Hello, It was mentioned many times in the past. Single quotation bar is 40 bytes. 8MB divided by 40 bytes is 200000 data bars.
Best regards, Tomasz Janeczko amibroker.com On 2010-03-11 12:29, Rob wrote: > TJ, > > what's the back of the envelope calculation we should do to work out if our > DB data set fits into on board CPU cache...?? > For example, if I have an 8MB L2 Cache... how many bars can I fit into that > comfortably...? > > Many Thanks > > --- In [email protected], Tomasz Janeczko<gro...@...> wrote: > >> Hello, >> >> There is no such thing as "no limit". Your HARDWARE IS LIMITED, 3rd >> party data vendor HAS LIMITS on amounts of data sent. >> The limits are there for a reason. To allow smooth REAL TIME OPERATION. >> If you override limits you are shooting yourself in a foot and will face >> problems with real-time operation. >> *DO NOT override limits* >> Real-time database must be able to keep up with data stream counting >> even thousands of ticks per second PER SYMBOL. >> Everyone who thinks that his/her hardware has no limits is simply very, >> very, very wrong. >> The person who thinks so is deeply wrong because he/she does not know >> how the amount of memory affects the performance. >> You guys should run memtest86 program to see what is the difference >> between processing speed of ON-CHIP CPU CACHE >> and normal memory. The difference is TEN FOLD (or larger). There are in >> fact differences as large as 2x or 3x in speed between level-1 >> and level-2 caches. If you allow that your data are larger than your CPU >> cache is, you will automatically >> get 10x performance hit because of limited memory thoughput. CPU will >> WAIT for memory. Memory speeds are way behind processor speeds. >> >> If you need want "endless" database use LOCAL DATABASE only without >> external source. Such database working OFF-LINE >> is not subject to real-time constraints. >> >> Best regards, >> Tomasz Janeczko >> amibroker.com >> >> On 2010-03-11 11:19, Magesh wrote: >> >>> >>> Some how my mails aren't getting through into the group. Hoping to get >>> luckier this time. >>> >>> Thanks to supp...@..., for I got clarity on this mail that # >>> of Bar limitations is meant only for plugin-driven databases. >>> Though that solved my worries, as I use a local database for caching >>> RT data, I still am curious to understand how such scenarios are >>> handled in real-time while using Plugin driven databases >>> >>> In other words, how to preserve my data from getting truncated once >>> the size limit exceeds in a Plugin-Driven database. >>> Any thoughts or suggestions are much appreciated. >>> >>> thanks and regards >>> Magesh >>> >>> On 10/03/10 11:01 AM, Magesh wrote: >>> >>>> Does this mean a limitation of AB for saving data to infinite without >>>> truncating? >>>> >>>> I am using a real-time stream, Base Time Interval is "Tick" and No. >>>> of Bars=500,000. >>>> Total no of symbols = 10 (all with real-time Tick). >>>> I have a fixed layout, and no frequent change in symbols. >>>> >>>> And with my rough math of a tick for every 2 seconds, >>>> # of bars per trading day = 11700 bars >>>> Max # of days of history (@ 500,000 bars)= 43 days >>>> Max # of days of history (@ 1,500,000 bars) = 128 days >>>> >>>> My questions are: >>>> 1) Is my understandings on the bar count, size per symbol and limit >>>> is correct? >>>> >>>> 2) Is there any ways of overcoming this limit, my reason being, I >>>> would like to hold the historical tick size data for more than a year >>>> (at-least to start with)? >>>> >>>> 3) I think its scalable by altering "Base Time Interval" from "Tick" >>>> to "5/15 seconds" and will allow me to store up to 18& 60 months >>>> approx. of data respectively. Is this right? >>>> >>>> 4) What's the max integer limit (size of variable) for MaximumNoOfBars? >>>> >>>> 5) Can alternate dBs (MySQL)be used in synch with AB's database, so >>>> that periodic push/flushing of AB's data into an external dBase? (as >>>> I won't be looking or using historical intraday's in realtime or >>>> atleast not so frequently) >>>> >>>> Btw, this is a total scaled down version of my requirement, as my >>>> database is just about a month old and currently I have about 30 >>>> symbols and just begun learning AFL and back-testing/explorations. >>>> And with the current bar count setting, I think my database will >>>> start getting truncated anytime sooner (for few of the symbols >>>> updated via RT). >>>> >>>> So I would like to keep my options very open for any kind/type of >>>> suggestions as my current attempt is to have AB retain data and stop >>>> draining LIFO. >>>> >>>> Thanks in Advance, >>>> Magesh >>>> >>>> >>>> P.S.:I couldn't find any updates beyond this chain on this email >>>> thread subject from gmane, so any pointers or suggestions in this >>>> direction will be of great help for me. >>>> >>>> >>>> >>>> On 02/08/08 3:59 PM, Herman wrote: >>>> >>>>> Hi Tomasz (or anyone who knows), >>>>> >>>>> >>>>> Could you define "advanced users and powerful computers"? >>>>> >>>>> >>>>> Who would use this feature and what what exactly does it do? >>>>> >>>>> >>>>> Thanks, >>>>> >>>>> herman >>>>> >>>>> >>>>> >>>>> Friday, August 1, 2008, 7:21:11 AM, you wrote: >>>>> >>>>> >>>>> >>>>>> No, it shouldn't. This key is a "hidden extra feature" for advanced >>>>>> >>>>> >>>>>> users having computers powerful enough to handle extra load. >>>>>> >>>>> >>>>>> By default the key does not exist and then the default max is 500000. >>>>>> >>>>> >>>>> >>>>>> Best regards, >>>>>> >>>>> >>>>>> Tomasz Janeczko >>>>>> >>>>> >>>>>> amibroker.com >>>>>> >>>>> >>>>>> ----- Original Message ----- >>>>>> >>>>> >>>>>> From: "progster01" >>>>>> >>>>> <progster-sfbTBCYm2/nd5v35psfx2nbpr1lh4...@... >>>>> <mailto:progster-sfbTBCYm2/nd5v35psfx2nbpr1lh4...@...>> >>>>> >>>>> >>>>>> To:<amibroker-hhksg33tihhbjbujkae...@... >>>>>> >>>>> <mailto:amibroker-hhksg33tihhbjbujkae...@...>> >>>>> >>>>> >>>>>> Sent: Friday, August 01, 2008 12:55 PM >>>>>> >>>>> >>>>>> Subject: [amibroker] Re: Database settings and the amount of data saved >>>>>> >>>>> >>>>> >>>>> >>>>> >>>>>>>> Make sure you check the path exactly! The key name is >>>>>>>> >>>>> >>>>>>>> HKEY_CURRENT_USER\Software\TJP\Broker\Settings\MaximumNumber >>>>>>>> >>>>> >>>>>>>> OfBars >>>>>>>> >>>>> >>>>>>>> (watch out for line truncations) >>>>>>>> >>>>> >>>>> >>>>>>>> The key is a DWORD. >>>>>>>> >>>>> >>>>> >>>>>>> This key does not exist on the machine I'm looking at (which has AB >>>>>>> >>>>> >>>>>>> 5.15 installed). >>>>>>> >>>>> >>>>> >>>>>>> Obviously I could add it myself, but "should" it already be there? >>>>>>> >>>>> >>>>> >>>>>>> IOW, what is the design scenario for the creation of this key? >>>>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>>> ------------------------------------ >>>>>>> >>>>> >>>>> >>>>>>> Please note that this group is for discussion between users only. >>>>>>> >>>>> >>>>> >>>>>>> To get support from AmiBroker please send an e-mail directly to >>>>>>> >>>>> >>>>>>> SUPPORT {at} amibroker.com >>>>>>> >>>>> >>>>> >>>>>>> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG: >>>>>>> >>>>> >>>>>>> http://www.amibroker.com/devlog/ >>>>>>> >>>>> >>>>> >>>>>>> For other support material please check also: >>>>>>> >>>>> >>>>>>> http://www.amibroker.com/support.html >>>>>>> >>>>> >>>>>>> Yahoo! Groups Links >>>>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>> ------------------------------------ >>>>>> >>>>> >>>>> >>>>>> Please note that this group is for discussion between users only. >>>>>> >>>>> >>>>> >>>>>> To get support from AmiBroker please send an e-mail directly to >>>>>> >>>>> >>>>>> SUPPORT {at} amibroker.com >>>>>> >>>>> >>>>> >>>>>> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG: >>>>>> >>>>> >>>>>> http://www.amibroker.com/devlog/ >>>>>> >>>>> >>>>> >>>>>> For other support material please check also: >>>>>> >>>>> >>>>>> http://www.amibroker.com/support.html >>>>>> >>>>> >>>>>> Yahoo! Groups Links >>>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>> (Yahoo! ID required) >>>>>> >>>>> >>>>> >>>>> >>>>>> mailto:amibroker-fullfeatured-hhksg33tihhbjbujkae...@... >>>>>> >>>>> >>>>> <mailto:amibroker-unsubscribe-hhksg33tihhbjbujkae...@...> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>> >>> >>> >> > > > > ------------------------------------ > > **** IMPORTANT PLEASE READ **** > This group is for the discussion between users only. > This is *NOT* technical support channel. > > TO GET TECHNICAL SUPPORT send an e-mail directly to > SUPPORT {at} amibroker.com > > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at > http://www.amibroker.com/feedback/ > (submissions sent via other channels won't be considered) > > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG: > http://www.amibroker.com/devlog/ > > Yahoo! Groups Links > > > > >
