/src/postgres/src/backend/utils/adt/array_userfuncs.c

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/*-------------------------------------------------------------------------
 *
 * array_userfuncs.c
 *    Misc user-visible array support functions
 *
 * Copyright (c) 2003-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/array_userfuncs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_operator_d.h"
#include "catalog/pg_type.h"
#include "common/int.h"
#include "common/pg_prng.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "nodes/supportnodes.h"
#include "port/pg_bitutils.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/tuplesort.h"
#include "utils/typcache.h"

/*
 * SerialIOData
 *    Used for caching element-type data in array_agg_serialize
 */
typedef struct SerialIOData
{
  FmgrInfo  typsend;
} SerialIOData;

/*
 * DeserialIOData
 *    Used for caching element-type data in array_agg_deserialize
 */
typedef struct DeserialIOData
{
  FmgrInfo  typreceive;
  Oid     typioparam;
} DeserialIOData;

/*
 * ArraySortCachedInfo
 *    Used for caching catalog data in array_sort
 */
typedef struct ArraySortCachedInfo
{
  ArrayMetaState array_meta;  /* metadata for array_create_iterator */
  Oid     elem_lt_opr;  /* "<" operator for element type */
  Oid     elem_gt_opr;  /* ">" operator for element type */
  Oid     array_type;   /* pg_type OID of array type */
} ArraySortCachedInfo;

static Datum array_position_common(FunctionCallInfo fcinfo);


/*
 * fetch_array_arg_replace_nulls
 *
 * Fetch an array-valued argument in expanded form; if it's null, construct an
 * empty array value of the proper data type.  Also cache basic element type
 * information in fn_extra.
 *
 * Caution: if the input is a read/write pointer, this returns the input
 * argument; so callers must be sure that their changes are "safe", that is
 * they cannot leave the array in a corrupt state.
 *
 * If we're being called as an aggregate function, make sure any newly-made
 * expanded array is allocated in the aggregate state context, so as to save
 * copying operations.
 */
static ExpandedArrayHeader *
fetch_array_arg_replace_nulls(FunctionCallInfo fcinfo, int argno)
{
  ExpandedArrayHeader *eah;
  Oid     element_type;
  ArrayMetaState *my_extra;
  MemoryContext resultcxt;

  /* If first time through, create datatype cache struct */
  my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
  if (my_extra == NULL)
  {
    my_extra = (ArrayMetaState *)
      MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                 sizeof(ArrayMetaState));
    my_extra->element_type = InvalidOid;
    fcinfo->flinfo->fn_extra = my_extra;
  }

  /* Figure out which context we want the result in */
  if (!AggCheckCallContext(fcinfo, &resultcxt))
    resultcxt = CurrentMemoryContext;

  /* Now collect the array value */
  if (!PG_ARGISNULL(argno))
  {
    MemoryContext oldcxt = MemoryContextSwitchTo(resultcxt);

    eah = PG_GETARG_EXPANDED_ARRAYX(argno, my_extra);
    MemoryContextSwitchTo(oldcxt);
  }
  else
  {
    /* We have to look up the array type and element type */
    Oid     arr_typeid = get_fn_expr_argtype(fcinfo->flinfo, argno);

    if (!OidIsValid(arr_typeid))
      ereport(ERROR,
          (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
           errmsg("could not determine input data type")));
    element_type = get_element_type(arr_typeid);
    if (!OidIsValid(element_type))
      ereport(ERROR,
          (errcode(ERRCODE_DATATYPE_MISMATCH),
           errmsg("input data type is not an array")));

    eah = construct_empty_expanded_array(element_type,
                       resultcxt,
                       my_extra);
  }

  return eah;
}

/*-----------------------------------------------------------------------------
 * array_append :
 *    push an element onto the end of a one-dimensional array
 *----------------------------------------------------------------------------
 */
Datum
array_append(PG_FUNCTION_ARGS)
{
  ExpandedArrayHeader *eah;
  Datum   newelem;
  bool    isNull;
  Datum   result;
  int      *dimv,
         *lb;
  int     indx;
  ArrayMetaState *my_extra;

  eah = fetch_array_arg_replace_nulls(fcinfo, 0);
  isNull = PG_ARGISNULL(1);
  if (isNull)
    newelem = (Datum) 0;
  else
    newelem = PG_GETARG_DATUM(1);

  if (eah->ndims == 1)
  {
    /* append newelem */
    lb = eah->lbound;
    dimv = eah->dims;

    /* index of added elem is at lb[0] + (dimv[0] - 1) + 1 */
    if (pg_add_s32_overflow(lb[0], dimv[0], &indx))
      ereport(ERROR,
          (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
           errmsg("integer out of range")));
  }
  else if (eah->ndims == 0)
    indx = 1;
  else
    ereport(ERROR,
        (errcode(ERRCODE_DATA_EXCEPTION),
         errmsg("argument must be empty or one-dimensional array")));

  /* Perform element insertion */
  my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;

  result = array_set_element(EOHPGetRWDatum(&eah->hdr),
                 1, &indx, newelem, isNull,
                 -1, my_extra->typlen, my_extra->typbyval, my_extra->typalign);

  PG_RETURN_DATUM(result);
}

/*
 * array_append_support()
 *
 * Planner support function for array_append()
 */
Datum
array_append_support(PG_FUNCTION_ARGS)
{
  Node     *rawreq = (Node *) PG_GETARG_POINTER(0);
  Node     *ret = NULL;

  if (IsA(rawreq, SupportRequestModifyInPlace))
  {
    /*
     * We can optimize in-place appends if the function's array argument
     * is the array being assigned to.  We don't need to worry about array
     * references within the other argument.
     */
    SupportRequestModifyInPlace *req = (SupportRequestModifyInPlace *) rawreq;
    Param    *arg = (Param *) linitial(req->args);

    if (arg && IsA(arg, Param) &&
      arg->paramkind == PARAM_EXTERN &&
      arg->paramid == req->paramid)
      ret = (Node *) arg;
  }

  PG_RETURN_POINTER(ret);
}

/*-----------------------------------------------------------------------------
 * array_prepend :
 *    push an element onto the front of a one-dimensional array
 *----------------------------------------------------------------------------
 */
Datum
array_prepend(PG_FUNCTION_ARGS)
{
  ExpandedArrayHeader *eah;
  Datum   newelem;
  bool    isNull;
  Datum   result;
  int      *lb;
  int     indx;
  int     lb0;
  ArrayMetaState *my_extra;

  isNull = PG_ARGISNULL(0);
  if (isNull)
    newelem = (Datum) 0;
  else
    newelem = PG_GETARG_DATUM(0);
  eah = fetch_array_arg_replace_nulls(fcinfo, 1);

  if (eah->ndims == 1)
  {
    /* prepend newelem */
    lb = eah->lbound;
    lb0 = lb[0];

    if (pg_sub_s32_overflow(lb0, 1, &indx))
      ereport(ERROR,
          (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
           errmsg("integer out of range")));
  }
  else if (eah->ndims == 0)
  {
    indx = 1;
    lb0 = 1;
  }
  else
    ereport(ERROR,
        (errcode(ERRCODE_DATA_EXCEPTION),
         errmsg("argument must be empty or one-dimensional array")));

  /* Perform element insertion */
  my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;

  result = array_set_element(EOHPGetRWDatum(&eah->hdr),
                 1, &indx, newelem, isNull,
                 -1, my_extra->typlen, my_extra->typbyval, my_extra->typalign);

  /* Readjust result's LB to match the input's, as expected for prepend */
  Assert(result == EOHPGetRWDatum(&eah->hdr));
  if (eah->ndims == 1)
  {
    /* This is ok whether we've deconstructed or not */
    eah->lbound[0] = lb0;
  }

  PG_RETURN_DATUM(result);
}

/*
 * array_prepend_support()
 *
 * Planner support function for array_prepend()
 */
Datum
array_prepend_support(PG_FUNCTION_ARGS)
{
  Node     *rawreq = (Node *) PG_GETARG_POINTER(0);
  Node     *ret = NULL;

  if (IsA(rawreq, SupportRequestModifyInPlace))
  {
    /*
     * We can optimize in-place prepends if the function's array argument
     * is the array being assigned to.  We don't need to worry about array
     * references within the other argument.
     */
    SupportRequestModifyInPlace *req = (SupportRequestModifyInPlace *) rawreq;
    Param    *arg = (Param *) lsecond(req->args);

    if (arg && IsA(arg, Param) &&
      arg->paramkind == PARAM_EXTERN &&
      arg->paramid == req->paramid)
      ret = (Node *) arg;
  }

  PG_RETURN_POINTER(ret);
}

/*-----------------------------------------------------------------------------
 * array_cat :
 *    concatenate two nD arrays to form an nD array, or
 *    push an (n-1)D array onto the end of an nD array
 *----------------------------------------------------------------------------
 */
Datum
array_cat(PG_FUNCTION_ARGS)
{
  ArrayType  *v1,
         *v2;
  ArrayType  *result;
  int      *dims,
         *lbs,
        ndims,
        nitems,
        ndatabytes,
        nbytes;
  int      *dims1,
         *lbs1,
        ndims1,
        nitems1,
        ndatabytes1;
  int      *dims2,
         *lbs2,
        ndims2,
        nitems2,
        ndatabytes2;
  int     i;
  char     *dat1,
         *dat2;
  bits8    *bitmap1,
         *bitmap2;
  Oid     element_type;
  Oid     element_type1;
  Oid     element_type2;
  int32   dataoffset;

  /* Concatenating a null array is a no-op, just return the other input */
  if (PG_ARGISNULL(0))
  {
    if (PG_ARGISNULL(1))
      PG_RETURN_NULL();
    result = PG_GETARG_ARRAYTYPE_P(1);
    PG_RETURN_ARRAYTYPE_P(result);
  }
  if (PG_ARGISNULL(1))
  {
    result = PG_GETARG_ARRAYTYPE_P(0);
    PG_RETURN_ARRAYTYPE_P(result);
  }

  v1 = PG_GETARG_ARRAYTYPE_P(0);
  v2 = PG_GETARG_ARRAYTYPE_P(1);

  element_type1 = ARR_ELEMTYPE(v1);
  element_type2 = ARR_ELEMTYPE(v2);

  /* Check we have matching element types */
  if (element_type1 != element_type2)
    ereport(ERROR,
        (errcode(ERRCODE_DATATYPE_MISMATCH),
         errmsg("cannot concatenate incompatible arrays"),
         errdetail("Arrays with element types %s and %s are not "
               "compatible for concatenation.",
               format_type_be(element_type1),
               format_type_be(element_type2))));

  /* OK, use it */
  element_type = element_type1;

  /*----------
   * We must have one of the following combinations of inputs:
   * 1) one empty array, and one non-empty array
   * 2) both arrays empty
   * 3) two arrays with ndims1 == ndims2
   * 4) ndims1 == ndims2 - 1
   * 5) ndims1 == ndims2 + 1
   *----------
   */
  ndims1 = ARR_NDIM(v1);
  ndims2 = ARR_NDIM(v2);

  /*
   * short circuit - if one input array is empty, and the other is not, we
   * return the non-empty one as the result
   *
   * if both are empty, return the first one
   */
  if (ndims1 == 0 && ndims2 > 0)
    PG_RETURN_ARRAYTYPE_P(v2);

  if (ndims2 == 0)
    PG_RETURN_ARRAYTYPE_P(v1);

  /* the rest fall under rule 3, 4, or 5 */
  if (ndims1 != ndims2 &&
    ndims1 != ndims2 - 1 &&
    ndims1 != ndims2 + 1)
    ereport(ERROR,
        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
         errmsg("cannot concatenate incompatible arrays"),
         errdetail("Arrays of %d and %d dimensions are not "
               "compatible for concatenation.",
               ndims1, ndims2)));

  /* get argument array details */
  lbs1 = ARR_LBOUND(v1);
  lbs2 = ARR_LBOUND(v2);
  dims1 = ARR_DIMS(v1);
  dims2 = ARR_DIMS(v2);
  dat1 = ARR_DATA_PTR(v1);
  dat2 = ARR_DATA_PTR(v2);
  bitmap1 = ARR_NULLBITMAP(v1);
  bitmap2 = ARR_NULLBITMAP(v2);
  nitems1 = ArrayGetNItems(ndims1, dims1);
  nitems2 = ArrayGetNItems(ndims2, dims2);
  ndatabytes1 = ARR_SIZE(v1) - ARR_DATA_OFFSET(v1);
  ndatabytes2 = ARR_SIZE(v2) - ARR_DATA_OFFSET(v2);

  if (ndims1 == ndims2)
  {
    /*
     * resulting array is made up of the elements (possibly arrays
     * themselves) of the input argument arrays
     */
    ndims = ndims1;
    dims = (int *) palloc(ndims * sizeof(int));
    lbs = (int *) palloc(ndims * sizeof(int));

    dims[0] = dims1[0] + dims2[0];
    lbs[0] = lbs1[0];

    for (i = 1; i < ndims; i++)
    {
      if (dims1[i] != dims2[i] || lbs1[i] != lbs2[i])
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("cannot concatenate incompatible arrays"),
             errdetail("Arrays with differing element dimensions are "
                   "not compatible for concatenation.")));

      dims[i] = dims1[i];
      lbs[i] = lbs1[i];
    }
  }
  else if (ndims1 == ndims2 - 1)
  {
    /*
     * resulting array has the second argument as the outer array, with
     * the first argument inserted at the front of the outer dimension
     */
    ndims = ndims2;
    dims = (int *) palloc(ndims * sizeof(int));
    lbs = (int *) palloc(ndims * sizeof(int));
    memcpy(dims, dims2, ndims * sizeof(int));
    memcpy(lbs, lbs2, ndims * sizeof(int));

    /* increment number of elements in outer array */
    dims[0] += 1;

    /* make sure the added element matches our existing elements */
    for (i = 0; i < ndims1; i++)
    {
      if (dims1[i] != dims[i + 1] || lbs1[i] != lbs[i + 1])
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("cannot concatenate incompatible arrays"),
             errdetail("Arrays with differing dimensions are not "
                   "compatible for concatenation.")));
    }
  }
  else
  {
    /*
     * (ndims1 == ndims2 + 1)
     *
     * resulting array has the first argument as the outer array, with the
     * second argument appended to the end of the outer dimension
     */
    ndims = ndims1;
    dims = (int *) palloc(ndims * sizeof(int));
    lbs = (int *) palloc(ndims * sizeof(int));
    memcpy(dims, dims1, ndims * sizeof(int));
    memcpy(lbs, lbs1, ndims * sizeof(int));

    /* increment number of elements in outer array */
    dims[0] += 1;

    /* make sure the added element matches our existing elements */
    for (i = 0; i < ndims2; i++)
    {
      if (dims2[i] != dims[i + 1] || lbs2[i] != lbs[i + 1])
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("cannot concatenate incompatible arrays"),
             errdetail("Arrays with differing dimensions are not "
                   "compatible for concatenation.")));
    }
  }

  /* Do this mainly for overflow checking */
  nitems = ArrayGetNItems(ndims, dims);
  ArrayCheckBounds(ndims, dims, lbs);

  /* build the result array */
  ndatabytes = ndatabytes1 + ndatabytes2;
  if (ARR_HASNULL(v1) || ARR_HASNULL(v2))
  {
    dataoffset = ARR_OVERHEAD_WITHNULLS(ndims, nitems);
    nbytes = ndatabytes + dataoffset;
  }
  else
  {
    dataoffset = 0;     /* marker for no null bitmap */
    nbytes = ndatabytes + ARR_OVERHEAD_NONULLS(ndims);
  }
  result = (ArrayType *) palloc0(nbytes);
  SET_VARSIZE(result, nbytes);
  result->ndim = ndims;
  result->dataoffset = dataoffset;
  result->elemtype = element_type;
  memcpy(ARR_DIMS(result), dims, ndims * sizeof(int));
  memcpy(ARR_LBOUND(result), lbs, ndims * sizeof(int));
  /* data area is arg1 then arg2 */
  memcpy(ARR_DATA_PTR(result), dat1, ndatabytes1);
  memcpy(ARR_DATA_PTR(result) + ndatabytes1, dat2, ndatabytes2);
  /* handle the null bitmap if needed */
  if (ARR_HASNULL(result))
  {
    array_bitmap_copy(ARR_NULLBITMAP(result), 0,
              bitmap1, 0,
              nitems1);
    array_bitmap_copy(ARR_NULLBITMAP(result), nitems1,
              bitmap2, 0,
              nitems2);
  }

  PG_RETURN_ARRAYTYPE_P(result);
}


/*
 * ARRAY_AGG(anynonarray) aggregate function
 */
Datum
array_agg_transfn(PG_FUNCTION_ARGS)
{
  Oid     arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
  MemoryContext aggcontext;
  ArrayBuildState *state;
  Datum   elem;

  if (arg1_typeid == InvalidOid)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("could not determine input data type")));

  /*
   * Note: we do not need a run-time check about whether arg1_typeid is a
   * valid array element type, because the parser would have verified that
   * while resolving the input/result types of this polymorphic aggregate.
   */

  if (!AggCheckCallContext(fcinfo, &aggcontext))
  {
    /* cannot be called directly because of internal-type argument */
    elog(ERROR, "array_agg_transfn called in non-aggregate context");
  }

  if (PG_ARGISNULL(0))
    state = initArrayResult(arg1_typeid, aggcontext, false);
  else
    state = (ArrayBuildState *) PG_GETARG_POINTER(0);

  elem = PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1);

  state = accumArrayResult(state,
               elem,
               PG_ARGISNULL(1),
               arg1_typeid,
               aggcontext);

  /*
   * The transition type for array_agg() is declared to be "internal", which
   * is a pass-by-value type the same size as a pointer.  So we can safely
   * pass the ArrayBuildState pointer through nodeAgg.c's machinations.
   */
  PG_RETURN_POINTER(state);
}

Datum
array_agg_combine(PG_FUNCTION_ARGS)
{
  ArrayBuildState *state1;
  ArrayBuildState *state2;
  MemoryContext agg_context;
  MemoryContext old_context;

  if (!AggCheckCallContext(fcinfo, &agg_context))
    elog(ERROR, "aggregate function called in non-aggregate context");

  state1 = PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0);
  state2 = PG_ARGISNULL(1) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(1);

  if (state2 == NULL)
  {
    /*
     * NULL state2 is easy, just return state1, which we know is already
     * in the agg_context
     */
    if (state1 == NULL)
      PG_RETURN_NULL();
    PG_RETURN_POINTER(state1);
  }

  if (state1 == NULL)
  {
    /* We must copy state2's data into the agg_context */
    state1 = initArrayResultWithSize(state2->element_type, agg_context,
                     false, state2->alen);

    old_context = MemoryContextSwitchTo(agg_context);

    for (int i = 0; i < state2->nelems; i++)
    {
      if (!state2->dnulls[i])
        state1->dvalues[i] = datumCopy(state2->dvalues[i],
                         state1->typbyval,
                         state1->typlen);
      else
        state1->dvalues[i] = (Datum) 0;
    }

    MemoryContextSwitchTo(old_context);

    memcpy(state1->dnulls, state2->dnulls, sizeof(bool) * state2->nelems);

    state1->nelems = state2->nelems;

    PG_RETURN_POINTER(state1);
  }
  else if (state2->nelems > 0)
  {
    /* We only need to combine the two states if state2 has any elements */
    int     reqsize = state1->nelems + state2->nelems;
    MemoryContext oldContext = MemoryContextSwitchTo(state1->mcontext);

    Assert(state1->element_type == state2->element_type);

    /* Enlarge state1 arrays if needed */
    if (state1->alen < reqsize)
    {
      /* Use a power of 2 size rather than allocating just reqsize */
      state1->alen = pg_nextpower2_32(reqsize);
      state1->dvalues = (Datum *) repalloc(state1->dvalues,
                         state1->alen * sizeof(Datum));
      state1->dnulls = (bool *) repalloc(state1->dnulls,
                         state1->alen * sizeof(bool));
    }

    /* Copy in the state2 elements to the end of the state1 arrays */
    for (int i = 0; i < state2->nelems; i++)
    {
      if (!state2->dnulls[i])
        state1->dvalues[i + state1->nelems] =
          datumCopy(state2->dvalues[i],
                state1->typbyval,
                state1->typlen);
      else
        state1->dvalues[i + state1->nelems] = (Datum) 0;
    }

    memcpy(&state1->dnulls[state1->nelems], state2->dnulls,
         sizeof(bool) * state2->nelems);

    state1->nelems = reqsize;

    MemoryContextSwitchTo(oldContext);
  }

  PG_RETURN_POINTER(state1);
}

/*
 * array_agg_serialize
 *    Serialize ArrayBuildState into bytea.
 */
Datum
array_agg_serialize(PG_FUNCTION_ARGS)
{
  ArrayBuildState *state;
  StringInfoData buf;
  bytea    *result;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = (ArrayBuildState *) PG_GETARG_POINTER(0);

  pq_begintypsend(&buf);

  /*
   * element_type. Putting this first is more convenient in deserialization
   */
  pq_sendint32(&buf, state->element_type);

  /*
   * nelems -- send first so we know how large to make the dvalues and
   * dnulls array during deserialization.
   */
  pq_sendint64(&buf, state->nelems);

  /* alen can be decided during deserialization */

  /* typlen */
  pq_sendint16(&buf, state->typlen);

  /* typbyval */
  pq_sendbyte(&buf, state->typbyval);

  /* typalign */
  pq_sendbyte(&buf, state->typalign);

  /* dnulls */
  pq_sendbytes(&buf, state->dnulls, sizeof(bool) * state->nelems);

  /*
   * dvalues.  By agreement with array_agg_deserialize, when the element
   * type is byval, we just transmit the Datum array as-is, including any
   * null elements.  For by-ref types, we must invoke the element type's
   * send function, and we skip null elements (which is why the nulls flags
   * must be sent first).
   */
  if (state->typbyval)
    pq_sendbytes(&buf, state->dvalues, sizeof(Datum) * state->nelems);
  else
  {
    SerialIOData *iodata;
    int     i;

    /* Avoid repeat catalog lookups for typsend function */
    iodata = (SerialIOData *) fcinfo->flinfo->fn_extra;
    if (iodata == NULL)
    {
      Oid     typsend;
      bool    typisvarlena;

      iodata = (SerialIOData *)
        MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                   sizeof(SerialIOData));
      getTypeBinaryOutputInfo(state->element_type, &typsend,
                  &typisvarlena);
      fmgr_info_cxt(typsend, &iodata->typsend,
              fcinfo->flinfo->fn_mcxt);
      fcinfo->flinfo->fn_extra = iodata;
    }

    for (i = 0; i < state->nelems; i++)
    {
      bytea    *outputbytes;

      if (state->dnulls[i])
        continue;
      outputbytes = SendFunctionCall(&iodata->typsend,
                       state->dvalues[i]);
      pq_sendint32(&buf, VARSIZE(outputbytes) - VARHDRSZ);
      pq_sendbytes(&buf, VARDATA(outputbytes),
             VARSIZE(outputbytes) - VARHDRSZ);
    }
  }

  result = pq_endtypsend(&buf);

  PG_RETURN_BYTEA_P(result);
}

Datum
array_agg_deserialize(PG_FUNCTION_ARGS)
{
  bytea    *sstate;
  ArrayBuildState *result;
  StringInfoData buf;
  Oid     element_type;
  int64   nelems;
  const char *temp;

  if (!AggCheckCallContext(fcinfo, NULL))
    elog(ERROR, "aggregate function called in non-aggregate context");

  sstate = PG_GETARG_BYTEA_PP(0);

  /*
   * Initialize a StringInfo so that we can "receive" it using the standard
   * recv-function infrastructure.
   */
  initReadOnlyStringInfo(&buf, VARDATA_ANY(sstate),
               VARSIZE_ANY_EXHDR(sstate));

  /* element_type */
  element_type = pq_getmsgint(&buf, 4);

  /* nelems */
  nelems = pq_getmsgint64(&buf);

  /* Create output ArrayBuildState with the needed number of elements */
  result = initArrayResultWithSize(element_type, CurrentMemoryContext,
                   false, nelems);
  result->nelems = nelems;

  /* typlen */
  result->typlen = pq_getmsgint(&buf, 2);

  /* typbyval */
  result->typbyval = pq_getmsgbyte(&buf);

  /* typalign */
  result->typalign = pq_getmsgbyte(&buf);

  /* dnulls */
  temp = pq_getmsgbytes(&buf, sizeof(bool) * nelems);
  memcpy(result->dnulls, temp, sizeof(bool) * nelems);

  /* dvalues --- see comment in array_agg_serialize */
  if (result->typbyval)
  {
    temp = pq_getmsgbytes(&buf, sizeof(Datum) * nelems);
    memcpy(result->dvalues, temp, sizeof(Datum) * nelems);
  }
  else
  {
    DeserialIOData *iodata;

    /* Avoid repeat catalog lookups for typreceive function */
    iodata = (DeserialIOData *) fcinfo->flinfo->fn_extra;
    if (iodata == NULL)
    {
      Oid     typreceive;

      iodata = (DeserialIOData *)
        MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                   sizeof(DeserialIOData));
      getTypeBinaryInputInfo(element_type, &typreceive,
                   &iodata->typioparam);
      fmgr_info_cxt(typreceive, &iodata->typreceive,
              fcinfo->flinfo->fn_mcxt);
      fcinfo->flinfo->fn_extra = iodata;
    }

    for (int i = 0; i < nelems; i++)
    {
      int     itemlen;
      StringInfoData elem_buf;

      if (result->dnulls[i])
      {
        result->dvalues[i] = (Datum) 0;
        continue;
      }

      itemlen = pq_getmsgint(&buf, 4);
      if (itemlen < 0 || itemlen > (buf.len - buf.cursor))
        ereport(ERROR,
            (errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
             errmsg("insufficient data left in message")));

      /*
       * Rather than copying data around, we just initialize a
       * StringInfo pointing to the correct portion of the message
       * buffer.
       */
      initReadOnlyStringInfo(&elem_buf, &buf.data[buf.cursor], itemlen);

      buf.cursor += itemlen;

      /* Now call the element's receiveproc */
      result->dvalues[i] = ReceiveFunctionCall(&iodata->typreceive,
                           &elem_buf,
                           iodata->typioparam,
                           -1);
    }
  }

  pq_getmsgend(&buf);

  PG_RETURN_POINTER(result);
}

Datum
array_agg_finalfn(PG_FUNCTION_ARGS)
{
  Datum   result;
  ArrayBuildState *state;
  int     dims[1];
  int     lbs[1];

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0);

  if (state == NULL)
    PG_RETURN_NULL();   /* returns null iff no input values */

  dims[0] = state->nelems;
  lbs[0] = 1;

  /*
   * Make the result.  We cannot release the ArrayBuildState because
   * sometimes aggregate final functions are re-executed.  Rather, it is
   * nodeAgg.c's responsibility to reset the aggcontext when it's safe to do
   * so.
   */
  result = makeMdArrayResult(state, 1, dims, lbs,
                 CurrentMemoryContext,
                 false);

  PG_RETURN_DATUM(result);
}

/*
 * ARRAY_AGG(anyarray) aggregate function
 */
Datum
array_agg_array_transfn(PG_FUNCTION_ARGS)
{
  Oid     arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
  MemoryContext aggcontext;
  ArrayBuildStateArr *state;

  if (arg1_typeid == InvalidOid)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("could not determine input data type")));

  /*
   * Note: we do not need a run-time check about whether arg1_typeid is a
   * valid array type, because the parser would have verified that while
   * resolving the input/result types of this polymorphic aggregate.
   */

  if (!AggCheckCallContext(fcinfo, &aggcontext))
  {
    /* cannot be called directly because of internal-type argument */
    elog(ERROR, "array_agg_array_transfn called in non-aggregate context");
  }


  if (PG_ARGISNULL(0))
    state = initArrayResultArr(arg1_typeid, InvalidOid, aggcontext, false);
  else
    state = (ArrayBuildStateArr *) PG_GETARG_POINTER(0);

  state = accumArrayResultArr(state,
                PG_GETARG_DATUM(1),
                PG_ARGISNULL(1),
                arg1_typeid,
                aggcontext);

  /*
   * The transition type for array_agg() is declared to be "internal", which
   * is a pass-by-value type the same size as a pointer.  So we can safely
   * pass the ArrayBuildStateArr pointer through nodeAgg.c's machinations.
   */
  PG_RETURN_POINTER(state);
}

Datum
array_agg_array_combine(PG_FUNCTION_ARGS)
{
  ArrayBuildStateArr *state1;
  ArrayBuildStateArr *state2;
  MemoryContext agg_context;
  MemoryContext old_context;

  if (!AggCheckCallContext(fcinfo, &agg_context))
    elog(ERROR, "aggregate function called in non-aggregate context");

  state1 = PG_ARGISNULL(0) ? NULL : (ArrayBuildStateArr *) PG_GETARG_POINTER(0);
  state2 = PG_ARGISNULL(1) ? NULL : (ArrayBuildStateArr *) PG_GETARG_POINTER(1);

  if (state2 == NULL)
  {
    /*
     * NULL state2 is easy, just return state1, which we know is already
     * in the agg_context
     */
    if (state1 == NULL)
      PG_RETURN_NULL();
    PG_RETURN_POINTER(state1);
  }

  if (state1 == NULL)
  {
    /* We must copy state2's data into the agg_context */
    old_context = MemoryContextSwitchTo(agg_context);

    state1 = initArrayResultArr(state2->array_type, InvalidOid,
                  agg_context, false);

    state1->abytes = state2->abytes;
    state1->data = (char *) palloc(state1->abytes);

    if (state2->nullbitmap)
    {
      int     size = (state2->aitems + 7) / 8;

      state1->nullbitmap = (bits8 *) palloc(size);
      memcpy(state1->nullbitmap, state2->nullbitmap, size);
    }

    memcpy(state1->data, state2->data, state2->nbytes);
    state1->nbytes = state2->nbytes;
    state1->aitems = state2->aitems;
    state1->nitems = state2->nitems;
    state1->ndims = state2->ndims;
    memcpy(state1->dims, state2->dims, sizeof(state2->dims));
    memcpy(state1->lbs, state2->lbs, sizeof(state2->lbs));
    state1->array_type = state2->array_type;
    state1->element_type = state2->element_type;

    MemoryContextSwitchTo(old_context);

    PG_RETURN_POINTER(state1);
  }

  /* We only need to combine the two states if state2 has any items */
  else if (state2->nitems > 0)
  {
    MemoryContext oldContext;
    int     reqsize = state1->nbytes + state2->nbytes;
    int     i;

    /*
     * Check the states are compatible with each other.  Ensure we use the
     * same error messages that are listed in accumArrayResultArr so that
     * the same error is shown as would have been if we'd not used the
     * combine function for the aggregation.
     */
    if (state1->ndims != state2->ndims)
      ereport(ERROR,
          (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
           errmsg("cannot accumulate arrays of different dimensionality")));

    /* Check dimensions match ignoring the first dimension. */
    for (i = 1; i < state1->ndims; i++)
    {
      if (state1->dims[i] != state2->dims[i] || state1->lbs[i] != state2->lbs[i])
        ereport(ERROR,
            (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
             errmsg("cannot accumulate arrays of different dimensionality")));
    }


    oldContext = MemoryContextSwitchTo(state1->mcontext);

    /*
     * If there's not enough space in state1 then we'll need to reallocate
     * more.
     */
    if (state1->abytes < reqsize)
    {
      /* use a power of 2 size rather than allocating just reqsize */
      state1->abytes = pg_nextpower2_32(reqsize);
      state1->data = (char *) repalloc(state1->data, state1->abytes);
    }

    if (state2->nullbitmap)
    {
      int     newnitems = state1->nitems + state2->nitems;

      if (state1->nullbitmap == NULL)
      {
        /*
         * First input with nulls; we must retrospectively handle any
         * previous inputs by marking all their items non-null.
         */
        state1->aitems = pg_nextpower2_32(Max(256, newnitems + 1));
        state1->nullbitmap = (bits8 *) palloc((state1->aitems + 7) / 8);
        array_bitmap_copy(state1->nullbitmap, 0,
                  NULL, 0,
                  state1->nitems);
      }
      else if (newnitems > state1->aitems)
      {
        int     newaitems = state1->aitems + state2->aitems;

        state1->aitems = pg_nextpower2_32(newaitems);
        state1->nullbitmap = (bits8 *)
          repalloc(state1->nullbitmap, (state1->aitems + 7) / 8);
      }
      array_bitmap_copy(state1->nullbitmap, state1->nitems,
                state2->nullbitmap, 0,
                state2->nitems);
    }

    memcpy(state1->data + state1->nbytes, state2->data, state2->nbytes);
    state1->nbytes += state2->nbytes;
    state1->nitems += state2->nitems;

    state1->dims[0] += state2->dims[0];
    /* remaining dims already match, per test above */

    Assert(state1->array_type == state2->array_type);
    Assert(state1->element_type == state2->element_type);

    MemoryContextSwitchTo(oldContext);
  }

  PG_RETURN_POINTER(state1);
}

/*
 * array_agg_array_serialize
 *    Serialize ArrayBuildStateArr into bytea.
 */
Datum
array_agg_array_serialize(PG_FUNCTION_ARGS)
{
  ArrayBuildStateArr *state;
  StringInfoData buf;
  bytea    *result;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = (ArrayBuildStateArr *) PG_GETARG_POINTER(0);

  pq_begintypsend(&buf);

  /*
   * element_type. Putting this first is more convenient in deserialization
   * so that we can init the new state sooner.
   */
  pq_sendint32(&buf, state->element_type);

  /* array_type */
  pq_sendint32(&buf, state->array_type);

  /* nbytes */
  pq_sendint32(&buf, state->nbytes);

  /* data */
  pq_sendbytes(&buf, state->data, state->nbytes);

  /* abytes */
  pq_sendint32(&buf, state->abytes);

  /* aitems */
  pq_sendint32(&buf, state->aitems);

  /* nullbitmap */
  if (state->nullbitmap)
  {
    Assert(state->aitems > 0);
    pq_sendbytes(&buf, state->nullbitmap, (state->aitems + 7) / 8);
  }

  /* nitems */
  pq_sendint32(&buf, state->nitems);

  /* ndims */
  pq_sendint32(&buf, state->ndims);

  /* dims: XXX should we just send ndims elements? */
  pq_sendbytes(&buf, state->dims, sizeof(state->dims));

  /* lbs */
  pq_sendbytes(&buf, state->lbs, sizeof(state->lbs));

  result = pq_endtypsend(&buf);

  PG_RETURN_BYTEA_P(result);
}

Datum
array_agg_array_deserialize(PG_FUNCTION_ARGS)
{
  bytea    *sstate;
  ArrayBuildStateArr *result;
  StringInfoData buf;
  Oid     element_type;
  Oid     array_type;
  int     nbytes;
  const char *temp;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  sstate = PG_GETARG_BYTEA_PP(0);

  /*
   * Initialize a StringInfo so that we can "receive" it using the standard
   * recv-function infrastructure.
   */
  initReadOnlyStringInfo(&buf, VARDATA_ANY(sstate),
               VARSIZE_ANY_EXHDR(sstate));

  /* element_type */
  element_type = pq_getmsgint(&buf, 4);

  /* array_type */
  array_type = pq_getmsgint(&buf, 4);

  /* nbytes */
  nbytes = pq_getmsgint(&buf, 4);

  result = initArrayResultArr(array_type, element_type,
                CurrentMemoryContext, false);

  result->abytes = 1024;
  while (result->abytes < nbytes)
    result->abytes *= 2;

  result->data = (char *) palloc(result->abytes);

  /* data */
  temp = pq_getmsgbytes(&buf, nbytes);
  memcpy(result->data, temp, nbytes);
  result->nbytes = nbytes;

  /* abytes */
  result->abytes = pq_getmsgint(&buf, 4);

  /* aitems: might be 0 */
  result->aitems = pq_getmsgint(&buf, 4);

  /* nullbitmap */
  if (result->aitems > 0)
  {
    int     size = (result->aitems + 7) / 8;

    result->nullbitmap = (bits8 *) palloc(size);
    temp = pq_getmsgbytes(&buf, size);
    memcpy(result->nullbitmap, temp, size);
  }
  else
    result->nullbitmap = NULL;

  /* nitems */
  result->nitems = pq_getmsgint(&buf, 4);

  /* ndims */
  result->ndims = pq_getmsgint(&buf, 4);

  /* dims */
  temp = pq_getmsgbytes(&buf, sizeof(result->dims));
  memcpy(result->dims, temp, sizeof(result->dims));

  /* lbs */
  temp = pq_getmsgbytes(&buf, sizeof(result->lbs));
  memcpy(result->lbs, temp, sizeof(result->lbs));

  pq_getmsgend(&buf);

  PG_RETURN_POINTER(result);
}

Datum
array_agg_array_finalfn(PG_FUNCTION_ARGS)
{
  Datum   result;
  ArrayBuildStateArr *state;

  /* cannot be called directly because of internal-type argument */
  Assert(AggCheckCallContext(fcinfo, NULL));

  state = PG_ARGISNULL(0) ? NULL : (ArrayBuildStateArr *) PG_GETARG_POINTER(0);

  if (state == NULL)
    PG_RETURN_NULL();   /* returns null iff no input values */

  /*
   * Make the result.  We cannot release the ArrayBuildStateArr because
   * sometimes aggregate final functions are re-executed.  Rather, it is
   * nodeAgg.c's responsibility to reset the aggcontext when it's safe to do
   * so.
   */
  result = makeArrayResultArr(state, CurrentMemoryContext, false);

  PG_RETURN_DATUM(result);
}

/*-----------------------------------------------------------------------------
 * array_position, array_position_start :
 *      return the offset of a value in an array.
 *
 * IS NOT DISTINCT FROM semantics are used for comparisons.  Return NULL when
 * the value is not found.
 *-----------------------------------------------------------------------------
 */
Datum
array_position(PG_FUNCTION_ARGS)
{
  return array_position_common(fcinfo);
}

Datum
array_position_start(PG_FUNCTION_ARGS)
{
  return array_position_common(fcinfo);
}

/*
 * array_position_common
 *    Common code for array_position and array_position_start
 *
 * These are separate wrappers for the sake of opr_sanity regression test.
 * They are not strict so we have to test for null inputs explicitly.
 */
static Datum
array_position_common(FunctionCallInfo fcinfo)
{
  ArrayType  *array;
  Oid     collation = PG_GET_COLLATION();
  Oid     element_type;
  Datum   searched_element,
        value;
  bool    isnull;
  int     position,
        position_min;
  bool    found = false;
  TypeCacheEntry *typentry;
  ArrayMetaState *my_extra;
  bool    null_search;
  ArrayIterator array_iterator;

  if (PG_ARGISNULL(0))
    PG_RETURN_NULL();

  array = PG_GETARG_ARRAYTYPE_P(0);

  /*
   * We refuse to search for elements in multi-dimensional arrays, since we
   * have no good way to report the element's location in the array.
   */
  if (ARR_NDIM(array) > 1)
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("searching for elements in multidimensional arrays is not supported")));

  /* Searching in an empty array is well-defined, though: it always fails */
  if (ARR_NDIM(array) < 1)
    PG_RETURN_NULL();

  if (PG_ARGISNULL(1))
  {
    /* fast return when the array doesn't have nulls */
    if (!array_contains_nulls(array))
      PG_RETURN_NULL();
    searched_element = (Datum) 0;
    null_search = true;
  }
  else
  {
    searched_element = PG_GETARG_DATUM(1);
    null_search = false;
  }

  element_type = ARR_ELEMTYPE(array);
  position = (ARR_LBOUND(array))[0] - 1;

  /* figure out where to start */
  if (PG_NARGS() == 3)
  {
    if (PG_ARGISNULL(2))
      ereport(ERROR,
          (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
           errmsg("initial position must not be null")));

    position_min = PG_GETARG_INT32(2);
  }
  else
    position_min = (ARR_LBOUND(array))[0];

  /*
   * We arrange to look up type info for array_create_iterator only once per
   * series of calls, assuming the element type doesn't change underneath
   * us.
   */
  my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
  if (my_extra == NULL)
  {
    fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                            sizeof(ArrayMetaState));
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    my_extra->element_type = ~element_type;
  }

  if (my_extra->element_type != element_type)
  {
    get_typlenbyvalalign(element_type,
               &my_extra->typlen,
               &my_extra->typbyval,
               &my_extra->typalign);

    typentry = lookup_type_cache(element_type, TYPECACHE_EQ_OPR_FINFO);

    if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
      ereport(ERROR,
          (errcode(ERRCODE_UNDEFINED_FUNCTION),
           errmsg("could not identify an equality operator for type %s",
              format_type_be(element_type))));

    my_extra->element_type = element_type;
    fmgr_info_cxt(typentry->eq_opr_finfo.fn_oid, &my_extra->proc,
            fcinfo->flinfo->fn_mcxt);
  }

  /* Examine each array element until we find a match. */
  array_iterator = array_create_iterator(array, 0, my_extra);
  while (array_iterate(array_iterator, &value, &isnull))
  {
    position++;

    /* skip initial elements if caller requested so */
    if (position < position_min)
      continue;

    /*
     * Can't look at the array element's value if it's null; but if we
     * search for null, we have a hit and are done.
     */
    if (isnull || null_search)
    {
      if (isnull && null_search)
      {
        found = true;
        break;
      }
      else
        continue;
    }

    /* not nulls, so run the operator */
    if (DatumGetBool(FunctionCall2Coll(&my_extra->proc, collation,
                       searched_element, value)))
    {
      found = true;
      break;
    }
  }

  array_free_iterator(array_iterator);

  /* Avoid leaking memory when handed toasted input */
  PG_FREE_IF_COPY(array, 0);

  if (!found)
    PG_RETURN_NULL();

  PG_RETURN_INT32(position);
}

/*-----------------------------------------------------------------------------
 * array_positions :
 *      return an array of positions of a value in an array.
 *
 * IS NOT DISTINCT FROM semantics are used for comparisons.  Returns NULL when
 * the input array is NULL.  When the value is not found in the array, returns
 * an empty array.
 *
 * This is not strict so we have to test for null inputs explicitly.
 *-----------------------------------------------------------------------------
 */
Datum
array_positions(PG_FUNCTION_ARGS)
{
  ArrayType  *array;
  Oid     collation = PG_GET_COLLATION();
  Oid     element_type;
  Datum   searched_element,
        value;
  bool    isnull;
  int     position;
  TypeCacheEntry *typentry;
  ArrayMetaState *my_extra;
  bool    null_search;
  ArrayIterator array_iterator;
  ArrayBuildState *astate = NULL;

  if (PG_ARGISNULL(0))
    PG_RETURN_NULL();

  array = PG_GETARG_ARRAYTYPE_P(0);

  /*
   * We refuse to search for elements in multi-dimensional arrays, since we
   * have no good way to report the element's location in the array.
   */
  if (ARR_NDIM(array) > 1)
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
         errmsg("searching for elements in multidimensional arrays is not supported")));

  astate = initArrayResult(INT4OID, CurrentMemoryContext, false);

  /* Searching in an empty array is well-defined, though: it always fails */
  if (ARR_NDIM(array) < 1)
    PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));

  if (PG_ARGISNULL(1))
  {
    /* fast return when the array doesn't have nulls */
    if (!array_contains_nulls(array))
      PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
    searched_element = (Datum) 0;
    null_search = true;
  }
  else
  {
    searched_element = PG_GETARG_DATUM(1);
    null_search = false;
  }

  element_type = ARR_ELEMTYPE(array);
  position = (ARR_LBOUND(array))[0] - 1;

  /*
   * We arrange to look up type info for array_create_iterator only once per
   * series of calls, assuming the element type doesn't change underneath
   * us.
   */
  my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
  if (my_extra == NULL)
  {
    fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
                            sizeof(ArrayMetaState));
    my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
    my_extra->element_type = ~element_type;
  }

  if (my_extra->element_type != element_type)
  {
    get_typlenbyvalalign(element_type,
               &my_extra->typlen,
               &my_extra->typbyval,
               &my_extra->typalign);

    typentry = lookup_type_cache(element_type, TYPECACHE_EQ_OPR_FINFO);

    if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
      ereport(ERROR,
          (errcode(ERRCODE_UNDEFINED_FUNCTION),
           errmsg("could not identify an equality operator for type %s",
              format_type_be(element_type))));

    my_extra->element_type = element_type;
    fmgr_info_cxt(typentry->eq_opr_finfo.fn_oid, &my_extra->proc,
            fcinfo->flinfo->fn_mcxt);
  }

  /*
   * Accumulate each array position iff the element matches the given
   * element.
   */
  array_iterator = array_create_iterator(array, 0, my_extra);
  while (array_iterate(array_iterator, &value, &isnull))
  {
    position += 1;

    /*
     * Can't look at the array element's value if it's null; but if we
     * search for null, we have a hit.
     */
    if (isnull || null_search)
    {
      if (isnull && null_search)
        astate =
          accumArrayResult(astate, Int32GetDatum(position), false,
                   INT4OID, CurrentMemoryContext);

      continue;
    }

    /* not nulls, so run the operator */
    if (DatumGetBool(FunctionCall2Coll(&my_extra->proc, collation,
                       searched_element, value)))
      astate =
        accumArrayResult(astate, Int32GetDatum(position), false,
                 INT4OID, CurrentMemoryContext);
  }

  array_free_iterator(array_iterator);

  /* Avoid leaking memory when handed toasted input */
  PG_FREE_IF_COPY(array, 0);

  PG_RETURN_DATUM(makeArrayResult(astate, CurrentMemoryContext));
}

/*
 * array_shuffle_n
 *    Return a copy of array with n randomly chosen items.
 *
 * The number of items must not exceed the size of the first dimension of the
 * array.  We preserve the first dimension's lower bound if keep_lb,
 * else it's set to 1.  Lower-order dimensions are preserved in any case.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given only the elmtyp. However, the caller is
 * in a better position to cache this info across multiple calls.
 */
static ArrayType *
array_shuffle_n(ArrayType *array, int n, bool keep_lb,
        Oid elmtyp, TypeCacheEntry *typentry)
{
  ArrayType  *result;
  int     ndim,
         *dims,
         *lbs,
        nelm,
        nitem,
        rdims[MAXDIM],
        rlbs[MAXDIM];
  int16   elmlen;
  bool    elmbyval;
  char    elmalign;
  Datum    *elms,
         *ielms;
  bool     *nuls,
         *inuls;

  ndim = ARR_NDIM(array);
  dims = ARR_DIMS(array);
  lbs = ARR_LBOUND(array);

  elmlen = typentry->typlen;
  elmbyval = typentry->typbyval;
  elmalign = typentry->typalign;

  /* If the target array is empty, exit fast */
  if (ndim < 1 || dims[0] < 1 || n < 1)
    return construct_empty_array(elmtyp);

  deconstruct_array(array, elmtyp, elmlen, elmbyval, elmalign,
            &elms, &nuls, &nelm);

  nitem = dims[0];      /* total number of items */
  nelm /= nitem;        /* number of elements per item */

  Assert(n <= nitem);     /* else it's caller error */

  /*
   * Shuffle array using Fisher-Yates algorithm.  Scan the array and swap
   * current item (nelm datums starting at ielms) with a randomly chosen
   * later item (nelm datums starting at jelms) in each iteration.  We can
   * stop once we've done n iterations; then first n items are the result.
   */
  ielms = elms;
  inuls = nuls;
  for (int i = 0; i < n; i++)
  {
    int     j = (int) pg_prng_uint64_range(&pg_global_prng_state, i, nitem - 1) * nelm;
    Datum    *jelms = elms + j;
    bool     *jnuls = nuls + j;

    /* Swap i'th and j'th items; advance ielms/inuls to next item */
    for (int k = 0; k < nelm; k++)
    {
      Datum   elm = *ielms;
      bool    nul = *inuls;

      *ielms++ = *jelms;
      *inuls++ = *jnuls;
      *jelms++ = elm;
      *jnuls++ = nul;
    }
  }

  /* Set up dimensions of the result */
  memcpy(rdims, dims, ndim * sizeof(int));
  memcpy(rlbs, lbs, ndim * sizeof(int));
  rdims[0] = n;
  if (!keep_lb)
    rlbs[0] = 1;

  result = construct_md_array(elms, nuls, ndim, rdims, rlbs,
                elmtyp, elmlen, elmbyval, elmalign);

  pfree(elms);
  pfree(nuls);

  return result;
}

/*
 * array_shuffle
 *
 * Returns an array with the same dimensions as the input array, with its
 * first-dimension elements in random order.
 */
Datum
array_shuffle(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
  ArrayType  *result;
  Oid     elmtyp;
  TypeCacheEntry *typentry;

  /*
   * There is no point in shuffling empty arrays or arrays with less than
   * two items.
   */
  if (ARR_NDIM(array) < 1 || ARR_DIMS(array)[0] < 2)
    PG_RETURN_ARRAYTYPE_P(array);

  elmtyp = ARR_ELEMTYPE(array);
  typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
  if (typentry == NULL || typentry->type_id != elmtyp)
  {
    typentry = lookup_type_cache(elmtyp, 0);
    fcinfo->flinfo->fn_extra = typentry;
  }

  result = array_shuffle_n(array, ARR_DIMS(array)[0], true, elmtyp, typentry);

  PG_RETURN_ARRAYTYPE_P(result);
}

/*
 * array_sample
 *
 * Returns an array of n randomly chosen first-dimension elements
 * from the input array.
 */
Datum
array_sample(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
  int     n = PG_GETARG_INT32(1);
  ArrayType  *result;
  Oid     elmtyp;
  TypeCacheEntry *typentry;
  int     nitem;

  nitem = (ARR_NDIM(array) < 1) ? 0 : ARR_DIMS(array)[0];

  if (n < 0 || n > nitem)
    ereport(ERROR,
        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
         errmsg("sample size must be between 0 and %d", nitem)));

  elmtyp = ARR_ELEMTYPE(array);
  typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
  if (typentry == NULL || typentry->type_id != elmtyp)
  {
    typentry = lookup_type_cache(elmtyp, 0);
    fcinfo->flinfo->fn_extra = typentry;
  }

  result = array_shuffle_n(array, n, false, elmtyp, typentry);

  PG_RETURN_ARRAYTYPE_P(result);
}


/*
 * array_reverse_n
 *    Return a copy of array with reversed items.
 *
 * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
 * from the system catalogs, given only the elmtyp. However, the caller is
 * in a better position to cache this info across multiple calls.
 */
static ArrayType *
array_reverse_n(ArrayType *array, Oid elmtyp, TypeCacheEntry *typentry)
{
  ArrayType  *result;
  int     ndim,
         *dims,
         *lbs,
        nelm,
        nitem,
        rdims[MAXDIM],
        rlbs[MAXDIM];
  int16   elmlen;
  bool    elmbyval;
  char    elmalign;
  Datum    *elms,
         *ielms;
  bool     *nuls,
         *inuls;

  ndim = ARR_NDIM(array);
  dims = ARR_DIMS(array);
  lbs = ARR_LBOUND(array);

  elmlen = typentry->typlen;
  elmbyval = typentry->typbyval;
  elmalign = typentry->typalign;

  deconstruct_array(array, elmtyp, elmlen, elmbyval, elmalign,
            &elms, &nuls, &nelm);

  nitem = dims[0];      /* total number of items */
  nelm /= nitem;        /* number of elements per item */

  /* Reverse the array */
  ielms = elms;
  inuls = nuls;
  for (int i = 0; i < nitem / 2; i++)
  {
    int     j = (nitem - i - 1) * nelm;
    Datum    *jelms = elms + j;
    bool     *jnuls = nuls + j;

    /* Swap i'th and j'th items; advance ielms/inuls to next item */
    for (int k = 0; k < nelm; k++)
    {
      Datum   elm = *ielms;
      bool    nul = *inuls;

      *ielms++ = *jelms;
      *inuls++ = *jnuls;
      *jelms++ = elm;
      *jnuls++ = nul;
    }
  }

  /* Set up dimensions of the result */
  memcpy(rdims, dims, ndim * sizeof(int));
  memcpy(rlbs, lbs, ndim * sizeof(int));
  rdims[0] = nitem;

  result = construct_md_array(elms, nuls, ndim, rdims, rlbs,
                elmtyp, elmlen, elmbyval, elmalign);

  pfree(elms);
  pfree(nuls);

  return result;
}

/*
 * array_reverse
 *
 * Returns an array with the same dimensions as the input array, with its
 * first-dimension elements in reverse order.
 */
Datum
array_reverse(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
  ArrayType  *result;
  Oid     elmtyp;
  TypeCacheEntry *typentry;

  /*
   * There is no point in reversing empty arrays or arrays with less than
   * two items.
   */
  if (ARR_NDIM(array) < 1 || ARR_DIMS(array)[0] < 2)
    PG_RETURN_ARRAYTYPE_P(array);

  elmtyp = ARR_ELEMTYPE(array);
  typentry = (TypeCacheEntry *) fcinfo->flinfo->fn_extra;
  if (typentry == NULL || typentry->type_id != elmtyp)
  {
    typentry = lookup_type_cache(elmtyp, 0);
    fcinfo->flinfo->fn_extra = (void *) typentry;
  }

  result = array_reverse_n(array, elmtyp, typentry);

  PG_RETURN_ARRAYTYPE_P(result);
}

/*
 * array_sort
 *
 * Sorts the first dimension of the array.
 */
static ArrayType *
array_sort_internal(ArrayType *array, bool descending, bool nulls_first,
          FunctionCallInfo fcinfo)
{
  ArrayType  *newarray;
  Oid     collation = PG_GET_COLLATION();
  int     ndim,
         *dims,
         *lbs;
  ArraySortCachedInfo *cache_info;
  Oid     elmtyp;
  Oid     sort_typ;
  Oid     sort_opr;
  Tuplesortstate *tuplesortstate;
  ArrayIterator array_iterator;
  Datum   value;
  bool    isnull;
  ArrayBuildStateAny *astate = NULL;

  ndim = ARR_NDIM(array);
  dims = ARR_DIMS(array);
  lbs = ARR_LBOUND(array);

  /* Quick exit if we don't need to sort */
  if (ndim < 1 || dims[0] < 2)
    return array;

  /* Set up cache area if we didn't already */
  cache_info = (ArraySortCachedInfo *) fcinfo->flinfo->fn_extra;
  if (cache_info == NULL)
  {
    cache_info = (ArraySortCachedInfo *)
      MemoryContextAllocZero(fcinfo->flinfo->fn_mcxt,
                   sizeof(ArraySortCachedInfo));
    fcinfo->flinfo->fn_extra = cache_info;
  }

  /* Fetch and cache required data if we don't have it */
  elmtyp = ARR_ELEMTYPE(array);
  if (elmtyp != cache_info->array_meta.element_type)
  {
    TypeCacheEntry *typentry;

    typentry = lookup_type_cache(elmtyp,
                   TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
    cache_info->array_meta.element_type = elmtyp;
    cache_info->array_meta.typlen = typentry->typlen;
    cache_info->array_meta.typbyval = typentry->typbyval;
    cache_info->array_meta.typalign = typentry->typalign;
    cache_info->elem_lt_opr = typentry->lt_opr;
    cache_info->elem_gt_opr = typentry->gt_opr;
    cache_info->array_type = typentry->typarray;
  }

  /* Identify the sort operator to use */
  if (ndim == 1)
  {
    /* Need to sort the element type */
    sort_typ = elmtyp;
    sort_opr = (descending ? cache_info->elem_gt_opr : cache_info->elem_lt_opr);
  }
  else
  {
    /* Otherwise we're sorting arrays */
    sort_typ = cache_info->array_type;
    if (!OidIsValid(sort_typ))
      ereport(ERROR,
          (errcode(ERRCODE_UNDEFINED_OBJECT),
           errmsg("could not find array type for data type %s",
              format_type_be(elmtyp))));
    /* We know what operators to use for arrays */
    sort_opr = (descending ? ARRAY_GT_OP : ARRAY_LT_OP);
  }

  /*
   * Fail if we don't know how to sort.  The error message is chosen to
   * match what array_lt()/array_gt() will say in the multidimensional case.
   */
  if (!OidIsValid(sort_opr))
    ereport(ERROR,
        errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
        errmsg("could not identify a comparison function for type %s",
             format_type_be(elmtyp)));

  /* Put the things to be sorted (elements or sub-arrays) into a tuplesort */
  tuplesortstate = tuplesort_begin_datum(sort_typ,
                       sort_opr,
                       collation,
                       nulls_first,
                       work_mem,
                       NULL,
                       TUPLESORT_NONE);

  array_iterator = array_create_iterator(array, ndim - 1,
                       &cache_info->array_meta);
  while (array_iterate(array_iterator, &value, &isnull))
  {
    tuplesort_putdatum(tuplesortstate, value, isnull);
  }
  array_free_iterator(array_iterator);

  /* Do the sort */
  tuplesort_performsort(tuplesortstate);

  /* Extract results into a new array */
  while (tuplesort_getdatum(tuplesortstate, true, false, &value, &isnull, NULL))
  {
    astate = accumArrayResultAny(astate, value, isnull,
                   sort_typ, CurrentMemoryContext);
  }
  tuplesort_end(tuplesortstate);

  newarray = DatumGetArrayTypeP(makeArrayResultAny(astate,
                           CurrentMemoryContext,
                           true));

  /* Adjust lower bound to match the input */
  ARR_LBOUND(newarray)[0] = lbs[0];

  return newarray;
}

Datum
array_sort(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);

  PG_RETURN_ARRAYTYPE_P(array_sort_internal(array,
                        false,
                        false,
                        fcinfo));
}

Datum
array_sort_order(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
  bool    descending = PG_GETARG_BOOL(1);

  PG_RETURN_ARRAYTYPE_P(array_sort_internal(array,
                        descending,
                        descending,
                        fcinfo));
}

Datum
array_sort_order_nulls_first(PG_FUNCTION_ARGS)
{
  ArrayType  *array = PG_GETARG_ARRAYTYPE_P(0);
  bool    descending = PG_GETARG_BOOL(1);
  bool    nulls_first = PG_GETARG_BOOL(2);

  PG_RETURN_ARRAYTYPE_P(array_sort_internal(array,
                        descending,
                        nulls_first,
                        fcinfo));
}

Coverage Report

Created: 2025-07-03 06:49