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255 lines
5.4 KiB
C
255 lines
5.4 KiB
C
/*
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* Integer array aggregator / enumerator
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*
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* Mark L. Woodward
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* DMN Digital Music Network.
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* www.dmn.com
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*
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* Copyright (C) Digital Music Network
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* December 20, 2001
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*
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* This file is the property of the Digital Music Network (DMN).
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* It is being made available to users of the PostgreSQL system
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* under the BSD license.
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*
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* NOTE: This module requires sizeof(void *) to be the same as sizeof(int)
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*/
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#include "postgres.h"
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#include <ctype.h>
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#include <sys/types.h>
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#include "access/heapam.h"
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#include "catalog/catname.h"
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#include "catalog/indexing.h"
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#include "catalog/pg_proc.h"
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#include "catalog/pg_type.h"
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#include "executor/executor.h"
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#include "utils/sets.h"
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#include "utils/syscache.h"
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#include "access/tupmacs.h"
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#include "access/xact.h"
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#include "fmgr.h"
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#include "miscadmin.h"
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#include "utils/array.h"
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#include "utils/builtins.h"
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#include "utils/memutils.h"
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#include "utils/lsyscache.h"
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/* Uncomment this define if you are compiling for postgres 7.2.x */
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/* #define PG_7_2 */
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/* This is actually a postgres version of a one dimensional array */
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typedef struct
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{
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ArrayType a;
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int items;
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int lower;
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int4 array[1];
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} PGARRAY;
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/* This is used to keep track of our position during enumeration */
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typedef struct callContext
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{
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PGARRAY *p;
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int num;
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int flags;
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} CTX;
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#define TOASTED 1
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#define START_NUM 8
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#define PGARRAY_SIZE(n) (sizeof(PGARRAY) + ((n-1)*sizeof(int4)))
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static PGARRAY *GetPGArray(int4 state, int fAdd);
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static PGARRAY *ShrinkPGArray(PGARRAY * p);
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Datum int_agg_state(PG_FUNCTION_ARGS);
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Datum int_agg_final_count(PG_FUNCTION_ARGS);
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Datum int_agg_final_array(PG_FUNCTION_ARGS);
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Datum int_enum(PG_FUNCTION_ARGS);
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PG_FUNCTION_INFO_V1(int_agg_state);
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PG_FUNCTION_INFO_V1(int_agg_final_count);
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PG_FUNCTION_INFO_V1(int_agg_final_array);
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PG_FUNCTION_INFO_V1(int_enum);
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/*
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* Manage the aggregation state of the array
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*
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* Need to specify a suitably long-lived memory context, or it will vanish!
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* PortalContext isn't really right, but it's close enough.
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*/
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static PGARRAY *
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GetPGArray(int4 state, int fAdd)
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{
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PGARRAY *p = (PGARRAY *) state;
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if (!state)
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{
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/* New array */
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int cb = PGARRAY_SIZE(START_NUM);
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p = (PGARRAY *) MemoryContextAlloc(PortalContext, cb);
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p->a.size = cb;
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p->a.ndim = 0;
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p->a.flags = 0;
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#ifndef PG_7_2
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p->a.elemtype = INT4OID;
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#endif
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p->items = 0;
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p->lower = START_NUM;
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}
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else if (fAdd)
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{ /* Ensure array has space */
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if (p->items >= p->lower)
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{
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PGARRAY *pn;
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int n = p->lower + p->lower;
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int cbNew = PGARRAY_SIZE(n);
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pn = (PGARRAY *) repalloc(p, cbNew);
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pn->a.size = cbNew;
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pn->lower = n;
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return pn;
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}
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}
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return p;
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}
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/* Shrinks the array to its actual size and moves it into the standard
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* memory allocation context, frees working memory */
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static PGARRAY *
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ShrinkPGArray(PGARRAY * p)
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{
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PGARRAY *pnew = NULL;
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if (p)
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{
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/* get target size */
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int cb = PGARRAY_SIZE(p->items);
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/* use current transaction context */
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pnew = palloc(cb);
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/*
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* Fix up the fields in the new structure, so Postgres understands
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*/
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memcpy(pnew, p, cb);
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pnew->a.size = cb;
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pnew->a.ndim = 1;
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pnew->a.flags = 0;
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#ifndef PG_7_2
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pnew->a.elemtype = INT4OID;
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#endif
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pnew->lower = 0;
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pfree(p);
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}
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return pnew;
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}
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/* Called for each iteration during an aggregate function */
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Datum
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int_agg_state(PG_FUNCTION_ARGS)
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{
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int4 state = PG_GETARG_INT32(0);
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int4 value = PG_GETARG_INT32(1);
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PGARRAY *p = GetPGArray(state, 1);
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if (!p)
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/* internal error */
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elog(ERROR, "no aggregate storage");
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else if (p->items >= p->lower)
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/* internal error */
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elog(ERROR, "aggregate storage too small");
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else
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p->array[p->items++] = value;
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PG_RETURN_INT32(p);
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}
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/* This is the final function used for the integer aggregator. It returns all the integers
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* collected as a one dimensional integer array */
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Datum
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int_agg_final_array(PG_FUNCTION_ARGS)
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{
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PGARRAY *pnew = ShrinkPGArray(GetPGArray(PG_GETARG_INT32(0), 0));
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if (pnew)
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PG_RETURN_POINTER(pnew);
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else
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PG_RETURN_NULL();
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}
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/* This function accepts an array, and returns one item for each entry in the array */
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Datum
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int_enum(PG_FUNCTION_ARGS)
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{
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PGARRAY *p = (PGARRAY *) PG_GETARG_POINTER(0);
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CTX *pc;
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ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
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if (!rsi || !IsA(rsi, ReturnSetInfo))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("int_enum called in context that cannot accept a set")));
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if (!p)
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{
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elog(WARNING, "no data sent");
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PG_RETURN_NULL();
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}
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if (!fcinfo->context)
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{
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/* Allocate a working context */
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pc = (CTX *) palloc(sizeof(CTX));
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/* Don't copy attribute if you don't need too */
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if (VARATT_IS_EXTENDED(p))
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{
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/* Toasted!!! */
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pc->p = (PGARRAY *) PG_DETOAST_DATUM_COPY(p);
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pc->flags = TOASTED;
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if (!pc->p)
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{
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/* internal error */
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elog(ERROR, "error in toaster; not detoasting");
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PG_RETURN_NULL();
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}
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}
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else
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{
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/* Untoasted */
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pc->p = p;
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pc->flags = 0;
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}
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fcinfo->context = (Node *) pc;
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pc->num = 0;
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}
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else
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/* use an existing one */
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pc = (CTX *) fcinfo->context;
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/* Are we done yet? */
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if (pc->num >= pc->p->items)
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{
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/* We are done */
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if (pc->flags & TOASTED)
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pfree(pc->p);
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pfree(fcinfo->context);
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fcinfo->context = NULL;
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rsi->isDone = ExprEndResult;
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}
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else
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/* nope, return the next value */
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{
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int val = pc->p->array[pc->num++];
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rsi->isDone = ExprMultipleResult;
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PG_RETURN_INT32(val);
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}
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PG_RETURN_NULL();
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}
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