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https://issues.apache.org/jira/browse/PHOENIX-4666?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16586633#comment-16586633
]
ASF GitHub Bot commented on PHOENIX-4666:
-----------------------------------------
Github user dbwong commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/298#discussion_r211432802
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/execute/HashJoinPlan.java ---
@@ -494,19 +540,37 @@ public ServerCache execute(HashJoinPlan parent)
throws SQLException {
if (hashExpressions != null) {
ResultIterator iterator = plan.iterator();
try {
- cache =
- parent.hashClient.addHashCache(ranges,
iterator,
- plan.getEstimatedSize(), hashExpressions,
singleValueOnly,
+ final byte[] cacheId;
+ String queryString =
plan.getStatement().toString().replaceAll("\\$[0-9]+", "\\$");
+ if (usePersistentCache) {
+ cacheId =
Arrays.copyOfRange(digest.digest(queryString.getBytes()), 0, 8);
+ boolean disablePersistentCache =
parent.delegate.getContext().getDisablePersistentCache(Bytes.toLong(cacheId));
+ if (!disablePersistentCache) {
+ try {
+ cache =
parent.hashClient.createServerCache(cacheId, parent.delegate);
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+ } else {
+ cacheId = Bytes.toBytes(RANDOM.nextLong());
+ }
+ System.out.println("Using cache ID " +
Hex.encodeHexString(cacheId) + " for " + queryString);
+ if (cache == null) {
--- End diff --
If disablePersistentCache == true this addHashCace is still using the
cacheId from the query string as opposed to a randomID. Is this intended?
Will this affect the future interactions with that cache?
> 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
> Attachments: PHOENIX-4666-subquery-cache-4.x-HBase-1.4.patch
>
>
> 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.
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