postgres.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,551 行 · 第 1/5 页

	 * Switch to appropriate context for constructing parsetrees.
	 *
	 * We have two strategies depending on whether the prepared statement is
	 * named or not.  For a named prepared statement, we do parsing in
	 * MessageContext and copy the finished trees into the prepared
	 * statement's private context; then the reset of MessageContext
	 * releases temporary space used by parsing and planning.  For an
	 * unnamed prepared statement, we assume the statement isn't going to
	 * hang around long, so getting rid of temp space quickly is probably
	 * not worth the costs of copying parse/plan trees.  So in this case,
	 * we set up a special context for the unnamed statement, and do all
	 * the parsing/planning therein.
	 */
	is_named = (stmt_name[0] != '\0');
	if (is_named)
	{
		/* Named prepared statement --- parse in MessageContext */
		oldcontext = MemoryContextSwitchTo(MessageContext);
	}
	else
	{
		/* Unnamed prepared statement --- release any prior unnamed stmt */
		unnamed_stmt_pstmt = NULL;
		if (unnamed_stmt_context)
		{
			DropDependentPortals(unnamed_stmt_context);
			MemoryContextDelete(unnamed_stmt_context);
		}
		unnamed_stmt_context = NULL;
		/* create context for parsing/planning */
		unnamed_stmt_context =
			AllocSetContextCreate(TopMemoryContext,
								  "unnamed prepared statement",
								  ALLOCSET_DEFAULT_MINSIZE,
								  ALLOCSET_DEFAULT_INITSIZE,
								  ALLOCSET_DEFAULT_MAXSIZE);
		oldcontext = MemoryContextSwitchTo(unnamed_stmt_context);
	}

	QueryContext = CurrentMemoryContext;

	/*
	 * Do basic parsing of the query or queries (this should be safe even
	 * if we are in aborted transaction state!)
	 */
	parsetree_list = pg_parse_query(query_string);

	/*
	 * We only allow a single user statement in a prepared statement. This
	 * is mainly to keep the protocol simple --- otherwise we'd need to
	 * worry about multiple result tupdescs and things like that.
	 */
	if (length(parsetree_list) > 1)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("cannot insert multiple commands into a prepared statement")));

	if (parsetree_list != NIL)
	{
		Node	   *parsetree = (Node *) lfirst(parsetree_list);
		int			i;

		/*
		 * Get the command name for possible use in status display.
		 */
		commandTag = CreateCommandTag(parsetree);

		/*
		 * If we are in an aborted transaction, reject all commands except
		 * COMMIT/ROLLBACK.  It is important that this test occur before
		 * we try to do parse analysis, rewrite, or planning, since all
		 * those phases try to do database accesses, which may fail in
		 * abort state. (It might be safe to allow some additional utility
		 * commands in this state, but not many...)
		 */
		if (IsAbortedTransactionBlockState())
		{
			bool		allowit = false;

			if (IsA(parsetree, TransactionStmt))
			{
				TransactionStmt *stmt = (TransactionStmt *) parsetree;

				if (stmt->kind == TRANS_STMT_COMMIT ||
					stmt->kind == TRANS_STMT_ROLLBACK)
					allowit = true;
			}

			if (!allowit)
				ereport(ERROR,
						(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
						 errmsg("current transaction is aborted, "
					 "commands ignored until end of transaction block")));
		}

		/*
		 * OK to analyze, rewrite, and plan this query.  Note that the
		 * originally specified parameter set is not required to be
		 * complete, so we have to use parse_analyze_varparams().
		 */
		if (log_parser_stats)
			ResetUsage();

		querytree_list = parse_analyze_varparams(parsetree,
												 &paramTypes,
												 &numParams);

		/*
		 * Check all parameter types got determined, and convert array
		 * representation to a list for storage.
		 */
		param_list = NIL;
		for (i = 0; i < numParams; i++)
		{
			Oid			ptype = paramTypes[i];

			if (ptype == InvalidOid || ptype == UNKNOWNOID)
				ereport(ERROR,
						(errcode(ERRCODE_INDETERMINATE_DATATYPE),
				  errmsg("could not determine data type of parameter $%d",
						 i + 1)));
			param_list = lappendo(param_list, ptype);
		}

		if (log_parser_stats)
			ShowUsage("PARSE ANALYSIS STATISTICS");

		querytree_list = pg_rewrite_queries(querytree_list);

		plantree_list = pg_plan_queries(querytree_list, true);
	}
	else
	{
		/* Empty input string.	This is legal. */
		commandTag = NULL;
		querytree_list = NIL;
		plantree_list = NIL;
		param_list = NIL;
	}

	/* If we got a cancel signal in analysis or planning, quit */
	CHECK_FOR_INTERRUPTS();

	/*
	 * Store the query as a prepared statement.  See above comments.
	 */
	if (is_named)
	{
		StorePreparedStatement(stmt_name,
							   query_string,
							   commandTag,
							   querytree_list,
							   plantree_list,
							   param_list);
	}
	else
	{
		PreparedStatement *pstmt;

		pstmt = (PreparedStatement *) palloc0(sizeof(PreparedStatement));
		/* query_string needs to be copied into unnamed_stmt_context */
		pstmt->query_string = pstrdup(query_string);
		/* the rest is there already */
		pstmt->commandTag = commandTag;
		pstmt->query_list = querytree_list;
		pstmt->plan_list = plantree_list;
		pstmt->argtype_list = param_list;
		pstmt->context = unnamed_stmt_context;
		/* Now the unnamed statement is complete and valid */
		unnamed_stmt_pstmt = pstmt;
	}

	MemoryContextSwitchTo(oldcontext);

	QueryContext = NULL;

	/*
	 * We do NOT close the open transaction command here; that only
	 * happens when the client sends Sync.	Instead, do
	 * CommandCounterIncrement just in case something happened during
	 * parse/plan.
	 */
	CommandCounterIncrement();

	/*
	 * Send ParseComplete.
	 */
	if (whereToSendOutput == Remote)
		pq_putemptymessage('1');

	if (save_log_statement_stats)
		ShowUsage("PARSE MESSAGE STATISTICS");

	debug_query_string = NULL;
}

/*
 * exec_bind_message
 *
 * Process a "Bind" message to create a portal from a prepared statement
 */
static void
exec_bind_message(StringInfo input_message)
{
	const char *portal_name;
	const char *stmt_name;
	int			numPFormats;
	int16	   *pformats = NULL;
	int			numParams;
	int			numRFormats;
	int16	   *rformats = NULL;
	int			i;
	PreparedStatement *pstmt;
	Portal		portal;
	ParamListInfo params;

	pgstat_report_activity("<BIND>");

	set_ps_display("BIND");

	/*
	 * Start up a transaction command so we can call functions etc. (Note
	 * that this will normally change current memory context.) Nothing
	 * happens if we are already in one.
	 */
	start_xact_command();

	/* Switch back to message context */
	MemoryContextSwitchTo(MessageContext);

	/* Get the fixed part of the message */
	portal_name = pq_getmsgstring(input_message);
	stmt_name = pq_getmsgstring(input_message);

	/* Get the parameter format codes */
	numPFormats = pq_getmsgint(input_message, 2);
	if (numPFormats > 0)
	{
		pformats = (int16 *) palloc(numPFormats * sizeof(int16));
		for (i = 0; i < numPFormats; i++)
			pformats[i] = pq_getmsgint(input_message, 2);
	}

	/* Get the parameter value count */
	numParams = pq_getmsgint(input_message, 2);

	if (numPFormats > 1 && numPFormats != numParams)
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
		errmsg("bind message has %d parameter formats but %d parameters",
			   numPFormats, numParams)));

	/* Find prepared statement */
	if (stmt_name[0] != '\0')
		pstmt = FetchPreparedStatement(stmt_name, true);
	else
	{
		/* special-case the unnamed statement */
		pstmt = unnamed_stmt_pstmt;
		if (!pstmt)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_PSTATEMENT),
				   errmsg("unnamed prepared statement does not exist")));
	}

	if (numParams != length(pstmt->argtype_list))
		ereport(ERROR,
				(errcode(ERRCODE_PROTOCOL_VIOLATION),
				 errmsg("bind message supplies %d parameters, but prepared statement \"%s\" requires %d",
					numParams, stmt_name, length(pstmt->argtype_list))));

	/*
	 * Create the portal.  Allow silent replacement of an existing portal
	 * only if the unnamed portal is specified.
	 */
	if (portal_name[0] == '\0')
		portal = CreatePortal(portal_name, true, true);
	else
		portal = CreatePortal(portal_name, false, false);

	PortalDefineQuery(portal,
					  pstmt->query_string,
					  pstmt->commandTag,
					  pstmt->query_list,
					  pstmt->plan_list,
					  pstmt->context);

	/*
	 * Fetch parameters, if any, and store in the portal's memory context.
	 *
	 * In an aborted transaction, we can't risk calling user-defined
	 * functions, but we can't fail to Bind either, so bind all parameters
	 * to null values.
	 */
	if (numParams > 0)
	{
		bool		isaborted = IsAbortedTransactionBlockState();
		List	   *l;
		MemoryContext oldContext;

		oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));

		params = (ParamListInfo)
			palloc0((numParams + 1) * sizeof(ParamListInfoData));

		i = 0;
		foreach(l, pstmt->argtype_list)
		{
			Oid			ptype = lfirsto(l);
			int32		plength;
			bool		isNull;

			plength = pq_getmsgint(input_message, 4);
			isNull = (plength == -1);

			if (!isNull)
			{
				const char *pvalue = pq_getmsgbytes(input_message, plength);

				if (isaborted)
				{
					/* We don't bother to check the format in this case */
					isNull = true;
				}
				else
				{
					int16		pformat;
					StringInfoData pbuf;
					char		csave;

					if (numPFormats > 1)
						pformat = pformats[i];
					else if (numPFormats > 0)
						pformat = pformats[0];
					else
						pformat = 0;	/* default = text */

					/*
					 * Rather than copying data around, we just set up a
					 * phony StringInfo pointing to the correct portion of
					 * the message buffer.	We assume we can scribble on
					 * the message buffer so as to maintain the convention
					 * that StringInfos have a trailing null.  This is
					 * grotty but is a big win when dealing with very
					 * large parameter strings.
					 */
					pbuf.data = (char *) pvalue;
					pbuf.maxlen = plength + 1;
					pbuf.len = plength;
					pbuf.cursor = 0;

					csave = pbuf.data[plength];
					pbuf.data[plength] = '\0';

					if (pformat == 0)
					{
						Oid			typInput;
						Oid			typElem;
						char	   *pstring;

						getTypeInputInfo(ptype, &typInput, &typElem);

						/*
						 * We have to do encoding conversion before
						 * calling the typinput routine.
						 */
						pstring = (char *)
							pg_client_to_server((unsigned char *) pbuf.data,
												plength);
						params[i].value =
							OidFunctionCall3(typInput,
											 CStringGetDatum(pstring),
											 ObjectIdGetDatum(typElem),
											 Int32GetDatum(-1));
						/* Free result of encoding conversion, if any */
						if (pstring != pbuf.data)
							pfree(pstring);
					}
					else if (pformat == 1)
					{
						Oid			typReceive;
						Oid			typElem;

						/*
						 * Call the parameter type's binary input
						 * converter
						 */
						getTypeBinaryInputInfo(ptype, &typReceive, &typElem);

						params[i].value =
							OidFunctionCall2(typReceive,
											 PointerGetDatum(&pbuf),
											 ObjectIdGetDatum(typElem));

						/* Trouble if it didn't eat the whole buffer */
						if (pbuf.cursor != pbuf.len)
							ereport(ERROR,
									(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
									 errmsg("incorrect binary data format in bind parameter %d",
											i + 1)));
					}
					else
					{
						ereport(ERROR,
								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
								 errmsg("unsupported format code: %d",
										pformat)));
					}

					/* Restore message buffer contents */
					pbuf.data[plength] = csave;
				}
			}

			params[i].kind = PARAM_NUM;
			params[i].id = i + 1;
			params[i].isnull = isNull;

			i++;
		}

		params[i].kind = PARAM_INVALID;

		MemoryContextSwitchTo(oldContext);
	}
	else
		params = NULL;

	/* Get the result format codes */
	numRFormats = pq_getmsgint(input_message, 2);
	if (numRFormats > 0)
	{
		rformats = (int16 *) palloc(numRFormats * sizeof(int16));
		for (i = 0; i < numRFormats; i++)
			rformats[i] = pq_getmsgint(input_message, 2);
	}

	pq_getmsgend(input_message);

	/*
	 * Start portal execution.
	 */
	PortalStart(portal, params);

	/*
	 * Apply the result format requests to the portal.
	 */
	PortalSetResultFormat(portal, numRFormats, rformats);

	/*
	 * Send BindComplete.
	 */
	if (whereToSendOutput == Remote)
		pq_putemptymessage('2');
}

/*
 * exec_execute_message
 *
 * Process an "Execute" message for a portal
 */
static void
exec_execute_message(const char *portal_name, long max_rows)
{
	CommandDest dest;
	DestReceiver *receiver;
	Portal		portal;
	bool		is_trans_stmt = false;
	bool		is_trans_exit = false;
	bool		completed;
	char		completionTag[COMPLETION_TAG_BUFSIZE];

	/* Adjust destination to tell printtup.c what to do */
	dest = whereToSendOutput;
	if (dest == Remote)
		dest = RemoteExecute;

	portal = GetPortalByName(portal_name);
	if (!PortalIsValid(portal))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_CURSOR),
				 errmsg("portal \"%s\" does not exist", portal_name)));

	/*
	 * If the original query was a null string, just return
	 * EmptyQueryResponse.
	 */
	if (portal->commandTag == NULL)
	{
		Assert(portal->parseTrees == NIL);
		NullCommand(dest);
		return;
	}

	if (portal->sourceText)
	{
		debug_query_string = portal->sourceText;
		pgstat_report_activity(portal->sourceText);
	}
	else
	{
		debug_query_string = "execute message";
		pgstat_report_activity("<EXECUTE>");
	}

	set_ps_display(portal->commandTag);

	BeginCommand(portal->commandTag, dest);

	/* Check for transaction-control commands */
	if (length(portal->parseTrees) == 1)