1. SWiM Panel on Stream Query Languages
Jennifer Widom
Stan Zdonik
Carlo Zaniolo
Dennis Shasha
Mike Franklin

2. Format Four representative continuous queries over data streams
I’ll present them in English
We’ll all present or them in our favorite query language
Demos at lunch
As we go we’ll develop a list of the most salient language features, differences, issues, tradeoffs, etc. (need scribe at board)

3. Stream Query Repository
The four queries were chosen from a repository we’ve been creating at Stanford
Informal description + relational schemas for four applications
English description of queries
Queries in various languages – you write them, send us the URL

4. The Queries Windowing and aggregation, self-join or subquery
Packets(pID, length, [time])
Generate the stream of packets whose length is greater than twice the average packet length over the last 1 hour
Windowing, stream “splitting,” stored relation
SquirrelSensors(sID, region, [time])
SquirrelType(sID, type) // stored relation
Create an alert when more than 20 type ‘A’ squirrels are in Jennifer’s backyard

5. The Queries (cont’d) Stream self-joins
SquirrelChirps(sID, loc, [time])
Stream an event each time 3 different squirrels within a pairwise distance of 5 meters from each other chirp within 10 seconds of each other
Super bonus query – windowing, stream transformations
Packets(pID, src, dest, length, [time])
Log packet count and total packet length for each “flow” – new flow defined by > 2 minute gap for (src,dest) pair

6. Query 1 in CQL Packets(pID, length, [time])
Generate the stream of packets whose length is greater than twice the average packet length over the last 1 hour
Select Istream()
From Packets [Now]
Where length >
(Select 2  Avg(length) From Packets [Range 1 Hour])

7. Query 2 in CQL SquirrelSensors(sID, region, [time])
SquirrelType(sID, type) // stored relation
Create an alert when more than 20 type ‘A’ squirrels are in Jennifer’s backyard
Select alert()
From SquirrelSensors [Partition by sID Rows 1] SS,
SquirrelType ST
Where SS.region = 'JW yard'
And SS.sID = ST.sID And ST.type = 'A'
Having Count() > 20

8. Query 3 in CQL SquirrelChirps(sID, loc, [time])
Stream an event each time 3 different squirrels within a pairwise distance of 5 meters from each other chirp within 10 seconds of each other
Select Rstream(S1.sID, S1.loc, S2.sID, S2.loc, S3.sID, S3.loc)
From SquirrelChirps [Now] S1,
SquirrelChirps [Range 10 Seconds] S2,
SquirrelChirps [Range 10 Seconds] S3
Where S1.sID <> S2.sID And S1.sID <> S3.sID And S2.sID <> S3.sID
And distance(S1.loc, S2.loc) < 5 meters
And distance(S1.loc, S3.loc) < 5 meters
And distance(S2.loc, S3.loc) < 5 meters

9. Query 4 (super bonus) in CQL
Packets(pID, src, dest, length, [time])
Log packet count and total packet length for each “flow” – new flow defined by > 2 minute gap for (src,dest) pair
FlowStartStream:
Istream(
(Select P., 1 as flowStartBit From Packets [Now] as P
Where (src, dest) Not In
(Select src, dest From Packets [Range 2 Minutes]
Where pID <> P.pID))
Union
(Select P., 0 as flowStartBit From Packets [Now] as P
Where (src, dest) In
Where pID <> P.pID)))

10. Query 4 in CQL (cont’d) FlowIDStream: Select Istream(P., flowID)
From FlowStartStream [Now] P,
(Select src, dest, Count() as flowID
From FlowStartStream
Where flowStartBit = 1
Group By src, dest) ID
Where P.src = ID.src and P.dest = ID.dest
FlowTable:
Select src, dest, Count(), Sum(length)
From FlowIDStream
Group By src, dest, flowID