Hi Alex
If I implement pagination as suggested by your answer in
https://stackoverflow.com/questions/50168236/cassandra-pagination-inside-partition/50172052#50172052,
would I be able to mix the `doable` approach and standard pagination approach?
For eg.
Say I have 5 records belonging to the same partition, divided by clustering
columns
* P1,c1
* P1,c2
* P1,c3
* P1,c4
* P1,c5
The fetch size is 1 so 1 record is returned per query. Initially, I get P1,c1
(without using pagination state) (Page1)
session.execute(whereClause
.setFetchSize(fetchSize)) //get one row from ResultSet. Cassandra might
return more or less though
I get the pagingstate and pass it to the client which then returns it so taht I
can get page2
newPagingState:PagingState = resultSet.getExecutionInfo.getPagingState
and then I get P1,c2 using pagination state of P1,c1 (Page2).
session.execute(whereClause
.setFetchSize(1) //TODOM - configure fetch size in config file.
.setPagingState(pagingState)) //get one row from ResultSet. Cassandra might
return more or less though
}
Now I want to go back to Page1 (P1,c1), so I’ll execute query specifying
clustering_key >=c1 and fetch size of 1. I suppose I’ll create s Simple
Statement in Java Driver like
Statement stmt = new SimpleStatement(
"SELECT * FROM ... where c1 >= some value")
Then I’ll execute the statement
resultSet = session.execute(stmt)
.setFetchSize(1)
}
Could I now get the pagestate of this resultSet and use it to go to page 2
newPagingState:PagingState = resultSet.getExecutionInfo.getPagingState //get
paging state from result of SELECT * FROM ... where c1 >= some value and pass
it to client
and when the client returns it, I use it to go to Page 2
session.execute(whereClause
.setFetchSize(1) //TODOM - configure fetch size in config file.
.setPagingState(pagingState)) //get one row from ResultSet. Cassandra might
return more or less though
}
My reason to ask is that I have read “Note that the paging state can only be
reused with the exact same statement (same query string, same parameters).” In
my case, are the query strings are different? To get next/forward records, I
use whereClause:Where but to go backwards records I use SimpleStatement. So I
don’t know if I can use the PagingState like the way I have mentioned above.
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
From: Alex Ott<mailto:[email protected]>
Sent: 23 October 2020 09:25
To: user<mailto:[email protected]>
Subject: Re: reverse paging state
Hi
for that version of the driver there is no build-in functionality for the
backward paging, although it's doable:
https://stackoverflow.com/questions/50168236/cassandra-pagination-inside-partition/50172052#50172052
for driver 4.9.0 there is a wrapper class that emultates random paging, with
tradeoff for performance:
https://docs.datastax.com/en/developer/java-driver/4.9/manual/core/paging/#offset-queries
On Fri, Oct 23, 2020 at 10:00 AM Manu Chadha
<[email protected]<mailto:[email protected]>> wrote:
In Java driver 3.4.0, how does one revert the order of paging? I want to
implement a “Back” button but I can’t figure out from the API docs if/how I can
make Cassandra (via the Java driver) search backwards.
https://docs.datastax.com/en/drivers/java/3.4/
The code I have written currently is
session.execute(whereClause
.setFetchSize(fetchSize)
.setPagingState(pagingState))
Thanks
Manu
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--
With best wishes, Alex Ott
http://alexott.net/
Twitter: alexott_en (English), alexott (Russian)
