update on every tick

Questions about MultiCharts and user contributed studies.
janus
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update on every tick

Postby janus » 20 Jul 2009

Can someone please verify the way "Update on every tick" for a study works? What does "tick" refer to? Does it refer to the tick of the data series the study is applied to, or does it refer to the tick of any of the data being collected for the same symbol by the system and stored in the database even if not displayed in the current workspace but in another one? I suspect it's the latter but need confirmation. If it is the latter then it's something everyone should be aware of as it means the study is being executed more often that one thinks. It's not an issue in most cases but can be for complex studies.

janus
Posts: 778
Joined: 25 May 2009
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Re: update on every tick

Postby janus » 21 Jul 2009

I spent some time investigating this. I picked a quiet time in the market to make it easier. I displayed a single 1 minute chart of the trade price of a symbol. No other charts. I added a simple study that printed the time (using time_s), the closing price and volume. The study was set to update on every tick.

The pattern I saw was as follows. There were nearly always two extra prints than there were entries in the trade tick database. What I saw is the first two prints were always the same price and volume, and so were the last two. This explains the extra two. However, when there's only one trade tick in the database, I see three not four prints.

Next, I added the 1 minute ask and bid charts for the same symbol. I saw more prints than before. For example, during 1 specific minute I saw 19 prints, yet the database showed 6 trade ticks, 5 ask ticks and 25 bid ticks.

After I removed the ask and bid charts, the prints reverted back to their previous pattern.

I was very careful making sure I was looking at the correct data in the database knowing the time_s prints displayed the ending minute time whereas the database entries were timestamped with the current time.

I'm not really complaining, just making sure I understand what is happening, even though I don't understand why. Out of curiosity, can anyone explain why all this is happening?


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