Change in asterixdb[master]: Compile a plan that matches user query in the case of nonpur...

[Yingyi Bu (Code Review)]

Yingyi Bu has posted comments on this change.

Change subject: Compile a plan that matches user query in the case of nonpure 
functions
......................................................................


Patch Set 4:

(2 comments)

I'm not sure how general the mechanism of "ConstantAtRuntimeExpressions()" is.  
Does it work with general cases?

For example,

for $x in dataset foo
let $time := current-time()
for $y in dataset bar
where $y.time > $time-50
return {
   "x_id": $x.id,
   "y_id": $y.id
} 


for $x in dataset foo
let $time := current-time()
return {
   "x_id": $x.id,
   "y_ids": for $y in dataset bar where $y.time > $time-50
} 

What's the query plan of the above queries look like?

https://asterix-gerrit.ics.uci.edu/#/c/1057/4/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/BTreeAccessMethod.java
File 
asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/BTreeAccessMethod.java:

Line 729:                 //Nonpure nonjoin case
It's not intuitive for me to understand the if condition, e.g., why this cannot 
lead to false positives or false dismissals?


https://asterix-gerrit.ics.uci.edu/#/c/1057/4/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/IOptimizableFuncExpr.java
File 
asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/am/IOptimizableFuncExpr.java:

Line 80:     ILogicalExpression[] getConstantAtRuntimeExpressions();
What does ConstantAtRuntimeExpressions() mean?

It's not obvious to me how this is general enough for nested subqueries?


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Gerrit-MessageType: comment
Gerrit-Change-Id: I2dec322b30835625430c06acd7626d902bada137
Gerrit-PatchSet: 4
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: Steven Jacobs <sjaco...@ucr.edu>
Gerrit-Reviewer: Jenkins <jenk...@fulliautomatix.ics.uci.edu>
Gerrit-Reviewer: Michael Blow <mb...@apache.org>
Gerrit-Reviewer: Preston Carman <prest...@apache.org>
Gerrit-Reviewer: Steven Jacobs <sjaco...@ucr.edu>
Gerrit-Reviewer: Yingyi Bu <buyin...@gmail.com>
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