Repository: incubator-zeppelin Updated Branches: refs/heads/master cd0010d69 -> 8b7556df1
[ZEPPELIN-382] Add Documentation for Cassandra interpreter in the doc⦠Linked **[JIRA]** [JIRA]: https://issues.apache.org/jira/browse/ZEPPELIN-382?jql=project%20%3D%20ZEPPELIN Author: DuyHai DOAN <[email protected]> Closes #384 from doanduyhai/CassandraInterpreterDocumentation and squashes the following commits: b0bf36a [DuyHai DOAN] [ZEPPELIN-382] Add Documentation for Cassandra interpreter in the doc pages Project: http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/repo Commit: http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/commit/8b7556df Tree: http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/tree/8b7556df Diff: http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/diff/8b7556df Branch: refs/heads/master Commit: 8b7556df11c732029d694bbd492b0d30865d3b0c Parents: cd0010d Author: DuyHai DOAN <[email protected]> Authored: Mon Nov 2 12:57:29 2015 +0100 Committer: Lee moon soo <[email protected]> Committed: Sun Nov 8 09:36:05 2015 +0900 ---------------------------------------------------------------------- .../img/docs-img/cassandra-DescribeSchema.png | Bin 0 -> 33600 bytes .../img/docs-img/cassandra-InteractiveHelp.png | Bin 0 -> 84626 bytes .../docs-img/cassandra-InterpreterBinding.png | Bin 0 -> 16963 bytes .../cassandra-InterpreterInstanceSelection.png | Bin 0 -> 24970 bytes .../img/docs-img/cassandra-InterpreterName.png | Bin 0 -> 26762 bytes .../docs-img/cassandra-InterpreterSelection.png | Bin 0 -> 36754 bytes .../docs-img/cassandra-NewInterpreterInList.png | Bin 0 -> 6518 bytes .../cassandra-NewInterpreterInstance.png | Bin 0 -> 23552 bytes docs/docs/index.md | 5 +- docs/docs/interpreter/cassandra.md | 807 +++++++++++++++++++ 10 files changed, 810 insertions(+), 2 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-DescribeSchema.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-DescribeSchema.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-DescribeSchema.png new file mode 100644 index 0000000..940ec2f Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-DescribeSchema.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-InteractiveHelp.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-InteractiveHelp.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InteractiveHelp.png new file mode 100644 index 0000000..fcd2c68 Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InteractiveHelp.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterBinding.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterBinding.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterBinding.png new file mode 100644 index 0000000..aae9a22 Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterBinding.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterInstanceSelection.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterInstanceSelection.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterInstanceSelection.png new file mode 100644 index 0000000..aeadb2b Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterInstanceSelection.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterName.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterName.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterName.png new file mode 100644 index 0000000..821b004 Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterName.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterSelection.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterSelection.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterSelection.png new file mode 100644 index 0000000..6dc97dc Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-InterpreterSelection.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInList.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInList.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInList.png new file mode 100644 index 0000000..b287f41 Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInList.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInstance.png ---------------------------------------------------------------------- diff --git a/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInstance.png b/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInstance.png new file mode 100644 index 0000000..36f6c3e Binary files /dev/null and b/docs/assets/themes/zeppelin/img/docs-img/cassandra-NewInterpreterInstance.png differ http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/docs/index.md ---------------------------------------------------------------------- diff --git a/docs/docs/index.md b/docs/docs/index.md index 6a0d341..11c35da 100644 --- a/docs/docs/index.md +++ b/docs/docs/index.md @@ -19,16 +19,17 @@ group: nav-right **[Interpreters in zeppelin](manual/interpreters.html)** +* [cassandra](./interpreter/cassandra.html) * [flink](./interpreter/flink.html) +* [geode](./interpreter/geode.html) * [hive](../docs/pleasecontribute.html) * [ignite](./interpreter/ignite.html) * [lens](./interpreter/lens.html) * [md](../docs/pleasecontribute.html) +* [postgresql, hawq](./interpreter/postgresql.html) * [sh](../docs/pleasecontribute.html) * [spark](./interpreter/spark.html) * [tajo](../docs/pleasecontribute.html) -* [postgresql, hawq](./interpreter/postgresql.html) -* [geode](./interpreter/geode.html) ### Display System http://git-wip-us.apache.org/repos/asf/incubator-zeppelin/blob/8b7556df/docs/docs/interpreter/cassandra.md ---------------------------------------------------------------------- diff --git a/docs/docs/interpreter/cassandra.md b/docs/docs/interpreter/cassandra.md new file mode 100644 index 0000000..b53295c --- /dev/null +++ b/docs/docs/interpreter/cassandra.md @@ -0,0 +1,807 @@ +--- +layout: page +title: "Cassandra Interpreter" +description: "Cassandra Interpreter" +group: manual +--- +{% include JB/setup %} + +<hr/> +## 1. Cassandra CQL Interpreter for Apache Zeppelin + +<br/> +<table class="table-configuration"> + <tr> + <th>Name</th> + <th>Class</th> + <th>Description</th> + </tr> + <tr> + <td>%cassandra</td> + <td>CassandraInterpreter</td> + <td>Provides interpreter for Apache Cassandra CQL query language</td> + </tr> +</table> + +<hr/> + +## 2. Enabling Cassandra Interpreter + + In a notebook, to enable the **Cassandra** interpreter, click on the **Gear** icon and select **Cassandra** + + <center> +  + +  + </center> + +<hr/> + +## 3. Using the Cassandra Interpreter + + In a paragraph, use **_%cassandra_** to select the **Cassandra** interpreter and then input all commands. + + To access the interactive help, type **HELP;** + + <center> +  + </center> + +<hr/> + +## 4. Interpreter Commands + + The **Cassandra** interpreter accepts the following commands + +<center> + <table class="table-configuration"> + <tr> + <th>Command Type</th> + <th>Command Name</th> + <th>Description</th> + </tr> + <tr> + <td nowrap>Help command</td> + <td>HELP</td> + <td>Display the interactive help menu</td> + </tr> + <tr> + <td nowrap>Schema commands</td> + <td>DESCRIBE KEYSPACE, DESCRIBE CLUSTER, DESCRIBE TABLES ...</td> + <td>Custom commands to describe the Cassandra schema</td> + </tr> + <tr> + <td nowrap>Option commands</td> + <td>@consistency, @retryPolicy, @fetchSize ...</td> + <td>Inject runtime options to all statements in the paragraph</td> + </tr> + <tr> + <td nowrap>Prepared statement commands</td> + <td>@prepare, @bind, @remove_prepared</td> + <td>Let you register a prepared command and re-use it later by injecting bound values</td> + </tr> + <tr> + <td nowrap>Native CQL statements</td> + <td>All CQL-compatible statements (SELECT, INSERT, CREATE ...)</td> + <td>All CQL statements are executed directly against the Cassandra server</td> + </tr> + </table> +</center> + +<hr/> +## 5. CQL statements + +This interpreter is compatible with any CQL statement supported by Cassandra. Ex: + +```sql + + INSERT INTO users(login,name) VALUES('jdoe','John DOE'); + SELECT * FROM users WHERE login='jdoe'; +``` + +Each statement should be separated by a semi-colon ( **;** ) except the special commands below: + +1. @prepare +2. @bind +3. @remove_prepare +4. @consistency +5. @serialConsistency +6. @timestamp +7. @retryPolicy +8. @fetchSize + +Multi-line statements as well as multiple statements on the same line are also supported as long as they are +separated by a semi-colon. Ex: + +```sql + + USE spark_demo; + + SELECT * FROM albums_by_country LIMIT 1; SELECT * FROM countries LIMIT 1; + + SELECT * + FROM artists + WHERE login='jlennon'; +``` + +Batch statements are supported and can span multiple lines, as well as DDL(CREATE/ALTER/DROP) statements: + +```sql + + BEGIN BATCH + INSERT INTO users(login,name) VALUES('jdoe','John DOE'); + INSERT INTO users_preferences(login,account_type) VALUES('jdoe','BASIC'); + APPLY BATCH; + + CREATE TABLE IF NOT EXISTS test( + key int PRIMARY KEY, + value text + ); +``` + +CQL statements are <strong>case-insensitive</strong> (except for column names and values). +This means that the following statements are equivalent and valid: + +```sql + + INSERT INTO users(login,name) VALUES('jdoe','John DOE'); + Insert into users(login,name) vAlues('hsue','Helen SUE'); +``` + +The complete list of all CQL statements and versions can be found below: +<center> + <table class="table-configuration"> + <tr> + <th>Cassandra Version</th> + <th>Documentation Link</th> + </tr> + <tr> + <td><strong>2.2</strong></td> + <td> + <a target="_blank" + href="http://docs.datastax.com/en/cql/3.3/cql/cqlIntro.html";> + http://docs.datastax.com/en/cql/3.3/cql/cqlIntro.html + </a> + </td> + </tr> + <tr> + <td><strong>2.1 & 2.0</strong></td> + <td> + <a target="_blank" + href="http://docs.datastax.com/en/cql/3.1/cql/cql_intro_c.html";> + http://docs.datastax.com/en/cql/3.1/cql/cql_intro_c.html + </a> + </td> + </tr> + <tr> + <td><strong>1.2</strong></td> + <td> + <a target="_blank" + href="http://docs.datastax.com/en/cql/3.0/cql/aboutCQL.html";> + http://docs.datastax.com/en/cql/3.0/cql/aboutCQL.html + </a> + </td> + </tr> + </table> +</center> + +<hr/> + +## 6. Comments in statements + +It is possible to add comments between statements. Single line comments start with the hash sign (#). Multi-line comments are enclosed between /** and **/. Ex: + +```sql + + #First comment + INSERT INTO users(login,name) VALUES('jdoe','John DOE'); + + /** + Multi line + comments + **/ + Insert into users(login,name) vAlues('hsue','Helen SUE'); +``` + +<hr/> + +## 7. Syntax Validation + +The interpreters is shipped with a built-in syntax validator. This validator only checks for basic syntax errors. +All CQL-related syntax validation is delegated directly to **Cassandra** + +Most of the time, syntax errors are due to **missing semi-colons** between statements or **typo errors**. + +<hr/> + +## 8. Schema commands + +To make schema discovery easier and more interactive, the following commands are supported: +<center> + <table class="table-configuration"> + <tr> + <th>Command</th> + <th>Description</th> + </tr> + <tr> + <td><strong>DESCRIBE CLUSTER;</strong></td> + <td>Show the current cluster name and its partitioner</td> + </tr> + <tr> + <td><strong>DESCRIBE KEYSPACES;</strong></td> + <td>List all existing keyspaces in the cluster and their configuration (replication factor, durable write ...)</td> + </tr> + <tr> + <td><strong>DESCRIBE TABLES;</strong></td> + <td>List all existing keyspaces in the cluster and for each, all the tables name</td> + </tr> + <tr> + <td><strong>DESCRIBE TYPES;</strong></td> + <td>List all existing user defined types in the <strong>current (logged) keyspace</strong></td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE FUNCTIONS <keyspace_name>;</strong></td> + <td>List all existing user defined functions in the given keyspace</td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE AGGREGATES <keyspace_name>;</strong></td> + <td>List all existing user defined aggregates in the given keyspace</td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE KEYSPACE <keyspace_name>;</strong></td> + <td>Describe the given keyspace configuration and all its table details (name, columns, ...)</td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE TABLE (<keyspace_name>).<table_name>;</strong></td> + <td> + Describe the given table. If the keyspace is not provided, the current logged in keyspace is used. + If there is no logged in keyspace, the default system keyspace is used. + If no table is found, an error message is raised + </td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE TYPE (<keyspace_name>).<type_name>;</strong></td> + <td> + Describe the given type(UDT). If the keyspace is not provided, the current logged in keyspace is used. + If there is no logged in keyspace, the default system keyspace is used. + If no type is found, an error message is raised + </td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE FUNCTION (<keyspace_name>).<function_name>;</strong></td> + <td>Describe the given user defined function. The keyspace is optional</td> + </tr> + <tr> + <td nowrap><strong>DESCRIBE AGGREGATE (<keyspace_name>).<aggregate_name>;</strong></td> + <td>Describe the given user defined aggregate. The keyspace is optional</td> + </tr> + </table> +</center> + +The schema objects (cluster, keyspace, table, type, function and aggregate) are displayed in a tabular format. +There is a drop-down menu on the top left corner to expand objects details. On the top right menu is shown the Icon legend. + +<br/> +<center> +  +</center> + +<hr/> + +## 9. Runtime Parameters + +Sometimes you want to be able to pass runtime query parameters to your statements. +Those parameters are not part of the CQL specs and are specific to the interpreter. +Below is the list of all parameters: + +<br/> +<center> + <table class="table-configuration"> + <tr> + <th>Parameter</th> + <th>Syntax</th> + <th>Description</th> + </tr> + <tr> + <td nowrap>Consistency Level</td> + <td><strong>@consistency=<em>value</em></strong></td> + <td>Apply the given consistency level to all queries in the paragraph</td> + </tr> + <tr> + <td nowrap>Serial Consistency Level</td> + <td><strong>@serialConsistency=<em>value</em></strong></td> + <td>Apply the given serial consistency level to all queries in the paragraph</td> + </tr> + <tr> + <td nowrap>Timestamp</td> + <td><strong>@timestamp=<em>long value</em></strong></td> + <td> + Apply the given timestamp to all queries in the paragraph. + Please note that timestamp value passed directly in CQL statement will override this value + </td> + </tr> + <tr> + <td nowrap>Retry Policy</td> + <td><strong>@retryPolicy=<em>value</em></strong></td> + <td>Apply the given retry policy to all queries in the paragraph</td> + </tr> + <tr> + <td nowrap>Fetch Size</td> + <td><strong>@fetchSize=<em>integer value</em></strong></td> + <td>Apply the given fetch size to all queries in the paragraph</td> + </tr> + </table> +</center> + + Some parameters only accept restricted values: + +<br/> +<center> + <table class="table-configuration"> + <tr> + <th>Parameter</th> + <th>Possible Values</th> + </tr> + <tr> + <td nowrap>Consistency Level</td> + <td><strong>ALL, ANY, ONE, TWO, THREE, QUORUM, LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM</strong></td> + </tr> + <tr> + <td nowrap>Serial Consistency Level</td> + <td><strong>SERIAL, LOCAL_SERIAL</strong></td> + </tr> + <tr> + <td nowrap>Timestamp</td> + <td>Any long value</td> + </tr> + <tr> + <td nowrap>Retry Policy</td> + <td><strong>DEFAULT, DOWNGRADING_CONSISTENCY, FALLTHROUGH, LOGGING_DEFAULT, LOGGING_DOWNGRADING, LOGGING_FALLTHROUGH</strong></td> + </tr> + <tr> + <td nowrap>Fetch Size</td> + <td>Any integer value</td> + </tr> + </table> +</center> + +>Please note that you should **not** add semi-colon ( **;** ) at the end of each parameter statement + +Some examples: + +```sql + + CREATE TABLE IF NOT EXISTS spark_demo.ts( + key int PRIMARY KEY, + value text + ); + TRUNCATE spark_demo.ts; + + # Timestamp in the past + @timestamp=10 + + # Force timestamp directly in the first insert + INSERT INTO spark_demo.ts(key,value) VALUES(1,'first insert') USING TIMESTAMP 100; + + # Select some data to make the clock turn + SELECT * FROM spark_demo.albums LIMIT 100; + + # Now insert using the timestamp parameter set at the beginning(10) + INSERT INTO spark_demo.ts(key,value) VALUES(1,'second insert'); + + # Check for the result. You should see 'first insert' + SELECT value FROM spark_demo.ts WHERE key=1; +``` + +Some remarks about query parameters: + +> 1. **many** query parameters can be set in the same paragraph +> 2. if the **same** query parameter is set many time with different values, the interpreter only take into account the first value +> 3. each query parameter applies to **all CQL statements** in the same paragraph, unless you override the option using plain CQL text (like forcing timestamp with the USING clause) +> 4. the order of each query parameter with regard to CQL statement does not matter + +<hr/> + +## 10. Support for Prepared Statements + +For performance reason, it is better to prepare statements before-hand and reuse them later by providing bound values. +This interpreter provides 3 commands to handle prepared and bound statements: + +1. **@prepare** +2. **@bind** +3. **@remove_prepared** + +Example: + +``` + + @prepare[statement_name]=... + + @bind[statement_name]=âtextâ, 1223, â2015-07-30 12:00:01â, null, true, [âlist_item1â, âlist_item2â] + + @bind[statement_name_with_no_bound_value] + + @remove_prepare[statement_name] +``` + +<br/> +#### a. @prepare +<br/> +You can use the syntax _"@prepare[statement_name]=SELECT ..."_ to create a prepared statement. +The _statement_name_ is **mandatory** because the interpreter prepares the given statement with the Java driver and +saves the generated prepared statement in an **internal hash map**, using the provided _statement_name_ as search key. + +> Please note that this internal prepared statement map is shared with **all notebooks** and **all paragraphs** because +there is only one instance of the interpreter for Cassandra + +> If the interpreter encounters **many** @prepare for the **same _statement_name_ (key)**, only the **first** statement will be taken into account. + +Example: + +``` + + @prepare[select]=SELECT * FROM spark_demo.albums LIMIT ? + + @prepare[select]=SELECT * FROM spark_demo.artists LIMIT ? +``` + +For the above example, the prepared statement is _SELECT * FROM spark_demo.albums LIMIT ?_. +_SELECT * FROM spark_demo.artists LIMIT ?_ is ignored because an entry already exists in the prepared statements map with the key select. + +In the context of **Zeppelin**, a notebook can be scheduled to be executed at regular interval, +thus it is necessary to **avoid re-preparing many time the same statement (considered an anti-pattern)**. +<br/> +<br/> +#### b. @bind +<br/> +Once the statement is prepared (possibly in a separated notebook/paragraph). You can bind values to it: + +``` + @bind[select_first]=10 +``` + +Bound values are not mandatory for the **@bind** statement. However if you provide bound values, they need to comply to some syntax: + +* String values should be enclosed between simple quotes ( â ) +* Date values should be enclosed between simple quotes ( â ) and respect the formats: + 1. yyyy-MM-dd HH:MM:ss + 2. yyyy-MM-dd HH:MM:ss.SSS +* **null** is parsed as-is +* **boolean** (true|false) are parsed as-is +* collection values must follow the **[standard CQL syntax]**: + * list: [âlist_item1â, âlist_item2â, ...] + * set: {âset_item1â, âset_item2â, â¦} + * map: {âkey1â: âval1â, âkey2â: âval2â, â¦} +* **tuple** values should be enclosed between parenthesis (see **[Tuple CQL syntax]**): (âtextâ, 123, true) +* **udt** values should be enclosed between brackets (see **[UDT CQL syntax]**): {stree_name: âBeverly Hillsâ, number: 104, zip_code: 90020, state: âCaliforniaâ, â¦} + +> It is possible to use the @bind statement inside a batch: +> +> ```sql +> +> BEGIN BATCH +> @bind[insert_user]='jdoe','John DOE' +> UPDATE users SET age = 27 WHERE login='hsue'; +> APPLY BATCH; +> ``` + +<br/> +#### c. @remove_prepare +<br/> +To avoid for a prepared statement to stay forever in the prepared statement map, you can use the +**@remove_prepare[statement_name]** syntax to remove it. +Removing a non-existing prepared statement yields no error. + +<hr/> + +## 11. Using Dynamic Forms + +Instead of hard-coding your CQL queries, it is possible to use the mustache syntax ( **\{\{ \}\}** ) to inject simple value or multiple choices forms. + +The syntax for simple parameter is: **\{\{input_Label=default value\}\}**. The default value is mandatory because the first time the paragraph is executed, +we launch the CQL query before rendering the form so at least one value should be provided. + +The syntax for multiple choices parameter is: **\{\{input_Label=value1 | value2 | ⦠| valueN \}\}**. By default the first choice is used for CQL query +the first time the paragraph is executed. + +Example: + +{% raw %} + #Secondary index on performer style + SELECT name, country, performer + FROM spark_demo.performers + WHERE name='{{performer=Sheryl Crow|Doof|Fanfarlo|Los Paranoia}}' + AND styles CONTAINS '{{style=Rock}}'; +{% endraw %} + + +In the above example, the first CQL query will be executed for _performer='Sheryl Crow' AND style='Rock'_. +For subsequent queries, you can change the value directly using the form. + +> Please note that we enclosed the **\{\{ \}\}** block between simple quotes ( **'** ) because Cassandra expects a String here. +> We could have also use the **\{\{style='Rock'\}\}** syntax but this time, the value displayed on the form is **_'Rock'_** and not **_Rock_**. + +It is also possible to use dynamic forms for **prepared statements**: + +{% raw %} + + @bind[select]=='{{performer=Sheryl Crow|Doof|Fanfarlo|Los Paranoia}}', '{{style=Rock}}' + +{% endraw %} + +<hr/> + +## 12. Execution parallelism and shared states + +It is possible to execute many paragraphs in parallel. However, at the back-end side, weâre still using synchronous queries. +_Asynchronous execution_ is only possible when it is possible to return a `Future` value in the `InterpreterResult`. +It may be an interesting proposal for the **Zeppelin** project. + +Another caveat is that the same `com.datastax.driver.core.Session` object is used for **all** notebooks and paragraphs. +Consequently, if you use the **USE _keyspace name_;** statement to log into a keyspace, it will change the keyspace for +**all current users** of the **Cassandra** interpreter because we only create 1 `com.datastax.driver.core.Session` object +per instance of **Cassandra** interpreter. + +The same remark does apply to the **prepared statement hash map**, it is shared by **all users** using the same instance of **Cassandra** interpreter. + +Until **Zeppelin** offers a real multi-users separation, there is a work-around to segregate user environment and states: +_create different **Cassandra** interpreter instances_ + +For this, first go to the **Interpreter** menu and click on the **Create** button +<br/> +<br/> +<center> +  +</center> + +In the interpreter creation form, put **cass-instance2** as **Name** and select the **cassandra** +in the interpreter drop-down list +<br/> +<br/> +<center> +  +</center> + + Click on **Save** to create the new interpreter instance. Now you should be able to see it in the interpreter list. + +<br/> +<br/> +<center> +  +</center> + +Go back to your notebook and click on the **Gear** icon to configure interpreter bindings. +You should be able to see and select the **cass-instance2** interpreter instance in the available +interpreter list instead of the standard **cassandra** instance. + +<br/> +<br/> +<center> +  +</center> + +<hr/> + +## 13. Interpreter Configuration + +To configure the **Cassandra** interpreter, go to the **Interpreter** menu and scroll down to change the parameters. +The **Cassandra** interpreter is using the official **[Cassandra Java Driver]** and most of the parameters are used +to configure the Java driver + +Below are the configuration parameters and their default value. + + + <table class="table-configuration"> + <tr> + <th>Property Name</th> + <th>Description</th> + <th>Default Value</th> + </tr> + <tr> + <td>cassandra.cluster</td> + <td>Name of the Cassandra cluster to connect to</td> + <td>Test Cluster</td> + </tr> + <tr> + <td>cassandra.compression.protocol</td> + <td>On wire compression. Possible values are: NONE, SNAPPY, LZ4</td> + <td>NONE</td> + </tr> + <tr> + <td>cassandra.credentials.username</td> + <td>If security is enable, provide the login</td> + <td>none</td> + </tr> + <tr> + <td>cassandra.credentials.password</td> + <td>If security is enable, provide the password</td> + <td>none</td> + </tr> + <tr> + <td>cassandra.hosts</td> + <td> + Comma separated Cassandra hosts (DNS name or IP address). + <br/> + Ex: '192.168.0.12,node2,node3' + </td> + <td>localhost</td> + </tr> + <tr> + <td>cassandra.interpreter.parallelism</td> + <td>Number of concurrent paragraphs(queries block) that can be executed</td> + <td>10</td> + </tr> + <tr> + <td>cassandra.keyspace</td> + <td> + Default keyspace to connect to. + <strong> + It is strongly recommended to let the default value + and prefix the table name with the actual keyspace + in all of your queries + </strong> + </td> + <td>system</td> + </tr> + <tr> + <td>cassandra.load.balancing.policy</td> + <td> + Load balancing policy. Default = <em>new TokenAwarePolicy(new DCAwareRoundRobinPolicy())</em> + To Specify your own policy, provide the <strong>fully qualify class name (FQCN)</strong> of your policy. + At runtime the interpreter will instantiate the policy using + <strong>Class.forName(FQCN)</strong> + </td> + <td>DEFAULT</td> + </tr> + <tr> + <td>cassandra.max.schema.agreement.wait.second</td> + <td>Cassandra max schema agreement wait in second</td> + <td>10</td> + </tr> + <tr> + <td>cassandra.pooling.core.connection.per.host.local</td> + <td>Protocol V2 and below default = 2. Protocol V3 and above default = 1</td> + <td>2</td> + </tr> + <tr> + <td>cassandra.pooling.core.connection.per.host.remote</td> + <td>Protocol V2 and below default = 1. Protocol V3 and above default = 1</td> + <td>1</td> + </tr> + <tr> + <td>cassandra.pooling.heartbeat.interval.seconds</td> + <td>Cassandra pool heartbeat interval in secs</td> + <td>30</td> + </tr> + <tr> + <td>cassandra.pooling.idle.timeout.seconds</td> + <td>Cassandra idle time out in seconds</td> + <td>120</td> + </tr> + <tr> + <td>cassandra.pooling.max.connection.per.host.local</td> + <td>Protocol V2 and below default = 8. Protocol V3 and above default = 1</td> + <td>8</td> + </tr> + <tr> + <td>cassandra.pooling.max.connection.per.host.remote</td> + <td>Protocol V2 and below default = 2. Protocol V3 and above default = 1</td> + <td>2</td> + </tr> + <tr> + <td>cassandra.pooling.max.request.per.connection.local</td> + <td>Protocol V2 and below default = 128. Protocol V3 and above default = 1024</td> + <td>128</td> + </tr> + <tr> + <td>cassandra.pooling.max.request.per.connection.remote</td> + <td>Protocol V2 and below default = 128. Protocol V3 and above default = 256</td> + <td>128</td> + </tr> + <tr> + <td>cassandra.pooling.new.connection.threshold.local</td> + <td>Protocol V2 and below default = 100. Protocol V3 and above default = 800</td> + <td>100</td> + </tr> + <tr> + <td>cassandra.pooling.new.connection.threshold.remote</td> + <td>Protocol V2 and below default = 100. Protocol V3 and above default = 200</td> + <td>100</td> + </tr> + <tr> + <td>cassandra.pooling.pool.timeout.millisecs</td> + <td>Cassandra pool time out in millisecs</td> + <td>5000</td> + </tr> + <tr> + <td>cassandra.protocol.version</td> + <td>Cassandra binary protocol version</td> + <td>3</td> + </tr> + <tr> + <td>cassandra.query.default.consistency</td> + <td> + Cassandra query default consistency level + <br/> + Available values: ONE, TWO, THREE, QUORUM, LOCAL_ONE, LOCAL_QUORUM, EACH_QUORUM, ALL + </td> + <td>ONE</td> + </tr> + <tr> + <td>cassandra.query.default.fetchSize</td> + <td>Cassandra query default fetch size</td> + <td>5000</td> + </tr> + <tr> + <td>cassandra.query.default.serial.consistency</td> + <td> + Cassandra query default serial consistency level + <br/> + Available values: SERIAL, LOCAL_SERIAL + </td> + <td>SERIAL</td> + </tr> + <tr> + <td>cassandra.reconnection.policy</td> + <td> + Cassandra Reconnection Policy. + Default = new ExponentialReconnectionPolicy(1000, 10 * 60 * 1000) + To Specify your own policy, provide the <strong>fully qualify class name (FQCN)</strong> of your policy. + At runtime the interpreter will instantiate the policy using + <strong>Class.forName(FQCN)</strong> + </td> + <td>DEFAULT</td> + </tr> + <tr> + <td>cassandra.retry.policy</td> + <td> + Cassandra Retry Policy. + Default = DefaultRetryPolicy.INSTANCE + To Specify your own policy, provide the <strong>fully qualify class name (FQCN)</strong> of your policy. + At runtime the interpreter will instantiate the policy using + <strong>Class.forName(FQCN)</strong> + </td> + <td>DEFAULT</td> + </tr> + <tr> + <td>cassandra.socket.connection.timeout.millisecs</td> + <td>Cassandra socket default connection timeout in millisecs</td> + <td>500</td> + </tr> + <tr> + <td>cassandra.socket.read.timeout.millisecs</td> + <td>Cassandra socket read timeout in millisecs</td> + <td>12000</td> + </tr> + <tr> + <td>cassandra.socket.tcp.no_delay</td> + <td>Cassandra socket TCP no delay</td> + <td>true</td> + </tr> + <tr> + <td>cassandra.speculative.execution.policy</td> + <td> + Cassandra Speculative Execution Policy. + Default = NoSpeculativeExecutionPolicy.INSTANCE + To Specify your own policy, provide the <strong>fully qualify class name (FQCN)</strong> of your policy. + At runtime the interpreter will instantiate the policy using + <strong>Class.forName(FQCN)</strong> + </td> + <td>DEFAULT</td> + </tr> + </table> + +<hr/> + +## 14. Bugs & Contacts + + If you encounter a bug for this interpreter, please create a **[JIRA]** ticket and ping me on Twitter + at **[@doanduyhai]** + + +[Cassandra Java Driver]: https://github.com/datastax/java-driver +[standard CQL syntax]: http://docs.datastax.com/en/cql/3.1/cql/cql_using/use_collections_c.html +[Tuple CQL syntax]: http://docs.datastax.com/en/cql/3.1/cql/cql_reference/tupleType.html +[UDT CQL syntax]: http://docs.datastax.com/en/cql/3.1/cql/cql_using/cqlUseUDT.html +[JIRA]: https://issues.apache.org/jira/browse/ZEPPELIN-382?jql=project%20%3D%20ZEPPELIN +[@doanduyhai]: https://twitter.com/doanduyhai
