Qore Programming Language Reference Manual  0.8.12.8
Qore::SQL::DatasourcePool Class Reference

Provides transparent per-thread, per-transaction datasource connection pooling. More...

Inheritance diagram for Qore::SQL::DatasourcePool:

Public Member Functions

nothing beginTransaction ()
 Manually allocates a persistent connection from the pool to the calling thread. More...
 
nothing clearEventQueue ()
 Clears the queue object for DBI events on the pool. More...
 
 clearWarningCallback ()
 clears any connection delay warning callback from the object More...
 
nothing commit ()
 Commits the current transaction and releases the connection to the pool. More...
 
 constructor (string driver, *string user, *string pass, *string db, *string encoding, *string host, softint min=3, softint max=10, softint port=0, *Qore::Thread::Queue queue, any arg)
 Creates the DatasourcePool object; attempts to load a DBI driver if the driver is not already present in Qore. More...
 
 constructor (string desc, *Qore::Thread::Queue queue, any arg)
 Creates a DatasourcePool object from a single string giving all parameters that can be parsed by parse_datasource() More...
 
 constructor (hash opts, *Qore::Thread::Queue queue, any arg)
 Creates a DatasourcePool object from a hash argument giving parameters for the constructor. More...
 
 copy ()
 Creates a new Datasource object with the same driver as the original and copies of all the connection parameters. More...
 
bool currentThreadInTransaction ()
 Returns True if the current thread is in a transaction (i.e. has a dedicated datasource allocation), False if not. More...
 
 destructor ()
 Throws an exception if any transactions are in progress and returns immediately; the object is destroyed after any in-progress requests are completed. More...
 
any exec (string sql,...)
 Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes an SQL command on the server and returns either the integer row count (for example, for updates, inserts, and deletes) or the data retrieved (for example, if a stored procedure is executed that returns values) More...
 
any execRaw (string sql)
 Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes an SQL command on the server and returns either the row count (for example, for updates and inserts) or the data retrieved (for example, if a stored procedure is executed that returns values) More...
 
int getCapabilities ()
 Returns an integer bitfield of DBI driver capabilities. More...
 
list getCapabilityList ()
 Returns a list of strings giving the capabilities of the current DBI driver. More...
 
any getClientVersion ()
 Retrieves the driver-specific client library version information; this method may not be implemented for all drivers. More...
 
hash getConfigHash ()
 Returns a datasource hash describing the configuration of the current object. More...
 
string getConfigString ()
 Returns a string giving the configuration of the current object in a format that can be parsed by parse_datasource() More...
 
*string getDBCharset ()
 Retrieves the database-specific charset set encoding for the object. More...
 
string getDBEncoding ()
 Retrieves the database-specific charset set encoding for the object. More...
 
*string getDBName ()
 Returns the database name parameter as a string or NOTHING if none is set. More...
 
string getDriverName ()
 Returns the name of the driver used for the object. More...
 
int getErrorTimeout ()
 Returns the error timeout period for waiting for a connection to come free as an integer giving milliseconds; note that timeout values less than or equal to zero mean that requests for a connection will wait indefinitely. More...
 
*string getHostName ()
 Returns the hostname parameter as a string or NOTHING if none is set. More...
 
int getMaximum ()
 Returns the maximum number of connections in this object. More...
 
int getMinimum ()
 Returns the minimum number of connections in this object. More...
 
string getOSCharset ()
 Returns the Qore character encoding name for the object as a string or "(unknown)" if none is set. More...
 
*string getOSEncoding ()
 Returns the Qore character encoding name for the object as a string or NOTHING if none is set. More...
 
any getOption (string opt)
 Returns the current value for the given option. More...
 
hash getOptionHash ()
 returns the valid options for the driver associated with the Datasource with descriptions and current values for the current Datasource object More...
 
*string getPassword ()
 Returns the password parameter as a string or NOTHING if none is set. More...
 
*int getPort ()
 Gets the port number that will be used for the next connection to the server. More...
 
any getServerVersion ()
 Returns the driver-specific server version data for the current connection. More...
 
*hash getUsageInfo ()
 Returns a hash with usage information about the DatasourcePool object. More...
 
*string getUserName ()
 Returns the username parameter as a string or NOTHING if none is set. More...
 
bool inTransaction ()
 Returns True if a transaction is currently in progress (meaning in this case that a datasource form the pool is dedicated to the calling thread), False if not. More...
 
nothing rollback ()
 Rolls back the current transaction and releases the connection to the pool. More...
 
any select (string sql,...)
 Executes an SQL select statement on the server and returns the result as a hash (column names) of lists (column values per row) More...
 
any selectRow (string sql,...)
 Executes an SQL select statement on the server and returns the first row as a hash (the column values) More...
 
any selectRows (string sql,...)
 Executes an SQL select statement on the server and returns the result as a list (rows) of hashes (the column values) More...
 
 setErrorTimeout (timeout ts)
 Sets the timeout period for waiting for a connection to come free; note that timeout values less than or equal to zero mean that requests for a connection will wait indefinitely. More...
 
nothing setEventQueue (Qore::Thread::Queue queue, any arg)
 Sets a queue object for DBI events on the pool. More...
 
 setWarningCallback (timeout ms, code callback, any arg)
 sets a connection delay warning callback to be called any time the delay assigning a connection from the pool exceeds the given timeout in milliseconds More...
 
string toString ()
 Returns a string with technical information about the object. More...
 
any vexec (string sql, *softlist vargs)
 Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes SQL code on the DB connection, taking a list for all bind arguments. More...
 
any vselect (string sql, *softlist vargs)
 Executes a select statement on the server and returns the results in a hash (column names) of lists (column values per row), taking a list for all bind arguments. More...
 
any vselectRow (string sql, *softlist vargs)
 Executes a select statement on the server and returns the first row as a hash (column names and values), taking a list for all bind arguments. More...
 
any vselectRows (string sql, *softlist vargs)
 Executes a select statement on the server and returns the results in a list (rows) of hashes (column names and values), taking a list for all bind arguments. More...
 
- Public Member Functions inherited from Qore::SQL::AbstractDatasource
bool currentThreadInTransaction ()
 Should return True if the current thread is in a transaction with this object, must be re-implemented in subclasses to provide the desired functionality. More...
 

Detailed Description

Provides transparent per-thread, per-transaction datasource connection pooling.

Restrictions:
Qore::PO_NO_DATABASE
Overview
In most cases, the DatasourcePool class can be used as a drop-in replacement for the Datasource class with autocommit disabled; when a transaction begins, a datasource will be automatically assigned to the calling thread, and it will only be released when a commit or rollback is called on the object. If no datasource is available, the calling thread will block until a datasource comes available.

Note that the same principles apply to SQL and database driver usage as with the Datasource class, see the Datasource class documentation for more information.

The DatasourcePool class uses Qore's thread resource tracking infrastructure to raise an exception if a thread terminates while a connection is allocated to it. If Qore user code enters a transaction with a DatasourcePool object and the thread terminates without closing the transaction (via DatasourcePool::commit() or DatasourcePool::rollback()), an exception will automatically be raised, the transaction will be rolled back, and the Datasource connection will be freed to the pool.

DatasourcePool Connection Allocations
The following methods allocate a persistent connection to the calling thread: The connection is released to the pool when DatasourcePool::commit() or DatasourcePool::rollback() are called (or in the case the thread terminates, in which case an exception is raised as well).

To begin a transaction with one of the select methods (for example, with "select for update"), call DatasourcePool::beginTransaction() first to manually dedicate a Datasource to the thread before calling the select method. Otherwise statements that should be in the same transaction may be executed in different connections.

Executing a DatasourcePool method while not in a transaction is realized by allocating a temporary connection to the calling thread which is re-released when the method returns. No explicit commits are executed by the class, therefore it is an error to execute transaction-relevant commands without first calling DatasourcePool::exec(), DatasourcePool::vexec(), DatasourcePool::execRaw(), or DatasourcePool::beginTransaction().

Note that the SQLStatement class also grabs allocates a persistent connection to the calling thread when executing if it is created using a DatasourcePool object in the constructor; for more information see the SQLStatement class documentation.
Thread Resource Handling
The DatasourcePool class manages connection allocations as a thread resource; if the connection is not released with a call to DatasourcePool::commit() or DatasourcePool::rollback() when the thread exits (or when Qore::throw_thread_resource_exceptions() or Qore::throw_thread_resource_exceptions_to_mark() is called), the transaction is rolled back automatically and a DATASOURCE-TRANSACTION-EXCEPTION exception is raised describing the situation.

Being an builtin class, the DatasourcePool class does not inherit AbstractThreadResource explicitly as a part of the exported API, and the internal AbstractThreadResource::cleanup() method cannot be overridden or suppressed.
Note
This class is not available with the PO_NO_DATABASE parse option
See also
SqlUtil for a high level database-independent API

Member Function Documentation

◆ beginTransaction()

nothing Qore::SQL::DatasourcePool::beginTransaction ( )
virtual

Manually allocates a persistent connection from the pool to the calling thread.

This method should be called when a transaction will be started with a DatasourcePool::select() method (or DatasourcePool::vselect(), etc).

This method does not make any communication with the server to start a transaction; it only allocates a persistent connection to the current thread in Qore.

To release the connection, call DatasourcePool::commit() or DatasourcePool::rollback()

Example:
db.beginTransaction();

Implements Qore::SQL::AbstractDatasource.

◆ clearEventQueue()

nothing Qore::SQL::DatasourcePool::clearEventQueue ( )

Clears the queue object for DBI events on the pool.

Since
Qore 0.8.9

◆ clearWarningCallback()

Qore::SQL::DatasourcePool::clearWarningCallback ( )

clears any connection delay warning callback from the object

Example:
ds.clearWarningCallback();
Since
Qore 0.8.9

◆ commit()

nothing Qore::SQL::DatasourcePool::commit ( )
virtual

Commits the current transaction and releases the connection to the pool.

Example:
db.commit();

Implements Qore::SQL::AbstractDatasource.

◆ constructor() [1/3]

Qore::SQL::DatasourcePool::constructor ( string  driver,
*string  user,
*string  pass,
*string  db,
*string  encoding,
*string  host,
softint  min = 3,
softint  max = 10,
softint  port = 0,
*Qore::Thread::Queue  queue,
any  arg 
)

Creates the DatasourcePool object; attempts to load a DBI driver if the driver is not already present in Qore.

Parameters
driverThe name of the DBI driver for the Datasource. See SQL Constants for builtin constants for DBI drivers shipped with Qore, or see the DBI driver documentation to use an add-on driver (this string should be the name of the driver to be loaded)
userThe user name for the new connection. Also see Datasource::setUserName() for a method that allows this parameter to be set after the constructor.
passThe password for the new connection. Also see Datasource::setPassword() for a method that allows this parameter to be set after the constructor.
dbThe database name for the new connection. Also see Datasource::setDBName() for a method that allows this parameter to be set after the constructor.
encodingThe database-specific name of the character encoding to use for the new connection. Also see Datasource::setDBCharset() for a method that allows this parameter to be set after the constructor. If no value is passed for this parameter, then the database character encoding corresponding to the default character encoding will be used instead.
hostThe host name for the new connection. Also see Datasource::setHostName() for a method that allows this parameter to be set after the constructor.
minThe minimum number of connections in the pool (this number of connections is opened in the constructor)
maxThe maximum number of connections in the pool (not more than this number of connections will be opened)
portThe port number for the new connection. Also see Datasource::setPort() for a method that allows this parameter to be set after the constructor.
queueAn optional Queue object to receive datasource events; note that the Queue passed cannot have any maximum size set or a QUEUE-ERROR will be thrown; passing NOTHING will clear any event queue
argan optional argument to be included in the arg key of datasource events
Example:
DatasourcePool db(DSPGSQL, "user", "pass", "database", "utf8", "localhost", 3, 10, 5432);
Exceptions
DATASOURCEPOOL-UNSUPPORTED-DATABASEDBI driver cannot be found
DATASOURCEPOOL-CONSTRUCTOR-ERRORinvalid min, max, or port argument
DBI-OPTION-ERRORunknown or unsupported option passed to driver

◆ constructor() [2/3]

Qore::SQL::DatasourcePool::constructor ( string  desc,
*Qore::Thread::Queue  queue,
any  arg 
)

Creates a DatasourcePool object from a single string giving all parameters that can be parsed by parse_datasource()

Parameters
desca datasource description string in the format that can be parsed by parse_datasource()
queueAn optional Queue object to receive datasource events; note that the Queue passed cannot have any maximum size set or a QUEUE-ERROR will be thrown; passing NOTHING will clear any event queue
argan optional argument to be included in the arg key of datasource events
Example:
DatasourcePool ds("pgsql:user/pass@db01(utf8)%localhost:5432");
Exceptions
DATASOURCE-UNSUPPORTED-DATABASEDBI driver cannot be loaded
DATASOURCE-CONSTRUCTOR-ERROmissing required parameter for connection; port value is <= 0
DBI-OPTION-ERRORunknown or unsupported option passed to driver
Since
Qore 0.8.6

◆ constructor() [3/3]

Qore::SQL::DatasourcePool::constructor ( hash  opts,
*Qore::Thread::Queue  queue,
any  arg 
)

Creates a DatasourcePool object from a hash argument giving parameters for the constructor.

Parameters
optsa hash giving parameters for the new datasource with the following possible keys (the "type" key is mandatory, also usable with the output of the parse_datasource() function):
  • type: (*string) The name of the database driver to use; this key is mandatory; if not present, an exception will be raised. See SQL Constants for builtin constants for DBI drivers shipped with Qore, or see the DBI driver documentation to use an add-on driver (this string should be the name of the driver to be loaded)
  • user: (*string) The user name for the new connection
  • pass: (*string) The password for the new connection
  • db: (*string) The database name for the new connection
  • charset: (*string) The database-specific name of the character encoding to use for the new connection. Also see DatasourcePool::setDBCharset() for a method that allows this parameter to be set after the constructor. If no value is passed for this parameter, then the database character encoding corresponding to the default character encoding for the Qore process will be used instead.
  • host: (*string) The host name for the new connection
  • port: (softint) The port number for the new connection
  • options: (hash) An optional hash having "min" and "max" keys giving the minimum and maximum number of connections in the pool, respectively; all other options will be passed to the database driver
queueAn optional Queue object to receive datasource events; note that the Queue passed cannot have any maximum size set or a QUEUE-ERROR will be thrown; passing NOTHING will clear any event queue
argan optional argument to be included in the arg key of datasource events
Example:
Datasource db(("type": DSPGSQL, "user": "username", "pass": "password", "db": "database", "charset": "utf8", "host": "localhost", "port": 5432, "options": ("min": 3, "max": 10)));
Exceptions
DATASOURCEPOOL-UNSUPPORTED-DATABASEDBI driver cannot be loaded
DATASOURCEPOOL-CONSTRUCTOR-ERRORmissing or invalid "driver" key, other key name not assigned to a string; "port" value is <= 0; invalid "min" or "max" keys
DBI-OPTION-ERRORunknown or unsupported option passed to driver

◆ copy()

Qore::SQL::DatasourcePool::copy ( )

Creates a new Datasource object with the same driver as the original and copies of all the connection parameters.

Example:
DatasourcePool new_dsp = dsp.copy();

◆ currentThreadInTransaction()

bool Qore::SQL::DatasourcePool::currentThreadInTransaction ( )

Returns True if the current thread is in a transaction (i.e. has a dedicated datasource allocation), False if not.

Returns
True if the current thread is in a transaction (i.e. has a dedicated datasource allocation), False if not
Code Flags:
CONSTANT
Example:
bool b = db.currentThreadInTransaction();
Since
Qore 0.8.7

◆ destructor()

Qore::SQL::DatasourcePool::destructor ( )

Throws an exception if any transactions are in progress and returns immediately; the object is destroyed after any in-progress requests are completed.

Example:
delete db;
Exceptions
DATASOURCEPOOL-ERRORThe destructor was called while a transaction was still in progress

◆ exec()

any Qore::SQL::DatasourcePool::exec ( string  sql,
  ... 
)
virtual

Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes an SQL command on the server and returns either the integer row count (for example, for updates, inserts, and deletes) or the data retrieved (for example, if a stored procedure is executed that returns values)

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

Parameters
sqlThe SQL command to execute on the server
...Include any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
The return value depends on the DBI driver; normally, for commands with placeholders, a hash is returned holding the values acquired from executing the SQL statement. For all other commands, normally an integer row count is returned. However, some DBI drivers also allow select statements to be executed through this interface, which would also return a hash (column names) of lists (values for each column).
Example:
int rows = db.exec("insert into table (varchar_col, timestamp_col, blob_col, numeric_col) values (%v, %v, %v, %d)", string, now(), binary, 100);
Note
see the documentation for the DBI driver being used for additional possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ execRaw()

any Qore::SQL::DatasourcePool::execRaw ( string  sql)
virtual

Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes an SQL command on the server and returns either the row count (for example, for updates and inserts) or the data retrieved (for example, if a stored procedure is executed that returns values)

This method does not do any variable binding, so it's useful for example for DDL statements etc

Warning:
Using this method to execute pure dynamic SQL many times with different SQL strings (as opposed to using the same string and binding by value instead of dynamic SQL) can affect application performance by prohibiting the efficient usage of the DB server's statement cache. See DB server documentation for variable binding and the SQL statement cache for more information.
Parameters
sqlThe SQL command to execute on the server; this string will not be subjected to any transformations for variable binding
Returns
The return value depends on the DBI driver; normally, for commands with placeholders, a hash is returned holding the values acquired from executing the SQL statement. For all other commands, normally an integer row count is returned. However, some DBI drivers also allow select statements to be executed through this interface, which would also return a hash (column names) of lists (values for each column).
Example:
db.execRaw("create table my_tab (id number, some_text varchar2(30))");
Note
see the documentation for the DBI driver being used for additional possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ getCapabilities()

int Qore::SQL::DatasourcePool::getCapabilities ( )

Returns an integer bitfield of DBI driver capabilities.

Returns
an integer bitfield of DBI driver capabilities; see DBI Capability Constants for the meaning of each bit
Code Flags:
CONSTANT
Example:
int caps = pool.getCapabilities();
if (!(caps & DBI_CAP_TRANSACTION_MANAGEMENT))
throw "DATASOURCE-ERROR", sprintf("DBI driver %y does not support transaction management", db.getDriverName());
Since
Qore 0.8.12

◆ getCapabilityList()

list Qore::SQL::DatasourcePool::getCapabilityList ( )

Returns a list of strings giving the capabilities of the current DBI driver.

Returns
a list of strings giving the capabilities of the current DBI driver
Code Flags:
CONSTANT
Example:
printf("driver %y has the following capabilities:\n", db.getDriverName());
foreach string cap in (db.getCapabilityList())
printf("- %s\n", cap);
Since
Qore 0.8.12

◆ getClientVersion()

any Qore::SQL::DatasourcePool::getClientVersion ( )
virtual

Retrieves the driver-specific client library version information; this method may not be implemented for all drivers.

Returns
the driver-specific client library version information; this method may not be implemented for all drivers; see the DBI driver documentation for the return data type and format
Example:
any ver = db.getClientVersion();
Note
see the documentation for the DBI driver being used for possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ getConfigHash()

hash Qore::SQL::DatasourcePool::getConfigHash ( )
virtual

Returns a datasource hash describing the configuration of the current object.

Code Flags:
CONSTANT
Example:
hash h = ds.getConfigHash();
Returns
a datasource hash describing the configuration of the current object
Since
Qore 0.8.8

Implements Qore::SQL::AbstractDatasource.

◆ getConfigString()

string Qore::SQL::DatasourcePool::getConfigString ( )
virtual

Returns a string giving the configuration of the current object in a format that can be parsed by parse_datasource()

Code Flags:
CONSTANT
Example:
string str = ds.getConfigString();
Returns
a string giving the configuration of the current object in a format that can be parsed by parse_datasource()
Since
Qore 0.8.8

Implements Qore::SQL::AbstractDatasource.

◆ getDBCharset()

*string Qore::SQL::DatasourcePool::getDBCharset ( )

Retrieves the database-specific charset set encoding for the object.

A method synonym for DatasourcePool::getDBEncoding() kept for backwards-compatibility

Returns
the database-specific charset set encoding for the object
Code Flags:
CONSTANT
Example:
string enc = db.getDBCharset();

◆ getDBEncoding()

string Qore::SQL::DatasourcePool::getDBEncoding ( )
virtual

Retrieves the database-specific charset set encoding for the object.

Returns
the database-specific charset set encoding for the object
Code Flags:
CONSTANT
Example:
string enc = db.getDBEncoding();
See also
DatasourcePool::getOSEncoding()

Implements Qore::SQL::AbstractDatasource.

◆ getDBName()

*string Qore::SQL::DatasourcePool::getDBName ( )
virtual

Returns the database name parameter as a string or NOTHING if none is set.

Returns
the database name parameter as a string or NOTHING if none is set
Code Flags:
CONSTANT
Example:
*string db = db.getDBName();

Implements Qore::SQL::AbstractDatasource.

◆ getDriverName()

string Qore::SQL::DatasourcePool::getDriverName ( )
virtual

Returns the name of the driver used for the object.

Returns
the name of the driver used for the object
Code Flags:
CONSTANT
Example:
string driver = db.getDriverName();

Implements Qore::SQL::AbstractDatasource.

◆ getErrorTimeout()

int Qore::SQL::DatasourcePool::getErrorTimeout ( )

Returns the error timeout period for waiting for a connection to come free as an integer giving milliseconds; note that timeout values less than or equal to zero mean that requests for a connection will wait indefinitely.

Code Flags:
CONSTANT
Example:
int ms = ds.getErrorTimeout();
Returns
the error timeout period for waiting for a connection to come free as an integer giving milliseconds; note that timeout values less than or equal to zero mean that requests for a connection will wait indefinitely
Since
Qore 0.8.9

◆ getHostName()

*string Qore::SQL::DatasourcePool::getHostName ( )
virtual

Returns the hostname parameter as a string or NOTHING if none is set.

Returns
the hostname parameter as a string or NOTHING if none is set
Code Flags:
CONSTANT
Example:
*string host = db.getHostName();

Implements Qore::SQL::AbstractDatasource.

◆ getMaximum()

int Qore::SQL::DatasourcePool::getMaximum ( )

Returns the maximum number of connections in this object.

Returns
the maximum number of connections in this object
Code Flags:
CONSTANT
Example:
int max = db.getMaximum();

◆ getMinimum()

int Qore::SQL::DatasourcePool::getMinimum ( )

Returns the minimum number of connections in this object.

Returns
the minimum number of connections in this object
Code Flags:
CONSTANT
Example:
int min = db.getMinimum();

◆ getOption()

any Qore::SQL::DatasourcePool::getOption ( string  opt)

Returns the current value for the given option.

Code Flags:
RET_VALUE_ONLY
Parameters
optthe option to get
Exceptions
DBI-OPTION-ERRORunknown or unsupported option passed to driver
Since
Qore 0.8.6

◆ getOptionHash()

hash Qore::SQL::DatasourcePool::getOptionHash ( )

returns the valid options for the driver associated with the Datasource with descriptions and current values for the current Datasource object

Code Flags:
CONSTANT
Returns
a hash where the keys are valid option names, and the values are hashes with the following keys:
  • "desc": a string description of the option
  • "type": a string giving the data type restriction for the option
  • "value": the current value of the option
Since
Qore 0.8.6

◆ getOSCharset()

string Qore::SQL::DatasourcePool::getOSCharset ( )

Returns the Qore character encoding name for the object as a string or "(unknown)" if none is set.

Returns
the Qore character encoding name for the object as a string or "(unknown)" if none is set
Code Flags:
CONSTANT
Example:
string enc = db.getOSCharset();
See also
DatasourcePool::getOSEncoding()

◆ getOSEncoding()

*string Qore::SQL::DatasourcePool::getOSEncoding ( )
virtual

Returns the Qore character encoding name for the object as a string or NOTHING if none is set.

Returns
the Qore character encoding name for the object as a string or NOTHING if none is set
Code Flags:
CONSTANT
Example:
*string enc = db.getOSEncoding();

Implements Qore::SQL::AbstractDatasource.

◆ getPassword()

*string Qore::SQL::DatasourcePool::getPassword ( )
virtual

Returns the password parameter as a string or NOTHING if none is set.

Returns
the password parameter as a string or NOTHING if none is set
Code Flags:
CONSTANT
Example:
*string pass = db.getPassword();

Implements Qore::SQL::AbstractDatasource.

◆ getPort()

*int Qore::SQL::DatasourcePool::getPort ( )
virtual

Gets the port number that will be used for the next connection to the server.

Invalid port numbers will cause an exception to be thrown when the connection is opened

Code Flags:
CONSTANT
Example:
*int port = db.getPort();

Implements Qore::SQL::AbstractDatasource.

◆ getServerVersion()

any Qore::SQL::DatasourcePool::getServerVersion ( )
virtual

Returns the driver-specific server version data for the current connection.

Returns
the driver-specific server version data for the current connection; see the DBI driver documentation for the return data type and format
Example:
any ver = db.getServerVersion();
Note
see the documentation for the DBI driver being used for additional possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ getUsageInfo()

*hash Qore::SQL::DatasourcePool::getUsageInfo ( )

Returns a hash with usage information about the DatasourcePool object.

Code Flags:
CONSTANT
Example:
hash h = ds.getUsageInfo();
Returns
a hash with the following keys (note that the callback, timeout, and optionally arg keys are only set if a warning callback is set):
  • callback: the closure or call reference set as the warning callback
  • timeout: an integer giving the timeout threshold in milliseconds before the warning callback is executed
  • arg: an optional argument passed to the warning callback
  • wait_max: the maximum number of microseconds that threads have had to wait for a free connection
  • stats_reqs: the total number of requests for connections / transactions on this DatasourcePool
  • stats_hits: the total number of requests for connections / transactions on this DatasourcePool that did not have to wait for a connection
Note
wait_max is reported in microseconds (1 ms = 1000 us) while the warning timeout has a resolution of milliseconds
Since
Qore 0.8.9

◆ getUserName()

*string Qore::SQL::DatasourcePool::getUserName ( )
virtual

Returns the username parameter as a string or NOTHING if none is set.

Returns
the username parameter as a string or NOTHING if none is set
Code Flags:
CONSTANT
Example:
*string user = db.getUserName();

Implements Qore::SQL::AbstractDatasource.

◆ inTransaction()

bool Qore::SQL::DatasourcePool::inTransaction ( )
virtual

Returns True if a transaction is currently in progress (meaning in this case that a datasource form the pool is dedicated to the calling thread), False if not.

Returns
True if a transaction is currently in progress (meaning in this case that a datasource form the pool is dedicated to the calling thread), False if not
Code Flags:
CONSTANT
Example:
bool b = db.inTransaction();

Implements Qore::SQL::AbstractDatasource.

◆ rollback()

nothing Qore::SQL::DatasourcePool::rollback ( )
virtual

Rolls back the current transaction and releases the connection to the pool.

Example:
db.rollback();

Implements Qore::SQL::AbstractDatasource.

◆ select()

any Qore::SQL::DatasourcePool::select ( string  sql,
  ... 
)
virtual

Executes an SQL select statement on the server and returns the result as a hash (column names) of lists (column values per row)

The return format of this method is suitable for use with context statements, for easy iteration and processing of query results. Alternatively, the HashListIterator class can be used to iterate the return value of this method.

Additionally, this format is a more efficient format than that returned by the Datasource::selectRows() method, because the column names are not repeated for each row returned. Therefore, for retrieving anything greater than small amounts of data, it is recommended to use this method instead of Datasource::selectRows().

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
...Include any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
This method returns a hash (the keys are the column names) of lists (the column data per row) when executed with an SQL select statement, however some DBI drivers allow any SQL to be executed through this method, in which case other data types can be returned (such as an integer for a row count or a hash for output parameters when executing a stored procedure). If no rows are found, a hash of column names assigned to empty lists is returned.
Example:
# bind a string and a date/time value by value in a query
hash query = db.select("select * from table where varchar_column = %v and timestamp_column > %v", string, 2007-10-11T15:31:26.289);
if (query.firstValue())
printf("got results\n");
Note
  • See the documentation for the DBI driver being used for additional possible exceptions
  • This method returns all the data available immediately; to process query data piecewise, use the SQLStatement class
See also

Implements Qore::SQL::AbstractDatasource.

◆ selectRow()

any Qore::SQL::DatasourcePool::selectRow ( string  sql,
  ... 
)
virtual

Executes an SQL select statement on the server and returns the first row as a hash (the column values)

If more than one row is returned, then it is treated as an error and a DBI-SELECT-ROW-ERROR is returned (however the DBI driver should raise its own exception here to avoid retrieving more than one row from the server). For a similar method taking a list for all bind arguments, see DatasourcePool::vselectRow().

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
...Include any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
This method normally returns a hash (the keys are the column names) of row data or NOTHING if no row is found for the query when executed with an SQL select statement, however some DBI drivers allow any SQL statement to be executed through this method (not only select statements), in this case other data types can be returned
Example:
*hash h = db.selectRow("select * from example_table where id = 1");
Exceptions
DBI-SELECT-ROW-ERRORmore than 1 row retrieved from the server
Note
see the documentation for the DBI driver being used for additional possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ selectRows()

any Qore::SQL::DatasourcePool::selectRows ( string  sql,
  ... 
)
virtual

Executes an SQL select statement on the server and returns the result as a list (rows) of hashes (the column values)

The return format of this method is not as memory efficient as that returned by the DatasourcePool::select() method, therefore for larger amounts of data, it is recommended to use DatasourcePool::select().

The usual return value of this method can be iterated with the ListHashIterator class.

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
...Include any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
Normally returns a list (rows) of hash (where the keys are the column names of each row) or NOTHING if no rows are found for the query, however some DBI drivers allow any SQL statement to be executed through this method (not only select statements), in this case other data types can be returned
Example:
*list list = db.selectRows("select * from example_table");
Note
see the documentation for the DBI driver being used for additional possible exceptions
See also
DatasourcePool::select()

Implements Qore::SQL::AbstractDatasource.

◆ setErrorTimeout()

Qore::SQL::DatasourcePool::setErrorTimeout ( timeout  ts)

Sets the timeout period for waiting for a connection to come free; note that timeout values less than or equal to zero mean that requests for a connection will wait indefinitely.

Example:
ds.setErrorTimeout(30s);
Since
Qore 0.8.9

◆ setEventQueue()

nothing Qore::SQL::DatasourcePool::setEventQueue ( Qore::Thread::Queue  queue,
any  arg 
)

Sets a queue object for DBI events on the pool.

Parameters
queuethe Queue object to receive datasource events; note that the Queue passed cannot have any maximum size set or a QUEUE-ERROR will be thrown; passing NOTHING will clear any event queue
argan argument to be included in the arg key of datasource events
Exceptions
QUEUE-ERRORthe Queue passed has a maximum size set
Since
Qore 0.8.9

◆ setWarningCallback()

Qore::SQL::DatasourcePool::setWarningCallback ( timeout  ms,
code  callback,
any  arg 
)

sets a connection delay warning callback to be called any time the delay assigning a connection from the pool exceeds the given timeout in milliseconds

Example:
code cb = sub (string dsstr, int us, int to) {
printf("WARNING: datasource pool %y took %f ms (threshold %d ms) to assign a new connection\n", dsstr, us.toNumber() / 1000n, to);
};
ds.setWarningCallback(5s, cb);
Parameters
msthe period of time with a resolution of milliseconds after which the callback will be called if a connection cannot be allocated in the given time period
callbacka closure or call reference taking three or four arguments: (string desc, int time, int warning_timeout[, any arg]) which will be passed a datasource description string for the pool, an integer giving the amount of time it took to acquire the connection in microseconds (divide by 1000 to get milliseconds), an integer giving the warning timeout threshold in milliseconds, and optionally the arg value passed to this method
argan optional argument that will be passed to the warning callback
Note
that the warning timeout has a resolution of milliseconds, but the actual wait time is reported in microseconds (1 ms = 1000 us)
Since
Qore 0.8.9

◆ toString()

string Qore::SQL::DatasourcePool::toString ( )

Returns a string with technical information about the object.

Returns
a string with technical information about the object
Code Flags:
CONSTANT
Example:
string str = db.toString();

◆ vexec()

any Qore::SQL::DatasourcePool::vexec ( string  sql,
*softlist  vargs 
)
virtual

Allocates a persistent connection to the current thread from the pool (if one has not already been allocated) and executes SQL code on the DB connection, taking a list for all bind arguments.

Same as DatasourcePool::exec() except takes an explicit list for bind arguments

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

Parameters
sqlThe SQL command to execute on the server
vargsInclude any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
The return value depends on the DBI driver; normally, for commands with placeholders, a hash is returned holding the values acquired from executing the SQL statement. For all other commands, normally an integer row count is returned. However, some DBI drivers also allow select statements to be executed through this interface, which would also return a hash (column names) of lists (values for each column).
Example:
int rows = db.vexec("insert into example_table value (%v, %v, %v)", arg_list);
Note
see the documentation for the DBI driver being used for additional possible exceptions

Implements Qore::SQL::AbstractDatasource.

◆ vselect()

any Qore::SQL::DatasourcePool::vselect ( string  sql,
*softlist  vargs 
)
virtual

Executes a select statement on the server and returns the results in a hash (column names) of lists (column values per row), taking a list for all bind arguments.

The return format of this method is suitable for use with context statements, for easy iteration and processing of query results. Alternatively, the HashListIterator class can be used to iterate the return value of this method.

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
vargsInclude any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
Normally returns a hash (the keys are the column names) of list (each hash key's value is a list giving the row data), however some DBI drivers allow any SQL statement to be executed through this method (not only select statements), in this case other data types can be returned. If no rows are found, a hash of column names assigned to empty lists is returned.
Example:
hash query = db.vselect("select * from example_table where id = %v and name = %v", arg_list);
if (query.firstValue())
printf("got results\n");
Note
  • See the documentation for the DBI driver being used for additional possible exceptions
  • This method returns all the data available immediately; to process query data piecewise, use the SQLStatement class
See also

Implements Qore::SQL::AbstractDatasource.

◆ vselectRow()

any Qore::SQL::DatasourcePool::vselectRow ( string  sql,
*softlist  vargs 
)
virtual

Executes a select statement on the server and returns the first row as a hash (column names and values), taking a list for all bind arguments.

This method is the same as the DatasourcePool::selectRow() method, except this method takes a single argument after the SQL command giving the list of bind value parameters

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
vargsInclude any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
This method normally returns a hash (the keys are the column names) of row data or NOTHING if no row is found for the query when executed with an SQL select statement, however some DBI drivers allow any SQL statement to be executed through this method (not only select statements), in this case other data types can be returned
Example:
*hash h = db.vselectRow("select * from example_table where id = %v and type = %v", arg_list);
Note
see the documentation for the DBI driver being used for additional possible exceptions
See also
DatasourcePool::selectRow()

Implements Qore::SQL::AbstractDatasource.

◆ vselectRows()

any Qore::SQL::DatasourcePool::vselectRows ( string  sql,
*softlist  vargs 
)
virtual

Executes a select statement on the server and returns the results in a list (rows) of hashes (column names and values), taking a list for all bind arguments.

Same as the Datasource::selectRows() method, except this method takes a single argument after the SQL command giving the list of bind value parameters.

The usual return value of this method can be iterated with the ListHashIterator class.

The return format of this method is not as memory efficient as that returned by the DatasourcePool::select() method, therefore for larger amounts of data, it is recommended to use DatasourcePool::select().

This method also accepts all bind parameters (%d, %v, %s, etc) as documented in Binding by Value and Placeholder

This method does not retain the datasource connection for the current thread if one was not already allocated before this method is called, so to execute select statements that begin a transaction (such as "select for update"), execute DatasourcePool::beginTransaction() first to ensure that the connection is dedicated to the calling thread.

Parameters
sqlThe SQL command to execute on the server
vargsInclude any values to be bound (using %v in the command string) or placeholder specifications (using :key_name in the command string) in order after the command string
Returns
Normally returns a list (rows) of hash (where the keys are the column names of each row) or NOTHING if no rows are found for the query, however some DBI drivers allow any SQL statement to be executed through this method (not only select statements), in this case other data types can be returned
Example:
*list list = db.vselectRows("select * from example_table where id = %v and type = %v", arg_list);
Note
see the documentation for the DBI driver being used for additional possible exceptions
See also
DatasourcePool::selectRows()

Implements Qore::SQL::AbstractDatasource.