I'm brand new to couchbase, and I'm developing a client which needs to issue prepared/parameterized n1ql queries via the c++ client library (https://github.com/couchbaselabs/libcouchbase-cxx). Issuing static queries is straightforward, but I haven't been able to find the correct process for issuing prepared queries. Has anybody been able to do this?
Following doc/example shows how to use the prepared stmt.
http://developer.couchbase.com/documentation/server/4.5/sdk/c/n1ql-queries-with-sdk.html
https://github.com/couchbaselabs/devguide-examples/blob/server-4.5/c/query-placeholders.cc
// To enable using prepared (optimized) statements, you can use
// the LCB_CMDN1QL_F_PREPCACHE flag. This is equivalent to setting
// 'adhoc=False' in other SDKs
cmd.cmdflags |= LCB_CMDN1QL_F_PREPCACHE;
rc = lcb_n1p_mkcmd(params, &cmd);
rc = lcb_n1ql_query(instance, &rows, &cmd);
lcb_wait(instance);
-Prasad
Related
I am trying to connect to a mobile network via a modem and a sim card. Every time I try to set the APN String and User Credentials in a Context via SetProvisionedContext() I get the E_INVALIDARG HRESULT.
As Parameters I used an Instance of MBN_CONTEXT, a wchar_t* in form of &std::vector<wchar_t>[0], and a ULONG*.
MBN_CONTEXT context;
std::vector<WCHAR> apnVector;
inParamAPN.GetCString(apnVector);
std::vector<WCHAR> userNameVec;
inParamUsername.GetCString(userNameVec);
std::vector<WCHAR> passwordVector;
inParamPassword.GetCString(passwordVector);
context.contextID = MBN_CONTEXT_ID_APPEND;
context.contextType = MBN_CONTEXT_TYPE_INTERNET;
context.accessString = &apnVector[0];
context.userName = &userNameVec[0];
context.password = &passwordVector[0];
context.compression = MBN_COMPRESSION_NONE;
context.authType = MBN_AUTH_PROTOCOL_PAP;
and later when I have the IMbnConnectionContext:
std::vector<WCHAR> providerVector;
InParamProvider.GetCString(providerVector);
ULONG requestID;
contextInterface->SetProvisionedContext(context, &providerVector[0], &requestID);
So my Question is: Which Parameter does the WinAPI have a Problem with, and how can I fix it?
Also any Tips of additional Sources for Information are appriciated.
All I have so far are the official MSDN and the Code Example contained in the Windows 7 SDK. Are there any further sources of Information I am not aware of? A google search didn't yield the hoped for results.
In the end I did not get it working as it should. I used the second way of connecting to a custom APN, by making a new connection profile. For this I used a XML filled with the Values I needed.
Along the way I encountered another problem with an unforseen Error Code which I described here.
Best regards,
Stefan
I am currently attempting to use transactions in my C++ app, but I have a problem with the ODBC's auto commit mode.
I am using the POCO libaries to create a connection to a PostgreSQL database on the same machine. Currently, I can send data to this database as single statements, but I cannot get my head around how to use Poco's transaction libraries to be able to send this data more quickly.
As I have several thousand records to insert, and so continuing to use single insert statements is extrememly slow and inpractical - So I am trying to use Poco's transaction to speed this up a bit (a fair bit).
The error I am encountering is a theoretically a simple one - Poco is throwing the following error:
'Invalid access: Session is in auto commit mode.'
I understand, as a result of this, I should somehow set "auto commit" to false - as it only allows me to commit data to the database line by line, rather than as a single transaction.
The problem is how I set this.
Currently, I have a session created from Session.h, that looks alot like this:
session = new Poco::Data::Session(
"ODBC",
connection_data.str()
);
Where connection data is a simple stringstream with the login information, password, database, server and "Driver={PostgreSQL ANSI};" to tell ODBC to utilize PostgreSQL's driver.
I have tried just setting a property "autocommit" to false through the session's setFeature or setProperty settings, this, of course, was to no avail. (it was more of a ditch attempt at this point).
session->setFeature("AUTOCOMMIT", false);
Looking around, I saw a possible alternative method by creating a ODBC sessionImpl directly from ODBC/session/SessionImpl.h instead of using this generic method above, and then creating a new session object from this.
The benefits of this are that ODBC's sessionImpl has references to autocommit mode in the header, which would suggest it would be able to handle this:
void autoCommit(const std::string&, bool val);
/// Sets autocommit property for the session.
However, having not used sessionImpl before, I cannot garuntee if this will work or if can can get this to work with the limited documentation available.
I am using C++ 03 (Not 11), with Visual Studio 2015
Poco 1.7.5
Boost (Where needed)
Would any one know the correct way of setting this feature (above) or a alternative method to achieving this?
edit: Looking at the source of poco, at:
https://github.com/pocoproject/poco/blob/develop/Data/ODBC/src/SessionImpl.cpp#L153
The property seems be named autoCommit, and looking at
https://github.com/pocoproject/poco/blob/develop/Data/include/Poco/Data/AbstractSessionImpl.h#L120
the case of the property names seem to matter. So, does it help if you use session->setFeature("autoCommit", false);?
Cant you just call session->begin(); and session->end(); on the corresponding Session object?
What is returned by session->canTransact()?
According to the doc begin() will start a new transaction, the doc does not mention any property that needs to be set before or after.
See: https://pocoproject.org/docs/Poco.Data.Session.html
Also faced a similar issue.
First of all before begin() need:
m_ses.setFeature("autoCommit", false);
m_ses.begin();
And the second issue is that this feature stays "autoCommit" in false for all other sessions. So don't forget for the next session call
session.setFeature("autoCommit", true);
It seems that c++ drivers doesn't accept mongodb connection uri format.
There's no documentation on how i should create connection string, any guess?
I need to connect to a replica set with 3 servers, and set readPreference options.
Create a connection to a replica set in MongoDB C++ client
Until the problems explained in #acm's answer are resolved, I have found a workaround to the bad Connection Strings of the C++ driver. You can create a DBClientReplicaSet using a vector of hosts and ports this way:
//First create a vector of hosts
//( you can ignore port numbers if yours are default)
vector<HostAndPort> hosts;
hosts.push_back(mongo::HostAndPort("YourHost1.com:portNumber1"));
hosts.push_back(mongo::HostAndPort("YourHost2.com:portNumber2"));
hosts.push_back(mongo::HostAndPort("YourHost3.com:portNumber3"));
//Then create a Replica Set DB Client:
mongo::DBClientReplicaSet connection("YourReplicaSetName",hosts,0);
//Connect to it now:
connection.connect();
//Authenticate to the database(s) if needed
std::string errmsg;
connection.auth("DB1Name","UserForDB1","pass1",errmsg);
connection.auth("DB2Name","UserForDB2","pass2",errmsg);
Now, you can use insert, update, etc. just as you did with DBClientConnection. For a quick fix, you can replace your references to DBClientConnection with DBClientBase (which is a parent to both DBClientConnection and DBClientReplicaSet)
Last pitfall: if you are using getLastError(), you must use it with the aimed database name like this:
connection.getLastError(std::string("DBName"));
cause otherwise it will always return "command failed: must log in" as described in this JIRA ticket.
Set the read preferences for every request
You have two ways to do that:
SlaveOK option
It lets your read queries be directed to secondary servers.
It takes place in the query options, which are at the end of the parameters of DBClientReplicaSet.query(). The options are listed in Mongo's official documentation
The one you would look for is mongo::QueryOption_SlaveOk, which will allow you to have reads made on secondary instances.
This is how you should call query();
connection.query("Database.Collection",
QUERY("_id" << id),
n,
m,
BSON("SomeField" << 1),
QueryOption_SlaveOk);
where n is the number of documents to return (0 if you don't want any limit), m the number to skip (defaults to 0), the next field is your projection and the last your query option.
To use several query option, you can use bitwise or | like this :
connection.query("Database.Collection",
QUERY("_id" << id),
n,
m,
BSON("SomeField" << 1),
QueryOption_SlaveOk | QueryOption_NoCursorTimeout | QueryOption_Exhaust);
Query::readPref option
The Query object has a readPref method which sets read preferences for a special query. It should be called for each query.
You can pass different arguments for more control. They are listed here.
So here's what you should do (I did not test that one cause I can't right now but it should work just fine)
/* you should pass an array for the tags. Not sure if this is required.
Anyway, let's create an empty array using the builder. */
BSONArrayBuilder bab;
/* if any, add your tags here */
connection.query("Database.Collection",
QUERY("_id" << id).readPref(ReadPreference_SecondaryPreferred, bab.arr()),
n,
m,
BSON("SomeField" << 1),
QueryOption_NoCursorTimeout | QueryOption_Exhaust);
Note: if any readPref option is used, it should override the slaveOk option.
Hope this helped.
Please see the connection string documentation for details on the connection string format.
(code links below are to 2.2.3 files)
To use a connection string with the C++ driver, you should use the ConnectionString class. You first call the ConnectionString::parse static method with a connection string to obtain a ConnectionString object. You then call ConnectionString::connect to obtain a DBClientBase object which you can then use to send queries.
As for read preference, at the moment I do not see a way to set the read preference in the connection string for the C++ driver, which would preclude a per-connection setting.
However, the implementation of DBClientBase returned by calling ConnectionString::parse with a string that identifies a replica set will return you an instance of DBClientReplicaSet. That class honors $readPreference in queries, so you can set your read preference on a per-query basis.
Since the current C++ drivers still do not accept the standard mongodb connection URIs, I've opened a ticket:
https://jira.mongodb.org/browse/CXX-2
Please vote for it to help get this fixed.
it seems like you can set read Preference before send a read request by call "readPref" method of your Query object. I'v not found a way to set read Preference on mongo collection object yet.
In my search for a way to deal with multi tenancy for play framework and postgresql schemas,i found this article
Here.
The problem is that i cannot figure out the way that i can execute plain sql statements in play(i am totally noob),can any one help please?.
In play you have the DB object that helps you getting the raw jdbc objects. If your query is a simple update without parameters you can do
DB.execute(simpleUpdate)
if your query is a simple select without parameters you can do
DB.executeQuery(simpleSelect)
if you have something more complex, with parameters, you can then use PreparedStatement by getting directly the connexion
PreparedStatement deleteStmt = DB.getConnection().prepareStatement(myStatement);
try {
deleteStmt.setString(1, myString);
deleteStmt.executeUpdate();
} finally {
deleteStmt.close();
}
We shard Postgres database using schemas. This is solution we've came up with. We add multiple DB connections in application.conf and initialize connection with custom SQL.
# application.conf
db.default.driver=org.postgresql.Driver
db.default.url="jdbc:postgresql://localhost/mytest"
db.default.user=your_user
db.default.password=passwd
db.default.initSQL="SET timezone = 'UTC';"
db.tp0.driver=org.postgresql.Driver
db.tp0.url="jdbc:postgresql://localhost/mytest"
db.tp0.user=your_user
db.tp0.password=passwd
db.tp0.initSQL="SET search_path TO tp0, public;SET timezone = 'UTC';"
Java code
EbeanServer tp0 = Ebean.getServer("tp0");
List<moneylog> res = tp0.find(moneylog.class).findList();
I have an application where I show data from a database. In fact we can say it's a database editor.
Now I want to perform update/delete command on this opened database. Using the following commands, the database opens successfully.
int nRet = sqlite3_open(szFile, &mpDB);
From C# (.net api) I am able to update data from database
dbCmd5 = New SQLiteCommand(
"update Tbl_Tmp_Cal_Res Load_Time=5 WHERE Part_Index= 5", g_dbFlow);
dbCmd5.ExecuteNonQuery()
But from C++ I am getting error 5 (database is locked)
C++ code
int nRet = sqlite3_open(szFile, &mpDB);//database opened successfully.
sqlite3_exec(mpDB, "UPDATE query", 0, 0, &szError);//Error for this statement
Multithreading is not used in application.
Is the database used from another location in the code? Since something else clearly seems to have the database locked, I would guess that you're using the database from another location in the code and have forgotten to call sqlite3_finalize on a select statement or something similar.
maybe you have forgotten authentication step (username/password & etc)