So ... I inserted an entry into a table with time stamps. The entry got inserted perfectly.
But the time stamp that got inserted was :
'2015-06-22 10:32:47'
I checked the time on the server:
Tue Jun 23 01:35:41 IST 2015
And inside mysql :
select now();
2015-06-23 01:33:57
So I check the time in irb.
time = Time.now
=> 2015-06-23 01:36:41 +0530
time.zone
=> "IST"
The time zone is right .. but I dont know where is it picking up the time from? I cant figure out where is it picking up 10:32 from ? and how do I fix it ?
Appreciate all your help.
Rails by design converts a datetime into UTC before inserting the value into the database.
This is because, in general, it's not possible to easily represent timezones in the database. Moreover, this approach guarantees the date will be consistent and/or easy to query in the following cases:
if the server time zone changes or you change server with a different timezone
if you want to query the date using a different timezone
if you want to format the date with different time zones depending on the user or other configs
You can customize the default timezone for the app, so that Rails will properly compute the correct difference to UTC when the value is stored into the database. However, you cannot change this behavior: times will always be converted into UTC before being stored in the database.
Generally speaking, if you properly use the Rails date transformation helpers, this shouldn't cause any issue.
For instance, if you want to query all the records where the time is past, the following query
Record.where('some_date < ?', Time.current)
will properly convert Time.current from your app timezone into UTC, and query the database accordingly.
Related
I am working on Hbase database and using apache Phoenix to access Hbase using normal SQL queries.
I have two columns in table which holds the current UTC timestamp in varchar and Date. after loading some data and when I query back Hbase I am getting strange results for event timestamp column which is of Date type.
Event UTC (Date) :2017-01-13 16:36:59.0
Event UTC (varchar):2017-01-13 21:36:59
above two values should be identical but for each record when querying back Event UTC ( Date) column giving me wrong result i.e exactly 5 hours behind.
I dont know from where this problem is coming .I am not saving any Timezone info and I am aware that Java Util or SQL timestamp doesnt store any time zone info, But really confused with the result set data when running a query. Please Help me in resolving this issue
Most likely it is because of the client's local time zone.
From official docs
Timestamp type:
the internal representation is based on a number of milliseconds since the epoch (which is based on a time in GMT), while java.sql.Timestamp will format timestamps based on the client's local time zone.
I am using DATETIME field to store my dates in MySQL. Without any timezone specified directly (there is just a datetime column)
But when timezone was changed on server MySQL updated all datetime columns according to new timezone.
Actually switching to EDT was the reason.
I don't need to recalculate my dates automatically - just want to store specific dates in it.
So even if tz changed manually to UTC from EST date should be same (from characters POV) if it was 2016-01-01 18:55 it should be same in any new tz..
I did not run any scripts\queries to update dates.
So it was performed either by MySQL itself or by server.
Need advice what I need to check to find and disable such feature.
Make sure you are using DATETIME and not TIMESTAMP
[From the MySQL documentation][1]:
MySQL converts TIMESTAMP values from the current time zone to UTC for storage, and back from UTC to the current time zone for retrieval. (This does not occur for other types such as DATETIME.)
You should also review this post (Duplicate):
Will changing a MySQL timezone change values of DateTime fields in a database?
I am sorry for the mess I brought
Just extended my query to grab some old dates - and it looks unchanged
So error defenetly in my code..
Anyway - thanks for your help
Need some ideas on how to convert an entire database TIMESTAMP columns from one timezone to another.
The current server is UTC, MySQL is also UTC so everything is good in that area. All time related columns are TIMESTAMPs. The problem is that when the time information was being entered, they were in EST/EDT. For example, enter start time: data is 1/1/2011 08:00:00 AM (EST/EDT). Because timezone wasn't implemented at the start, the database stored this as 08:00:00 UTC. So all the data in the database is stored like this. Once we get data that requires timezone info, this model will break.
The question is: how do you convert all these TIMESTAMP columns into the correct UTC time? The code will be changed to deal with this on the display side on a go-forward basis but what about historic data?
The simplest way seems to do a mysqldump --tz-utc of some sort and then import the data back, then release the code. However, I can't seem to find a good example of how to do this properly or if there are other ways to do this in the most efficient way possible.
Thanks!
Could you use the MySQL AddTime function to update the existing data?
UPDATE MyTable SET MyTimeColumn = ADDTIME (MyTimeColumn, -8:00:00) WHERE <the data is bad>
I am having this trouble in converting the exiting time string into a new Time object.
When I type this in console
t = Time.parse("8am")
2010-12-06 08:00:00 +0530
it gives back 08:00 as result as seen above.
But when I store this value using
business.start_time = t
business.save(:validate => false)
it stores 02:30 in MySql db.
This happens only when I store via console. When the same data comes from forms, it stores correctly as 08:00 in MySQL table. Is there any problem here. The time zone is set different from the default utc. Please help. what should i do.
I have to parse through all the records in a table and take one string attribute and convert it into its equivalent Time class value and store it in another attribute in the same table. I am writing a rake task for it. But while storing, I get 02:30 instead 08:00 (for example).
Be very careful with dates and MySQL. Datetime fields are stored as if they were strings in the db--so whatever Rails is sending in (check your log for the SQL) is what will be stored. I assume you're set to UTC in your environment.rb, so your Time object is being output in UTC as a string.
MySQL is poor (in my opinion) with respect to handling times in different zones and converting between zones.
I recommend you don't rush through your date handling. Always handle dates in your application and DB in UTC, and do any conversion to a specific timezone on a parsing (by specifying the timezone) or by formatting it in the view.
The time seems to be stored in UTC. Try setting the timezone correctly when starting your console session.
Say I have multiple servers in multiple locations and I want to use MySQL's datetime type for the field date and I always want to have the field date have the UTC timestamp so I would execute a UTC_TIMESTAMP() when I add it to the database. Now say I want to have MySQL output the UNIX TIMESTAMP for it.
When I do this on Server A I get the string "2009-06-17 12:00:00" doing the UNIX_TIMESTAMP(STRING) on it gives me the number 1245240000 back. Which is 2009-06-17 12:00:00 in UTC time. Now I do the same thing on Server B.
I get the same string back since its the UTC string but when executing UNIX_TIMESTAMP(STRING) again I get back the wrong number back 1245232800 which is the UTC +2 time. How do I get around this? Should I do the convertion from string to timestamp on the PHP side?
G'day,
I'll ask the obvious here, did you check the date and time on both machines?
Edit: ... and the MySQL timezone was the same on both machines?
Update: Ok. The problem is in the fact that the timestamp string being passed into UNIX_TIMESTAMP is interpreted to be a value in the current timezone which is then converted back to UTC so, because you're in MEZ, two hours is subtracted to return it back to UTC so 7200 is subtracted from your timestamp when it is converted back to a Unix timestring.
Hence, the variation you see when using UNIX_TIMESTAMP() to convert is back to a Unix Epoch timestring.
BTW Shouldn't you be using a TIMESTAMP type for storing off your UTC_TIMESTAMPs instead of DATETIME type?
Update: Decoupling presentation time from stored time is definitely the way to go. You can then reuse the same data all around the world and only have to convert to and from local time when you are presenting the data to a user.
If you don't do this then you are going to have to store off the timezone when the timestamp was made and then go into all sorts of complicated permutations of having to work out if
the local timezone was in daylight saving time when it was stored,
what the difference is between the timezone at the time that the data was stored and the timezone where the data is to be presented.
Leaving it all storeed as UTC gets rid of that.
Most users won't be that happy if they have to work out the local time themselves based on the UTC time returned so systems usually convert to current local time for the user.
This is of course if the user wants the data expressed in local time which is usually the case. The only widely used system I can think of, off the top of my head, that stores and presents its data in UTC is system for air traffic control and flight plan management which are always kept in UTC (or ZULU time to be more precise).
HTH
cheers,
Have you tried doing this?
Execute this instructions together.
SET time_zone = 'UTC';
SELECT FROM_UNIXTIME(0), UNIX_TIMESTAMP('2009-06-17 12:00:00');
// 1970-01-01 00:00:00 1245240000
They only affect the client session, not the server configuration.