DolphinDB is a high performance time series database. It is written in C++ and optimized for fast injection, storage, retrieval and analysis of time series data in fields such as quantitative finance, Internet of Things, real-time analytics, etc. DolphinDB runs extremely fast. It is also easy to use as the syntax of the programming language of DolphinDB is similar to SQL and Python.
Questions tagged [dolphindb]
764 questions
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votes
1 answer
How to set a condition filter on a string type field of a table?
The content of the table is as follows:
id = 0..4
tag = `FB`IBM`FB`IBM`AMZN
t =table(id, tag)
id
tag
0
FB
1
IBM
2
FB
3
IBM
4
AMZN
The schema of the table is as…
damie
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votes
1 answer
How to set scheduled task in dolphindb
How to set scheduled task in dolphindb?
I need to set a scheduled task such as to caculate the new data at 9 o'clock every night. How to make it?
user15518852
-1
votes
1 answer
how to set data expiration policy in DolphinDB
For the data in DolphinDB DFS databases, how can I set data expiration policy? For example, data before 6 months ago are automatically deleted. Thanks!
M Lewis
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votes
1 answer
How can I get NYSE trading days in a date range
How to generate a list of the NYSE trading days in a date range in DolphinDB?
Is there a function for that?
How can I get a trading day list?
Thanks in advance！
dylanlu
- 27
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votes
2 answers
How to get the latest 3 records of each group from dolphindb database?
My table name is trades, and its columns are permno, symbol, date, prc, shrout, ret, vol. I want to get the latest 3 records of each stock each date group. Does DolphinDB support such querying methods?
Summer.H
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-1
votes
1 answer
Does DolphinDB support retention policy?
In InfluxDB I can create a two-hour retention policy like this:
> CREATE RETENTION POLICY "two_hours" ON "food_data" DURATION 2h REPLICATION 1 DEFAULT
In VictoriaMetrics, retention is configured with -retentionPeriod command-line flag. For…
Ju Piece
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votes
2 answers
How to check the version of DolphinDB I am using?
I deployed a distributed cluster successfully with DolphinDB Docker Package. But how to check what version of DolphinDB has been installed? I wonder where to specify the version to download so that I can use an earlier version.
Here's the tutorial:…
Irenehj
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votes
2 answers
Does any of the time-series databases (kdb+, InfluxDB, DolphinDB, etc) offer functional programming?
Would like to use a time-series database with functional programming functionalities
Bob
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votes
1 answer
How to get the position of null values in a vector in DolphinDB？
For example, I would like to get the position of null in the following vector.
a=1 NULL 2 3 6 NULL 2 NULL
I have tried the following script:
re=isNull(a)
index=array(int,0,1)
for(i in 1..size(a)){
if(re[i]==true){
index.append!(i)
…
Summer.H
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votes
1 answer
DolphinDB: store results together from the same group in one column
table1 = table(10:0, ["id", "value"], [INT, STRING])
insert into table1 values((1,1,2,2,3,3), `1`2`3`4`5`6)
I am using DolphinDB and have a table like the following:
ID
Value
1
1
1
2
2
3
2
4
3
5
3
6
and this is the table I'd…
FFF
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votes
1 answer
use DolphinDB to delete rows with matching columns with table join
Now I have two tables t1 and t2 as shown in the screenshot.
I'd like to select the rows where both columns a and b in the left match those of the right table. Then delete them in the left table.
Would you please inform me if any DolphinDB functions…
winnie
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votes
1 answer
DolphinDB: how could I write data efficiently to a stream table or a dfs table?
I need help to improve the data writing performance in DolphinDB.
The client end receives stock quotation data, one at a time. Taking latency and throughput into consideration, how could I write data efficiently to a stream table or a dfs table? I…
Polly
- 603
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-4
votes
1 answer
How to call DolphinDB functions in the C++ plugins I defined?
For example, if I want to call the createPartitionedTable
(createPartitionedTable — DolphinDB 2.0 documentation ), what script should I write?
yiniwei
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-5
votes
1 answer
Does dolphindb support regular expression like the re in python?
I would like to ask, is there a function dolphindb, which can replace functions such as numbers in strings
damie
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