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Implementation of Function String in Sybase Replication Server(SRS)
03 weeks ago
These experience shared by Senior DBAs as name mentioned, Hope this will help you to understand more about function string from implementation point of view in a Replication environment:
Craig Oakley , Senior DBA.
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We used function strings when we wanted to replicate all columns to some servers, and only selected columns to other (web-facing) servers. This was particularly useful before Rep Server allowed multiple RepDefs on the same table. One concern was text columns which were not being replicated to the web-facing server: we had to create a function string to get a text pointer (we used a one-row table and just update all the text columns on top of each other, as the value was not needed on that server): failure to get a text pointer cause the DSI to go down, and we could not specify that as a condition to ignore.
Beyond this, I would imagine function strings could help specify how you want the update to be done, which could be a performance improvement. It would also allow for a different implementation at the replicate than there is at the primary (such as a table at the primary being two joined tables at the replicate).
Sukhesh Nair, Senior Sybase DBA
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We used to have a setup where data was replicated from sybase to oracle as also to a warm standby sybase server. Rep Server function strings helped in filtering data that would need to be passed to Oracle. It helped immensely in streamlining the data flow to targets by manipulating the incoming data through function string. I feel it is one of the most advanced and useful yet very less used capabilities of Sybase Rep Server.
The deterrent could be because of the complexity it would introduce to the replication system. The setup we had worked wonderfully and never gave us any major problems. Without proper monitoring (which needs to be scripted by DBAs) it used to be hard to maintain. Many of the current Rep Server administrators I see do not have adequate knowledge or experience of handling function strings.
Rey Wang , Senior Sybase DBA
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You can map the delete to no op with functional string.
Partha Gogoi Senior DBA
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We use function strings to transform data at the replicate..We have databases being replicated from Toronto and New York to London, Sydney and Singapore and the client ids are transformed at the replicate because, as per business requirements, the client ids are different at each site.. Of course , having a Universal client id would simplify things , but the systems and databases at each site grew independently until replication was set up and it would be a lot of rework to change all the client ids at the replicate sites
Øystein Grinaker Senior DBA
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A Function String could be used to change default behaviour.
Say you delete a row in a table on PDB, but you do not want to delete the row on the RDB. Then make a change in rs_delete. You may make the rs delete just to make a logical delete by updateing a deletemarker for that spesific row.
Source : Linkedin.com
Inserting data into a data-only-locked heap table
01 month ago
When users insert data into a data-only-locked heap table, Adaptive Server tracks page numbers where the inserts have recently occurred, and keeps the page number as a hint for future tasks that need space. Subsequent inserts to the table are directed to one of these pages. If the page is full, Adaptive Server allocates a new page and replaces the old hint with the new page number.
/***********************************************************************************************************
Blocking while many users are simultaneously inserting data is much less likely to occur during inserts to data-only-locked heap tables. When blocking occurs, Adaptive Server allocates a small number of empty pages
and directs new inserts to those pages using these newly allocated pages as hints.
**********************************************************************************************************/
For datarows-locked tables, blocking occurs only while the actual changes to the data page are being written; although row locks are held for the duration of the transaction, other rows can be inserted on the page. The row-level locks allow multiple transaction to hold locks on the page.
If conflicts occur during heap inserts
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Conflicts during inserts to heap tables are greatly reduced for data-onlylocked tables, but can still take place. If these conflicts slow inserts, some workarounds can be used, including:
• Switching to datarows locking, if the table uses datapages locking
• Using a clustered index to spread data inserts
• Partitioning the table, which provides additional hints and allows new pages to be allocated on each partition when blocking takes place
Inserting data into an allpages-locked heap table
01 month ago
When you insert data into an allpages-locked heap table, the data row is always added to the last page of the table. If there is no clustered index on a table, and the table is not partitioned, the sysindexes.root entry for the heap table stores a pointer to the last page of the heap to locate the page
where the data needs to be inserted.
If the last page is full, a new page is allocated in the current extent and linked onto the chain. If the extent is full, Adaptive Server looks for empty pages on other extents being used by the table. If no pages are available, a new extent is allocated to the table.
Conflicts during heap inserts
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If many users are trying to insert into an allpages-locked heap table at the same time, each insert must
wait for the preceding transaction to complete.
This problem of last-page conflicts on heaps is true for:
• Single row inserts using insert
• Multiple row inserts using select into or insert…select, or several insert statements in a batch
• Bulk copy into the table
Some workarounds for last-page conflicts on heaps include:
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• Switching to datapages or datarows locking
• Creating a clustered index that directs the inserts to different pages
• Partitioning the table, which creates multiple insert points for the table, giving you multiple “last pages” in an allpages-locked table
ASE database for SAP ERP
02 months ago
Hello all,
These are copilataion for Sybase ASE on SAP from the Rob’s Blog :
Read Full Story : http://blogs.sybase.com/database/2011/12/so-what-does-an-ase-database-look-like-in-sap-erp/
- SAP has released Business Suite on ASE version 15.7.
- All SAP application data resides in a single ASE database. There is another small database for use by SAP tools.
- The ASE database uses a 16KB page size.
- For ERP only (i.e. not counting CRM and the other Business Suite modules), the database contains about 80,000 tables and 170,000 indexes. This is because SAP ERP has many features and functions, all with their own set of tables. SAP customers typically run only a subset of all those functions so in practice a large part of those 80,000 tables will always remain empty.
- All SAP tables use datarowslocking (there is an interesting historical dimension.
- All tables names are in uppercase; some table names contain special characters, like the slash character in “/BCV/C_QATTR” (I don’t have a clue what that name means, BTW)
- Apart from the tables, there are also about 10,000 views. No stored procedures or triggers are used.
- SAP makes heavy use of dynamic SQL (also known as “prepared statements”).
- Many tables have a text or image column.
- All tables are owned by one database user (and that’s not the dbouser).
- The ASE database is accessed through ODBC.
- SAP makes frequent use of the built-in ASE Job Scheduler (originally added in ASE 12.5.1).
- The ASE server uses Unicode with the utf8 character set.
Logical or Database Devices and Physical Devices
02 months ago
Distinctions between logical or database devices and physical devices:
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• The physical disk or physical device is the actual hardware that stores the data.
• A database device or logical device is a piece of a physical disk that has been initialized (with the disk init command) for use by Adaptive Server. A database device can be an operating system file, an entire disk, or a disk partition.
• A segment is a named collection of database devices used by a database. The database devices that make up a segment can be located on separate physical devices.
• A partition is block of storage for a table. Partitioning a table splits it so that multiple tasks can access it simultaneously. When partitioned tables are placed on segments with a matching number of devices, each partition starts on a separate database device.
sp_helpdevice –> To get information about devices
sp_helpsegment –> To get information about segments
sp_helpartition –> To get information about partitions.
What’s in YOUR Architecture?
02 months ago
What’s in your architecture?
Probably not enough if you’re using just data modeling to integrate all the components of your enterprise, especially your information. To lay the
foundation of this paper, let’s start from the same level of understanding: the need for a common approach to managing all the aspects of information to
enable rapid business performance in the 21st century economy.
Competition in the marketplace is always fierce. To stay abreast, organizations must constantly analyze their customer needs and expectations, enhance
or innovate their business processes, and deliver products and services that create exceptional customer value. Organizations also need to be customercentric to forge long-term relationships with clients and consumers. Only organizations that are agile enough to respond to volatile market conditions
with innovation, expedited time-to-market processes, and reduced costs can differentiate themselves from the competition. Such agility occurs when a
company’s IT operations are closely aligned with its business operations. IT needs to understand business to implement technologies and applications that
support the current and future business goals.
Read Full Article @ http://www.sybase.com/files/White_Papers/Sybase_Whats_in_Your_Architecture_WP.pdf
K21– ASE’S KERNEL DESIGN FOR THE 21ST CENTURY – ASE 15.7’s THREADED KERNEL K21
0Basic Difference :
Process Kernel:
Pre-15.7 kernel (except Windows)
Each engine is a separate process
Retained in 15.7 for risk mitigation
Threaded Kernel:
Default kernel for 15.7
Each engine is a thread of a single process
Additional threads for handling I/O, etc.
ASE on Windows has always been thread based
http://www.sybase.com/files/Product_Overviews/ASE-15.7-New-Threaded-Kernel.pdf
How to run sybase query in different databases in one run
03 months ago
I would suggest to run SQL via shell script as below.
database.txt
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database1
database2
database3
query.txt
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select col1, col2 from table
go
write shell script
multiple_database_query.sh
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while read LINE
do
database=$LINE
isql -S “” -D “${database}” -i “query.txt”
done < database.txt
Database load error
03 months ago
Sometime “database is in use” error encounters while loading the database, this could be due to in-memory db tables might still active for the named database. So use the dbcc commands to clear those and reload the database.
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