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https://issues.apache.org/jira/browse/HAWQ-1252?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15818930#comment-15818930
]
ASF GitHub Bot commented on HAWQ-1252:
--------------------------------------
Github user dyozie commented on a diff in the pull request:
https://github.com/apache/incubator-hawq-docs/pull/83#discussion_r95630626
--- Diff: markdown/plext/using_pljava.html.md.erb ---
@@ -2,205 +2,222 @@
title: Using PL/Java
---
-This section contains an overview of the HAWQ PL/Java language.
+This section provides an overview of the HAWQ PL/Java procedural language
extension.
## <a id="aboutpljava"></a>About PL/Java
-With the HAWQ PL/Java extension, you can write Java methods using your
favorite Java IDE and install the JAR files that implement the methods in your
HAWQ cluster.
+With the PL/Java extension, you can write Java methods using your favorite
Java IDE and invoke the methods from PostgreSQL user-defined functions (UDFs).
-**Note**: If building HAWQ from source, you must specify PL/Java as a
build option when compiling HAWQ. To use PL/Java in a HAWQ deployment, you must
explicitly enable the PL/Java extension in all desired databases.
+The HAWQ PL/Java package is based on the open source PL/Java 1.4.0 and
provides the following features:
-The HAWQ PL/Java package is based on the open source PL/Java 1.4.0. HAWQ
PL/Java provides the following features.
-
-- Ability to execute PL/Java functions with Java 1.6 or 1.7.
-- Standardized utilities (modeled after the SQL 2003 proposal) to install
and maintain Java code in the database.
-- Standardized mappings of parameters and result. Complex types as well as
sets are supported.
-- An embedded, high performance, JDBC driver utilizing the internal HAWQ
Database SPI routines.
+- PL/Java function execution with Java 1.6 or 1.7.
+- Standardized mappings of Java and PostgreSQL parameters and results.
Complex types as well as sets are supported.
+- Two HAWQ Java languages:
+ - `java` - Tusted PL/Java language
+ - `javau` - Untrusted PL/Java language (superusers only)
+- An embedded, high performance, JDBC driver utilizing the internal HAWQ
Database Server Programming Interface (SPI).
- Metadata support for the JDBC driver. Both `DatabaseMetaData` and
`ResultSetMetaData` are included.
-- The ability to return a `ResultSet` from a query as an alternative to
building a ResultSet row by row.
+- A standard way of passing parameters and return values. Complex types
and sets are passed using the standard JDBC `ResultSet` class.
+- The ability to return a `ResultSet` from a query as an alternative to
building a `ResultSet` row by row.
- Full support for savepoints and exception handling.
-- The ability to use IN, INOUT, and OUT parameters.
-- Two separate HAWQ languages:
- - pljava, TRUSTED PL/Java language
- - pljavau, UNTRUSTED PL/Java language
- Transaction and Savepoint listeners enabling code execution when a
transaction or savepoint is committed or rolled back.
- Integration with GNU GCJ on selected platforms.
-A function in SQL will appoint a static method in a Java class. In order
for the function to execute, the appointed class must available on the class
path specified by the HAWQ server configuration parameter `pljava_classpath`.
The PL/Java extension adds a set of functions that helps to install and
maintain the Java classes. Classes are stored in normal Java archives, JAR
files. A JAR file can optionally contain a deployment descriptor that in turn
contains SQL commands to be executed when the JAR is deployed or undeployed.
The functions are modeled after the standards proposed for SQL 2003.
-
-PL/Java implements a standard way of passing parameters and return values.
Complex types and sets are passed using the standard JDBC ResultSet class.
-
-A JDBC driver is included in PL/Java. This driver calls HAWQ internal SPI
routines. The driver is essential since it is common for functions to make
calls back to the database to fetch data. When PL/Java functions fetch data,
they must use the same transactional boundaries that are used by the main
function that entered PL/Java execution context.
+PL/Java is optimized for performance. The Java virtual machine executes
within the same process as the backend, minimizing call overhead. PL/Java
brings the power of Java to the database itself, enabling the
database-intensive business logic to execute as close to the actual data as
possible.
-PL/Java is optimized for performance. The Java virtual machine executes
within the same process as the backend to minimize call overhead. PL/Java is
designed with the objective to enable the power of Java to the database itself
so that database intensive business logic can execute as close to the actual
data as possible.
-
-The standard Java Native Interface (JNI) is used when bridging calls
between the backend and the Java VM.
+Calls between the HAWQ backend and the Java VM are bridged using the
standard Java Native Interface (JNI).
## <a id="abouthawqpljava"></a>About HAWQ PL/Java
+PL/Java is embedded in your HAWQ product distribution or within your HAWQ
build if you chose to enable it as a build option. To use PL/Java in a HAWQ
deployment, you must explicitly enable the PL/Java extension in all desired
databases.
+
There are a few key differences between the implementation of PL/Java in
standard PostgreSQL and HAWQ.
-### <a id="pljavafunctions"></a>Functions
+### <a id="pljavafunctions"></a>Functions Not Supported
-The following functions are not supported in HAWQ. The classpath is
handled differently in a distributed HAWQ environment than in the PostgreSQL
environment.
+The following functions are not supported in HAWQ. The PL/Java classpath
is handled differently in a distributed HAWQ environment than that of the
PostgreSQL environment.
-- sqlj.install_jar
-- sqlj.install_jar
-- sqlj.replace_jar
-- sqlj.remove_jar
-- sqlj.get_classpath
-- sqlj.set_classpath
+- sqlj.install_jar()
+- sqlj.install_jar()
+- sqlj.replace_jar()
+- sqlj.remove_jar()
+- sqlj.get_classpath()
+- sqlj.set_classpath()
-HAWQ uses the `pljava_classpath` server configuration parameter in place
of the `sqlj.set_classpath` function.
+HAWQ uses the `pljava_classpath` server configuration parameter in place
of the `sqlj.set_classpath()` function.
### <a id="serverconfigparams"></a>Server Configuration Parameters
-PL/Java uses server configuration parameters to configure classpath, Java
VM, and other options. Refer to the [Server Configuration Parameter
Reference](../reference/HAWQSiteConfig.html) for general information about HAWQ
server configuration parameters.
+PL/Java uses server configuration parameters to configure the classpath,
Java Virtual Machine (VM), and other options. Refer to the [Server
Configuration Parameter Reference](../reference/HAWQSiteConfig.html) for
general information about HAWQ server configuration parameters.
-The following server configuration parameters are used by PL/Java in HAWQ.
These parameters replace the `pljava.*` parameters that are used in the
standard PostgreSQL PL/Java implementation.
+The following server configuration parameters are used by HAWQ PL/Java.
These parameters replace the `pljava.*` configuration parameters that are used
in the standard PostgreSQL PL/Java implementation.
#### pljava\_classpath
-A colon (:) separated list of the jar files containing the Java classes
used in any PL/Java functions. The jar files must be installed in the same
locations on all HAWQ hosts. With the trusted PL/Java language handler, jar
file paths must be relative to the `$GPHOME/lib/postgresql/java/` directory.
With the untrusted language handler (javaU language tag), paths may be relative
to `$GPHOME/lib/postgresql/java/` or absolute.
+A PL/Java user-defined function will appoint a static method in a Java
class. In order for the function to execute, the appointed class must be
available on the class path specified by the
[`pljava_classpath`](../reference/guc/parameter_definitions.html#pljava_classpath)
HAWQ server configuration parameter.
-#### pljava\_statement\_cache\_size
-
-Sets the size in KB of the Most Recently Used (MRU) cache for prepared
statements.
+`pljava_classpath` is a colon (:) separated list of the JAR files
implementing the Java classes referenced in any PL/Java user-defined functions.
The JAR files must be installed in the same locations on all HAWQ hosts. When
using the trusted PL/Java language handler (`java` language tag), JAR file
paths must be relative to the `$GPHOME/lib/postgresql/java/` directory.
Relative or absolute JAR file paths may be used with the untrusted PL/Java
language handler (`javau` language tag).
#### pljava\_release\_lingering\_savepoints
-If TRUE, lingering savepoints will be released on function exit. If FALSE,
they will be rolled back.
+[`pljava_release_lingering_savepoints`](../reference/guc/parameter_definitions.html#pljava_release_lingering_savepoints)
identifies the action to perform when lingering savepoints exist on exit of a
PL/Java user-defined function. If TRUE, lingering savepoints will be released
on function exit. If FALSE, lingering savepoints will be rolled back.
+
+#### pljava\_statement\_cache\_size
+
+[`pljava_statement_cache_size`](../reference/guc/parameter_definitions.html#pljava_statement_cache_size)
sets the size (in KB) of the Most Recently Used (MRU) cache for prepared
statements.
#### pljava\_vmoptions
-Defines the start up options for the Java VM.
+[`pljava_vmoptions`](../reference/guc/parameter_definitions.html#pljava_vmoptions)
defines the start-up options for the Java VM.
--- End diff --
Are these just typical space-delimited args, or colon-delimited again?
> PL/Java doc page - validate and enhance info
> --------------------------------------------
>
> Key: HAWQ-1252
> URL: https://issues.apache.org/jira/browse/HAWQ-1252
> Project: Apache HAWQ
> Issue Type: Improvement
> Components: Documentation
> Reporter: Lisa Owen
> Assignee: David Yozie
> Priority: Minor
>
> PL/Java docs section:
> - review and validate current content
> - make sure examples run and are relevant
> - develop new examples as appropriate
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