Commit b8a32fdc authored by unknown's avatar unknown

First round of edits to Ndb.hpp for Alcatel PDF.


ndb/include/ndbapi/Ndb.hpp:
  Edits for Alcatel PDF version (first set).
parent 66fe5d7c
...@@ -39,12 +39,12 @@ ...@@ -39,12 +39,12 @@
It is also possible to receive "events" triggered when data in the database in changed. It is also possible to receive "events" triggered when data in the database in changed.
This is done through the NdbEventOperation class. This is done through the NdbEventOperation class.
There are also some auxiliary classes, which are listed in the @ref hierarchy. There are also some auxiliary classes, which are listed in the class hierarchy.
The main structure of an application program is as follows: The main structure of an application program is as follows:
-# Construct and connect to a cluster using the Ndb_cluster_connection -# Connect to a cluster using the Ndb_cluster_connection
object. object.
-# initiate a database connection by constructing and initialising one or more Ndb objects. -# Initiate a database connection by constructing and initialising one or more Ndb objects.
-# Define and execute transactions using the NdbTransaction class. -# Define and execute transactions using the NdbTransaction class.
-# Delete Ndb objects. -# Delete Ndb objects.
-# Terminate the connection to the cluster (terminate instance of Ndb_cluster_connection). -# Terminate the connection to the cluster (terminate instance of Ndb_cluster_connection).
...@@ -69,8 +69,6 @@ ...@@ -69,8 +69,6 @@
commited (event if commit fails), and no further addition or definition of commited (event if commit fails), and no further addition or definition of
operations for this transaction is allowed. operations for this transaction is allowed.
@c STOP POINT -- js
@section secSync Synchronous Transactions @section secSync Synchronous Transactions
Synchronous transactions are defined and executed as follows: Synchronous transactions are defined and executed as follows:
...@@ -95,12 +93,12 @@ ...@@ -95,12 +93,12 @@
To execute several parallel synchronous transactions, one can either To execute several parallel synchronous transactions, one can either
use multiple Ndb objects in several threads, or start multiple use multiple Ndb objects in several threads, or start multiple
applications programs. application programs.
@section secNdbOperations Operations @section secNdbOperations Operations
Each NdbTransaction consists of a list of operations which are represented Each NdbTransaction consists of a list of operations, each of which is represented
by instances of NdbOperation, NdbScanOperation, NdbIndexOperation, and/or by an instance of NdbOperation, NdbScanOperation, NdbIndexOperation, or
NdbIndexScanOperation. NdbIndexScanOperation.
<h3>Single row operations</h3> <h3>Single row operations</h3>
...@@ -112,7 +110,7 @@ ...@@ -112,7 +110,7 @@
-# Specify attribute actions, using NdbOperation::getValue() -# Specify attribute actions, using NdbOperation::getValue()
Here are two brief examples illustrating this process. For the sake of Here are two brief examples illustrating this process. For the sake of
brevity, we omit error-handling. brevity, we omit error handling.
This first example uses an NdbOperation: This first example uses an NdbOperation:
@code @code
...@@ -151,17 +149,17 @@ ...@@ -151,17 +149,17 @@
creation and use of synchronous transactions. creation and use of synchronous transactions.
<h4>Step 1: Define single row operation type</h4> <h4>Step 1: Define single row operation type</h4>
The following types of operations exist: The following operation types are supported:
-# NdbOperation::insertTuple : -# NdbOperation::insertTuple() :
inserts a non-existing tuple inserts a non-existing tuple
-# NdbOperation::writeTuple : -# NdbOperation::writeTuple() :
updates an existing tuple if is exists, updates an existing tuple if is exists,
otherwise inserts a new tuple otherwise inserts a new tuple
-# NdbOperation::updateTuple : -# NdbOperation::updateTuple() :
updates an existing tuple updates an existing tuple
-# NdbOperation::deleteTuple : -# NdbOperation::deleteTuple() :
deletes an existing tuple deletes an existing tuple
-# NdbOperation::readTuple : -# NdbOperation::readTuple() :
reads an existing tuple with specified lock mode reads an existing tuple with specified lock mode
All of these operations operate on the unique tuple key. All of these operations operate on the unique tuple key.
...@@ -173,20 +171,22 @@ ...@@ -173,20 +171,22 @@
NdbTransaction::getNdbIndexOperation() for each operation. NdbTransaction::getNdbIndexOperation() for each operation.
<h4>Step 2: Specify Search Conditions</h4> <h4>Step 2: Specify Search Conditions</h4>
The search condition is used to select tuples using NdbOperation::equal() The search condition is used to select tuples. Search conditions are set using NdbOperation::equal().
<h4>Step 3: Specify Attribute Actions</h4> <h4>Step 3: Specify Attribute Actions</h4>
Now it is time to define which attributes should be read or updated. Next, it is necessary to determine which attributes should be read or updated.
Deletes can neither read nor set values, read can only read values and It is important to remember that:
updates can only set values. - Deletes can neither read nor set values, but only delete them
Normally the attribute is defined by its name but it is - Reads can only read values
also possible to use the attribute identity to define the - Updates can only set values
Normally the attribute is identified by name, but it is
also possible to use the attribute's identity to determine the
attribute. attribute.
NdbOperation::getValue() returns an NdbRecAttr object NdbOperation::getValue() returns an NdbRecAttr object
containing the read value. containing the read value.
To get the value, there is actually two methods. To obtain the actual value, one of two methods can be used;
The application can either the application can either
- use its own memory (passed through a pointer aValue) to - use its own memory (passed through a pointer aValue) to
NdbOperation::getValue(), or NdbOperation::getValue(), or
- receive the attribute value in an NdbRecAttr object allocated - receive the attribute value in an NdbRecAttr object allocated
...@@ -194,28 +194,28 @@ ...@@ -194,28 +194,28 @@
The NdbRecAttr object is released when Ndb::closeTransaction() The NdbRecAttr object is released when Ndb::closeTransaction()
is called. is called.
Thus, the application can not reference this object after Thus, the application cannot reference this object following
Ndb::closeTransaction() have been called. any subsequent call to Ndb::closeTransaction().
The result of reading data from an NdbRecAttr object before Attempting to read data from an NdbRecAttr object before
calling NdbTransaction::execute() is undefined. calling NdbTransaction::execute() yields an undefined result.
@subsection secScan Scan Operations @subsection secScan Scan Operations
Scans are roughly the equivalent of SQL cursors. Scans are roughly the equivalent of SQL cursors, providing a means to
preform high-speed row processing. A scan can be performed
Scans can either be performed on a table (@ref NdbScanOperation) or on either a table (using @ref NdbScanOperation) or
on an ordered index (@ref NdbIndexScanOperation). an ordered index (by means of an @ref NdbIndexScanOperation).
Scan operation are characteriesed by the following: Scan operations are characterised by the following:
- They can only perform reads (shared, exclusive or dirty) - They can perform only reads (shared, exclusive or dirty)
- They can potentially work with multiple rows - They can potentially work with multiple rows
- They can be used to update or delete multiple rows - They can be used to update or delete multiple rows
- They can operate on several nodes in parallell - They can operate on several nodes in parallel
After the operation is created using NdbTransaction::getNdbScanOperation() After the operation is created using NdbTransaction::getNdbScanOperation()
(or NdbTransaction::getNdbIndexScanOperation()), (or NdbTransaction::getNdbIndexScanOperation()),
it is defined in the following three steps: it is carried out in the following three steps:
-# Define the standard operation type, using NdbScanOperation::readTuples() -# Define the standard operation type, using NdbScanOperation::readTuples()
-# Specify search conditions, using @ref NdbScanFilter and/or -# Specify search conditions, using @ref NdbScanFilter and/or
@ref NdbIndexScanOperation::setBound() @ref NdbIndexScanOperation::setBound()
...@@ -223,10 +223,10 @@ ...@@ -223,10 +223,10 @@
-# Executing the transaction, using NdbTransaction::execute() -# Executing the transaction, using NdbTransaction::execute()
-# Iterating through the result set using NdbScanOperation::nextResult() -# Iterating through the result set using NdbScanOperation::nextResult()
Here are two brief examples illustrating this process. For the sake of Here are two brief examples illustrating this process. Once again, in order
brevity, we omit error-handling. to keep things relatively short and simple, we will forego any error handling.
This first example uses an NdbScanOperation: This first example performs a table scan, using an NdbScanOperation:
@code @code
// 1. Create // 1. Create
MyOperation= MyTransaction->getNdbScanOperation("MYTABLENAME"); MyOperation= MyTransaction->getNdbScanOperation("MYTABLENAME");
...@@ -245,7 +245,7 @@ ...@@ -245,7 +245,7 @@
MyRecAttr= MyOperation->getValue("ATTR2", NULL); MyRecAttr= MyOperation->getValue("ATTR2", NULL);
@endcode @endcode
The second example uses an NdbIndexScanOperation: Our second example uses an NdbIndexScanOperation to perform an index scan:
@code @code
// 1. Create // 1. Create
MyOperation= MyTransaction->getNdbIndexScanOperation("MYORDEREDINDEX", "MYTABLENAME"); MyOperation= MyTransaction->getNdbIndexScanOperation("MYORDEREDINDEX", "MYTABLENAME");
...@@ -262,77 +262,67 @@ ...@@ -262,77 +262,67 @@
MyRecAttr = MyOperation->getValue("ATTR2", NULL); MyRecAttr = MyOperation->getValue("ATTR2", NULL);
@endcode @endcode
Some additional discussion of each step required to perform a scan follows:
<h4>Step 1: Define scan operation operation type</h4> <h4>Step 1: Define scan operation operation type</h4>
Scan operations only support 1 operation, It is important to remember that only a single operation is supported for each scan operation
@ref NdbScanOperation::readTuples() (@ref NdbScanOperation::readTuples() or @ref NdbIndexScanOperation::readTuples()).
or @ref NdbIndexScanOperation::readTuples()
@note If you want to define multiple scan operations within the same @note If you want to define multiple scan operations within the same
transaction, then you need to call transaction, then you need to call
NdbTransaction::getNdbScanOperation() or NdbTransaction::getNdbScanOperation() or
NdbTransaction::getNdbIndexScanOperation() for each operation. NdbTransaction::getNdbIndexScanOperation() separately for <b>each</b> operation.
<h4>Step 2: Specify Search Conditions</h4> <h4>Step 2: Specify Search Conditions</h4>
The search condition is used to select tuples. The search condition is used to select tuples.
If no search condition is specified, the scan will return all rows If no search condition is specified, the scan will return all rows
in the table. in the table.
Search condition can be @ref NdbScanFilter which can be used on both The search condition can be an @ref NdbScanFilter (which can be used on both
@ref NdbScanOperation and @ref NdbIndexScanOperation or bounds which @ref NdbScanOperation and @ref NdbIndexScanOperation) or bounds which
can only be used on index scans, @ref NdbIndexScanOperation::setBound. can only be used on index scans (@ref NdbIndexScanOperation::setBound()).
An index scan can have both NdbScanFilter and bounds An index scan can use both NdbScanFilter and bounds.
@note When NdbScanFilter is used each row is examined but maybe not @note When NdbScanFilter is used, each row is examined, whether or not it is
returned. But when using bounds, only rows within bounds will be examined. actually returned. However, when using bounds, only rows within the bounds will be examined.
<h4>Step 3: Specify Attribute Actions</h4> <h4>Step 3: Specify Attribute Actions</h4>
Now it is time to define which attributes should be read. Next, it is necessary to define which attributes should be read.
Normally the attribute is defined by its name but it is As with transaction attributes, scan attributes are defined by name but it is
also possible to use the attribute identity to define the also possible to use the attributes' identities to define attributes.
attribute.
NdbOperation::getValue() returns an NdbRecAttr object As previously discussed (see @ref secSync), the value read is returned as an NdbRecAttr object by
containing the read value. the NdbOperation::getValue() method.
To get the value, there is actually two methods.
The application can either
- use its own memory (passed through a pointer aValue) to
NdbOperation::getValue(), or
- receive the attribute value in an NdbRecAttr object allocated
by the NDB API.
The NdbRecAttr object is released when Ndb::closeTransaction()
is called. Thus, the application can not reference this object after
Ndb::closeTransaction() have been called.
The result of reading data from an NdbRecAttr object before
calling NdbTransaction::execute() is undefined.
<h3> Using Scan to update/delete </h3> <h3>Using Scan to Update/Delete</h3>
Scanning can also be used to update/delete rows. Scanning can also be used to update or delete rows.
This is performed by This is performed by
-# Scan using exclusive locks, NdbOperation::LM_Exclusive -# Scanning using exclusive locks (using NdbOperation::LM_Exclusive)
-# When iterating through the result set, for each row optionally call -# When iterating through the result set, for each row optionally calling
either NdbScanOperation::updateCurrentTuple() or either NdbScanOperation::updateCurrentTuple() or
NdbScanOperation::deleteCurrentTuple() NdbScanOperation::deleteCurrentTuple()
-# If performing NdbScanOperation::updateCurrentTuple(), -# (If performing NdbScanOperation::updateCurrentTuple():)
set new values on record using ordinary @ref NdbOperation::setValue(). Setting new values for records simply by using @ref NdbOperation::setValue().
NdbOperation::equal() should <em>not</em> be called as the primary NdbOperation::equal() should <em>not</em> be called in such cases, as the primary
key is retreived from the scan. key is retrieved from the scan.
@note that the actual update/delete will not be performed until next @note The actual update or delete will not be performed until the next
NdbTransaction::execute (as with single row operations), call to NdbTransaction::execute(), just as with single row operations.
NdbTransaction::execute needs to be called before locks are released, NdbTransaction::execute() also must be called before any locks are released;
see @ref secScanLocks see @ref secScanLocks for more information.
<h4> Index scans specific features </h4> <h4>Features Specific to Index Scans</h4>
The following features are available when performing an index scan
- Scan subset of table using @ref NdbIndexScanOperation::setBound() When performing an index scan, it is possible to
- Ordering result set ascending or descending, scan only a subset of a table using @ref NdbIndexScanOperation::setBound().
@ref NdbIndexScanOperation::readTuples() In addition, result sets can be sorted in either ascending or descending order, using
- When using NdbIndexScanOperation::BoundEQ on partition key @ref NdbIndexScanOperation::readTuples(). Note that rows are returned unordered
only fragments containing rows will be scanned. by default, that is, unless <code>sorted</code> is set to <var>true</var>.
IN addition, when using NdbIndexScanOperation::BoundEQ on a partition key,
Rows are returned unordered unless sorted is set to true. only fragments containing rows will actually be scanned.
@comment STOP POINT 20050108 13.35 GMT JS
@note When performing sorted scan, parameter parallelism to @note When performing sorted scan, parameter parallelism to
NdbIndexScanOperation::readTuples() will NdbIndexScanOperation::readTuples() will
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