postgres.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * postgres.c
 *	  POSTGRES C Backend Interface
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.119 1999/07/02 18:09:27 momjian Exp $
 *
 * NOTES
 *	  this is the "main" module of the postgres backend and
 *	  hence the main module of the "traffic cop".
 *
 *-------------------------------------------------------------------------
 */

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/param.h>			/* for MAXHOSTNAMELEN on most */
#ifndef MAXHOSTNAMELEN
#include <netdb.h>				/* for MAXHOSTNAMELEN on some */
#endif
#ifndef MAXHOSTNAMELEN			/* for MAXHOSTNAMELEN under sco3.2v5.0.2 */
#include <sys/socket.h>
#endif
#include <errno.h>
#if HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif	 /* aix */
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#ifdef __CYGWIN32__
#include <getopt.h>
#endif

#include "postgres.h"
#include "miscadmin.h"
#include "fmgr.h"

#include "access/xact.h"
#include "catalog/catname.h"
#include "commands/async.h"
#include "executor/execdebug.h"
#include "executor/executor.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "libpq/libpq-be.h"
#include "libpq/pqsignal.h"
#include "nodes/pg_list.h"
#include "nodes/print.h"
#include "optimizer/cost.h"
#include "optimizer/planner.h"
#include "optimizer/prep.h"
#include "parser/parser.h"
#include "rewrite/rewriteHandler.h"		/* for QueryRewrite() */
#include "storage/bufmgr.h"
#include "tcop/dest.h"
#include "tcop/fastpath.h"
#include "tcop/pquery.h"
#include "tcop/tcopdebug.h"
#include "tcop/tcopprot.h"		/* where declarations for this file go */
#include "tcop/utility.h"
#include "utils/mcxt.h"
#include "utils/rel.h"
#include "utils/ps_status.h"
#include "utils/temprel.h"
#include "nodes/parsenodes.h"
#include "../backend/parser/parse.h"

#ifdef NOT_USED
#include "nodes/relation.h"
#endif

#ifdef NOT_USED
#include "optimizer/xfunc.h"
#endif

#ifdef NOT_USED
#include "nodes/plannodes.h"
#endif

#ifdef NOT_USED
#include "nodes/memnodes.h"
#endif

#include "utils/trace.h"

#ifdef MULTIBYTE
#include "mb/pg_wchar.h"
#endif

/*
 * Trace flags, see backend/utils/misc/trace.c
 */
#define Verbose				pg_options[TRACE_VERBOSE]
#define DebugPrintQuery		pg_options[TRACE_QUERY]
#define DebugPrintPlan		pg_options[TRACE_PLAN]
#define DebugPrintParse		pg_options[TRACE_PARSE]
#define DebugPrintRewrittenParsetree \
							pg_options[TRACE_REWRITTEN]
#define DebugPPrintPlan		pg_options[TRACE_PRETTY_PLAN]
#define DebugPPrintParse	pg_options[TRACE_PRETTY_PARSE]
#define DebugPPrintRewrittenParsetree \
							pg_options[TRACE_PRETTY_REWRITTEN]
#define ShowParserStats		pg_options[TRACE_PARSERSTATS]
#define ShowPlannerStats	pg_options[TRACE_PLANNERSTATS]
#define ShowExecutorStats	pg_options[TRACE_EXECUTORSTATS]
#ifdef LOCK_MGR_DEBUG
#define LockDebug			pg_options[TRACE_LOCKS]
#endif

#define DeadlockCheckTimer	pg_options[OPT_DEADLOCKTIMEOUT]
#define HostnameLookup		pg_options[OPT_HOSTLOOKUP]
#define ShowPortNumber		pg_options[OPT_SHOWPORTNUMBER]

/* ----------------
 *		global variables
 * ----------------
 */

/*static bool	EnableRewrite = true; , never changes why have it*/
CommandDest whereToSendOutput;

/* Define status buffer needed by PS_SET_STATUS */
PS_DEFINE_BUFFER;

extern int	lockingOff;
extern int	NBuffers;

int			dontExecute = 0;
static int	ShowStats;
static bool IsEmptyQuery = false;

char		relname[80];		/* current relation name */

/* note: these declarations had better match tcopprot.h */
DLLIMPORT sigjmp_buf Warn_restart;
bool		InError;

extern int	NBuffers;

static int	EchoQuery = 0;		/* default don't echo */
time_t		tim;
char		pg_pathname[256];
FILE	   *StatFp;

/* ----------------
 *		people who want to use EOF should #define DONTUSENEWLINE in
 *		tcop/tcopdebug.h
 * ----------------
 */
#ifndef TCOP_DONTUSENEWLINE
int			UseNewLine = 1;		/* Use newlines query delimiters (the
								 * default) */

#else
int			UseNewLine = 0;		/* Use EOF as query delimiters */

#endif	 /* TCOP_DONTUSENEWLINE */

/*
** Flags for expensive function optimization -- JMH 3/9/92
*/
int			XfuncMode = 0;

/*
 * ----------------
 *	 Note: _exec_repeat_ defaults to 1 but may be changed
 *		   by a DEBUG command.	 If you set this to a large
 *		   number N, run a single query, and then set it
 *		   back to 1 and run N queries, you can get an idea
 *		   of how much time is being spent in the parser and
 *		   planner b/c in the first case this overhead only
 *		   happens once.  -cim 6/9/91
 * ----------------
*/
int			_exec_repeat_ = 1;

/* ----------------------------------------------------------------
 *		decls for routines only used in this file
 * ----------------------------------------------------------------
 */
static char InteractiveBackend(char *inBuf);
static char SocketBackend(char *inBuf);
static char ReadCommand(char *inBuf);
static void pg_exec_query(char *query_string);


/* ----------------------------------------------------------------
 *		routines to obtain user input
 * ----------------------------------------------------------------
 */

/* ----------------
 *	InteractiveBackend() is called for user interactive connections
 *	the string entered by the user is placed in its parameter inBuf.
 * ----------------
 */

static char
InteractiveBackend(char *inBuf)
{
	char	   *stuff = inBuf;	/* current place in input buffer */
	int			c;				/* character read from getc() */
	bool		end = false;	/* end-of-input flag */
	bool		backslashSeen = false;	/* have we seen a \ ? */

	/* ----------------
	 *	display a prompt and obtain input from the user
	 * ----------------
	 */
	printf("backend> ");
	fflush(stdout);

	for (;;)
	{
		if (UseNewLine)
		{
			/* ----------------
			 *	if we are using \n as a delimiter, then read
			 *	characters until the \n.
			 * ----------------
			 */
			while ((c = getc(stdin)) != EOF)
			{
				if (c == '\n')
				{
					if (backslashSeen)
					{
						stuff--;
						continue;
					}
					else
					{
						/* keep the newline character */
						*stuff++ = '\n';
						*stuff++ = '\0';
						break;
					}
				}
				else if (c == '\\')
					backslashSeen = true;
				else
					backslashSeen = false;

				*stuff++ = (char) c;
			}

			if (c == EOF)
				end = true;
		}
		else
		{
			/* ----------------
			 *	otherwise read characters until EOF.
			 * ----------------
			 */
			while ((c = getc(stdin)) != EOF)
				*stuff++ = (char) c;

			if (stuff == inBuf)
				end = true;
		}

		if (end)
		{
			if (Verbose)
				puts("EOF");
			IsEmptyQuery = true;
			proc_exit(0);
		}

		/* ----------------
		 *	otherwise we have a user query so process it.
		 * ----------------
		 */
		break;
	}

	/* ----------------
	 *	if the query echo flag was given, print the query..
	 * ----------------
	 */
	if (EchoQuery)
		printf("query: %s\n", inBuf);
	fflush(stdout);

	return 'Q';
}

/* ----------------
 *	SocketBackend()		Is called for frontend-backend connections
 *
 *	If the input is a query (case 'Q') then the string entered by
 *	the user is placed in its parameter inBuf.
 *
 *	If the input is a fastpath function call (case 'F') then
 *	the function call is processed in HandleFunctionRequest().
 *	(now called from PostgresMain())
 * ----------------
 */

static char
SocketBackend(char *inBuf)
{
	char		qtype;
	char		result = '\0';

	/* ----------------
	 *	get input from the frontend
	 * ----------------
	 */
	qtype = '?';
	if (pq_getbytes(&qtype, 1) == EOF)
	{
		/* ------------
		 *	when front-end applications quits/dies
		 * ------------
		 */
		proc_exit(0);
	}

	switch (qtype)
	{
			/* ----------------
			 *	'Q': user entered a query
			 * ----------------
			 */
		case 'Q':
			pq_getstr(inBuf, MAX_PARSE_BUFFER);
			result = 'Q';
			break;

			/* ----------------
			 *	'F':  calling user/system functions
			 * ----------------
			 */
		case 'F':
			pq_getstr(inBuf, MAX_PARSE_BUFFER); /* ignore the rest of the
												 * line */
			result = 'F';
			break;

			/* ----------------
			 *	'X':  frontend is exiting
			 * ----------------
			 */
		case 'X':
			result = 'X';
			break;

			/* ----------------
			 *	otherwise we got garbage from the frontend.
			 *
			 *	XXX are we certain that we want to do an elog(FATAL) here?
			 *		-cim 1/24/90
			 * ----------------
			 */
		default:
			elog(FATAL, "Socket command type %c unknown", qtype);
			break;
	}
	return result;
}

/* ----------------
 *		ReadCommand reads a command from either the frontend or
 *		standard input, places it in inBuf, and returns a char
 *		representing whether the string is a 'Q'uery or a 'F'astpath
 *		call.
 * ----------------
 */
static char
ReadCommand(char *inBuf)
{
	if (IsUnderPostmaster)
		return SocketBackend(inBuf);
	else
		return InteractiveBackend(inBuf);
}

List *
pg_parse_and_plan(char *query_string,	/* string to execute */
				  Oid *typev,	/* argument types */
				  int nargs,	/* number of arguments */
				  List **queryListP,	/* returned pointer to the parse
										 * trees */
				  CommandDest dest,		/* where results should go */
				  bool aclOverride)
{
	List	   *querytree_list = NIL;
	List	   *plan_list = NIL;
	List	   *querytree_list_item;
	Query	   *querytree;
	Plan	   *plan;
	List	   *new_list;
	List	   *rewritten;

	if (DebugPrintQuery)
	{
		if (DebugPrintQuery > 3)
		{
			/* Print the query string as is if query debug level > 3 */
			TPRINTF(TRACE_QUERY, "query: %s", query_string);
		}
		else
		{
			/* Print condensed query string to fit in one log line */
			char		buff[MAX_QUERY_SIZE + 1];
			char		c,
					   *s,
					   *d;
			int			n,
						is_space = 1;

			for (s = query_string, d = buff, n = 0; (c = *s) && (n < MAX_QUERY_SIZE); s++)
			{
				switch (c)
				{
					case '\r':
					case '\n':
					case '\t':
						c = ' ';
						/* fall through */
					case ' ':
						if (is_space)
							continue;
						is_space = 1;
						break;
					default:
						is_space = 0;
						break;
				}
				*d++ = c;
				n++;
			}
			*d = '\0';
			TPRINTF(TRACE_QUERY, "query: %s", buff);
		}
	}

	/* ----------------
	 *	(1) parse the request string into a list of parse trees
	 * ----------------
	 */
	if (ShowParserStats)
		ResetUsage();

	querytree_list = parser(query_string, typev, nargs);

	if (ShowParserStats)
	{
		fprintf(stderr, "! Parser Stats:\n");
		ShowUsage();
	}

	/* ----------------
	 *	(2) rewrite the queries, as necessary
	 *
	 *	rewritten queries are collected in new_list.  Note there may be
	 *	more or fewer than in the original list.
	 * ----------------
	 */
	new_list = NIL;
	foreach(querytree_list_item, querytree_list)
	{
		querytree = (Query *) lfirst(querytree_list_item);

		if (DebugPrintParse || DebugPPrintParse)
		{
			if (DebugPPrintParse)
			{
				TPRINTF(TRACE_PRETTY_PARSE, "parser outputs:");
				nodeDisplay(querytree);
			}
			else
			{
				TPRINTF(TRACE_PARSE, "parser outputs:");
				printf("\n%s\n\n", nodeToString(querytree));
			}
		}

		if (querytree->commandType == CMD_UTILITY)
		{
			/* don't rewrite utilities, just dump 'em into new_list */
			new_list = lappend(new_list, querytree);
		}
		else
		{
			/* rewrite regular queries */
			rewritten = QueryRewrite(querytree);
			new_list = nconc(new_list, rewritten);
		}
	}

	querytree_list = new_list;

	/*
	 * Override ACL checking if requested
	 */
	if (aclOverride)
	{
		foreach(querytree_list_item, querytree_list)
		{
			List	   *l;

			querytree = (Query *) lfirst(querytree_list_item);

			if (querytree->commandType == CMD_UTILITY)
				continue;

			foreach(l, querytree->rtable)
			{
				RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);

				rte->skipAcl = TRUE;
			}
		}
	}

	if (DebugPrintRewrittenParsetree || DebugPPrintRewrittenParsetree)
	{
		if (DebugPPrintRewrittenParsetree)
		{
			TPRINTF(TRACE_PRETTY_REWRITTEN, "after rewriting:");

			foreach(querytree_list_item, querytree_list)
			{
				querytree = (Query *) lfirst(querytree_list_item);
				nodeDisplay(querytree);
				printf("\n");
			}
		}
		else
		{
			TPRINTF(TRACE_REWRITTEN, "after rewriting:");

			foreach(querytree_list_item, querytree_list)
			{
				querytree = (Query *) lfirst(querytree_list_item);
				printf("\n%s\n\n", nodeToString(querytree));
			}
		}
	}

	foreach(querytree_list_item, querytree_list)
	{
		querytree = (Query *) lfirst(querytree_list_item);

		/*
		 * For each query that isn't a utility invocation, generate a
		 * plan.
		 */

		if (querytree->commandType != CMD_UTILITY)
		{

			if (IsAbortedTransactionBlockState())
			{
				/* ----------------
				 *	 the EndCommand() stuff is to tell the frontend
				 *	 that the command ended. -cim 6/1/90
				 * ----------------
				 */
				char	   *tag = "*ABORT STATE*";

				EndCommand(tag, dest);

				elog(NOTICE, "(transaction aborted): %s",
					 "queries ignored until END");

				if (queryListP)
					*queryListP = NIL;
				return NIL;
			}

			if (ShowPlannerStats)
				ResetUsage();

			/* call that optimizer */
			plan = planner(querytree);

			if (ShowPlannerStats)
			{
				fprintf(stderr, "! Planner Stats:\n");
				ShowUsage();
			}
			plan_list = lappend(plan_list, plan);
#ifdef INDEXSCAN_PATCH
			/* ----------------
			 *	Print plan if debugging.
			 *	This has been moved here to get debugging output
			 *	also for queries in functions.	DZ - 27-8-1996
			 * ----------------
			 */
			if (DebugPrintPlan || DebugPPrintPlan)
			{
				if (DebugPPrintPlan)
				{