) palloc(numargs * sizeof(Oid));
      outargnames = (char **) palloc(numargs * sizeof(char *));
      numoutargs = 0;
      for (i = 0; i < numargs; i++)
      {
            char     *pname;

            if (argmodes[i] == PROARGMODE_IN ||
                  argmodes[i] == PROARGMODE_VARIADIC)
                  continue;
            Assert(argmodes[i] == PROARGMODE_OUT ||
                     argmodes[i] == PROARGMODE_INOUT ||
                     argmodes[i] == PROARGMODE_TABLE);
            outargtypes[numoutargs] = argtypes[i];
            if (argnames)
                  pname = TextDatumGetCString(argnames[i]);
            else
                  pname = NULL;
            if (pname == NULL || pname[0] == '\0')
            {
                  /* Parameter is not named, so gin up a column name */
                  pname = (char *) palloc(32);
                  snprintf(pname, 32, "column%d", numoutargs + 1);
            }
            outargnames[numoutargs] = pname;
            numoutargs++;
      }

      /*
       * If there is no output argument, or only one, the function does not
       * return tuples.
       */
      if (numoutargs < 2)
            return NULL;

      desc = CreateTemplateTupleDesc(numoutargs, false);
      for (i = 0; i < numoutargs; i++)
      {
            TupleDescInitEntry(desc, i + 1,
                                       outargnames[i],
                                       outargtypes[i],
                                       -1,
                                       0);
      }

      return desc;
}


/*
 * RelationNameGetTupleDesc
 *
 * Given a (possibly qualified) relation name, build a TupleDesc.
 *
 * Note: while this works as advertised, it's seldom the best way to
 * build a tupdesc for a function's result type.  It's kept around
 * only for backwards compatibility with existing user-written code.
 */
TupleDesc
RelationNameGetTupleDesc(const char *relname)
{
      RangeVar   *relvar;
      Relation    rel;
      TupleDesc   tupdesc;
      List     *relname_list;

      /* Open relation and copy the tuple description */
      relname_list = stringToQualifiedNameList(relname);
      relvar = makeRangeVarFromNameList(relname_list);
      rel = relation_openrv(relvar, AccessShareLock);
      tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
      relation_close(rel, AccessShareLock);

      return tupdesc;
}

/*
 * TypeGetTupleDesc
 *
 * Given a type Oid, build a TupleDesc.  (In most cases you should be
 * using get_call_result_type or one of its siblings instead of this
 * routine, so that you can handle OUT parameters, RECORD result type,
 * and polymorphic results.)
 *
 * If the type is composite, *and* a colaliases List is provided, *and*
 * the List is of natts length, use the aliases instead of the relation
 * attnames.  (NB: this usage is deprecated since it may result in
 * creation of unnecessary transient record types.)
 *
 * If the type is a base type, a single item alias List is required.
 */
TupleDesc
TypeGetTupleDesc(Oid typeoid, List *colaliases)
{
      TypeFuncClass functypclass = get_type_func_class(typeoid);
      TupleDesc   tupdesc = NULL;

      /*
       * Build a suitable tupledesc representing the output rows
       */
      if (functypclass == TYPEFUNC_COMPOSITE)
      {
            /* Composite data type, e.g. a table's row type */
            tupdesc = lookup_rowtype_tupdesc_copy(typeoid, -1);

            if (colaliases != NIL)
            {
                  int               natts = tupdesc->natts;
                  int               varattno;

                  /* does the list length match the number of attributes? */
                  if (list_length(colaliases) != natts)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                                     errmsg("number of aliases does not match number of columns")));

                  /* OK, use the aliases instead */
                  for (varattno = 0; varattno < natts; varattno++)
                  {
                        char     *label = strVal(list_nth(colaliases, varattno));

                        if (label != NULL)
                              namestrcpy(&(tupdesc->attrs[varattno]->attname), label);
                  }

                  /* The tuple type is now an anonymous record type */
                  tupdesc->tdtypeid = RECORDOID;
                  tupdesc->tdtypmod = -1;
            }
      }
      else if (functypclass == TYPEFUNC_SCALAR)
      {
            /* Base data type, i.e. scalar */
            char     *attname;

            /* the alias list is required for base types */
            if (colaliases == NIL)
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("no column alias was provided")));

            /* the alias list length must be 1 */
            if (list_length(colaliases) != 1)
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                    errmsg("number of aliases does not match number of columns")));

            /* OK, get the column alias */
            attname = strVal(linitial(colaliases));

            tupdesc = CreateTemplateTupleDesc(1, false);
            TupleDescInitEntry(tupdesc,
                                       (AttrNumber) 1,
                                       attname,
                                       typeoid,
                                       -1,
                                       0);
      }
      else if (functypclass == TYPEFUNC_RECORD)
      {
            /* XXX can't support this because typmod wasn't passed in ... */
            ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("could not determine row description for function returning record")));
      }
      else
      {
            /* crummy error message, but parser should have caught this */
            elog(ERROR, "function in FROM has unsupported return type");
      }

      return tupdesc;
}

Generated by  Doxygen 1.6.0   Back to index