I am using Cassandra 3.11.13 and I have table with timestamp column. Where are my data stored in terms of +0 timezone, i.e. 2022-10-14 07:51:00.000000+0000, but I am hosting in Kazakhstan GMT+6
I want to export certain rows and certain period of time. When I am exporting into CSV, I am getting a file with timezone +0.
I tried to query like select * from table_name where primary_key = 'smth' and timestamp > '2022-10-14T06:30:00+0600' and timestamp < '2022-10-14T23:59:59+0600', but it's changed nothing.
Question is: How can I fetch timestamp with certain/correct timestamp?
The CQL timestamp data type is encoded as the number of milliseconds since Unix epoch (Jan 1, 1970 00:00 GMT) so its value is encoded in UTC timezone. Clients also display timestamps with a UTC timezone by default.
If you want the data to be displayed in your timezone, you need to configure your app or client to a specific timezone. For example, you can configure cqlsh to use a different timezone by specifying it in the cqlshrc file:
;; Display timezone
timezone = Australia/Melbourne
You can find a sample copy of cqlshrc here. Note that you will need to install the pytz Python library to use different timezones with cqlsh.
For details, see Cassandra CQL shell. Cheers!
Related
I'm making a small employee management system in which I have to play with dates in many places like attendance, leaves etc.
I use luxon for dates in my node.js project. Ex: DateTime.fromISO("2020-10-15"); gives me this in the console: 2020-10-15T00:00:00.000+05:00
but when I save it in mongodb it becomes 2020-10-14T19:00:00.000+00:00 and this is problematic because i need to query objects to check if there is an attendance marked in the same day or to get today's attendance. How can I solve this issue?
Storage
When MongoDB stores time-type data, it is first converted to UTC time and then stored in the database. The date submitted by the client is East 5, and the conversion to UTC time is minus 5 hours;
Read
MongoDB will convert the UTC date stored in the database into the East 5 zone of the client according to the time zone of the client, and then return it to the client
MongoDB only has a timestamp type, it does not have a date type. Dates are converted to times when they are stored. Which timezone the date is interpreted to be in can vary, looks like your driver uses the beginning of specified date in UTC. Ruby works the same way and you can read more about the principle here.
To "solve this issue", either only store and query by timestamps in MongoDB, converting dates to timestamps in your application, or understand how your language and driver converts dates to timestamps (note that JS Date type is actually a timestamp).
I have a column "postingdate" with datatype timestamp in Cassandra. I am using spring data Cassandra to save current date/time in this column when posting happens (Instant.now()). This is inserting date/time in UTC.
I have to select records which got posted on "2018-11-06". In table I have one record posted on this date and postingdate column is showing that as "2018-11-07 04:25:24+0000" in UTC.
I am running following query -
select * from mytable where id='5' and postingdate >=
'2018-11-06 00:00:00' and postingdate <= '2018-11-06 23:59:59';
Running this query on Dev Center console (or CQLSH), is giving me same results irrespective of timezone. I tried that in PST as well as IST and got the same result. Is Cassandra doing PST -> UTC OR IST -> UTC conversion before executing the query? If yes then how?
Per documentation:
When timezone is excluded, it's set to the client or coordinator timezone.
You can configure default timezone for CQLSH either by setting the TZ environment variable, or by specifying the timezone parameter in the cqlshrc configuration file.
I have json logs with timestamp(UTC TIME) in it. I map keys and values to Cassandra Table keys and Insert the record. However, Cassandra converts the already UTC timestamps to UTC again by subtracting 5 hours from the timestamp. The timezone here is (GMT + 5).
cqlsh> INSERT INTO myTable (id,time) VAlUES (abc123, 2018-01-12T12:32:31);
Now the time is already UTC time and its still inserts a timestamp of 5 hours ago.
How can I resolve this?
If you're using cqlsh to insert data, then you can specify default timezone in the cqlshrc file using the timezone parameter (see default cqlshrc as example).
If you insert dates programmatically, then you need to convert your time into corresponding type matching to the Cassandra's timestamp type (java.util.Date for Java, for example). In your case change could be simple - just append Z to timestamp string as pointed by Ralf
I am new in Cassandra. I have a Cassandra( V: 3.11 ) table (data). It is having a column timeStampCol of timestamp type and I am inserting a value in it.
insert into data (timeStampCol) values('2017-05-02 17:33:03');
While accessing the data from table
select * from data;
I got result like -
# Row 1
----------+------------------------------------
timeStampCol | 2017-05-02 08:33:03.000000+0000
Inserted value and retrieved values are different for time.
Reason might be timezone, how can I get it correct ?
Your selected timestamp value is correct, it's just showing in different timezone.
If you insert data into timestamp column without providing timezone like this one :
insert into data (timeStampCol) values('2017-05-02 17:33:03');
Cassandra will choose coordinator timezone
If no time zone is specified, the time zone of the Cassandra coordinator node handing the write request is used. For accuracy, DataStax recommends specifying the time zone rather than relying on the time zone configured on the Cassandra nodes.
You Need To Convert the String date into java.util.Date and set the timezone of coordinator node, In my case it was GMT+6
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Date date = dateFormat.parse("2012-01-21");
dateFormat.setTimeZone(TimeZone.getTimeZone("GMT+6")); //Change this time zone
Source : https://docs.datastax.com/en/cql/3.0/cql/cql_reference/timestamp_type_r.html
Cassandra will assume incoming data in the timezone it is set up. For example if you have Cassandra set up in IST, and even though incoming data is UTC, Cassandra will convert it back to UTC, considering data to be in IST.
You might have to set Cassandra coordinator timezone in code or calculate the time difference between the incoming data timezone and Cassandra timezone and add/subtract that from incoming data before it is written to Cassandra. This way you will have the exact timestamps written to Cassandra.
I've written a program that reads a file containing the date (in yyyy/MM/dd format) and uses the Datastax Java Driver to read the date and add it to a cassandra table.
So for instance, if my record contains a date value of '2010/06/01', then this date value gets converted into a date object (using the SimpleDateFormat class).
However, when I view the data (containing the date) in the database, I see that the date (which in the cassandra table is a timestamp type) shows the following:
2010-06-01 00:00:00+0100
The issue here is that I don't want the timestamp to have "+0100" (to indicate that this is british summer time), rather I'd want to store the date just as "2010-06-01 00:00:00+0000".
I've done the following to my program to try and 'ignore' the timezone by doing the following:
SimpleTimeZone tz = new SimpleTimeZone(0, "Out Timezone");
TimeZone.setDefault(tz);
String dateStringFromFile = "2010/06/01";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
Date theDate = sdf.parse(dateStringFromFile);
...Now when I add debug statements to my program, I can see that the date shows "2010-06-01 00:00:00+0000" on my log file (this is right for me). However when i see the date stored in Cassandra, i still see that the date shows as
"2010-06-01 00:00:00+0100" and not "2010-06-01 00:00:00+0000".
Is there anything on the cassandra side that I would have to change or update to ignore the timezone (i.e. not put +0100 on the date and to put +0000), so that the timestamp shows as "2010-06-01 00:00:00+0000"?
Please note that I am running Cassandra 3.0.5 on a Docker VM (Centos linux), Java 8.
Any advice is appreciated.
Thanks.
This solution has been sorted out. Nothing to do with cqlshrc. Its to do with forcing the timezone as 0 (like the code in the original post) and getting the time in milliseconds and writing that to the database - (which is a timestamp type column)