I have a column family and syntax like this:
CREATE TABLE sr_number_callrecord (
id int,
callerph text,
sr_number text,
callid text,
start_time text,
plan_id int,
PRIMARY KEY((sr_number), start_time, callerph)
);
I want to do the query like :
a) select * from dummy where sr_number='+919xxxx8383'
and start_time >='2014-12-02 08:23:18' limit 10;
b) select * from dummy where sr_number='+919xxxxxx83'
and start_time >='2014-12-02 08:23:18'
and callerph='+9120xxxxxxxx0' limit 10;
First query works fine but second query is giving error like
Bad Request: PRIMARY KEY column "callerph" cannot be restricted
(preceding column "start_time" is either not restricted or by a non-EQ
relation)
If I get the result in first query, In second query I am just adding one
more cluster key to get filter result and the row will be less
Just like you cannot skip PRIMARY KEY components, you may only use a non-equals operator on the last component that you query (which is why your 1st query works).
If you do need to serve both of the queries you have listed above, then you will need to have separate query tables for each. To serve the second query, a query table (with the same columns) will work if you define it with a PRIMARY KEY like this:
PRIMARY KEY((sr_number), callerph, start_time)
That way you are still specifying the parts of your PRIMARY KEY in order, and your non-equals condition is on the last PRIMARY KEY component.
There are certain restrictions in the way the primary key columns are to be used in the where clause http://docs.datastax.com/en/cql/3.1/cql/cql_reference/select_r.html
One solution that will work in your situation is to change the order of clustering columns in the primary key
CREATE TABLE sr_number_callrecord (
id int,
callerph text,
sr_number text,
callid text,
start_time text,
plan_id int,
PRIMARY KEY((sr_number), callerph, start_time,)
);
Now you can use range query on the last column as
select * from sr_number_callrecord where sr_number = '1234' and callerph = '+91123' and start_time >= '1234';
Related
I am looking for a good way to store time specific data in cassandra.
Each entry can look like (start_time, value). Later, I would like to retrieve the current value.
Logic of retrieving current value is like following.
Find all rows with start_time<=current_time.
Then find the value with maximum start_time from the rows obtained in the first step.
PS:- Edited the question to make it more clear
The exact requirements are not possible. But we can get close to it with one more column.
First, to be able to use <= operator, your start_time column need to be the clustering key of your table.
Then, you need a different partition key. You could choose a fixed value but it could bring problems when the partition will have too many rows. Then you should better use something like the year or the month of the start_time.
CREATE TABLE time_specific_table (
year bigint,
start_time timestamp,
value text,
PRIMARY KEY((year), start_time)
) WITH CLUSTERING ORDER BY (start_time DESC);
The problem is that when you will query the table, you will need to know the value of the partition key :
Find all rows with start_time<=current_time
SELECT * FROM time_specific_table
WHERE year = :year AND start_time <= :time;
select the value with maximum start_time
SELECT * FROM time_specific_table
WHERE year = :year LIMIT 1;
Create two separate table like below :
CREATE TABLE data (
start_time timestamp,
value int,
PRIMARY KEY(start_time, value)
);
CREATE TABLE current_value (
partition int PRIMARY KEY,
value int
);
Now you have to insert data into both table, to insert data into second table use a static value like 1
INSERT INTO current_value(partition, value) VALUES(1, 10);
Now In current value table your data will be upsert and You will get latest value whenever you select.
I have the following Apache Cassandra Table working.
CREATE TABLE user_songs (
member_id int,
song_id int,
title text,
timestamp timeuuid,
album_id int,
album_title text,
artist_names set<text>,
PRIMARY KEY ((member_id, song_id), title)
) WITH CLUSTERING ORDER BY (title ASC)
CREATE INDEX user_songs_member_id_idx ON music.user_songs (member_id);
When I try to do a select * FROM user_songs WHERE member_id = 1; I thought the Clustering Order by title would have given me a sorted ASC of the return - but it doesn't
Two questions:
Is there something with the table in terms of ordering or PK?
Do I need more tables for my needs in order to have a sorted title by member_id.
Note - my Cassandra queries for this table are:
Find all songs with member_id
Remove a song from memeber_id given song_id
Hence why the PK is composite
UPDATE
It is simialr to: Query results not ordered despite WITH CLUSTERING ORDER BY
However one of the suggestion in the comments is to put member_id,song_id,title as primary instead of the composite that I currently have. When I do that It seems that I cannot delete with only song_id and member_id which is the data that I get for deleting (hence title is missing when deleting)
I have a cassandra table defined like this:
CREATE TABLE test.test(
id text,
time bigint,
tag text,
mstatus boolean,
lonumb int,
PRIMARY KEY (id, time, tag)
)
And I want to select one column using select.
I tried:
select * from test where lonumb = 4231;
It gives:
code=2200 [Invalid query] message="No indexed columns present in by-columns clause with Equal operator"
Also I cannot do
select * from test where mstatus = true;
Doesn't cassandra support where as a part of CQL? How to correct this?
You can only use WHERE on the indexed or primary key columns. To correct your issue you will need to create an index.
CREATE INDEX iname
ON keyspacename.tablename(columname)
You can see more info here.
But you have to keep in mind that this query will have to run against all nodes in the cluster.
Alternatively you might rethink your table structure if the lonumb is something you'll do the most queries on.
Jny is correct in that WHERE is only valid on columns in the PRIMARY KEY, or those where a secondary index has been created for. One way to solve this issue is to create a specific query table for lonumb queries.
CREATE TABLE test.testbylonumb(
id text,
time bigint,
tag text,
mstatus boolean,
lonumb int,
PRIMARY KEY (lonumb, time, id)
)
Now, this query will work:
select * from testbylonumb where lonumb = 4231;
It will return all CQL rows where lonumb = 4231, sorted by time. I put id on the PRIMARY KEY to ensure uniqueness.
select * from test where mstatus = true;
This one is trickier. Indexes and keys on low-cardinality columns (like booleans) are generally considered a bad idea. See if there's another way you could model that. Otherwise, you could experiment with a secondary index on mstatus, but only use it when you specify a partition key (lonumb in this case), like this:
select * from testbylonumb where lonumb = 4231 AND mstatus = true;
Maybe that wouldn't perform too badly, as you are restricting it to a specific partition. But I definitely wouldn't ever do a SELECT * on mstatus.
I'm working on Cassandra, trying to get to know how it works. Encountered something strange while using IN operator. Example:
Table:
CREATE TABLE test_time (
name text,
age int,
time timeuuid,
"timestamp" timestamp,
PRIMARY KEY ((name, age), time)
)
I have inserted few dummy data. Used IN operator as follows:
SELECT * from test_time
where name="9" and age=81
and time IN (c7c88000-190e-11e4-8000-000000000000, c7c88000-190e-11e4-7000-000000000000);
It worked properly.
Then, added a column of type Map. Table will look like:
CREATE TABLE test_time (
name text,
age int,
time timeuuid,
name_age map<text, int>,
"timestamp" timestamp,
PRIMARY KEY ((name, age), time)
)
On executing same query, I got following error:
Bad Request: Cannot restrict PRIMARY KEY part time by IN relation as a collection is selected by the query
From the above examples, we can say, IN operator doesn't work if there are any column of type collection(Map or List) in the table.
I don't understand why it behaves like this. Please let me know If I'm missing anything here. Thanks in advance.
Yup...that is a limitation. You can do the following:
select * from ...where name='9' and age=81 and time > x and time < y
select [columns except collection] from ...where name='9' and age=81 and time in (...)
You can then filter client side, or do another query.
You can either include your column as a part of partitioning expression in the primary key
CREATE TABLE test_time (
name text,
age int,
time timeuuid,
"timestamp" timestamp,
PRIMARY KEY ((name, time), age)
);
or create a separate Materialized View to satisfy your query requirements:
CREATE MATERIALIZED VIEW test_time_mv AS
SELECT * FROM test_time
WHERE name IS NOT NULL AND time IS NOT NULL AND age IS NOT NULL
PRIMARY KEY ((name, time), age);
Now use the Materialized View in your query instead of the base table:
SELECT * from test_time_mv
where name='9'
and age=81
and time IN (c7c88000-190e-11e4-8000-000000000000,
c7c88000-190e-11e4-7000-000000000000);
I have a column family with primary key definition like this:
...
PRIMARY KEY ((website_id, item_id), user_id, date)
which will be queried using queries such as:
SELECT * FROM myCF
WHERE website_id = 30 AND item_id = 10
AND user_id = 0 AND date > 'some_date' ;
However, I'd like to keep my column family ordered by date only, such as SELECT date FROM myCF ; would return the most recent inserted date.
Due to the order of clustering columns, what I get is an order per user_id then per date.
If I change the primary key definition to:
PRIMARY KEY ((website_id, item_id), date, user_id)
I can no longer run the same query, as date must be restricted is user_id is.
I thought there might be some way to say:
...
PRIMARY KEY ((website_id, shop_id), store_id, date)
) WITH CLUSTERING ORDER BY (store_id RANDOMPLEASE, date DESC) ;
But it doesn't seem to exist. Worst, maybe this is completely stupid and I don't get why.
Is there any ways of achieving this? Am I missing something?
Many thanks!
Your query example restricts user_id so that should work with the second table format. But if you are actually trying to run queries like
SELECT * FROM myCF
WHERE website_id = 30 AND item_id = 10
AND date > 'some_date'
Then you need an additional table which is created to handle those queries, it would only order on Date and not on user id
Create Table LookupByDate ... PRIMARY KEY ((website_id, item_id), date)
In addition to your primary query, if all you try to get is "return the most recent inserted date", you may not need an additional table. You can use "static column" to store the last update time per partition. CASSANDRA-6561
It probably won't help your particular case (since I imagine your list of all users is unmanagably large), but if the condition on the first clustering column is matching one of a relatively small set of values then you can use IN.
SELECT * FROM myCF
WHERE website_id = 30 AND item_id = 10
AND user_id IN ? AND date > 'some_date'
Don't use IN on the partition key because this will create an inefficient query that hits multiple nodes putting stress on the coordinator node. Instead, execute multiple asynchronous queries in parallel. But IN on a clustering column is absolutely fine.