Tips and Tricks for SAP Sybase IQ

Tips and Tricks for Optimizing
Performance with SAP Sybase
IQ

Mark Mumy
IQ Technology Specialist
SAP
mark.mumy@sap.com

Disclaimer
In this session we will be giving tips and guidelines for IQ to
provide novices and experienced DBAs with information they
may not know
This is by no means exhaustive. We strongly suggest taking
advantage of the education course offerings available to
enhance your in-depth knowledge of IQ

2 – November 8, 2012

Agenda
• Sizing
• Configuration
• Indexes
• Monitoring


Sizing


Memory Summary
Operating System .5 to 1 GB RAM  Monitor the “IQ Dynamic
Filesystem Cache 20% of RAM
Memory” in sp_iqstatus
All Other Applications  Lists the current, and
maximum RAM that IQ has
IQ Catalog Memory -c/-cl/-ch parameters allocated for all memory
structures
IQ Thread Memory stack size * thread count
 Swap recommendation is
Load Memory (pre 15.2) per concurrent load
still 1x virtual memory
Bitmap Memory per concurrent load
 Some customers run with 4-
IQ Main Cache 40% of remaining RAM 8 GB
IQ Temporary Cache 60% of remaining RAM
 I prefer to run with 25-100
GB depending on total RAM
Backup Memory per backup instance  May seem excessive, but it
can help avoid the dreaded
“all available virtual memory
exhausted” error!

Quick Sizing Reference
• RAM: 4-8 GB per core (prefer 8, settle for 4)
• RAM: Give IQ 75% of available RAM (assumes there are no other major
consumers of RAM on the host)

• Storage: Prefer RAID 10 for write intensive systems and temp store
• IQ can drive 50-500 MB/sec on and off disk per core in the multiplex so
size disks accordingly, but ground the sizing in reality and service levels

• MAIN Store disk: 2-5 drives per core on the host or in the entire
multiplex
• TEMP Store disk: 2-5 drives per core on the host
• The number of drives does NOT include any overhead needed by RAID

• MAIN Store Fiber Controllers/HBAs: 1 per 5-10 cores
• TEMP Store Fiber Controllers/HBAs: 1 per 5-10 cores

Sizing CPUs for Load
• For systems with 4 or fewer CPUs, expect to load roughly 10-20
GB of data per hour per CPU
 A 4 CPU system should be able to load about 40 GB of raw data per hour
• For systems with 8 or more CPUs, expect a load rate of 20-50 GB
per hour per CPU
 An 8 CPU system should be able to load between 160 and 400 GB of raw
data per hour
• Load times with this approach will vary greatly based on CPU
count / speed and the number and types of indexes on the table
being loaded
• For each BLOB or CLOB being loaded into IQ a single CPU will be
necessary for maximum performance
• IQ 16 will change these ratios as we move to a 100% parallel load
engine

Sizing CPUs for Queries
• On average, 1-2 CPU per active query – more if queries are
complex and can be run in parallel
• As IQ matures, we constantly push the engine to run more
queries fully parallel
 This changes the sizing from how many cores per query to what is the
service level we need to achieve and how many cores will that take
• Most queries are now run in parallel and can consume all
CPU resources on the host
• IQ will blend single and multi-user query performance and
rebalance resources as the workload changes
 As more queries appear on the run queue, the available resources will
change and IQ will adjust accordingly


Sizing Memory
• Total system RAM should be based on 4-8 GB RAM per core
 Threads do not matter
 Allocate no more than 75% of total RAM to the main and temp caches
 Shared memory is not used by Sybase IQ except in small amounts for
client/server communication where both are on the same host
• Typically, we want more temp cache for loading as the HG
indexes are built in temp cache
• For queries the mix of main to temp will vary depending on
a few factors:
 If there are temp tables, we want more temp cache
 If the queries contain a lot of ordering and grouping, this will use work
tables based in temp cache
 Typically, we weigh main and temp cache at 50/50 or 40/60 split


Configuration

10 – November 8, 2012

Creation Options
• Uppercase and lowercase?
 Can force IQ to treat all text data as CASE IGNORE or CASE RESPECT
 CASE RESPECT has slightly better performance but puts a burden on
applications to compare data with the appropriate case
• Page size
 Default is 128k which is acceptable for most sites
 Increase the page size as the database and table sizes (rowcounts)
increase
 Increasing the page size should be accompanied by an increase in
RAM
• Collation and sort orders
 Can only be set at database creation
 If it needs to be changed the database must be rebuilt

11 – November 8, 2012

Runtime Options (config file)
• -iqnumbercpus
 Should be set to match the physical core count, not the total
processing threads that are on the host
 Caveat is IBM p-series where this can be tested and adjusted to a
value between physical cores and total SMT threads
• -gm
 Total number of users that can connect
 Keep this setting low as memory is carved based on this value. This
can impact query performance.
• -gn
 Should be set to 1.5x the –gm setting (default is –gm + 5)

12 – November 8, 2012

Database Options (set options)
• FORCE_NO_SCROLL_CURSORS
 Should always be set to ON
 Very few applications require this to be OFF
 Can improve query performance
• Append_Load
 Can be used to improve load performance
 Will not reuse Row ID’s or the space occupied by those Row ID’s
 Great for systems where large, contiguous chunks of data are deleted

13 – November 8, 2012

Indexes

14 – November 8, 2012

SAP Sybase IQ Index Types
Key Characteristics
TYPE USAGE
 Fast Projection Compressed raw data for result sets • Most columns will have at least one index
(Default)
• Index selection decisions based on column
 Low Fast Low cardinality data (up to 1000 cardinality (number of unique values)
unique values)
 High Non-Group Aggregation on the fly and range • Multiple indexes used to resolve a query
searches
 High Group Key fields and groupings for cross- • Indexes are self maintaining
tabular
• No optimizer statistics to update
 Date, Time, DT Date ranges, date part operations
• Indexes are compressed
 Multi-Column Concatenated indexes
 Word, Text Sophisticated key word or phrase • Index advisor demystifies index selection
string searches with boolean,
ranking, proximity, fuzzy features
 Compare Column comparisons

15 – November 8, 2012

Should We Index?
• Is the column searchable?
• Is the column a join column?
• Is the column a date/time/datetime
datatype?
• Will the column be part of an
aggregation?
• Will the column be part of a group
by?

16 – November 8, 2012

When To Use Indexes

TYPE When to use it
 Fast Projection This is the default storage for a column. You can only influence the type of Fast
Project via the IQ UNIQUE() syntax or Minimize_Storage option

 High Group Low cardinality data (over 2000 unique values) where the columns are used in a
WHERE clause for searching or joins. Also include columned used in a GROUP BY.

 Low Fast Low cardinality data (up to 2000 unique values) where the columns are used in a
WHERE clause for searching or joins

 High Non-Group Not used that much as the functionality has been implemented in other indexes
(date, hg, lf)

 Date, Time, DTTM All date fields should have these indexes

 Word, Text Use only if you will be using the word or text search capabilities in IQ

 Compare Use when comparing 2 columns in the same table.

 Multi-Column Usually used for primary keys and for columns in a GROUP BY. Make sure that
every column has an LF or HG as well!

17 – November 8, 2012

Monitoring

18 – November 8, 2012

Monitoring
• Hardware and storage utilities
 iostat, vmstat, top, glance, gpm, sar, etc.
 Use tools to monitor the hardware and storage for any potential
bottlenecks outside of IQ
• IQ utilities
 sp_iqsysmon
 Sybase Control Center
 3rd party tools like Bradmark Surveillance DBA and White Sands
ProActive DBA

19 – November 8, 2012

Monitoring via sp_iqsysmon
• sp_iqsysmon is a great tool to consolidate the individual
monitoring!!
• SAP Sybase IQ Monitor offers a series of “views” of the
counters to showing differing aspects of the server and
buffer cache workload
• A consolidated interface for the iq utilities command that is
much easier to use and provides a way to run multiple
reports with a single command

20 – November 8, 2012

Monitoring via Sybase Control Center
• Sybase Control Center
 Sybase Central is being deprecated in version 16
 Is a separate download via the product download center
 Leverages a lightweight client (browser) with a server component so
that users need not install software
• Graphical interface that presents the data in a way that
highlights issues visually
• Most counters that are in sp_iqsysmon are available in
Sybase Control Center

21 – November 8, 2012

Monitoring Guidance
• Use sp_iqsysmon or Sybase Control Center when issues arise
and active monitoring is needed
• Frequency and key items
 Run at 10-15 second intervals for the duration of the issue
(sp_iqsysmon), or actively via Sybase Control Center
 Thread use/starvation
 Cache usage
 Cache hit rates
 Dirty page grabs
 Page rereads
 Physical and logical i/os

22 – November 8, 2012

Query Monitoring
• Leverage HTML query plans!
• Query plan settings (off by default) to provide optimal query information to
DBA’s and engineering
 set temporary option query_plan='off';
 set temporary option query_plan_as_html='on';
 set temporary option query_plan_as_html_directory=‘qplans';
 set temporary option query_plan_after_run='on';
 set temporary option query_timing='on';
 set temporary option query_detail='on';
 set temporary option DML_options10='on';
 set temporary option Query_Name = ‘Query Name‘

• Should not be set globally as the Sybase IQ MSG file or query plan directory
will grow rapidly
• No need to set both Query_Plan and Query_Plan_As_HTML
 Query_Plan is on by default, but should be turned off immediately to keep the IQ
message file output to a minimum
 This is much more difficult to read than the HTML plans and is note widely
used
23 – November 8, 2012

Index Monitoring
• Index advice and monitoring is off by default
• Turn on the index advisor globally and keep 1000 rows of advice
 set option public.index_advisor='on';
 set option public.index_advisor_max_rows=1000;

• Will output data to HTML and text based query plans, if on
• Will output advice to an in-memory structure that can be accessed
via sp_iqindexadvice()
• Captures the advised index type, where it was used, the last time the
advice was generated, and the number of times this piece of advice
was made
• The advisor will recommend any index that will cost less
 This could be 1 ms or 1 i/o less
 Be smart about the advice and whether or not you want to implement
it
24 – November 8, 2012

Troubleshooting Advice
• Determine where the issue is
 External to IQ
 Monitor the OS, hardware, and storage for any bottlenecks or issues
 Look for high CPU use, high CPU system time, low CPU user time, high wait time
 Look for I/O service times that are more than 10 ms
 Internal to IQ
 Enable the index advisor and look for missing indexes (this is usually the culprit)
 Enable HTML query plans and the index advisor if the issue is with a single query
 If the overall health is in question, leverage sp_iqsysmon at 30-60 intervals for a
few days
 Sysmon output can then be parsed looking for the key items previously discussed

25 – November 8, 2012

Useful links
• SAP Sybase IQ Users Group
 http://iqug.dssolutions.com/
 Send an email to iqug-subscribe@dssolutions.com - follow the info in
the reply email to finalize subscription
• SAP Sybase Education Curriculum
 https://training.sap.com/us/en/courses-and-curricula/sybase
• Sybooks IQ 15.4 Documentation
 http://infocenter.sybase.com/help/index.jsp?topic=/com.sybase.infoc
enter.help.iq.15.4/title.htm
• SAP Sybase IQ Sizing Guide
 http://www.sybase.com/detail?id=1093493

27 – November 8, 2012

Tips and Tricks for SAP Sybase IQ

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