Sunday, 30 April 2017

Converting Unix Timestamp into SQL Server DateTime

It is well known that developing and integrating applications based on different technologies may end up being a huge challenge, especially when it comes to dealing with data stored in diverse data type formats as it is Timestamp in Unix and DateTime in SQL Server. This post intents to show you a method in SQL Server to convert Unix Timestamp into Datetime. Here it is:

CREATE FUNCTION [dbo].[UNIX_TIMESTAMP_TO_DATETIME] (
@timestamp integer
)
RETURNS datetime
AS
BEGIN
  DECLARE @return datetime
  SET @timestamp = @timestamp - 18000
  SELECT @return = DATEADD(second, @timestamp,{d '1970-01-01'});
   
  RETURN @return
END

The function takes as a parameter a Unix Timestamp value so that it is converted into Datetime, and it will then give you the equivalent value in SQL Server Datetime format.  I know it might not be the be-all and end-all, nevertheless, I am pretty sure it will be use for many people. I hope you make the most out of it. That’s all for now. Let me know any remarks you may have. Thanks for reading. Stay tuned.

Wednesday, 12 April 2017

Checking Disk Space usage and Database Files usage per partition disk

When it comes to monitoring and managing disk space we may have some graphic tools to help us complete these tasks rapidly, nevertheless, not everybody can afford to pay the tools, and most of them do not give some details we may need on the spur of the moment. For example, we may have the need to check how much disk space is occupied by database files exclusively so that a wise decision can be made to ensure we are using disk space properly of a database server. We may need to see a report something like this.



In the report we can appreciate that all partition disks are displayed, each of them has information related to the space used in total (db_file_size_on_disk_db) by all database files (data & log) and it also includes the equivalent in percentage (db_file_size_on_disk_pct). Thus, we will be able to know whether or not the disk space is being using properly. Furthermore, disk space capacity and disk space available in gigabytes and percentage can also seen (disk_capacity_gb, disk_space_available_gb, disk_space_available_pct).

Now it is high time to show the code to get that report containing that information:

CREATE PROC [dbo].[sp_DBA_mon_db_files_size_on_disk] (@volume_mount_point char(1)=NULL)
/*WITH ENCRYPTION*/
AS
begin
if (@volume_mount_point is not null )
begin
    SELECT    vs.volume_mount_point, 
    vs.logical_volume_name,   
    
    DB_NAME(f.database_id) database_name,  f.type_desc,
    vs.total_bytes/1024/1024/1024.0 AS [disk_capacity_gb],
    cast( f.[size] / 128 /1024.0 as decimal(10,2)) AS [db_file_size_on_disk_gb],  
    cast( ( f.[size]*100/ 128 /1024.0 ) /   (vs.total_bytes/1024/1024/1024.0 )  as DECIMAL(10,2) ) AS [db_file_size_on_disk_pct],
    cast(vs.available_bytes/1024/1024/1024.0 as DECIMAL(10,2)) AS [disk_space_available_gb],    
   cast ( ( vs.available_bytes *100.0  / vs.total_bytes) as DECIMAL(10,2) )  AS [disk_space_available_pct],
   f.physical_name,
   vs.file_system_type  
    FROM  sys.master_files AS f
    CROSS APPLY   sys.dm_os_volume_stats(f.database_id, f.file_id) AS vs
    WHERE   f.database_id < 32767 and  vs.volume_mount_point=@volume_mount_point + ':\'
    order  by f.[size]  desc
end
 else
  begin
    SELECT vs.volume_mount_point, 
        vs.logical_volume_name,                
        vs.total_bytes/1024/1024/1024.0 AS [disk_capacity_gb],
        cast(SUM( f.[size] / 128 /1024.0) as decimal(10,2)) AS [db_file_size_on_disk_gb],  
       cast( (SUM( f.[size]/ 128 /1024.0) *100) /   (vs.total_bytes/1024/1024/1024.0 )  as DECIMAL(10,2) ) AS [db_file_size_on_disk_pct],
        cast(vs.available_bytes/1024/1024/1024.0  as DECIMAL(10,2)) AS [disk_space_available_gb],    
       cast ( ( vs.available_bytes *100.0  / vs.total_bytes) as DECIMAL(10,2) )  AS [disk_space_available_pct],
       vs.file_system_type  
    FROM  sys.master_files AS f
    CROSS APPLY   sys.dm_os_volume_stats(f.database_id, f.file_id) AS vs
    WHERE   f.database_id < 32767
    group by  vs.volume_mount_point,vs.total_bytes ,   vs.logical_volume_name,  vs.total_bytes ,vs.file_system_type  ,  vs.available_bytes 
    
 end
end
    

The report could receive the letter of the partition disk as a parameter, and also it can be omitted. As you can see in the definition of the stored procedure, the default value for @volume_mount_point is NULL which means, according to the logic of it, that general information will be displayed, that is the report in the graphic, otherwise, giving the letter of a partition will allow you to get detail information for every database file located in that disk partition. That's is all for now. I hope it is useful and practical for you.  Let me know any remarks you may have. Thanks for reading. Stay tuned.

Wednesday, 5 April 2017

Looking into Modern_Spanish and Latin1_General

The collations Modern_Spanish and Latin1_General are both Windows collations and support the same character set (Code Page 1252), but there are some differences between both collations related to the treatment of some characters in terms of sorting/doing comparisons. Some of the differences are noticeable especially when Accent-Insensitive is used, in Modern_Spanish n and ñ are considered different characters whereas in Latin1_General they are considered a character and an accented version of the same character.

Today I am going to show off an example to make it clear so that you can take it on board to pre-empt unforeseen results or conflict of collations. This example is based on Modern_Spanish_CI_AI and Latin1_General_CI_AI.

create table TempTable (
   Text_in_Latin1  varchar(100) collate Latin1_General_CI_AI,
   Text_in_Modern varchar(100) collate Modern_Spanish_CI_AI
)
go
insert into TempTable values ('Español', 'Español')
insert into TempTable values ('Espanol', 'Espanol')
insert into TempTable values ('Espanól', 'Espanól')
go
select Text_in_Latin1 from TempTable where Text_in_Latin1='Espanol'
go
select Text_in_Modern from TempTable where Text_in_Modern='Espanol'
go
drop table TempTable

Text_in_Latin1
--------------------------------------
Español
Espanol
Espanól

Text_in_Modern
--------------------------------------
Espanol
Espanól

As you can see, the first result demonstrates that Español, Espanol and Espanól are treated as the same word when we use Accent-Insensitive whereas in the second one Español and Espanol are treated as different words. It is worth noting that you only must change the collation if you really understand the behaviour change. For example, one might think that Latin1_General_CI_AS (Windows Collation) and SQL_Latin1_General_CP1_CI_AS (SQL Collation) are the same, but they are not the same, there is a slight difference in the short behaviour between both for specific special characters like '-'. Here another example about it.

create table TempTable (
   Text_in_Latin1  varchar(100) collate Latin1_General_CI_AS,
   Text_in_SQL_Latin1 varchar(100) collate SQL_Latin1_General_CP1_CI_AS
)
go
insert into TempTable values ('es-pe', 'es-pe')
insert into TempTable values ('espe', 'espe')
go
select Text_in_Latin1 from TempTable order by Text_in_Latin1
go
select Text_in_SQL_Latin1 from TempTable order by Text_in_SQL_Latin1
go
drop table TempTable

Text_in_Latin1
---------------------------------------
espe
es-pe

Text_in_SQL_Latin1
---------------------------------------
es-pe
espe

To be honest, I personally like having the same collation for all databases, but it has to be done carefully and, more importantly, if you really want that change. That is all for now, let me know any remarks you may have.