Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/tajo/pull/442#discussion_r28203962
--- Diff: tajo-common/src/main/java/org/apache/tajo/conf/TajoConf.java ---
@@ -203,6 +203,7 @@ public static int setDateOrder(int dateOrder) {
// Query Configuration
QUERY_SESSION_TIMEOUT("tajo.query.session.timeout-sec", 60,
Validators.min("0")),
+ QUERY_SESSION_CACHE_SIZE("tajo.query.session.cache-size", 1000000,
Validators.min("1000000")),
--- End diff --
1. *tajo.query.session.query-cache-size-kb*, then? No problem.
2. On minimum cache size, let say 1K-size cache holding 10 x 100Byte SQL
queries. The effect is small. In this case, we had better off the cache. In
that sense, we need to guide the effective cache size practically.
3. If cache is off, the cache will be null and Tajo will avoid checking the
cache. I agree that it's important.
4. This query cache will be important especially for *PreparedStatement* of
TAJO-1435. (I'm working on this too.) PreparedStatement is popular in real
enterprise environments. I did add PLACE_HOLDER in SQL syntax for '?' of
PreparedStatement and am trying to replace them after cloning Expr. (Anyway,
this is beyond the scope of this issue).
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
