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ASF GitHub Bot commented on PHOENIX-4666: ----------------------------------------- Github user maryannxue commented on a diff in the pull request: https://github.com/apache/phoenix/pull/298#discussion_r183136068 --- Diff: phoenix-core/src/main/java/org/apache/phoenix/memory/GlobalMemoryManager.java --- @@ -159,6 +161,10 @@ protected void finalize() throws Throwable { } private void freeMemory() { +// System.out.println("Free memory! " + size); --- End diff -- I think this a mistake, missed from your code clean-up. > Add a subquery cache that persists beyond the life of a query > ------------------------------------------------------------- > > Key: PHOENIX-4666 > URL: https://issues.apache.org/jira/browse/PHOENIX-4666 > Project: Phoenix > Issue Type: Improvement > Reporter: Marcell Ortutay > Assignee: Marcell Ortutay > Priority: Major > > The user list thread for additional context is here: > [https://lists.apache.org/thread.html/e62a6f5d79bdf7cd238ea79aed8886816d21224d12b0f1fe9b6bb075@%3Cuser.phoenix.apache.org%3E] > ---- > A Phoenix query may contain expensive subqueries, and moreover those > expensive subqueries may be used across multiple different queries. While > whole result caching is possible at the application level, it is not possible > to cache subresults in the application. This can cause bad performance for > queries in which the subquery is the most expensive part of the query, and > the application is powerless to do anything at the query level. It would be > good if Phoenix provided a way to cache subquery results, as it would provide > a significant performance gain. > An illustrative example: > SELECT * FROM table1 JOIN (SELECT id_1 FROM large_table WHERE x = 10) > expensive_result ON table1.id_1 = expensive_result.id_2 AND table1.id_1 = > \{id} > In this case, the subquery "expensive_result" is expensive to compute, but it > doesn't change between queries. The rest of the query does because of the > \{id} parameter. This means the application can't cache it, but it would be > good if there was a way to cache expensive_result. > Note that there is currently a coprocessor based "server cache", but the data > in this "cache" is not persisted across queries. It is deleted after a TTL > expires (30sec by default), or when the query completes. > This is issue is fairly high priority for us at 23andMe and we'd be happy to > provide a patch with some guidance from Phoenix maintainers. We are currently > putting together a design document for a solution, and we'll post it to this > Jira ticket for review in a few days. -- This message was sent by Atlassian JIRA (v7.6.3#76005)