[游戏开发]Shardingsphere 4.1.1 版本坑

?

SELECT
	COUNT(*)
FROM
	(
		SELECT
			XXX
		FROM
			XXX r
		LEFT JOIN YYY d ON r.id = d.resource_position_id
		AND d.tenant_code = '10001'
		WHERE
			1 = 1
		AND r.custom_id = ?
		AND r.is_deleted = 'N'
		AND r.tenant_code = '10001'
		GROUP BY
			r.id
	) TOTAL

?1、SelectStatementContext 初始化

    public SelectStatementContext(SelectStatement sqlStatement, GroupByContext groupByContext, OrderByContext orderByContext, ProjectionsContext projectionsContext, PaginationContext paginationContext) {
        super(sqlStatement);
        this.tablesContext = new TablesContext(sqlStatement.getSimpleTableSegments());
        this.groupByContext = groupByContext;
        this.orderByContext = orderByContext;
        this.projectionsContext = projectionsContext;
        this.paginationContext = paginationContext;
        this.containsSubquery = this.containsSubquery();
    }

2、注意

this.tablesContext = new TablesContext(sqlStatement.getSimpleTableSegments());

SelectStatement.java

public Collection<SimpleTableSegment> getSimpleTableSegments() {
        Collection<SimpleTableSegment> result = new LinkedList();
        Iterator var2 = this.tableReferences.iterator();

        while(var2.hasNext()) {
            TableReferenceSegment each = (TableReferenceSegment)var2.next();
            result.addAll(each.getTables());
        }

        return result;
    }

TableReferenceSegment.java

public Collection<SimpleTableSegment> getTables() {
        Collection<SimpleTableSegment> tables = new LinkedList();
        if (null != this.tableFactor && this.tableFactor.getTable() instanceof SimpleTableSegment) {
            tables.add((SimpleTableSegment)this.tableFactor.getTable());
        }

        if (!this.joinedTables.isEmpty()) {
            Iterator var2 = this.joinedTables.iterator();

            while(var2.hasNext()) {
                JoinedTableSegment each = (JoinedTableSegment)var2.next();
                if (null != each.getTable()) {
                    tables.add((SimpleTableSegment)each.getTable());
                }
            }
        }

此时tableFactor的类型为SubquerySegment(startIndex=21, stopIndex=555, select=org.apache.shardingsphere.sql.parser.sql.statement.dml.SelectStatement@8a91e92)，getTables拿到的是空集合

3、执行查询时,实例化路由引擎

ShardingRouteEngineFactory.java

public static ShardingRouteEngine newInstance(ShardingRule shardingRule, ShardingSphereMetaData metaData, SQLStatementContext sqlStatementContext, ShardingConditions shardingConditions, ConfigurationProperties properties) {
        SQLStatement sqlStatement = sqlStatementContext.getSqlStatement();
        Collection<String> tableNames = sqlStatementContext.getTablesContext().getTableNames();
        if (sqlStatement instanceof TCLStatement) {
            return new ShardingDatabaseBroadcastRoutingEngine();
        } else if (sqlStatement instanceof DDLStatement) {
            return new ShardingTableBroadcastRoutingEngine(metaData.getSchema(), sqlStatementContext);
        } else if (sqlStatement instanceof DALStatement) {
            return getDALRoutingEngine(shardingRule, sqlStatement, tableNames);
        } else if (sqlStatement instanceof DCLStatement) {
            return getDCLRoutingEngine(sqlStatementContext, metaData);
        } else if (shardingRule.isAllInDefaultDataSource(tableNames)) {
            return new ShardingDefaultDatabaseRoutingEngine(tableNames);
        } else if (shardingRule.isAllBroadcastTables(tableNames)) {
            return (ShardingRouteEngine)(sqlStatement instanceof SelectStatement ? new ShardingUnicastRoutingEngine(tableNames) : new ShardingDatabaseBroadcastRoutingEngine());
        } else if (sqlStatementContext.getSqlStatement() instanceof DMLStatement && tableNames.isEmpty() && shardingRule.hasDefaultDataSourceName()) {
            return new ShardingDefaultDatabaseRoutingEngine(tableNames);
        } else {
            return (ShardingRouteEngine)((!(sqlStatementContext.getSqlStatement() instanceof DMLStatement) || !shardingConditions.isAlwaysFalse()) && !tableNames.isEmpty() && shardingRule.tableRuleExists(tableNames) ? getShardingRoutingEngine(shardingRule, sqlStatementContext, shardingConditions, tableNames, properties) : new ShardingUnicastRoutingEngine(tableNames));
        }
    }

此时，tableNames，拿到的是空，因为第1步，初始化时，tables是空，最后一步拿到的是默认随机路由引擎ShardingUnicastRoutingEngine

4、路由问题

ShardingUnicastRoutingEngine.java

public RouteResult route(ShardingRule shardingRule) {
        RouteResult result = new RouteResult();
        String dataSourceName = shardingRule.getShardingDataSourceNames().getRandomDataSourceName();
        RouteMapper dataSourceMapper = new RouteMapper(dataSourceName, dataSourceName);
        ArrayList tableMappers;
        if (shardingRule.isAllBroadcastTables(this.logicTables)) {
            tableMappers = new ArrayList(this.logicTables.size());
            Iterator var6 = this.logicTables.iterator();

            while(var6.hasNext()) {
                String each = (String)var6.next();
                tableMappers.add(new RouteMapper(each, each));
            }

            result.getRouteUnits().add(new RouteUnit(dataSourceMapper, tableMappers));
        } else if (this.logicTables.isEmpty()) {
            result.getRouteUnits().add(new RouteUnit(dataSourceMapper, Collections.emptyList()));
        } else if (1 == this.logicTables.size()) {
            String logicTableName = (String)this.logicTables.iterator().next();
            if (!shardingRule.findTableRule(logicTableName).isPresent()) {
                result.getRouteUnits().add(new RouteUnit(dataSourceMapper, Collections.emptyList()));
                return result;
            }

            DataNode dataNode = shardingRule.getDataNode(logicTableName);
            result.getRouteUnits().add(new RouteUnit(dataSourceMapper, Collections.singletonList(new RouteMapper(logicTableName, dataNode.getTableName()))));
        } else {
            tableMappers = new ArrayList(this.logicTables.size());
            Set<String> availableDatasourceNames = null;
            boolean first = true;
            Iterator var8 = this.logicTables.iterator();

            while(var8.hasNext()) {
                String each = (String)var8.next();
                TableRule tableRule = shardingRule.getTableRule(each);
                DataNode dataNode = (DataNode)tableRule.getActualDataNodes().get(0);
                tableMappers.add(new RouteMapper(each, dataNode.getTableName()));
                Set<String> currentDataSourceNames = new HashSet(tableRule.getActualDatasourceNames().size());
                Iterator var13 = tableRule.getActualDataNodes().iterator();

                while(var13.hasNext()) {
                    DataNode eachDataNode = (DataNode)var13.next();
                    currentDataSourceNames.add(eachDataNode.getDataSourceName());
                }

                if (first) {
                    availableDatasourceNames = currentDataSourceNames;
                    first = false;
                } else {
                    availableDatasourceNames = Sets.intersection((Set)availableDatasourceNames, currentDataSourceNames);
                }
            }

            if (((Set)availableDatasourceNames).isEmpty()) {
                throw new ShardingSphereConfigurationException("Cannot find actual datasource intersection for logic tables: %s", new Object[]{this.logicTables});
            }

            dataSourceName = shardingRule.getShardingDataSourceNames().getRandomDataSourceName((Collection)availableDatasourceNames);
            result.getRouteUnits().add(new RouteUnit(new RouteMapper(dataSourceName, dataSourceName), tableMappers));
        }

        return result;
    }

String dataSourceName = shardingRule.getShardingDataSourceNames().getRandomDataSourceName();

数据源是个随机出来的数据源，不走分库算法