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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How to subscribe data using DolphinDB Python API?
I want to subscribe data from DolphinDB, and I have run these codes in DolphinDB:
share streamTable(10000:0,`time`sym`price`id, [TIMESTAMP,SYMBOL,DOUBLE,INT]) as trades
setStreamTableFilterColumn(trades, `sym)
insert into trades values(take(now(),…
Maria
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How to generate sql col with binary function in DolphinDB script?
In DolphinDB script, I can generate SQL queries on the fly with functions like sql, sqlCol, etc. But I found that sqlCol only support unary functions, the following script doesn't work.
t = table(1..10 as c0, 1..10 as c1)
query = sql(sqlCol([c0,…
siupan
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4 answers
rewrite a kdb script in DolphinDB database
I am trying to rewrite a kdb script in DolphinDB.
Let me first explain what I need to do. If a signal is above a threshold T1, we establish a long position in the security. We don't want to close the position as soon as the signal dips below T1, so…
Steven
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In DolphinDB, why can't controller node find agent node?
I'm configuring a multi-physical node cluster deployment.
1. The controller node is on linux debian of Oracle virtual machine( bridge mode)
2. The agent node and data nodes are on the windows of the host machine.
3. Agent node and controller node…
rc618
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What is the difference between workerNum and localExcutors in the dolphindb configuration file?
What is the difference between workerNum and localExcutors in the dolphindb configuration file? In tutorial, we often see that workerNum is 1 larger than localExcutors,that is why?
pengfei
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1 answer
How to automatically increase partition value when using VALUE partitioning?
When using HASH partitioning, I don't need to consider how many partition values are in advance. When using VALUE partitioning, can I automatically create new partitions if there are new partition values?
pengfei
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1 answer
How to load text from csv file specify table schema using function "loadText"?
How to specify table schema when using function loadText dealing with csv file?
When I loadText from csv file
loadText("/data/myhome/test.csv"),but the result are not what I expected, so How can I specify table schema when I load csv file using…
pengfei
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1 answer
why cannot see the in-memory table that I created through JAVA API from DolphinDB GUI?
I created a in-memory table "t1" and loaded data into it through DolphinDB Java API. Then I started DolphinDG java GUI, "select * from t1", why "t1" cannot be recognized?
dovish618
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sum of all columns for each row in DolphinDB database
For a table with around 100 columns, how can I quickly calculate the sum of all columns for each row in DolphinDB? Looks like all DolphinDB functions for a table apply to columns, not rows.
Steven
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How to migrate DolphinDB cluster onto another machine
Our company is using DolphinDB on a daily basis. As time goes by, we have too much data on our old server. So we decided to migrate our cluster onto to another Dell PowerEdge server with 128 cores. We did this by copying all the data onto the new…
siupan
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The number of partitions [100000] relevant to the query is too large
I execute the following script in dolphindb.
select count(*) from pt
It throws an exception.The number of partitions [100000] relevant to the query is too large. Please add more specific filtering conditions on partition columns in WHERE clause, or…
Winter.Z
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1 answer
DFS is not enabled or the system is not a data node.?
When the following scripts are executed in the DolphinDB GUI, an exception
DFS is not enabled or the system is not a data node.
is thrown, and I confirm that the configuration item `enableDFS = 1'has been set.
DB =…
LIN.L
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1 answer
Delete Partitioned Table
How to delete data from partitioned table in DolphinDB? I tried to use delete command, but it will throw exception.
It is not allowed to delete rows from tables other than basic in-memory tables and segmented in-memory tables.
Lan Zhang
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1 answer
Is there a limit to the number of partition columns of DolphinDB?
does DolphinDB have a limit on the number of partition columns that can be specified?
Suppose most of the columns of a table have the same value range(100 columns), can I create the partition table by specifying all of them?
dovish618
- 156
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Why is there no change in memory usage when I clear a table in DolphinDB?
I create an in-memory table in DolphinDB with the following…
Winter.Z
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