dhis2-users team mailing list archive

[Saptarshi Purkayastha <sunbiz@xxxxxxxxx>]

I don't think I meant to convey that DHIS2 doesn't work on MySQL.
Its just extremely difficult to test all features on all platforms for
developers. This is true for all projects. Users have to take initiative to
report issues of running DHIS2 on MySQL, if developers have missed
something.

I just highlighted through testing that DHIS2 datamart ran faster on
PostgreSQL 9.2. It might be that MariaDB community, which has been making
good strides on MySQL, might perform on par or better than PostgreSQL for
DHIS2. With SkySQL aligning teams, Oracle might be pushed to release more
of their Enterprise-only features to the community version also. DHIS2 core
developers just don't have resources to test on all platforms.
Implementations might have to discover these over time.

---
Regards,
Saptarshi PURKAYASTHA

My Tech Blog:  http://sunnytalkstech.blogspot.com
You Live by CHOICE, Not by CHANCE


On 8 May 2013 10:32, Hannan Khan <hannank@xxxxxxxxx> wrote:

>  Dear Saptarshi
>
>
>
> Thank you for helping to convert one of the Bangladesh database from MySQL
> to PostgreSQL. But there is still a long way to go.
>
>
>
> So far all tables are converted and the metadata are exported from MySQL
> and imported into PostgreSQL. What we find that the import has lots of
> inconsistency and we are trying to find solution. Few problems we already
> solved but I need the reason. We are working on it and within few days I
> will write to you all for reason and help. But the man challenge is to
> convert 32 million data value and 26000 orgunit and associated tables
> because of this metadata conversion problem.
>
> What I find the DHIS2 version 2.11 is not suitable for MySQL which is not
> fare. We just tuned our MySQL Server and 5.6 have significant improvement
> in performance.* So I am requesting the community to reconsider the use
> of MySQL as well.*
>
> Regars
>
> Hannan Khan
> On Tue, May 7, 2013 at 6:53 PM, Saptarshi Purkayastha <sunbiz@xxxxxxxxx>wrote:
>
>> Hello DHIS users and devs,
>>
>> Apologies for the long email... Should have probably been multiple
>> blogpost to reduce its length...
>>
>> I recently encountered a situation with a very large implementation of
>> DHIS2 having problems generating data mart.
>> Thus no reports were generated and only data entry was being done. I
>> thought I'd share some of the experiences to solve these issues, so that it
>> might be useful to other implementers.
>> Some changes will be needed in the DHIS2 source, so sending this to the
>> dev list also, where dev-related discussions can follow-up.
>>
>> While PostgreSQL is our recommended database, many implementations have
>> also used MySQL.
>> My findings clearly highlight that DHIS2 performs much better on
>> PostgreSQL and there are also some bugs related to MySQL dialect.
>> Total org units - 26303
>> Total Monthly datasets - 9
>> Total Daily dataset - 1
>> Total Yearly dataset - 3
>>
>> The implementation has about 34 million datavalues (non-zero)... but I
>> pruned it for my benchmarking. I added 1-million datavalues and ran the
>> data mart.
>> The results are from my fairly good laptop (quad-core i7; 8GB RAM; tuned
>> JVM; tuned MySQL 5.5 (4GB RAM); tuned PostgreSQL 9.2 (4GB RAM); 240GB SSD)
>> Using DHIS2 2.11. When doing MySQL benchmark turned off all services
>> including postgres and vice versa.
>> Java Opts:  -Xmx3G -Xms768m -XX:MaxPermSize=512m
>> Java version: 1.7.0_21 x64
>> Java vendor: Oracle Corporation OS name: WindowsMySQL = datamart
>> completed in 3hrs 46min 12sec
>> PostgreSQL = datamart completed in 2hrs 5min 16sec
>>
>> So, it is obvious that PostgreSQL is doing datamart much faster. The
>> advantages might scale better if larger number of datavalues
>> One could argue MySQL 5.6 has many performance improvements, I didn't
>> have time to explore that.
>> The migration to PostgreSQL has some challenges. Following are steps I
>> followed:
>>
>>  - Take the mysqldump
>>  - replace bit(1) to tinyint(1) in the SQL file
>>  - You'll see that column names are camelCase. This is an issue because
>> postgres will added a double quotes around to get case-sensitivity, which
>> MySQL by default nicely excludes.
>> So you'll have to make all column names to lowercase and remove the quote
>> characters. I did this with a simple java program. There are 150-odd column
>> names that need changes.
>>  - Used Navcat premium (trial version or SQLSquirrel also has this
>> feature). "Data transfer" is the name of the feature that will move data
>> from MySQL to Postgres
>>  - In MySQL non-standard use of boolean (which came only a few yrs back),
>> its converted to smallint in Postgres. I wrote a JDBC program to change
>> column type from smallint to boolean. A single table example is as follows
>> that can be made into a looping procedure as well in pure PSQL.
>> ALTER TABLE indicator ALTER COLUMN annualized TYPE boolean
>>     USING CASE WHEN annualized = 0 THEN FALSE
>>            WHEN annualized = 1 THEN TRUE
>>            ELSE NULL
>>     END;
>>  - remove NULL values from minimumvalue column of minmaxdatalement table
>> DELETE from minmaxdatalement WHERE minimumvalue=NULL
>>  - remove NULL values from maximumvalue column of minmaxdatalement table
>> DELETE from minmaxdatalement WHERE maximumvalue=NULL
>>  - remove NULL values from name column of relationshiptype table
>> DELETE from relationshiptype WHERE name=NULL
>>  - blobs to bytea conversion is a mess and I had to truncate. Probably a
>> JDBC based connector program will do better conversion, but I just
>> truncated it and accepted the data loss to systemsetting and usersetting :-)
>> *
>> Devs*:
>> We need to make all column names lowercase in hbm.xml files in code. This
>> will ensure portability and is generally a good practice.
>> We should also have a convention of using last_updated instead of
>> lastUpdated in column names, as is the common practice.
>>
>> ---
>> Regards,
>> Saptarshi PURKAYASTHA
>>
>> My Tech Blog:  http://sunnytalkstech.blogspot.com
>> You Live by CHOICE, Not by CHANCE
>>
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>>
>