Posts by CM Wang on InterSystems Developer Community

Question

CM Wang · Jun 27, 2018

Parse binary data by InterSystems ObjectScript

I am trying to read some binary data from a local file or through socket.

The binary data is like H.264 codec, I need to read data BYTE by BYTE (even BIT by BIT) and decide the next step based on the data read so far.

I check the documentation and it seems like most of the sample focus on human readable IO, ie: LINE by LINE.

Could I achieve my goal through COS?

Thanks.

#Caché #ObjectScript

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Question

CM Wang · Dec 27, 2017

the associativity when the INNER JOIN and LEFT JOIN are mixed

select * from A left join B on A.x = B.x inner join C on B.y = C.y

does Cache SQL treat the join path: LEFT_JOIN(A,INNER_JOIN(B.C)) also a valid candidate path?

Thanks.

#SQL #Caché

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Question

CM Wang · Aug 18, 2017

%Dictionary.StorageSQLMapDefinition

I want to manipulate all the objects whose type is%Dictionary.StorageSQLMapDefinition by %OpenId

However, I don't know the exact id to feed into %OpenId, is there a way to query all the existing ids of %Dictionary.StorageSQLMapDefinition in a namespace?

Thanks.

#Caché

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Question

CM Wang · Aug 16, 2017

PROTECT error

I try to run below two statements

Set tRS = ##class(%ResultSet).%New("%Dictionary.ClassDefinition:SubclassOf")
set tSC = tRS.Execute("%Persistent")

and I always get <PROTECT>check+5^%Dictionary.ClassDefinitionQuery.1

The login user is _SYSTEM and should have all the permissions.

I cannot run queries in the $SYSTEM.SQL.Shell(). I would get <PROTECT>%GenerateMetadata+16^%SQL.StatementMetadata.1

However, when I run the query through SMP, everything is fine.

Any idea where could I start to investigate ?

Thanks.

#Caché

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Question

CM Wang · Aug 16, 2017

How to get the number of global references for a dynamic sql statement

In $system.SQL.Shell(), it would also report the number of global references for a given query.

Is it possible that I could also get this statistics from the %SQL.Statement interface when I launch a dynamic sql?

Thanks.

#Object Data Model #Caché

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Question

CM Wang · Aug 15, 2017

How to get all the names of the classes which inherits %Persistent

I want to retrieve all the names of classes which are %Persistent in a namespace by COS.

Any suggestion, Thanks.

#Object Data Model #Caché

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Question

CM Wang · Aug 2, 2017

How to log out from Cache terminal

How could I log out from Cache terminal (connected through csession) and back to the system shell?

Thanks.

#Beginner #Caché #Terminal

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Question

CM Wang · Jul 21, 2017

how to redirect IO

I get a third party routine which outputs some messages to standard output during execution.

Is it possible that I could direct the messages to other device so my terminal would never see this messages?

Thanks.

#Caché #Terminal

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Question

CM Wang · Jul 20, 2017

What is the most efficient way to store/retrieve the data into/from global

Type 1:

^global(key1,key2,key3,val1) = ""
^global(key1,key2,key3,val2) = ""
^global(key1,key2,key3,valn) = ""

Type 2:

^global(key1,key2,key3) = $lb(val1,val2,.....valn)

the number of val may be just dozens, but also possible to 10K

Thanks.

#Caché

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Question

CM Wang · Jul 18, 2017

How to dynamically change the entry defined in SQL storage map

I have a class and I would like to dynamically change its selectivity attribute in run-time and then call $system.OBJ.Compile to

recompile the class. I have changed the selectivity to a global, but it seems like it does not work. Any suggestions? Thanks.

#Caché #Compiler

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Question

CM Wang · Jul 16, 2017

How to configure the size for global buffer

Below are the output messages when Cache start.

Allocated 178MB shared memory: 1MB global buffers, 26MB routine buffers

I try to configure the global buffer size by [System] -> [Configuration] -> [Memory and Startup] from SMP,

but it seems like the changes does not apply to the global buffer.

Thanks for your help.

#Caché

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Question

CM Wang · Jul 16, 2017

How to index a class

I have two persistent classes defined. Lets call it Parent and Child.

Child class is one of the property of Parent Class.

I would like to define a index on Child class.

So what is the default behaviour I defined a index on a non simple data type member?

Any possibility that I could customized the behaviour ? For example. Child class has three properties.

Could I configure the index to index any combinations of these three properties?

Thanks for your help.

#Indexing #Object Data Model #Caché

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Question

CM Wang · Jul 14, 2017

How to specify the UrlMap for Rest call

Hi,

I have a UrlMap like the one below.

What if I have to pass two parameters to QueryResults, how to do configure Url?

#Object Data Model #Caché

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Question

CM Wang · Jul 14, 2017

The command to kill all globals given the namespace

Hi,

Is there any COS command could kill all the globals given the namespace?

Thanks.

#Object Data Model #Caché

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Question

CM Wang · Jul 5, 2017

stored procedure %SYSTEM.SQL_TableExists

"SELECT %SYSTEM.SQL_TableExists('table name') "could work as expected under SQL shell,

but for "CALL %SYSTEM.SQL_TableExists('table name')" does not work (not any error reported, it just show nothing).

Is there any reason why CALL could not be applied to a stored procedure?

Thanks.

#Caché #SQL

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Question

CM Wang · Jul 3, 2017

How to escape the single quote in the single quoted string

I have a stored procedure like below:

Call USER.SP('select * from Sample.Person where SSN='aaaaa'','0','S')

How could I escape the single quotes for aaaaa? I try double single quotes but in vain.

Thanks you.

#Object Data Model #SQL #Caché

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Question

CM Wang · Jun 26, 2017

The COS APIs to get O.S version and the Cache installed directory

Hi,

I would like to retrieve the O.S version (Windows or Unix) and Cache installed directory.

which COS apis should I use ?

Thanks for your help.

#API #Caché

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Question

CM Wang · Jun 26, 2017

How to execute external unix/windows commands from COS

I would like to invoke some unix/windows commands from COS, any API could do that?

Also, I would like to set up some Environment Variables for this process which would execute the above external command.

Anyway to achieve that?

Thanks for your help.

#API #Callout #Caché

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Question

CM Wang · Jun 19, 2017

How to expose the specific database via ECP

Hi,

I want to attach one local namespace on instance A to the database on instance B.

How could I use ECP to achieve my goal?

Should I config instance B as ECP data server? If so, how could I explicitly specify which database on instance B could be exposed ?

Thanks for your help.

#ECP #Caché

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Question

CM Wang · Mar 15, 2017

How to check Cache is unicode or 8 bit installed

Hi,

Any COS API could detect the underlying system is supported unicode or not ?

Thanks for your help.

#Caché

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