Well you're trying to do a join. How much data is actually in TableB?
You might consider denormalizing so that you don't have to query TableB,
the data you need is already in TableA.
You could use a Get (single trip) for the inner loop rather than a
Scanner (which requires multiple round-trips). You could even use a Get
for the outer loop by making your table wide instead of tall.
Row Key: TYPE|VALUE
Column: link:ID
And you have a column for each ID within that TYPE|VALUE row.
Also, don't forget to close your scanners if you do use scanners.
JG
llpind wrote:
Assume a schema like so:
TableA======================
Row Key: TYPE|VALUE|ID
Column: link:ID (irrelevant)
TableB======================
Row Key: ID
Column: typeval:TYPE|VALUE
===========================
I need to iterate over the TableA using a Scanner to get all IDs based on
TYPE|VALUE, then for each ID I need to get from TableB what TYPE|VALUE’s
it’s tied to (a many to many).
Assume I have a list of TYPE|VALUES in a List, and need to process through
this data. Done something like this:
for (String typeVal : list){
Scan tblAScan = new Scan(Bytes.toBytes(typeVal + “|”),
Bytes.toBytes(typeVal + “|A”)); //give me all IDs for matching TYPE|VAL
ResultScanner s1 = tblA.getScanner(tblAScan);
for (Result tblBRowResult = s1.next(); tblBRowResult != null;
tblBRowResult = s1.next()){
Scan tblBScan = new Scan(Bytes.toBytes(tblBRowResult.getValue() ),
Bytes.toBytes(typeVal + “ ”)); //IDs are all numeric
ResultScanner s2 = tblA.getScanner(tblAScan);
List results = s2.next().list(); //only care about column data here,
since ID is row key
for (KeyValue kv : results){
//do stuff
kv.getValue();
}
}
}
