[teiid-issues] [JBoss JIRA] (TEIID-2381) Expanded source hint support

[ https://issues.jboss.org/browse/TEIID-2381?page=com.atlassian.jira.plugin... ] Steven Hawkins resolved TEIID-2381. ----------------------------------- Fix Version/s: 8.5 (was: 8.4.1) Resolution: Partially Completed Checked into 8.5 since this is a sizable change and may have follow-on changes. Can be pulled into 8.4.1 if needed. The change allows for the source hint to appear in any query (with, subquery, etc.), not just a user level query. And any usage of a source hint in a view will be preserved and a list of all applicable hints will be sent to the ExecutionContext (getHints and getGeneralHints). The getHint and getGeneralHint methods still exist and will return a space concatenated string of the applicable hints. No attempt was made in the source hint of either directing if the top level hint should effectively override lower hints nor to add a general global syntax for hint application. As such this still remains a somewhat crude mechanism in situations involving multiple source queries to the same source. There is also a behavior change here in that the source hint will no longer be applicable to procedure plans and non-merged subqueries (that is any scalar/exists/in that is not rewriten as a join). With clause items, inline, and the those queries that are transitively exposed by view access are all considered affected by the source hint and will accumulate in a single hint. For example: WITH x as (SELECT /*+ sh:'x' */ e1 from pm1.g2) SELECT /*+ sh:'foo' bar:'leading' */ g1.e1 from pm1.g1, x where g1.e1 = x.e1 order by g1.e1 limit 1 If it is pushed as a single query will then the pushdown would effectively be: WITH x as (SELECT e1 from pm1.g2) SELECT /*+ sh:'foo x' bar:'leading' */ g1.e1 from pm1.g1, x where g1.e1 = x.e1 order by g1.e1 limit 1 Note the combination of the general hints in the main select (which is considered the root query). It may alternatively be desirable to keep the source hint in the nearest query and altering the translator sql objects rather than squashing to a single hint on the ExecutionContext - however with non-preserved views we are forced to merge the hint upward and we just assuming that WITH should be treated the same way. If pushed as two queries, we have: SELECT /*+ sh:'x' */ e1 from pm1.g2 and SELECT /*+ sh:'foo' bar:'leading' */ g1.e1 from pm1.g1 At some point OPTION MAKE [NOT] DEP, NO CACHE, and the source hint mechanism need to be rationalized (see also TEIID-2263) and have the specification syntax expanded so that the user can be more exacting as to where the hint is applicable. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira