[GitHub] [incubator-doris] EmmyMiao87 commented on a change in pull request #4014: Add framework of mv selector

[GitBox <gi...@apache.org>]

EmmyMiao87 commented on a change in pull request #4014:
URL: https://github.com/apache/incubator-doris/pull/4014#discussion_r450093057



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File path: fe/src/main/java/org/apache/doris/analysis/QueryStmt.java
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@@ -113,6 +113,40 @@
     // represent the "INTO OUTFILE" clause
     protected OutFileClause outFileClause;
 
+    /**
+     * If the query stmt belongs to CreateMaterializedViewStmt,
+     * such as
+     * `CREATE MATERIALIZED VIEW mv AS SELECT bitmap_union(to_bitmap(k1)) from table`
+     * query stmt will not be rewrite by MVRewriter.
+     * The `bitmap_union(to_bitmap(k1))` is the definition of the mv column rather then a expr.
+     * So `forbiddenMVRewrite` will be set to true to protect the definition of the mv column from being overwritten.
+     * <p>
+     * In other query case, `forbiddenMVRewrite` is always false.
+     */
+    private boolean forbiddenMVRewrite = false;
+
+    /**
+     * If the tuple id in `disableMVRewriteTupleIds`, the expr which belongs to this tuple will not be MVRewritten.
+     * Initially this set is an empty set.
+     * When the scan node is unable to match any index in selecting the materialized view,
+     *   the tuple is added to this set.
+     * The query will be re-executed, and this tuple will not be mv rewritten.
+     * For example:
+     * TableA: (k1 int, k2 int, k3 int)
+     * MV: (k1 int, mv_bitmap_union_k2 bitmap bitmap_union)
+     * Query: select k3, bitmap_union(to_bitmap(k2)) from TableA
+     * First analyze: MV rewriter enable and this set is empty
+     *     select k3, bitmap_union(mv_bitmap_union_k2) from TableA
+     * SingleNodePlanner: could not select any index for TableA
+     *     Add table to disableMVRewriteTupleIds.
+     * `disableMVRewriteTupleIds` = {TableA}
+     * Re-executed:
+     * Second analyze: MV rewrite disable in table and use origin stmt.
+     *     select k3, bitmap_union(to_bitmap(k2)) from TableA
+     * SingleNodePlanner: base index selected

Review comment:
       Under normal circumstances, the tuple id of the first parsing statement and the second parsing statement should be the same.
   If it involves query rewriting, I tested it, and no new tuple will be generated. So in theory, there is no problem.




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