I have a varchar column in redshift table where the time is stored in 24 hours format, e.g, 17:00, I want to query the table and convert the format to 12 hours format showing AM or PM in time. When I test like to_char('17:00'::time,'HH12:MI AM') it works fine but when I put column name in place of hardcoded value querying the table,
SELECT to_char(prepoll_start::time,'HH12:MI AM')
FROM votecast.poll_hours AS ph
WHERE ph.prepoll_start is not null
and state = 'AL'
AND tab_elec_type = 'primary'
It won't work, gives an error
Invalid operation: Specified types or functions (one per INFO message) not supported on Redshift tables.;
Postgres version is 8.0.2
Please let me know what am doing wrong :(
First I had to create a timestamp value out of the time available. Then fetch the time in a 12 hour format.
select to_char( to_timestamp('1900-01-01 '||prepoll_start||':00' ,'YYYY/MM/DD HH:MI:SS') , 'HH12:MI AM')
from votecast.poll_hours;
Amazon Redshift does not support a TIME data type.
See: Datetime Types - Amazon Redshift
However, you are correct that it seems to support TIME for non-table related operations.
I tried playing around with string manipulation but was unable to get beyond the error you experienced. I think it is because TIME is recognized on the leader node, but fails to run on the compute nodes. (This is similar to the behaviour of time_series().)
Thus, you won't be able to use the TIME data type for anything that relies on table data.
Related
Trying to determine the time difference between two timestamp fields in postgres in HH24:MI:SS format, i.e.
date_started and date_completed
that have the following data:
date_started = 12/11/2021 09:11:00
date_completed = 12/11/2021 09:19:00
Using the following query:
select to_char(AGE(date_completed, date_started),'hh24:mi:ss') as "time_diff"
from my_table
returns the following value: 00:07:59
Notes: both these fields have a data type of: timestamp without timezone
My question is, why is this not actually returning 00:08:00 seeing that it is exactly, 8 minutes difference?
Solved my issue using the following:
select to_char(AGE(DATE_TRUNC('second', date_completed::timestamp), DATE_TRUNC('second', date_started::timestamp)),'hh24:mi:ss') as "time_diff"
from my_table
Reference SO: Discard milliseconds part from timestamp
Just want to also acknowledge #Bohemian for their input in assisting me to solve this issue wrt microseconds.
What is the best way to store a timestamp value in Postgresql in a specific format.
For example I would like to store a TIMESTAMP '2020-07-09 17:29:30.873513Z' down to the minute and ignore seconds value.
I can drop the seconds by using date_trunc('minute', TIMESTAMP '2020-07-09 17:29:30.873513Z') Is there anyway for me to specify this format in the column itself when I create a table?
Don't store formatted timestamps in the database, use timestamp with time zone or timestamp without time zone. You would lose powerful datetime arithmetic, value checking and waste storage space.
To have the values truncated to minute precision, use a BEFORE INSERT trigger that uses date_trunc on the value.
If you want to ascertain that only such values are stored, add a check constraint.
I would like to recommend not to drop seconds or anything from the stored data. Because it will create issues while you process the data later. And if you have to eliminate anything, you may eliminate it while retrieving the data.
Use the following code while creation of table
col_name timestamp without time zone DEFAULT timezone('gmt'::text, now())
This will give you a result as shown in the following image:
Good Luck.
I have a large data and in that one field be like Wed Sep 15 19:17:44 +0100 2010 and I need to insert that field in Hive.
I am getting troubled for choosing data type. I tried both timestamp and date but getting null values when loading from CSV file.
The data type is a String as it is text. If you want to convert it, I would suggest a TIMESTAMP. However you will need to do this conversion yourself while loading the data or (even better) afterwards.
To convert to a timestamp, you can use the following syntax:
CAST(FROM_UNIXTIME(UNIX_TIMESTAMP(<date_column>,'FORMAT')) as TIMESTAMP)
Your format seems complex though. My suggestion is to load it as a string and then just do a simple query on the first record until you get it working.
SELECT your_column as string_representation,
CAST(FROM_UNIXTIME(UNIX_TIMESTAMP(<date_column>,'FORMAT')) as TIMESTAMP) as timestamp_representation
FROM your_table
LIMIT 1
You can find more information on the format here: http://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html
My advice would be to concat some substrings first and try to convert only the day, month, year part before you look at time and timezone et cetera.
I am building a map in CartoDB which uses Postgres. I'm simply trying to display my dates as: 10-16-2014 but, haven't been able to because Postgres includes an unneeded timestamp in every date column.
Should I alter the column to remove the timestamp or, is it simply a matter of a (correct) SELECT query? I can SELECT records from a date range no problem with:
SELECT * FROM mytable
WHERE myTableDate >= '2014-01-01' AND myTableDate < '2014-12-31'
However, my dates appear in my CartoDB maps as: 2014-10-16T00:00:00Z and I'm just trying to get the popups on my maps to read: 10-16-2014.
Any help would be appreciated - Thank you!
You are confusing storage with display.
Store a timestamp or date, depending on whethether you need time or not.
If you want formatted output, ask the database for formatted output with to_char, e.g.
SELECT col1, col2, to_char(col3, 'DD-MM-YY'), ... FROM ...;
See the PostgreSQL manual.
There is no way to set a user-specified date output format. Dates are always output in ISO format. If PostgreSQL let you specify other formats without changing the SQL query text it'd really confuse client drivers and applications that expect the date format the protocol specifies and get something entirely different.
You have two basic options.
1 Change the column from a timestamp to a date column.
2 Cast to date in your SQL query (i.e. mytimestamp::date works).
In general if this is a presentation issue, I don't usually think that is a good reason to muck around with the database structure. That's better handled by client-side processing or casting in an SQL query. On the other hand if the issue is a semantic one, then you may want to revisit your database structure.
Redshift only support TIMESTAMP format, I want to dump some data that is originally stored in Postgres in time without time zone format. My data looks like this: 15:30:00
When I COPY my data into Redshift, it says Invalid timestamp format or value [YYYY-MM-DD HH24:MI:SS], error code 1206.
My current workaround is to create that column in Redshift as CHAR(8)
Thanks
There's no other solution that to use the char(8).
Redshift does not support timezones.
Workaround would be to parse data to UTC and store time difference in separate column. You will be able to calculate local time by adding/substracting hours to the UTC data.