StarRocks 物化视图2 - 查询优化

    public enum MatchMode {
        // all tables and join types match
        COMPLETE,
        // all tables match but join types do not
        PARTIAL,
        // all join types match but query has more tables
        QUERY_DELTA,
        // all join types match but view has more tables
        VIEW_DELTA,
        NOT_MATCH
    }

    public OptExpression rewrite() {
        final OptExpression queryExpression = mvRewriteContext.getQueryExpression();
        final OptExpression mvExpression = materializationContext.getMvExpression();
        final List<Table> queryTables = mvRewriteContext.getQueryTables();
        final List<Table> mvTables = MvUtils.getAllTables(mvExpression);

        MatchMode matchMode = getMatchMode(queryTables, mvTables);
      
     public static MatchMode getMatchMode(List<Table> queryTables, List<Table> mvTables) {
        MatchMode matchMode = MatchMode.NOT_MATCH;
        if (queryTables.size() == mvTables.size() && Sets.newHashSet(queryTables).containsAll(mvTables)) {
            matchMode = MatchMode.COMPLETE;
        } else if (queryTables.size() > mvTables.size() && queryTables.containsAll(mvTables)) {
            matchMode = MatchMode.QUERY_DELTA;
        } else if (queryTables.size() < mvTables.size() && Sets.newHashSet(mvTables).containsAll(queryTables)) {
            matchMode = MatchMode.VIEW_DELTA;
        }
        return matchMode;
    }

    private boolean canMVRewriteIfMVHasExtraTables(MaterializedView mv,
                                                   Set<Table> queryTables) {

        // 1. when mv has foreign key constraints, it's ok whether query has extra tables or mv has extra tables.
        if (mv.hasForeignKeyConstraints()) {
            return true;
        }
        Set<Table> baseTables = mv.getBaseTableInfos().stream().map(x -> x.getTableChecked())
                .filter(x -> !x.isView() && !x.isMaterializedView())
                .collect(Collectors.toSet());
        Set<Table> extraTables =  baseTables.stream().filter(t -> !queryTables.contains(t)).collect(Collectors.toSet());
        if (extraTables.isEmpty()) {
            return true;
        }
        // 2. otherwise extra base tables should contain foreign constraints
        if (extraTables.stream().anyMatch(baseTable -> !(baseTable.hasForeignKeyConstraints() ||
                baseTable.hasUniqueConstraints()))) {
            Set<String> extraTableNames = extraTables.stream().map(Table::getName).collect(Collectors.toSet());
            logMVPrepare(connectContext, mv, "Exclude mv {} because it contains extra base tables: {}",
                    mv.getName(), Joiner.on(",").join(extraTableNames));
            return false;
        }
        return true;
    }

    private OptExpression rewriteViewDelta(List<Table> queryTables,
                                           List<Table> mvTables,
                                           PredicateSplit mvPredicateSplit,
                                           ReplaceColumnRefRewriter mvColumnRefRewriter,
                                           OptExpression queryExpression,
                                           OptExpression mvExpression) {
        // short circuit for tables without foreign-key/primary-key
        if (!optimizerContext.getSessionVariable().isEnableKeMvOp()
                && mvTables.stream().allMatch(table -> !table.hasForeignKeyConstraints())
                && !materializationContext.getMv().hasForeignKeyConstraints()) {
            logMVRewrite(mvRewriteContext, String.format("query table size:%d, mv table size:%d, " +
                    "can not try view delta rewrite because no FK constraints", queryTables.size(), mvTables.size()));
            return null;
        }

-- 物化视图成功优化 StarRocks支持将物化视图刷新任务的部分中间结果落盘
ALTER MATERIALIZED VIEW mv2 SET ('session.enable_spill' = 'true');
-- 3.2 版本物化视图刷新任务的默认超时时间为5分钟，v3.2版本之后默认为1小时。
ALTER MATERIALIZED VIEW mv2 SET ( 'session.query_timeout' = '4000' );