I need to convert the value stored in a bigint column to a date field. The first step of the conversion involves converting it to timestamp, and subsequently use the TRUNC method to convert this column to a date value.
However, my query is failing while converting the bigint value to timestamp.
The error that I'm getting is:-
Amazon Invalid operation: cannot cast type bigint to timestamp without time zone;
The query I'm trying for now is something like this:-
select ts::timestamp from events limit 1;
I was able to avoid the time zone error by using the method described in this thread: https://stackoverflow.com/a/36399361
My dates are based on epochs, and I was able to do the following:
SELECT
(TIMESTAMP 'epoch' + contract_start_date * INTERVAL '1 Second ')
FROM
table_name
SELECT TIMESTAMP 'epoch' + {column of bigint}/1000 * INTERVAL '1 second' as adate FROM tbl
If you are starting with a POSIX timestamp, and trying to get a timezone aware datetime value, you will need to supply a timezone - even if you later want to truncate the time part away. I'm not familiar with redshift, but perhaps there is a way to specify you mean UTC.
Related
Usually we use EXTRACT (FROM YEAR date_column) = 2000 (let it be 2000 year). Also we can add EXTRACT (MONTH FROM date_column) = 1 (let it be January). Also we can extract a day - EXTRACT (DAY FROM date_column) = 5 (let it 5). But is it possible to use the pattern for this data? How does it look like in Postgres SQL
Say we have the table Shipment, the columns - date_payment, quantity, sum.
I'd like to get the table that content all shipments for 01.01.2020
How to query this table with data format 'YYYY-MM-DD', not using EXTRACT-function?
If the date column is a date type then:
SELECT * FROM some_table WHERE date_col = '2020-01-01';
If the column is timestamp or timestamptz then:
SELECT * FROM some_table WHERE date_trunc('day', date_col) = '2020-01-01'
Beware that with timestamptz time zones come into play when doing the date_trunc. From here date_trunc:
When the input value is of type timestamp with time zone, the truncation is performed with respect to a particular time zone; for example, truncation to day produces a value that is midnight in that zone. By default, truncation is done with respect to the current TimeZone setting, but the optional time_zone argument can be provided to specify a different time zone. The time zone name can be specified in any of the ways described in Section 8.5.3.
For a timestamp value per the above link:
A time zone cannot be specified when processing timestamp without time zone or interval inputs. These are always taken at face value.
Using psycopg to connect to a Redshift DB I am trying to group by date (in a specific time zone, given at query time). All date_times are stored without time zone (and correspond to UTC timestamps).
I have been trying the following:
SELECT DISTINCT DATE(TIME_ZONE(%(time_zone)s, date_time_dim.timestamp)) AS date,
SUM(meals.sugar_in_g) AS total_sugar
FROM meals
INNER JOIN date_time_dim
ON meals.created_at = date_time_dim.timestamp
WHERE meals.patient_id=%(patient_id)s
AND date_time_dim.timestamp >= %(utc_start_date_time)s
AND date_time_dim.timestamp <= %(utc_end_date_time)s
GROUP BY date
ORDER BY date ASC;
with the following query dictionary:
utc_start_date_time UTC-converted date time
utc_end_date_time UTC-converted date time
patient_id an integer
time_zone, a string, ex: 'US/Hawaii'
The goal being to have one entry for each date (in the given time zone).
What I tried gives me:
function time_zone("unknown", timestamp without time zone) does not exist
What am I missing ?
Edit: This is the same with CONVERT_TIME_ZONE, with and without source time_zone, with and without type casting time_zone to VARCHAR.
The function in Redshift to return a timestamp in a different timezone is TIMEZONE() not TIME_ZONE() - see https://docs.aws.amazon.com/redshift/latest/dg/Date_functions_header.html
I have a postgres database carrying date/time information in a text format. There is no way of changing it, but I have to retrieve those values as milisecons since epoch.
I managed to make a query, converting those date-time records to timestamps so that I get a correct "max" function behaviour like so:
SELECT max(TO_TIMESTAMP(column_name, 'YYYY/MM/DD HH24:MI:SS'))
FROM table_name;
But converting other results into miliseconds does not seem to work. And all the examples int the documentation and forums showcase only the usage for some literal value, not a value selected from a database. So lines like these don't work:
SELECT EXTRACT(EPOCH FROM TIMESTAMP
(select max(TO_TIMESTAMP(column_name, 'YYYY/MM/DD HH24:MI:SS'))
FROM table_name));
SELECT EXTRACT(EPOCH FROM TIMESTAMP
(select TO_TIMESTAMP(column_name,'YYYY/MM/DD HH24:MI:SS')
FROM table_name));
SELECT EXTRACT(EPOCH FROM TIMESTAMP WITH TIME ZONE(
SELECT TO_TIMESTAMP(column_name, 'YYYY/MM/DD HH24:MI:SS')
FROM table_name));
SELECT EXTRACT(EPOCH FROM TIMESTAMP WITH TIME ZONE TO_TIMESTAMP
(column_name, 'YYYY/MM/DD HH24:MI:SS'))
FROM table_name;
Is there an actual way to accomplish what I want by using a query, or I have to do something more complicated?
P.S.
Of course I can just retrieve all the infomation as text and use Qt (QDateTime) to convert it to miliseconds, but It would be more expensive and I was wondering if there is a way to ask the database to do it for me.
The timestamp keyword is only needed for literals (constants), not if you have a proper timestamp value available:
SELECT extract(epoch from max(TO_TIMESTAMP(column_name, 'YYYY/MM/DD HH24:MI:SS')))
FROM table_name;
Note that epoch represents seconds, not milliseconds.
I connected my redshift to dbeaver and while running select * on my table i got in the time column - 1541079087394 which is bigint. how can i shel run the query in order to get time stamp with date and time like in kibana - May 20th 2019, 10:49:16.949.
Time columns are not bigint, however you probably can convert that integer to a timestamp using this code method
select timestamp 'epoch' + your_bigint_col/1000 * interval '1 second' AS your_column_alias
from your_table
This is assuming that your bigint is epoch, you didn't say.
Image I have a table containing the following two columns:
timestampwithouttimezone (of type TIMESTAMP WITHOUT TIME ZONE)
utcoffset (of type INTEGER)
I want to convert those two column to a single one of type TIMESTAMP WITH TIME ZONE. Can this be achieved using a ALTER TABLE ALTER COLUMN [column] SET DATE TYPE TIMESTAMP WITH TIME ZONE query and the additional USING clause?
Or do I need a separate UPDATE query that takes the offset and sets the timezone of the timestamps? If that's the case, what would that query be? I can't find any examples that show how to update the timezone using an integer.
You could do that like this, assuming the offset is in hours:
ALTER TABLE mytab
ALTER timestampwithouttimezone
TYPE timestamp with time zone
USING CAST (timestampwithouttimezone::text || ' '
|| to_char(utcoffset, 'S00FM')
AS timestamp with time zone),
DROP utcoffset;