pl_exec.c

PostgreSQL7.4.6 for Linux

/**********************************************************************
 * pl_exec.c		- Executor for the PL/pgSQL
 *			  procedural language
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.93.2.1 2004/02/24 01:44:47 tgl Exp $
 *
 *	  This software is copyrighted by Jan Wieck - Hamburg.
 *
 *	  The author hereby grants permission  to  use,  copy,	modify,
 *	  distribute,  and	license this software and its documentation
 *	  for any purpose, provided that existing copyright notices are
 *	  retained	in	all  copies  and  that	this notice is included
 *	  verbatim in any distributions. No written agreement, license,
 *	  or  royalty  fee	is required for any of the authorized uses.
 *	  Modifications to this software may be  copyrighted  by  their
 *	  author  and  need  not  follow  the licensing terms described
 *	  here, provided that the new terms are  clearly  indicated  on
 *	  the first page of each file where they apply.
 *
 *	  IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY
 *	  PARTY  FOR  DIRECT,	INDIRECT,	SPECIAL,   INCIDENTAL,	 OR
 *	  CONSEQUENTIAL   DAMAGES  ARISING	OUT  OF  THE  USE  OF  THIS
 *	  SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF, EVEN
 *	  IF  THE  AUTHOR  HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
 *	  DAMAGE.
 *
 *	  THE  AUTHOR  AND	DISTRIBUTORS  SPECIFICALLY	 DISCLAIM	ANY
 *	  WARRANTIES,  INCLUDING,  BUT	NOT  LIMITED  TO,  THE	IMPLIED
 *	  WARRANTIES  OF  MERCHANTABILITY,	FITNESS  FOR  A  PARTICULAR
 *	  PURPOSE,	AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON
 *	  AN "AS IS" BASIS, AND THE AUTHOR	AND  DISTRIBUTORS  HAVE  NO
 *	  OBLIGATION   TO	PROVIDE   MAINTENANCE,	 SUPPORT,  UPDATES,
 *	  ENHANCEMENTS, OR MODIFICATIONS.
 *
 **********************************************************************/

#include "plpgsql.h"
#include "pl.tab.h"

#include <ctype.h>
#include <setjmp.h>

#include "access/heapam.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "executor/spi_priv.h"
#include "funcapi.h"
#include "optimizer/clauses.h"
#include "parser/parse_expr.h"
#include "tcop/tcopprot.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"


static const char *const raise_skip_msg = "RAISE";

/*
 * All plpgsql function executions within a single transaction share
 * the same executor EState for evaluating "simple" expressions.  Each
 * function call creates its own "eval_econtext" ExprContext within this
 * estate.  We destroy the estate at transaction shutdown to ensure there
 * is no permanent leakage of memory (especially for xact abort case).
 *
 * If a simple PLpgSQL_expr has been used in the current xact, it is
 * linked into the active_simple_exprs list.
 */
static EState *simple_eval_estate = NULL;
static PLpgSQL_expr *active_simple_exprs = NULL;

/************************************************************
 * Local function forward declarations
 ************************************************************/
static void plpgsql_exec_error_callback(void *arg);
static PLpgSQL_var *copy_var(PLpgSQL_var * var);
static PLpgSQL_rec *copy_rec(PLpgSQL_rec * rec);

static int exec_stmt_block(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_block * block);
static int exec_stmts(PLpgSQL_execstate * estate,
		   PLpgSQL_stmts * stmts);
static int exec_stmt(PLpgSQL_execstate * estate,
		  PLpgSQL_stmt * stmt);
static int exec_stmt_assign(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_assign * stmt);
static int exec_stmt_perform(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_perform * stmt);
static int exec_stmt_getdiag(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_getdiag * stmt);
static int exec_stmt_if(PLpgSQL_execstate * estate,
			 PLpgSQL_stmt_if * stmt);
static int exec_stmt_loop(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_loop * stmt);
static int exec_stmt_while(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_while * stmt);
static int exec_stmt_fori(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_fori * stmt);
static int exec_stmt_fors(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_fors * stmt);
static int exec_stmt_select(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_select * stmt);
static int exec_stmt_open(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_open * stmt);
static int exec_stmt_fetch(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_fetch * stmt);
static int exec_stmt_close(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_close * stmt);
static int exec_stmt_exit(PLpgSQL_execstate * estate,
			   PLpgSQL_stmt_exit * stmt);
static int exec_stmt_return(PLpgSQL_execstate * estate,
				 PLpgSQL_stmt_return * stmt);
static int exec_stmt_return_next(PLpgSQL_execstate * estate,
					  PLpgSQL_stmt_return_next * stmt);
static int exec_stmt_raise(PLpgSQL_execstate * estate,
				PLpgSQL_stmt_raise * stmt);
static int exec_stmt_execsql(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_execsql * stmt);
static int exec_stmt_dynexecute(PLpgSQL_execstate * estate,
					 PLpgSQL_stmt_dynexecute * stmt);
static int exec_stmt_dynfors(PLpgSQL_execstate * estate,
				  PLpgSQL_stmt_dynfors * stmt);

static void plpgsql_estate_setup(PLpgSQL_execstate * estate,
					 PLpgSQL_function * func,
					 ReturnSetInfo *rsi);
static void exec_eval_cleanup(PLpgSQL_execstate * estate);

static void exec_prepare_plan(PLpgSQL_execstate * estate,
				  PLpgSQL_expr * expr);
static bool exec_simple_check_node(Node *node);
static void exec_simple_check_plan(PLpgSQL_expr * expr);
static Datum exec_eval_simple_expr(PLpgSQL_execstate * estate,
					  PLpgSQL_expr * expr,
					  bool *isNull,
					  Oid *rettype);

static void exec_assign_expr(PLpgSQL_execstate * estate,
				 PLpgSQL_datum * target,
				 PLpgSQL_expr * expr);
static void exec_assign_value(PLpgSQL_execstate * estate,
				  PLpgSQL_datum * target,
				  Datum value, Oid valtype, bool *isNull);
static void exec_eval_datum(PLpgSQL_execstate * estate,
				PLpgSQL_datum * datum,
				Oid expectedtypeid,
				Oid *typeid,
				Datum *value,
				bool *isnull);
static int exec_eval_integer(PLpgSQL_execstate * estate,
					PLpgSQL_expr * expr,
					bool *isNull);
static bool exec_eval_boolean(PLpgSQL_execstate * estate,
							  PLpgSQL_expr * expr,
							  bool *isNull);
static Datum exec_eval_expr(PLpgSQL_execstate * estate,
			   PLpgSQL_expr * expr,
			   bool *isNull,
			   Oid *rettype);
static int exec_run_select(PLpgSQL_execstate * estate,
				PLpgSQL_expr * expr, int maxtuples, Portal *portalP);
static void exec_move_row(PLpgSQL_execstate * estate,
			  PLpgSQL_rec * rec,
			  PLpgSQL_row * row,
			  HeapTuple tup, TupleDesc tupdesc);
static HeapTuple make_tuple_from_row(PLpgSQL_execstate * estate,
									 PLpgSQL_row * row,
									 TupleDesc tupdesc);
static char *convert_value_to_string(Datum value, Oid valtype);
static Datum exec_cast_value(Datum value, Oid valtype,
				Oid reqtype,
				FmgrInfo *reqinput,
				Oid reqtypelem,
				int32 reqtypmod,
				bool *isnull);
static Datum exec_simple_cast_value(Datum value, Oid valtype,
					   Oid reqtype, int32 reqtypmod,
					   bool *isnull);
static void exec_init_tuple_store(PLpgSQL_execstate * estate);
static bool compatible_tupdesc(TupleDesc td1, TupleDesc td2);
static void exec_set_found(PLpgSQL_execstate * estate, bool state);


/* ----------
 * plpgsql_exec_function	Called by the call handler for
 *				function execution.
 * ----------
 */
Datum
plpgsql_exec_function(PLpgSQL_function * func, FunctionCallInfo fcinfo)
{
	PLpgSQL_execstate estate;
	ErrorContextCallback plerrcontext;
	int			i;

	/*
	 * Setup the execution state
	 */
	plpgsql_estate_setup(&estate, func, (ReturnSetInfo *) fcinfo->resultinfo);

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpgsql_exec_error_callback;
	plerrcontext.arg = &estate;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	/*
	 * Make local execution copies of all the datums
	 */
	estate.err_text = gettext_noop("during initialization of execution state");
	for (i = 0; i < func->ndatums; i++)
	{
		switch (func->datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_var((PLpgSQL_var *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_REC:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_rec((PLpgSQL_rec *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_ARRAYELEM:
				estate.datums[i] = func->datums[i];
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
		}
	}

	/*
	 * Store the actual call argument values into the variables
	 */
	estate.err_text = gettext_noop("while storing call arguments into local variables");
	for (i = 0; i < func->fn_nargs; i++)
	{
		int			n = func->fn_argvarnos[i];

		switch (estate.datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[n];

					var->value = fcinfo->arg[i];
					var->isnull = fcinfo->argnull[i];
					var->freeval = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
				{
					PLpgSQL_row *row = (PLpgSQL_row *) estate.datums[n];
					TupleTableSlot *slot = (TupleTableSlot *) fcinfo->arg[i];
					HeapTuple	tup;
					TupleDesc	tupdesc;

					if (!fcinfo->argnull[i])
					{
						Assert(slot != NULL);
						tup = slot->val;
						tupdesc = slot->ttc_tupleDescriptor;
						exec_move_row(&estate, NULL, row, tup, tupdesc);
					}
					else
					{
						/* If arg is null, treat it as an empty row */
						exec_move_row(&estate, NULL, row, NULL, NULL);
					}
				}
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
		}
	}

	/*
	 * Initialize the other variables to NULL values for now. The default
	 * values are set when the blocks are entered.
	 */
	estate.err_text = gettext_noop("while initializing local variables to NULL");
	for (i = estate.found_varno; i < estate.ndatums; i++)
	{
		switch (estate.datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[i];

					var->value = 0;
					var->isnull = true;
					var->freeval = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_REC:
			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_ARRAYELEM:
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
		}
	}

	/*
	 * Set the magic variable FOUND to false
	 */
	exec_set_found(&estate, false);

	/*
	 * Now call the toplevel block of statements
	 */
	estate.err_text = NULL;
	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
	if (exec_stmt_block(&estate, func->action) != PLPGSQL_RC_RETURN)
	{
		estate.err_stmt = NULL;
		estate.err_text = NULL;
		ereport(ERROR,
		   (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
			errmsg("control reached end of function without RETURN")));
	}

	/*
	 * We got a return value - process it
	 */
	estate.err_stmt = NULL;
	estate.err_text = gettext_noop("while casting return value to function's return type");

	fcinfo->isnull = estate.retisnull;

	if (estate.retisset)
	{
		ReturnSetInfo *rsi = estate.rsi;

		/* Check caller can handle a set result */
		if (!rsi || !IsA(rsi, ReturnSetInfo) ||
			(rsi->allowedModes & SFRM_Materialize) == 0)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));
		rsi->returnMode = SFRM_Materialize;

		/* If we produced any tuples, send back the result */
		if (estate.tuple_store)
		{
			rsi->setResult = estate.tuple_store;
			if (estate.rettupdesc)
			{
				MemoryContext oldcxt;

				oldcxt = MemoryContextSwitchTo(estate.tuple_store_cxt);
				rsi->setDesc = CreateTupleDescCopy(estate.rettupdesc);
				MemoryContextSwitchTo(oldcxt);
			}
		}
		estate.retval = (Datum) 0;
		fcinfo->isnull = true;
	}
	else if (!estate.retisnull)
	{
		if (estate.retistuple)
		{
			/* Copy tuple to upper executor memory */
			/* Here we need to return a TupleTableSlot not just a tuple */
			estate.retval = (Datum)
				SPI_copytupleintoslot((HeapTuple) (estate.retval),
									  estate.rettupdesc);
		}
		else
		{
			/* Cast value to proper type */
			estate.retval = exec_cast_value(estate.retval, estate.rettype,
											func->fn_rettype,
											&(func->fn_retinput),
											func->fn_rettypelem,
											-1,
											&fcinfo->isnull);

			/*
			 * If the functions return type isn't by value, copy the value
			 * into upper executor memory context.
			 */
			if (!fcinfo->isnull && !func->fn_retbyval)
			{
				Size		len;
				void	   *tmp;

				len = datumGetSize(estate.retval, false, func->fn_rettyplen);
				tmp = (void *) SPI_palloc(len);
				memcpy(tmp, DatumGetPointer(estate.retval), len);
				estate.retval = PointerGetDatum(tmp);
			}
		}
	}

	/* Clean up any leftover temporary memory */
	if (estate.eval_econtext != NULL)
		FreeExprContext(estate.eval_econtext);
	estate.eval_econtext = NULL;
	exec_eval_cleanup(&estate);

	/*
	 * Pop the error context stack
	 */
	error_context_stack = plerrcontext.previous;

	/*
	 * Return the functions result
	 */
	return estate.retval;
}


/* ----------
 * plpgsql_exec_trigger		Called by the call handler for
 *				trigger execution.
 * ----------
 */
HeapTuple
plpgsql_exec_trigger(PLpgSQL_function * func,
					 TriggerData *trigdata)
{
	PLpgSQL_execstate estate;
	ErrorContextCallback plerrcontext;
	int			i;
	PLpgSQL_var *var;
	PLpgSQL_rec *rec_new,
			   *rec_old;
	HeapTuple	rettup;

	/*
	 * Setup the execution state
	 */
	plpgsql_estate_setup(&estate, func, NULL);

	/*
	 * Setup error traceback support for ereport()
	 */
	plerrcontext.callback = plpgsql_exec_error_callback;
	plerrcontext.arg = &estate;
	plerrcontext.previous = error_context_stack;
	error_context_stack = &plerrcontext;

	/*
	 * Make local execution copies of all the datums
	 */
	estate.err_text = gettext_noop("during initialization of execution state");
	for (i = 0; i < func->ndatums; i++)
	{
		switch (func->datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_var((PLpgSQL_var *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_REC:
				estate.datums[i] = (PLpgSQL_datum *)
					copy_rec((PLpgSQL_rec *) (func->datums[i]));
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_ARRAYELEM:
			case PLPGSQL_DTYPE_TRIGARG:
				estate.datums[i] = func->datums[i];
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d", func->datums[i]->dtype);
		}
	}

	/*
	 * Put the OLD and NEW tuples into record variables
	 */
	rec_new = (PLpgSQL_rec *) (estate.datums[func->new_varno]);
	rec_new->freetup = false;
	rec_new->freetupdesc = false;
	rec_old = (PLpgSQL_rec *) (estate.datums[func->old_varno]);
	rec_old->freetup = false;
	rec_old->freetupdesc = false;

	if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
	{
		/*
		 * Per-statement triggers don't use OLD/NEW variables
		 */
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
	}
	else if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_trigtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
	}
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_newtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
	{
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else
		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");

	/*
	 * Assign the special tg_ variables