Github user DaveBirdsall commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/333#discussion_r53705620
--- Diff: core/sql/sqlcomp/CmpSeabaseDDLtable.cpp ---
@@ -356,6 +356,9 @@ void CmpSeabaseDDL::createSeabaseTableLike(
query += keyClause;
}
+ // send any user CQDs down
+ Lng32 retCode = sendAllControls(FALSE, FALSE, TRUE);
+
--- End diff --
I think not. And here is why: If I do the CREATE TABLE LIKE from sqlci, the
CREATE TABLE LIKE logic executes in the master and the under-the-covers vanilla
CREATE TABLE executes in a tdm_arkcmp child. In sqlci, any CQD done in the
master is also done in the child. So, in the sqlci case, the CQDs will be
identical. As far as I know this has no ill effect. CQDs have an anomaly
though: They are not propagated more than one level down. UPDATE STATS runs in
a tdm_arkcmp child of sqlci (or MXOSRVR). The CREATE TABLE LIKE that UPDATE
STATS executes runs in a tdm_arkcmp child of that process (that is, a
grandchild of the sqlci). This seems to be intentional: UPDATE STATS wants to
tightly control what CQDs execute in that process. The under-the-covers vanilla
CREATE TABLE runs in a tdm_arkcmp child of the one running CREATE TABLE LIKE
(that is, a great-grandchild of sqlci). UPDATE STATS itself executes a
controlled set of CQDS; these reach the grandchild tdm_arkcmp (that is, the one
runni
ng CREATE TABLE LIKE) but not the great-grandchild. But it is an accident of
implementation that the vanilla CREATE TABLE runs one more process down. So,
sending the CQDs down seems harmless (as it works that way from sqlci now) and
appropriate (as UPDATE STATS has already controlled the CQDs run by the
grandchild). Apologies for all the words; this would be much clearer if drawn
in a picture.
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