postgres.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 2,390 行 · 第 1/5 页

		PortalDefineQuery(portal,
						  query_string,
						  commandTag,
						  querytree_list,
						  plantree_list,
						  MessageContext);

		/*
		 * Start the portal.  No parameters here.
		 */
		PortalStart(portal, NULL, InvalidSnapshot);

		/*
		 * Select the appropriate output format: text unless we are doing a
		 * FETCH from a binary cursor.	(Pretty grotty to have to do this here
		 * --- but it avoids grottiness in other places.  Ah, the joys of
		 * backward compatibility...)
		 */
		format = 0;				/* TEXT is default */
		if (IsA(parsetree, FetchStmt))
		{
			FetchStmt  *stmt = (FetchStmt *) parsetree;

			if (!stmt->ismove)
			{
				Portal		fportal = GetPortalByName(stmt->portalname);

				if (PortalIsValid(fportal) &&
					(fportal->cursorOptions & CURSOR_OPT_BINARY))
					format = 1; /* BINARY */
			}
		}
		PortalSetResultFormat(portal, 1, &format);

		/*
		 * Now we can create the destination receiver object.
		 */
		receiver = CreateDestReceiver(dest, portal);

		/*
		 * Switch back to transaction context for execution.
		 */
		MemoryContextSwitchTo(oldcontext);

		/*
		 * Run the portal to completion, and then drop it (and the receiver).
		 */
		(void) PortalRun(portal,
						 FETCH_ALL,
						 receiver,
						 receiver,
						 completionTag);

		(*receiver->rDestroy) (receiver);

		PortalDrop(portal, false);

		if (IsA(parsetree, TransactionStmt))
		{
			/*
			 * If this was a transaction control statement, commit it. We will
			 * start a new xact command for the next command (if any).
			 */
			finish_xact_command();
		}
		else if (lnext(parsetree_item) == NULL)
		{
			/*
			 * If this is the last parsetree of the query string, close down
			 * transaction statement before reporting command-complete.  This
			 * is so that any end-of-transaction errors are reported before
			 * the command-complete message is issued, to avoid confusing
			 * clients who will expect either a command-complete message or an
			 * error, not one and then the other.  But for compatibility with
			 * historical Postgres behavior, we do not force a transaction
			 * boundary between queries appearing in a single query string.
			 */
			finish_xact_command();
		}
		else
		{
			/*
			 * We need a CommandCounterIncrement after every query, except
			 * those that start or end a transaction block.
			 */
			CommandCounterIncrement();
		}

		/*
		 * Tell client that we're done with this query.  Note we emit exactly
		 * one EndCommand report for each raw parsetree, thus one for each SQL
		 * command the client sent, regardless of rewriting. (But a command
		 * aborted by error will not send an EndCommand report at all.)
		 */
		EndCommand(completionTag, dest);
	}							/* end loop over parsetrees */

	/*
	 * Close down transaction statement, if one is open.
	 */
	finish_xact_command();

	/*
	 * If there were no parsetrees, return EmptyQueryResponse message.
	 */
	if (!parsetree_list)
		NullCommand(dest);

	QueryContext = NULL;

	/*
	 * Combine processing here as we need to calculate the query duration in
	 * both instances.
	 */
	if (save_log_duration || save_log_min_duration_statement != -1)
	{
		long		usecs;

		gettimeofday(&stop_t, NULL);
		if (stop_t.tv_usec < start_t.tv_usec)
		{
			stop_t.tv_sec--;
			stop_t.tv_usec += 1000000;
		}
		usecs = (long) (stop_t.tv_sec - start_t.tv_sec) * 1000000 +
			(long) (stop_t.tv_usec - start_t.tv_usec);

		/* Only print duration if we previously printed the statement. */
		if (was_logged && save_log_duration)
			ereport(LOG,
					(errmsg("duration: %ld.%03ld ms",
							(long) ((stop_t.tv_sec - start_t.tv_sec) * 1000 +
								  (stop_t.tv_usec - start_t.tv_usec) / 1000),
						 (long) (stop_t.tv_usec - start_t.tv_usec) % 1000)));

		/*
		 * Output a duration_statement to the log if the query has exceeded
		 * the min duration, or if we are to print all durations.
		 */
		if (save_log_min_duration_statement == 0 ||
			(save_log_min_duration_statement > 0 &&
			 usecs >= save_log_min_duration_statement * 1000))
			ereport(LOG,
					(errmsg("duration: %ld.%03ld ms  statement: %s%s",
							(long) ((stop_t.tv_sec - start_t.tv_sec) * 1000 +
								  (stop_t.tv_usec - start_t.tv_usec) / 1000),
							(long) (stop_t.tv_usec - start_t.tv_usec) % 1000,
							query_string,
							prepare_string ? prepare_string : "")));
	}

	if (save_log_statement_stats)
		ShowUsage("QUERY STATISTICS");

	if (prepare_string != NULL)
		pfree(prepare_string);

	debug_query_string = NULL;
}

/*
 * exec_parse_message
 *
 * Execute a "Parse" protocol message.
 */
static void
exec_parse_message(const char *query_string,	/* string to execute */
				   const char *stmt_name,		/* name for prepared stmt */
				   Oid *paramTypes,		/* parameter types */
				   int numParams)		/* number of parameters */
{
	MemoryContext oldcontext;
	List	   *parsetree_list;
	const char *commandTag;
	List	   *querytree_list,
			   *plantree_list,
			   *param_list;
	bool		is_named;
	bool		save_log_statement_stats = log_statement_stats;

	/*
	 * Report query to various monitoring facilities.
	 */
	debug_query_string = query_string;

	pgstat_report_activity(query_string);

	set_ps_display("PARSE");

	if (save_log_statement_stats)
		ResetUsage();

	if (log_statement == LOGSTMT_ALL)
		ereport(LOG,
				(errmsg("statement: PREPARE %s AS %s",
						(*stmt_name != '\0') ? stmt_name : "<unnamed>",
						query_string)));

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

	/*
	 * 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 (list_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 *) linitial(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() &&
			!IsTransactionExitStmt(parsetree))
			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 = lappend_oid(param_list, ptype);
		}

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

		querytree_list = pg_rewrite_queries(querytree_list);

		/*
		 * If this is the unnamed statement and it has parameters, defer query
		 * planning until Bind.  Otherwise do it now.
		 */
		if (!is_named && numParams > 0)
			plantree_list = NIL;
		else
			plantree_list = pg_plan_queries(querytree_list, NULL, 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 == DestRemote)
		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 != list_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, list_length(pstmt->argtype_list))));

	/*
	 * If we are in aborted transaction state, the only portals we can
	 * actually run are those containing COMMIT or ROLLBACK commands. We
	 * disallow binding anything else to avoid problems with infrastructure
	 * that expects to run inside a valid transaction.	We also disallow
	 * binding any parameters, since we can't risk calling user-defined I/O
	 * functions.
	 */
	if (IsAbortedTransactionBlockState() &&