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Posted to commits@geode.apache.org by km...@apache.org on 2016/10/14 22:17:27 UTC
[29/94] [abbrv] [partial] incubator-geode git commit: GEODE-1952
Consolidated docs under a single geode-docs directory
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_index/using_indexes_with_equijoin_queries_multiple_regions.html.md.erb
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+---
+title: Using Indexes on Equi-Join Queries using Multiple Regions
+---
+
+To query across multiple regions, identify all equi-join conditions. Then, create as few indexes for the equi-join conditions as you can while still joining all regions.
+
+<a id="concept_DB2407C49F064B04AA58BC9D1DBA3666__section_70735ED43C4D47B0A19B910BB7E3A1DA"></a>
+If there are equi-join conditions that redundantly join two regions (in order to more finely filter the data, for example), then creating redundant indexes for these joins will negatively impact performance. Create indexes only on one equi-join condition for each region pair.
+
+In this example query:
+
+``` pre
+SELECT DISTINCT *
+FROM /investors inv, /securities sc, /orders or,
+inv.ordersPlaced inv_op, or.securities or_sec
+ WHERE inv_op.orderID = or.orderID
+ AND or_sec.secID = sc.secID
+```
+
+All conditions are required to join the regions, so you would create four indexes, two for each equi-join condition:
+
+| FROM clause | Indexed expression |
+|------------------------------------------|--------------------|
+| /investors inv, inv.ordersPlaced inv\_op | inv\_op.orderID |
+| /orders or, or.securities or\_sec | or.orderID |
+
+| FROM clause | Indexed expression |
+|-----------------------------------|--------------------|
+| /orders or, or.securities or\_sec | or\_sec.secID |
+| /securities sc | sc.secID |
+
+Adding another condition to the example:
+
+``` pre
+SELECT DISTINCT *
+FROM /investors inv, /securities sc, /orders or,
+inv.ordersPlaced inv_op, or.securities or_sec, sc.investors sc_invs
+ WHERE inv_op.orderID = or.orderID
+ AND or_sec.secID = sc.secID
+ AND inv.investorID = sc_invs.investorID
+```
+
+You would still only want to use four indexes in all, as that's all you need to join all of the regions. You would need to choose the most performant two of the following three index pairs:
+
+| FROM clause | Indexed expression |
+|------------------------------------------|--------------------|
+| /investors inv, inv.ordersPlaced inv\_op | inv\_op.orderID |
+| /orders or, or.securities or\_sec | or.orderID |
+
+| FROM clause | Indexed expression |
+|---------------------------------------|--------------------|
+| /orders or, or.securities or\_sec | or\_sec.secID |
+| /securities sc, sc.investors sc\_invs | sc.secID |
+
+| FROM clause | Indexed expression |
+|------------------------------------------|---------------------|
+| /investors inv, inv.ordersPlaced inv\_op | inv.investorID |
+| /securities sc, sc.investors sc\_invs | sc\_invs.investorID |
+
+The most performant set is that which narrows the data to the smallest result set possible. Examine your data and experiment with the three index pairs to see which provides the best performance.
+
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_select/aggregates.html.md.erb
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+---
+title: OQL Aggregate Functions
+---
+
+The aggregate functions
+```MIN```,
+```MAX```,
+```AVG```,
+```AVG``` over a DISTINCT expression,
+```SUM``` over a DISTINCT expression,
+```COUNT```, and
+```COUNT``` over a DISTINCT expression
+are supported.
+The ```GROUP BY``` extension is also supported where appropriate.
+
+The ```MIN``` function returns the smallest of the selected
+expression.
+The type of the expression must evaluate to a
+```java.lang.Comparable```.
+
+The ```MAX``` function returns the largest of the selected
+expression.
+The type of the expression must evaluate to a
+```java.lang.Comparable```.
+
+The ```AVG``` function returns the arithmetic mean of the set
+formed by the selected expression.
+The type of the expression must evaluate to a
+```java.lang.Number```.
+For partitioned regions,
+each node's buckets provide both a sum and the number of elements
+to the node executing the query,
+such that a correct average may be computed.
+
+The ```AVG``` function where the DISTINCT modifier is applied
+to the expression returns the arithmetic mean of the set
+of unique (distinct) values.
+The type of the expression must evaluate to a
+```java.lang.Number```.
+For partitioned regions,
+the distinct values in a node's buckets are returned
+to the node executing the query.
+The query node can then calculate the avarage over
+the values that are unique across nodes,
+after eliminating duplicate values that come from separate nodes.
+
+The ```SUM``` function returns the sum over the set
+formed by the selected expression.
+The type of the expression must evaluate to a
+```java.lang.Number```.
+For partitioned regions,
+each node's buckets compute a sum over that node,
+returning that sum
+to the node executing the query,
+when then sums across all nodes.
+
+The ```SUM``` function where the DISTINCT modifier is applied
+to the expression returns the sum over the set
+of unique (distinct) values.
+The type of the expression must evaluate to a
+```java.lang.Number```.
+For partitioned regions,
+the distinct values in a node's buckets are returned
+to the node executing the query.
+The query node can then calculate the sum over
+the values that are unique across nodes,
+after eliminating duplicate values that come from separate nodes.
+
+The ```COUNT``` function returns the quantity of values in the set
+formed by the selected expression.
+For example, to return the quantity of employees who have a
+positive sales amount:
+
+``` pre
+SELECT count(e.sales) FROM /employees e WHERE e.sales > 0.0
+```
+
+The ```COUNT``` function where the DISTINCT modifier is applied
+returns the quantity of unique (distinct) values in the set
+formed by the selected expression.
+
+## GROUP BY Extension for Aggregate Functions
+
+```GROUP BY``` is required
+when aggregate functions are used in combination
+with other selected items.
+It permits ordering.
+For example,
+
+``` pre
+SELECT ID, MAX(e.sales) FROM /employees e GROUP BY ID
+```
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_select/the_from_clause.html.md.erb
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+---
+title: FROM Clause
+---
+
+<a id="the_from_clause__section_FAEBC02C4E414F91B1CA8D33E11218AF"></a>
+Use the FROM clause to bring the data you need into scope for the rest of your query. The FROM clause also includes object typing and iterator variables.
+
+The query engine resolves names and path expressions according to the name space that is currently in scope in the query.
+
+## <a id="the_from_clause__section_CF6063A6C5134EFC89C43D106B6A6D4D" class="no-quick-link"></a>Path Expressions
+
+The initial name space for any query is composed of:
+
+- **Regions.** In the context of a query, the name of a region is specified by its full path starting with a forward slash ( / ) and delimited by the forward slash between region names. For example, **/exampleRegion** or **/root/exampleRegion**.
+- **Region querying attributes**. From a region path, you can access the Region object's public fields and methods, referred to in querying as the region's attributes. For example, **/exampleRegion.size**.
+- **Top-level region data.** You can access entry keys and entry data through the region path.
+ 1. `/exampleRegion.keySet` returns the Set of entry keys in the region
+ 2. `/exampleRegion.entryset` returns the Set of Region.Entry objects
+ 3. `/exampleRegion.values` returns the Collection of entry values
+ 4. `/exampleRegion` returns the Collection of entry values
+
+New name spaces are brought into scope based on the FROM clause in the SELECT statement.
+
+**Examples:**
+
+Query a region for all distinct values. Return a collection of unique entry values from the region:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion
+```
+
+Query the top level region data using entrySet. Return the keys and positions of Region.Entry objects whose mktValue attribute is greater than 25.00:
+
+``` pre
+SELECT key, positions FROM /exampleRegion.entrySet, value.positions.values positions WHERE positions.mktValue >= 25.00
+```
+
+Query the region for its entry values. Return a set of unique values from Region.Entry objects that have the key equal to 1:
+
+``` pre
+SELECT DISTINCT entry.value FROM /exampleRegion.entries entry WHERE entry.key = '1'
+```
+
+Query the region for its entry values. Return the set of all entry values in which the `ID` field is greater than 1000:
+
+``` pre
+SELECT * FROM /exampleRegion.entries entry WHERE entry.value.ID > 1000
+```
+
+Query entry keys in the region. Return a set of entry keys in the region that have the key equal to '1':
+
+``` pre
+SELECT * FROM /exampleRegion.keySet key WHERE key = '1'
+```
+
+Query values in the region. Return a collection of entry values in the region that have the status attribute value of 'active':
+
+``` pre
+SELECT * FROM /exampleRegion.values portfolio WHERE portfolio.status = 'active'
+```
+
+## <a id="the_from_clause__section_AB1734C16DC348479C00FD6829B933AA" class="no-quick-link"></a>Aliases and Synonyms
+
+In query strings, you can use aliases in path expressions (region and its objects) so that you can refer to the region or objects in other places in the query.
+
+You can also use the **AS** keyword to provide a label for joined path expressions.
+
+**Examples:**
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.status = 'active'
+```
+
+``` pre
+SELECT * FROM /exampleRegion p, p.positions.values AS pos WHERE pos.secId != '1'
+```
+
+## <a id="the_from_clause__section_A5B42CCB7C924949954AEC2DAAD51134" class="no-quick-link"></a>Object Typing
+
+Specifying object type in the FROM clause helps the query engine to process the query at optimal speed. Apart from specifying the object types during configuration (using key-constraint and value-constraint), type can be explicitly specified in the query string.
+
+**Example:**
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion, positions.values positions TYPE Position WHERE positions.mktValue >= 25.00
+```
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_select/the_import_statement.html.md.erb
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+---
+title: IMPORT Statement
+---
+
+It is sometimes necessary for an OQL query to refer to the class of an object. In cases where the same class name resides in two different namescopes (packages), you must be able to differentiate the classes having the same name.
+
+The **IMPORT** statement is used to establish a name for a class in a query.
+
+``` pre
+IMPORT package.Position;
+SELECT DISTINCT * FROM /exampleRegion, positions.values positions TYPE Position WHERE positions.mktValue >= 25.00
+```
+
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_select/the_select_statement.html.md.erb
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+---
+title: SELECT Statement
+---
+
+The SELECT statement allows you to filter data from the collection of object(s) returned by a WHERE search operation. The projection list is either specified as \* or as a comma delimited list of expressions.
+
+For \*, the interim results of the WHERE clause are returned from the query.
+
+**Examples:**
+
+Query all objects from the region using \*. Returns the Collection of portfolios (The exampleRegion contains Portfolio as values).
+
+``` pre
+SELECT * FROM /exampleRegion
+```
+
+Query secIds from positions. Returns the Collection of secIds from the positions of active portfolios:
+
+``` pre
+SELECT secId FROM /exampleRegion, positions.values TYPE Position
+WHERE status = 'active'
+```
+
+Returns a Collection of struct<type: String, positions: map> for the active portfolios. The second field of the struct is a Map ( jav.utils.Map ) object, which contains the positions map as the value:
+
+``` pre
+SELECT "type", positions FROM /exampleRegion
+WHERE status = 'active'
+```
+
+Returns a Collection of struct<portfolios: Portfolio, values: Position> for the active portfolios:
+
+``` pre
+SELECT * FROM /exampleRegion, positions.values
+TYPE Position WHERE status = 'active'
+```
+
+Returns a Collection of struct<pflo: Portfolio, posn: Position> for the active portfolios:
+
+``` pre
+SELECT * FROM /exampleRegion portfolio, positions positions
+TYPE Position WHERE portfolio.status = 'active'
+```
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_1B7762EC686A4808B1D12E8851954E82" class="no-quick-link"></a>SELECT Statement Results
+
+The result of a SELECT statement is either UNDEFINED or is a Collection that implements the [SelectResults](/releases/latest/javadoc/org/apache/geode/cache/query/SelectResults.html) interface.
+
+The SelectResults returned from the SELECT statement is either:
+
+1. A collection of objects, returned for these two cases:
+ - When only one expression is specified by the projection list and that expression is not explicitly specified using the fieldname:expression syntax
+ - When the SELECT list is \* and a single collection is specified in the FROM clause
+
+2. A collection of Structs that contains the objects
+
+When a struct is returned, the name of each field in the struct is determined following this order of preference:
+
+1. If a field is specified explicitly using the fieldname:expression syntax, the fieldname is used.
+2. If the SELECT projection list is \* and an explicit iterator expression is used in the FROM clause, the iterator variable name is used as the field name.
+3. If the field is associated with a region or attribute path, the last attribute name in the path is used.
+4. If names cannot be decided based on these rules, arbitrary unique names are generated by the query processor.
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_972EE73A6F3E4427B6A99DB4EDF5860D" class="no-quick-link"></a>DISTINCT
+
+Use the DISTINCT keyword if you want to limit the results set to unique rows. Note that in the current version of Geode you are no longer required to use the DISTINCT keyword in your SELECT statement.
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion
+```
+
+**Note:**
+If you are using DISTINCT queries, you must implement the equals and hashCode methods for the objects that you query.
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_25D7055B33EC47B19B1B70264B39212F" class="no-quick-link"></a>LIMIT
+
+You can use the LIMIT keyword at the end of the query string to limit the number of values returned.
+
+For example, this query returns at most 10 values:
+
+``` pre
+SELECT * FROM /exampleRegion LIMIT 10
+```
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_D9DF0F785CA94EF8B367C3326CC12990" class="no-quick-link"></a>ORDER BY
+
+You can order your query results in ascending or descending order by using the ORDER BY clause. You must use DISTINCT when you write ORDER BY queries.
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion WHERE ID < 101 ORDER BY ID
+```
+
+The following query sorts the results in ascending order:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion WHERE ID < 101 ORDER BY ID asc
+```
+
+The following query sorts the results in descending order:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion WHERE ID < 101 ORDER BY ID desc
+```
+
+**Note:**
+If you are using ORDER BY queries, you must implement the equals and hashCode methods for the objects that you query.
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_69DCAD624E9640028BC86FD67649DEB2" class="no-quick-link"></a>Preset Query Functions
+
+Geode provides several built-in functions for evaluating or filtering data returned from a query. They include the following:
+
+<table>
+<colgroup>
+<col width="33%" />
+<col width="33%" />
+<col width="33%" />
+</colgroup>
+<thead>
+<tr class="header">
+<th>Function</th>
+<th>Description</th>
+<th>Example</th>
+</tr>
+</thead>
+<tbody>
+<tr class="odd">
+<td>ELEMENT(expr)</td>
+<td>Extracts a single element from a collection or array. This function throws a <code class="ph codeph">FunctionDomainException</code> if the argument is not a collection or array with exactly one element.</td>
+<td><pre class="pre codeblock"><code>ELEMENT(SELECT DISTINCT *
+ FROM /exampleRegion
+ WHERE id = 'XYZ-1').status = 'active'</code></pre></td>
+</tr>
+<tr class="even">
+<td>IS_DEFINED(expr)</td>
+<td>Returns TRUE if the expression does not evaluate to UNDEFINED.</td>
+<td><pre class="pre codeblock"><code>IS_DEFINED(SELECT DISTINCT *
+FROM /exampleRegion p
+WHERE p.status = 'active')</code></pre></td>
+</tr>
+<tr class="odd">
+<td>IS_UNDEFINED (expr)</td>
+<td>Returns TRUE if the expression evaluates to UNDEFINED. In most queries, undefined values are not included in the query results. The IS_UNDEFINED function allows undefined values to be included, so you can identify element with undefined values.</td>
+<td><pre class="pre codeblock"><code>SELECT DISTINCT *
+FROM /exampleRegion p
+WHERE IS_UNDEFINED(p.status)</code></pre></td>
+</tr>
+<tr class="even">
+<td>NVL(expr1, expr2)</td>
+<td>Returns expr2 if expr1 is null. The expressions can be query parameters (bind arguments), path expressions, or literals.</td>
+<td>�</td>
+</tr>
+<tr class="odd">
+<td>TO_DATE(date_str, format_str)</td>
+<td>Returns a Java Data class object. The arguments must be String S with date_str representing the date and format_str representing the format used by date_str. The format_str you provide is parsed using java.text.SimpleDateFormat.</td>
+<td>�</td>
+</tr>
+</tbody>
+</table>
+
+## <a id="concept_85AE7D6B1E2941ED8BD2A8310A81753E__section_B2CBA00EB83F463DAF4769D7859C64C8" class="no-quick-link"></a>COUNT
+
+The COUNT keyword returns the number of results that match the query selection conditions specified in the WHERE clause. Using COUNT allows you to determine the size of a results set. The COUNT statement always returns an integer as its result.
+
+The following queries are example COUNT queries that return region entries:
+
+``` pre
+SELECT COUNT(*) FROM /exampleRegion
+```
+
+``` pre
+SELECT COUNT(*) FROM /exampleRegion WHERE ID > 0
+```
+
+``` pre
+SELECT COUNT(*) FROM /exampleRegion WHERE ID > 0 LIMIT 50
+```
+
+``` pre
+SELECT COUNT(*) FROM /exampleRegion
+WHERE ID >0 AND status LIKE 'act%'
+```
+
+``` pre
+SELECT COUNT(*) FROM /exampleRegion
+WHERE ID IN SET(1,2,3,4,5)
+```
+
+The following COUNT query returns the total number of StructTypes that match the query's selection criteria.
+
+``` pre
+SELECT COUNT(*)
+FROM /exampleRegion p, p.positions.values pos
+WHERE p.ID > 0 AND pos.secId 'IBM'
+```
+
+The following COUNT query uses the DISTINCT keyword and eliminates duplicates from the number of results.
+
+``` pre
+SELECT DISTINCT COUNT(*)
+FROM /exampleRegion p, p.positions.values pos
+WHERE p.ID > 0 OR p.status = 'active' OR pos.secId
+OR pos.secId = 'IBM'
+```
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/query_select/the_where_clause.html.md.erb
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+---
+title: WHERE Clause
+---
+
+<a id="the_where_clause__section_56BB3A7F44124CA9BFBC20E19399C6E4"></a>
+Each FROM clause expression must resolve to a collection of objects. The collection is then available for iteration in the query expressions that follow in the WHERE clause.
+
+For example:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.status = 'active'
+```
+
+The entry value collection is iterated by the WHERE clause, comparing the status field to the string 'active'. When a match is found, the value object of the entry is added to the return set.
+
+In the next example query, the collection specified in the first FROM clause expression is used by the rest of the SELECT statement, including the second FROM clause expression.
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion, positions.values p WHERE p.qty > 1000.00
+```
+
+## <a id="the_where_clause__section_99CA3FA508B740DCBAB4F01F8F9B1390" class="no-quick-link"></a>Implementing equals and hashCode Methods
+
+You must implement the `equals` and `hashCode` methods in your custom objects if you are doing ORDER BY and DISTINCT queries on the objects. The methods must conform to the properties and behavior documented in the online Java API documentation for `java.lang.Object`. Inconsistent query results may occur if these methods are absent.
+
+If you have implemented `equals` and `hashCode` methods in your custom objects, you must provide detailed implementations of these methods so that queries execute properly against the objects. For example, assume that you have defined a custom object (CustomObject) with the following variables:
+
+``` pre
+int ID
+int otherValue
+```
+
+Let's put two CustomObjects (we'll call them CustomObjectA and CustomObjectB) into the cache:
+
+CustomObjectA:
+
+``` pre
+ID=1
+otherValue=1
+```
+
+CustomObjectB:
+
+``` pre
+ID=1
+otherValue=2
+```
+
+If you have implemented the equals method to simply match on the ID field (ID == ID), queries will produce unpredictable results.
+
+The following query:
+
+``` pre
+SELECT * FROM /CustomObjects c
+WHERE c.ID > 1 AND c.ID < 3
+AND c.otherValue > 0 AND c.otherValue < 3
+```
+
+returns two objects, however the objects will be two of either CustomObjectA or CustomObjectB.
+
+Alternately, the following query:
+
+``` pre
+SELECT * FROM /CustomObjects c
+WHERE c.ID > 1 AND c.ID < 3
+AND c.otherValue > 1 AND c.otherValue < 3
+```
+
+returns either 0 results or 2 results of CustomObjectB, depending on which entry is evaluated last.
+
+To avoid unpredictable querying behavior, implement detailed versions of the `equals` and `hashCode` methods.
+
+If you are comparing a non-primitive field of the object in the WHERE clause, use the `equals` method instead of the `=` operator. For example instead of `nonPrimitiveObj = objToBeCompared` use `nonPrimitiveObj.equals(objToBeCompared)`.
+
+## <a id="the_where_clause__section_7484AD999D01473385628246697F37F6" class="no-quick-link"></a>Querying Serialized Objects
+
+Objects must implement serializable if you will be querying partitioned regions or if you are performing client-server querying.
+
+If you are using PDX serialization, you can access the values of individual fields without having to deserialize the entire object. This is accomplished by using PdxInstance, which is a wrapper around the serialized stream. The PdxInstance provides a helper method that takes field-name and returns the value without deserializing the object. While evaluating the query, the query engine will access field values by calling the getField method thus avoiding deserialization.
+
+To use PdxInstances in querying, ensure that PDX serialization reads are enabled in your server's cache. In gfsh, execute the following command before starting up your data members:
+
+``` pre
+gfsh>configure pdx --read-serialized=true
+```
+
+See [configure pdx](../../tools_modules/gfsh/command-pages/configure.html#topic_jdkdiqbgphqh) for more information.
+
+In cache.xml, set the following:
+
+``` pre
+// Cache configuration setting PDX read behavior
+<cache>
+ <pdx read-serialized="true">
+ ...
+ </pdx>
+</cache>
+```
+
+## <a id="the_where_clause__section_75A114F9FEBF40A586621CAA1780DBD3" class="no-quick-link"></a>Attribute Visibility
+
+You can access any object or object attribute that is available in the current scope of a query. In querying, an object's attribute is any identifier that can be mapped to a public field or method in the object. In the FROM specification, any object that is in scope is valid. Therefore, at the beginning of a query, all locally cached regions and their attributes are in scope.
+
+For attribute Position.secId which is public and has getter method "getSecId()", the query can be written as the following:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.position1.secId = '1'
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.position1.SecId = '1'
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.position1.getSecId() = '1'
+```
+
+The query engine tries to evaluate the value using the public field value. If a public field value is not found, it makes a get call using field name (note that the first character is uppercase.)
+
+## <a id="the_where_clause__section_EB7B976238104C0EACD959C52E5BD75B" class="no-quick-link"></a>Joins
+
+If collections in the FROM clause are not related to each other, the WHERE clause can be used to join them.
+
+The statement below returns all portfolios from the /exampleRegion and /exampleRegion2 regions that have the same status.
+
+``` pre
+SELECT * FROM /exampleRegion portfolio1, /exampleRegion2 portfolio2 WHERE portfolio1.status = portfolio2.status
+```
+
+To create indexes for region joins you create single-region indexes for both sides of the join condition. These are used during query execution for the join condition. Partitioned regions do not support region joins. For more information on indexes, see [Working with Indexes](../query_index/query_index.html).
+
+**Examples:**
+
+Query two regions. Return the ID and status for portfolios that have the same status.
+
+``` pre
+SELECT portfolio1.ID, portfolio2.status FROM /exampleRegion portfolio1, /exampleRegion2 portfolio2 WHERE portfolio1.status = portfolio2.status
+```
+
+Query two regions, iterating over all `positions` within each portfolio. Return all 4-tuples consisting of the value from each of the two regions and the value portion of the `positions` map from both regions in which the `secId` field of positions match.
+
+``` pre
+SELECT * FROM /exampleRegion portfolio1, portfolio1.positions.values positions1, /exampleRegion2 portfolio2, portfolio2.positions.values positions2 WHERE positions1.secId = positions2.secId
+```
+
+Same query as the previous example, with the additional constraint that matches will have a `ID` of 1.
+
+``` pre
+SELECT * FROM /exampleRegion portfolio1, portfolio1.positions.values positions1, /exampleRegion2 portfolio2, portfolio2.positions.values positions2 WHERE portfolio1.ID = 1 AND positions1.secId = positions2.secId
+```
+
+## <a id="the_where_clause__section_D91E0B06FFF6431490CC0BFA369425AD" class="no-quick-link"></a>LIKE
+
+Geode offers limited support for the LIKE predicate. LIKE can be used to mean 'equals to'. If you terminate the string with a wildcard ('%'), it behaves like 'starts with'. You can also place a wildcard (either '%' or '\_') at any other position in the comparison string. You can escape the wildcard characters to represent the characters themselves.
+
+**Note:**
+The '\*' wildcard is not supported in OQL LIKE predicates.
+
+You can also use the LIKE predicate when an index is present.
+
+**Examples:**
+
+Query the region. Return all objects where status equals 'active':
+
+``` pre
+SELECT * FROM /exampleRegion p WHERE p.status LIKE 'active'
+```
+
+Query the region using a wild card for comparison. Returns all objects where status begins with 'activ':
+
+``` pre
+SELECT * FROM /exampleRegion p WHERE p.status LIKE 'activ%'
+```
+
+## Case Insensitive Fields
+
+You can use the Java String class methods `toUpperCase` and `toLowerCase` to transform fields where you want to perform a case-insensitive search. For example:
+
+``` pre
+SELECT entry.value FROM /exampleRegion.entries entry WHERE entry.value.toUpperCase LIKE '%BAR%'
+```
+
+or
+
+``` pre
+SELECT * FROM /exampleRegion WHERE foo.toLowerCase LIKE '%bar%'
+```
+
+## <a id="the_where_clause__section_D2F8D17B52B04895B672E2FCD675A676" class="no-quick-link"></a>Method Invocations
+
+To use a method in a query, use the attribute name that maps to the public method you want to invoke.
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.positions.size >= 2 - maps to positions.size()
+```
+
+Methods declared to return void evaluate to null when invoked through the query processor.
+
+You cannot invoke a static method. See [Enum Objects](the_where_clause.html#the_where_clause__section_59E7D64746AE495D942F2F09EF7DB9B5) for more information.
+
+**Methods without parameters**
+
+If the attribute name maps to a public method that takes no parameters, just include the method name in the query string as an attribute. For example, emps.isEmpty is equivalent to emps.isEmpty().
+
+In the following example, the query invokes isEmpty on positions, and returns the set of all portfolios with no positions:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.positions.isEmpty
+```
+
+**Methods with parameters**
+
+To invoke methods with parameters, include the method name in the query string as an attribute and provide method arguments between parentheses.
+
+This example passes the argument "Bo" to the public method, and returns all names that begin with "Bo".
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion p WHERE p.name.startsWith('Bo')
+```
+
+For overloaded methods, the query processor decides which method to call by matching the runtime argument types with the parameter types required by the method. If only one method's signature matches the parameters provided, it is invoked. The query processor uses runtime types to match method signatures.
+
+If more than one method can be invoked, the query processor chooses the method whose parameter types are the most specific for the given arguments. For example, if an overloaded method includes versions with the same number of arguments, but one takes a Person type as an argument and the other takes an Employee type, derived from Person, Employee is the more specific object type. If the argument passed to the method is compatible with both types, the query processor uses the method with the Employee parameter type.
+
+The query processor uses the runtime types of the parameters and the receiver to determine the proper method to invoke. Because runtime types are used, an argument with a null value has no typing information, and so can be matched with any object type parameter. When a null argument is used, if the query processor cannot determine the proper method to invoke based on the non-null arguments, it throws an `AmbiguousNameException`.
+
+## <a id="the_where_clause__section_59E7D64746AE495D942F2F09EF7DB9B5" class="no-quick-link"></a>Enum Objects
+
+To write a query based on the value of an Enum object field, you must use the `toString` method of the enum object or use a query bind parameter.
+
+For example, the following query is NOT valid:
+
+``` pre
+//INVALID QUERY
+select distinct * from /QueryRegion0 where aDay = Day.Wednesday
+```
+
+The reason it is invalid is that the call to `Day.Wednesday` involves a static class and method invocation which is not supported.
+
+Enum types can be queried by using toString method of the enum object or by using bind parameter. When you query using the toString method, you must already know the constraint value that you wish to query. In the following first example, the known value is 'active'.
+
+**Examples:**
+
+Query enum type using the toString method:
+
+``` pre
+// eStatus is an enum with values 'active' and 'inactive'
+select * from /exampleRegion p where p.eStatus.toString() = 'active'
+```
+
+Query enum type using a bind parameter. The value of the desired Enum field ( Day.Wednesday) is passed as an execution parameter:
+
+``` pre
+select distinct * from /QueryRegion0 where aDay = $1
+```
+
+## <a id="the_where_clause__section_AC12146509F141378E493078540950C7" class="no-quick-link"></a>IN and SET
+
+The IN expression is a boolean indicating if one expression is present inside a collection of expressions of compatible type. The determination is based on the expressions' equals semantics.
+
+If `e1` and `e2` are expressions, `e2` is a collection, and `e1` is an object or a literal whose type is a subtype or the same type as the elements of `e2`, then `e1 IN e2` is an expression of type boolean.
+
+The expression returns:
+
+- TRUE if e1 is not UNDEFINED and is contained in collection e2
+- FALSE if e1 is not UNDEFINED and is not contained in collection e2 \#
+- UNDEFINED if e1 is UNDEFINED
+
+For example, `2 IN SET(1, 2, 3)` is TRUE.
+
+Another example is when the collection you are querying into is defined by a subquery. This query looks for companies that have an active portfolio on file:
+
+``` pre
+SELECT name, address FROM /company
+ WHERE id IN (SELECT id FROM /portfolios WHERE status = 'active')
+```
+
+The interior SELECT statement returns a collection of ids for all /portfolios entries whose status is active. The exterior SELECT iterates over /company, comparing each entry\u2019s id with this collection. For each entry, if the IN expression returns TRUE, the associated name and address are added to the outer SELECT\u2019s collection.
+
+**Comparing Set Values**
+
+The following is an example of a set value type comparison where sp is of type Set:
+
+``` pre
+SELECT * FROM /exampleRegion WHERE sp = set('20','21','22')
+```
+
+In this case, if sp only contains '20' and '21', then the query will evalute to false. The query compares the two sets and looks for the presence of all elements in both sets.
+
+For other collections types like list, the query can be written as follows:
+
+``` pre
+SELECT * FROM /exampleRegion WHERE sp.containsAll(set('20','21','22))
+```
+
+where sp is of type List.
+
+In order to use it for Set value, the query can be written as:
+
+``` pre
+SELECT * FROM /exampleRegion WHERE sp IN SET (set('20','21','22'),set('10',11','12'))
+```
+
+where a set value is searched in collection of set values.
+
+One problem is that you cannot create indexes on Set or List types (collection types) that are not comparable. To workaround this, you can create an index on a custom collection type that implements Comparable.
+
+## <a id="the_where_clause__section_E7206D045BEC4F67A8D2B793922BF213" class="no-quick-link"></a>Double.NaN and Float.NaN Comparisons
+
+The comparison behavior of Double.NaN and Float.NaN within Geode queries follow the semantics of the JDK methods Float.compareTo and Double.compareTo.
+
+In summary, the comparisons differ in the following ways from those performed by the Java language numerical comparison operators (<, <=, ==, >= >) when applied to primitive double [float] values:
+
+- Double.NaN \[Float.NaN\] is considered to be equal to itself and greater than all other double \[float\] values (including Double.POSITIVE\_INFINITY \[Float.POSITIVE\_INFINITY\]).
+- 0.0d \[0.0f\] is considered by this method to be greater than -0.0d \[-0.0f\].
+
+Therefore, Double.NaN\[Float.NaN\] is considered to be larger than Double.POSITIVE\_INFINITY\[Float.POSITIVE\_INFINITY\]. Here are some example queries and what to expect.
+
+| If p.value is NaN, the following query: | Evaluates to: | Appears in the result set? |
+|------------------------------------------------------------------------------------------------|-------------------|--------------------------------|
+| `SELECT * FROM /positions p WHERE p.value = 0` | false | no |
+| `SELECT * FROM /positions p WHERE p.value > 0` | true | yes |
+| `SELECT * FROM /positions p WHERE p.value >= 0` | true | yes |
+| `SELECT * FROM /positions p WHERE p.value < 0` | false | no |
+| `SELECT * FROM /positions p WHERE p.value <= 0` | false | no |
+| **When p.value and p.value1 are both NaN, the following query:** | **Evaluates to:** | **Appears in the result set:** |
+| `SELECT * FROM /positions p WHERE p.value = p.value1 ` | true | yes |
+
+If you combine values when defining the following query in your code, when the query is executed the value itself is considered UNDEFINED when parsed and will not be returned in the result set.
+
+``` pre
+String query = "SELECT * FROM /positions p WHERE p.value =" + Float.NaN
+```
+
+Executing this query, the value itself is considered UNDEFINED when parsed and will not be returned in the result set.
+
+To retrieve NaN values without having another field already stored as NaN, you can define the following query in your code:
+
+``` pre
+String query = "SELECT * FROM /positions p WHERE p.value > " + Float.MAX_VALUE;
+
+```
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/querying_basics/chapter_overview.html.md.erb
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+---
+title: Querying
+---
+
+Geode provides a SQL-like querying language called OQL that allows you to access data stored in Geode regions.
+
+Since Geode regions are key-value stores where values can range from simple byte arrays to complex nested objects, Geode uses a query syntax based on OQL (Object Query Language) to query region data. OQL is very similar to SQL, but OQL allows you to query complex objects, object attributes, and methods.
+
+- **[Geode Querying FAQ and Examples](../../getting_started/querying_quick_reference.html)**
+
+ This topic answers some frequently asked questions on querying functionality. It provides examples to help you get started with Geode querying.
+
+- **[Basic Querying](../../developing/querying_basics/query_basics.html)**
+
+ This section provides a high-level introduction to Geode querying such as building a query string and describes query language features.
+
+- **[Advanced Querying](../../developing/query_additional/advanced_querying.html)**
+
+ This section includes advanced querying topics such as using query indexes, using query bind parameters, querying partitioned regions and query debugging.
+
+
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+---
+title: Comments in Query Strings
+---
+
+Comment lines being with `--` (double dash). Comment blocks begin with `/*` and end with `*/`. For example:
+
+``` pre
+SELECT * --my comment
+FROM /exampleRegion /* here is
+a comment */ WHERE status = \u2018active\u2019
+```
+
+
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+---
+title: Monitoring Queries for Low Memory
+---
+
+<a id="topic_685CED6DE7D0449DB8816E8ABC1A6E6F"></a>
+
+
+The query monitoring feature prevents out-of-memory exceptions from occurring when you execute queries or create indexes.
+
+This feature is automatically enabled when you set a `critical-heap-percentage` attribute for the resource-manager element in cache.xml or by using the `cache.getResourceManager().setCriticalHelpPercentage(float heapPercentage)` API. Use this feature to cancel out queries that are taking too long and to warn the user that there are low memory conditions when they are running queries or creating indexes.
+
+You can override this feature by setting the system property `gemfire.cache.DISABLE_QUERY_MONITOR_FOR_LOW_MEMORY` to true.
+
+When the query memory monitoring feature is on, the default query time out is set to five hours. You can override this value by setting a larger or smaller, non -1 value to the existing query time out system variable `gemfire.cache.MAX_QUERY_EXECUTION_TIME`.
+
+When system memory is low (as determined by the critical heap percentage threshold that you defined in cache.xml or in the getResourceManager API ), queries will throw a `QueryExecutionLowMemoryException`. Any indexes that are in the process of being created will throw an `InvalidIndexException` with the message indicating the reason.
+
+## <a id="topic_685CED6DE7D0449DB8816E8ABC1A6E6F__section_2E9DEEC9D9C94D038543DDE03BC60B20" class="no-quick-link"></a>Partitioned Region Queries and Low Memory
+
+Partitioned region queries are likely causes for out-of-memory exceptions. If query monitoring is enabled, partitioned region queries drop or ignore results that are being gathered by other servers if the executing server is low in memory.
+
+Query-monitoring does not address a scenario in which a low-level collection is expanded while the partitioned region query is gathering results. For example, if a row is added and then causes a Java level collection or array to expand, it is possible to then encounter an out-of-memory exception. This scenario is rare and is only possible if the collection size itself expands before a low memory condition is met and then expands beyond the remaining available memory. As a workaround, in the event that you encounter this situation, you may be able to tune the system by additionally lowering the `critical-heap-percentage`.
+
+
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+---
+title: Advantages of OQL
+---
+
+The following list describes some of the advantages of using an OQL-based querying language:
+
+- You can query on any arbitrary object
+- You can navigate object collections
+- You can invoke methods and access the behavior of objects
+- Data mapping is supported
+- You are not required to declare types. Since you do not need type definitions, you can work across multiple languages
+- You are not constrained by a schema
+
+
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+---
+title: Performance Considerations
+---
+
+This topic covers considerations for improving query performance.
+
+<a id="performance_considerations__section_2DA52BD8C72A4D01982CA8A44954ADAF"></a>
+Some general performance tips:
+
+- Improve query performance whenever possible by creating indexes. See [Tips and Guidelines on Using Indexes](../query_index/indexing_guidelines.html#indexing_guidelines) for some scenarios for using indexes.
+- Use bind parameters for frequently used queries. When you use a bind parameter, the query is compiled once. This improves the subsequent performance of the query when it is re-run. See [Using Query Bind Parameters](../query_additional/using_query_bind_parameters.html#concept_173E775FE46B47DF9D7D1E40680D34DF) for more details.
+- When querying partitioned regions, execute the query using the FunctionService. This function allows you to target a particular node, which will improve performance greatly by avoiding query distribution. See [Querying a Partitioned Region on a Single Node](../query_additional/query_on_a_single_node.html#concept_30B18A6507534993BD55C2C9E0544A97) for more information.
+- Use key indexes when querying data that has been partitioned by a key or field value. See [Optimizing Queries on Data Partitioned by a Key or Field Value](../query_additional/partitioned_region_key_or_field_value.html#concept_3010014DFBC9479783B2B45982014454).
+- The size of a query result set depends on the restrictiveness of the query and the size of the total data set. A partitioned region can hold much more data than other types of regions, so there is more potential for larger result sets on partitioned region queries. This could cause the member receiving the results to run out of memory if the result set is very large.
+
+
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+---
+title: Basic Querying
+---
+
+This section provides a high-level introduction to Geode querying such as building a query string and describes query language features.
+
+<a id="querying_with_oql__section_828A9660B5014DCAA883A58A45E6B51A"></a>
+Geode provides a SQL-like querying language that allows you to access data stored in Geode regions. Since Geode regions are key-value stores where values can range from simple byte arrays to complex nested objects, Geode uses a query syntax based on OQL (Object Query Language) to query region data. OQL and SQL have many syntactical similarities, however they have significant differences. For example, while OQL does not offer all of the capabilities of SQL like aggregates, OQL does allow you to execute queries on complex object graphs, query object attributes and invoke object methods.
+
+The syntax of a typical Geode OQL query is:
+
+``` pre
+[IMPORT package]
+SELECT [DISTINCT] projectionList
+FROM collection1, [collection2, \u2026]
+[WHERE clause]
+[ORDER BY order_criteria [desc]]
+```
+
+Therefore, a simple Geode OQL query resembles the following:
+
+``` pre
+SELECT DISTINCT * FROM /exampleRegion WHERE status = \u2018active\u2019
+```
+
+An important characteristic of Geode querying to note is that by default, Geode queries on the values of a region and not on keys. To obtain keys from a region, you must use the keySet path expression on the queried region. For example, `/exampleRegion.keySet`.
+
+For those new to the Geode querying, see also the [Geode Querying FAQ and Examples](../../getting_started/querying_quick_reference.html#reference_D5CE64F5FD6F4A808AEFB748C867189E).
+
+- **[Advantages of OQL](../../developing/querying_basics/oql_compared_to_sql.html)**
+
+- **[Writing and Executing a Query in Geode](../../developing/querying_basics/running_a_query.html)**
+
+- **[Building a Query String](../../developing/querying_basics/what_is_a_query_string.html)**
+
+- **[OQL Syntax and Semantics](../../developing/query_additional/query_language_features.html)**
+
+- **[Query Language Restrictions and Unsupported Features](../../developing/querying_basics/restrictions_and_unsupported_features.html)**
+
+
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+---
+title: Query Language Grammar
+---
+
+## <a id="query_grammar_and_reserved_words__section_F6DF7EBA0201463F9F19645849748D54" class="no-quick-link"></a>Language Grammar
+
+Notation used in the grammar:
+n
+A nonterminal symbol that has to appear at some place within the grammar on the left side of a rule. All nonterminal symbols have to be derived to be terminal symbols.
+
+ ***t***
+A terminal symbol (shown in italic bold).
+
+x y
+x followed by y
+
+x | y
+x or y
+
+(x | y)
+x or y
+
+\[ x \]
+x or empty
+
+{ x }
+A possibly empty sequence of x.
+
+ *comment*
+descriptive text
+
+Grammar list:
+
+``` pre
+symbol ::= expression
+query_program ::= [ imports semicolon ] query [semicolon]
+imports ::= import { semicolon import }
+import ::= IMPORT qualifiedName [ AS identifier ]
+query ::= selectExpr | expr
+selectExpr ::= SELECT DISTINCT projectionAttributes fromClause [ whereClause ]
+projectionAttributes ::= * | projectionList
+projectionList ::= projection { comma projection }
+projection ::= field | expr [ AS identifier ]
+field ::= identifier colon expr
+fromClause ::= FROM iteratorDef { comma iteratorDef }
+iteratorDef ::= expr [ [ AS ] identifier ] [ TYPE identifier ] | identifier IN expr [ TYPE identifier ]
+whereClause ::= WHERE expr
+expr ::= castExpr
+castExpr ::= orExpr | left_paren identifier right_paren castExpr
+orExpr ::= andExpr { OR andExpr }
+andExpr ::= equalityExpr { AND equalityExpr }
+equalityExpr ::= relationalExpr { ( = | <> | != ) relationalExpr }
+relationalExpr ::= inExpr { ( < | <= | > | >= ) inExpr }
+inExpr ::= unaryExpr { IN unaryExpr }
+unaryExpr ::= [ NOT ] unaryExpr
+postfixExpr ::= primaryExpr { left_bracket expr right_bracket }
+ | primaryExpr { dot identifier [ argList ] }
+argList ::= left_paren [ valueList ] right_paren
+qualifiedName ::= identifier { dot identifier }
+primaryExpr ::= functionExpr
+ | identifier [ argList ]
+ | undefinedExpr
+ | collectionConstruction
+ | queryParam
+ | literal
+ | ( query )
+ | region_path
+functionExpr ::= ELEMENT left_paren query right_paren
+ | NVL left_paren query comma query right_paren
+ | TO_DATE left_paren query right_paren
+undefinedExpr ::= IS_UNDEFINED left_paren query right_paren
+ | IS_DEFINED left_paren query right_paren
+collectionConstruction ::= SET left_paren [ valueList ] right_paren
+valueList ::= expr { comma expr }
+queryParam ::= $ integerLiteral
+region_path ::= forward_slash region_name { forward_slash region_name }
+region_name ::= name_character { name_character }
+identifier ::= letter { name_character }
+literal ::= booleanLiteral
+ | integerLiteral
+ | longLiteral
+ | doubleLiteral
+ | floatLiteral
+ | charLiteral
+ | stringLiteral
+ | dateLiteral
+ | timeLiteral
+ | timestampLiteral
+ | NULL
+ | UNDEFINED
+booleanLiteral ::= TRUE | FALSE
+integerLiteral ::= [ dash ] digit { digit }
+longLiteral ::= integerLiteral L
+floatLiteral ::= [ dash ] digit { digit } dot digit { digit } [ ( E | e ) [ plus | dash ] digit { digit } ] F
+doubleLiteral ::= [ dash ] digit { digit } dot digit { digit } [ ( E | e ) [ plus | dash ] digit { digit } ] [ D ]
+charLiteral ::= CHAR single_quote character single_quote
+stringLiteral ::= single_quote { character } single_quote
+dateLiteral ::= DATE single_quote integerLiteral dash integerLiteral dash integerLiteral single_quote
+timeLiteral ::= TIME single_quote integerLiteral colon
+ integerLiteral colon integerLiteral single_quote
+timestampLiteral ::= TIMESTAMP single_quote
+ integerLiteral dash integerLiteral dash integerLiteral integerLiteral colon
+ integerLiteral colon
+ digit { digit } [ dot digit { digit } ] single_quote
+letter ::= any unicode letter
+character ::= any unicode character except 0xFFFF
+name_character ::= letter | digit | underscore
+digit ::= any unicode digit
+```
+
+The expressions in the following are all terminal characters:
+
+``` pre
+dot ::= .
+left_paren ::= (
+right_paren ::= )
+left_bracket ::= [
+right_bracket ::= ]
+single_quote ::= \u2019
+underscore ::= _
+forward_slash ::= /
+comma ::= ,
+semicolon ::= ;
+colon ::= :
+dash ::= -
+plus ::= +
+
+```
+
+## <a id="query_grammar_and_reserved_words__section_B074373F2ED44DC7B98652E70ABC5D5D" class="no-quick-link"></a>Language Notes
+
+- Query language keywords such as SELECT, NULL, and DATE are case-insensitive. Identifiers such as attribute names, method names, and path expressions are case-sensitive.
+- Comment lines begin with -- (double dash).
+- Comment blocks begin with /\* and end with \*/.
+- String literals are delimited by single-quotes. Embedded single-quotes are doubled.
+
+ Examples:
+
+ ``` pre
+ 'Hello' value = Hello
+ 'He said, ''Hello''' value = He said, 'Hello'
+ ```
+
+- Character literals begin with the CHAR keyword followed by the character in single quotation marks. The single-quotation mark character itself is represented as `CHAR ''''` (with four single quotation marks).
+- In the TIMESTAMP literal, there is a maximum of nine digits after the decimal point.
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/querying_basics/querying_partitioned_regions.html.md.erb
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+---
+title: Querying Partitioned Regions
+---
+
+Geode allows you to manage and store large amounts of data across distributed nodes using partitioned regions. The basic unit of storage for a partitioned region is a bucket, which resides on a Geode node and contains all the entries that map to a single hashcode. In a typical partitioned region query, the system distributes the query to all buckets across all nodes, then merges the result sets and sends back the query results.
+
+<a id="querying_partitioned_regions__section_4C603563DEDC4303818FB8F894470457"></a>
+The following list summarizes the querying functionality supported by Geode for partitioned regions:
+
+- **Ability to target specific nodes in a query**. If you know that a specific bucket contains the data that you want to query, you can use a function to ensure that your query only runs the specific node that holds the data. This can greatly improve query efficiency. The ability to query data on a specific node is only available if you are using functions and if the function is executed on one single region. In order to do this, you need to use `Query.execute(RegionFunctionContext context)`. See the [Java API](/releases/latest/javadoc/org/apache/geode/cache/query/Query.html) and [Querying a Partitioned Region on a Single Node](../query_additional/query_on_a_single_node.html#concept_30B18A6507534993BD55C2C9E0544A97) for more details.
+- **Ability to optimize partitioned region query performance using key indexes**. You can improve query performance on data that is partitioned by key or a field value by creating a key index and then executing the query using use `Query.execute(RegionFunctionContext context)` with the key or field value used as filter. See the [Java API](/releases/latest/javadoc/org/apache/geode/cache/query/Query.html) and [Optimizing Queries on Data Partitioned by a Key or Field Value](../query_additional/partitioned_region_key_or_field_value.html#concept_3010014DFBC9479783B2B45982014454) for more details.
+- **Ability to perform equi-join queries between partitioned regions and between partitioned regions and replicated regions**. Join queries between partitioned region and between partitioned regions and replicated regions are supported through the function service. In order to perform equi-join operations on partitioned regions or partitioned regions and replicated regions, the partitioned regions must be colocated, and you need to use the need to use `Query.execute(RegionFunctionContext context)`. See the [Java API](/releases/latest/javadoc/org/apache/geode/cache/query/Query.html) and [Performing an Equi-Join Query on Partitioned Regions](../partitioned_regions/join_query_partitioned_regions.html#concept_B930D276F49541F282A2CFE639F107DD) for more details.
+
+- **[Using ORDER BY on Partitioned Regions](../../developing/query_additional/order_by_on_partitioned_regions.html)**
+
+- **[Querying a Partitioned Region on a Single Node](../../developing/query_additional/query_on_a_single_node.html)**
+
+- **[Optimizing Queries on Data Partitioned by a Key or Field Value](../../developing/query_additional/partitioned_region_key_or_field_value.html)**
+
+- **[Performing an Equi-Join Query on Partitioned Regions](../../developing/partitioned_regions/join_query_partitioned_regions.html)**
+
+- **[Partitioned Region Query Restrictions](../../developing/query_additional/partitioned_region_query_restrictions.html)**
+
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/querying_basics/reserved_words.html.md.erb
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+---
+title: Reserved Words
+---
+
+## <a id="concept_4F288B1F9579422FA481FBE2C3ADD007__section_3415163C3EFB46A6BE873E2606C9DE0F" class="no-quick-link"></a>Reserved Words
+
+These words are reserved for the query language and may not be used as identifiers. The words with asterisk (`*`) after them are not currently used by Geode, but are reserved for future implementation.
+
+<table>
+<colgroup>
+<col width="25%" />
+<col width="25%" />
+<col width="25%" />
+<col width="25%" />
+</colgroup>
+<tbody>
+<tr class="odd">
+<td><pre class="pre codeblock"><code>abs*
+all
+and
+andthen*
+any*
+array
+as
+asc
+avg*
+bag*
+boolean
+by
+byte
+char
+collection
+count
+date
+declare*
+define*
+desc </code></pre></td>
+<td><pre class="pre codeblock"><code>dictionary
+distinct
+double
+element
+enum*
+except*
+exists*
+false
+first*
+flatten*
+float
+for*
+from
+group*
+having*
+import
+in
+int
+intersect*
+interval* </code></pre></td>
+<td><pre class="pre codeblock"><code>is_defined
+is_undefined
+last*
+like
+limit
+list*
+listtoset*
+long
+map
+max*
+min*
+mod*
+nil
+not
+null
+nvl
+octet
+or
+order </code></pre></td>
+<td><pre class="pre codeblock"><code>orelse*
+query*
+select
+set
+short
+some*
+string
+struct*
+sum*
+time
+timestamp
+to_date
+true
+type
+undefine*
+undefined
+union*
+unique*
+where</code></pre></td>
+</tr>
+</tbody>
+</table>
+
+To access any method, attribute, or named object that has the same name as a query language reserved word, enclose the name within double quotation marks.
+
+Examples:
+
+``` pre
+SELECT DISTINCT "type" FROM /portfolios WHERE status = 'active'
+```
+
+``` pre
+SELECT DISTINCT * FROM /region1 WHERE emps."select"() < 100000
+```
+
+
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diff --git a/geode-docs/developing/querying_basics/restrictions_and_unsupported_features.html.md.erb b/geode-docs/developing/querying_basics/restrictions_and_unsupported_features.html.md.erb
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+---
+title: Query Language Restrictions and Unsupported Features
+---
+
+At a high level, Geode does not support the following querying features:
+
+- Indexes targeted for joins across more than one region are not supported
+- Static method invocations. For example, the following query is invalid:
+
+ ``` pre
+ SELECT DISTINCT * FROM /QueryRegion0 WHERE aDay = Day.Wednesday
+ ```
+
+- You cannot create an index on fields using Set/List types (Collection types) that are not comparable. The OQL index implementation expects fields to be Comparable. To workaround this, you can create a custom Collection type that implements Comparable.
+- ORDER BY is only supported with DISTINCT queries.
+
+In addition, there are some specific limitations on partitioned region querying. See [Partitioned Region Query Restrictions](../query_additional/partitioned_region_query_restrictions.html#concept_5353476380D44CC1A7F586E5AE1CE7E8).
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/querying_basics/running_a_query.html.md.erb
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+---
+title: Writing and Executing a Query in Geode
+---
+
+<a id="running_a_querying__section_C285160AF91C4486A39444C3A22D6475"></a>
+The Geode QueryService provides methods to create the Query object. You can then use the Query object to perform query-related operations.
+
+The QueryService instance you should use depends on whether you are querying the local cache of an application or if you want your application to query the server cache.
+
+## <a id="running_a_querying__section_8B9C3F5BFBA6421A81EEB404DBE512C2" class="no-quick-link"></a>Querying a Local Cache
+
+To query the application's local cache or to query other members, use `org.apache.geode.cache.Cache.getQueryService`.
+
+**Sample Code**
+
+``` pre
+ // Identify your query string.
+ String queryString = "SELECT DISTINCT * FROM /exampleRegion";
+
+ // Get QueryService from Cache.
+ QueryService queryService = cache.getQueryService();
+
+ // Create the Query Object.
+ Query query = queryService.newQuery(queryString);
+
+ // Execute Query locally. Returns results set.
+ SelectResults results = (SelectResults)query.execute();
+
+ // Find the Size of the ResultSet.
+ int size = results.size();
+
+ // Iterate through your ResultSet.
+ Portfolio p = (Portfolio)results.iterator().next(); /* Region containing Portfolio object. */
+```
+
+## <a id="running_a_querying__section_BAD35A249F784095857CC6848F91F6A4" class="no-quick-link"></a>Querying a Server Cache from a Client
+
+To perform a client to server query, use `org.apache.geode.cache.client.Pool.getQueryService`.
+
+**Sample Code**
+
+``` pre
+// Identify your query string.
+ String queryString = "SELECT DISTINCT * FROM /exampleRegion";
+
+ // Get QueryService from client pool.
+ QueryService queryService = pool.getQueryService();
+
+ // Create the Query Object.
+ Query query = queryService.newQuery(queryString);
+
+ // Execute Query locally. Returns results set.
+ SelectResults results = (SelectResults)query.execute();
+
+ // Find the Size of the ResultSet.
+ int size = results.size();
+
+ // Iterate through your ResultSet.
+ Portfolio p = (Portfolio)results.iterator().next(); /* Region containing Portfolio object. */
+```
+
+Refer to the following JavaDocs for specific APIs:
+
+- [Query package](/releases/latest/javadoc/org/apache/geode/cache/query/package-summary.html)
+- [QueryService](/releases/latest/javadoc/org/apache/geode/cache/query/QueryService.html)
+
+**Note:**
+You can also perform queries using the gfsh `query` command. See [query](../../tools_modules/gfsh/command-pages/query.html).
+
+
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+---
+title: Supported Character Sets
+---
+
+Geode query language supports the full ASCII and Unicode character sets.
+
+
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+---
+title: Building a Query String
+---
+
+<a id="what_is_a_query_string__section_1866AE6026DE4D66A2CD2363C1BC0406"></a>
+A query string is a fully formed OQL statement that can be passed to a query engine and executed against a data set. To build a query string, you combine supported keywords, expressions, and operators to create an expression that returns the information you require.
+
+A query string follows the rules specified by the query language and grammar. It can include:
+
+- **Namescopes**. For example, the IMPORT statement. See [IMPORT Statement](../query_select/the_import_statement.html#concept_2E9F15B2FE9041238B54736103396BF7).
+- **Path expressions**. For example, in the query `SELECT * FROM /exampleRegion`,` /exampleRegion` is a path expression. See [FROM Clause](../query_select/the_from_clause.html#the_from_clause).
+- **Attribute names**. For example, in the query `SELECT DISTINCT * FROM /exampleRegion p WHERE p.position1.secId = '1'`, we access the `secId` attribute of the Position object. See [WHERE Clause](../query_select/the_where_clause.html#the_where_clause).
+- **Method invocations**. For example, in the query `SELECT DISTINCT * FROM /exampleRegion p WHERE p.name.startsWith('Bo')`, we invoke the `startsWith` method on the Name object. See [WHERE Clause](../query_select/the_where_clause.html#the_where_clause).
+- **Operators**. For example, comparison operators (=,<,>,<>), unary operators (NOT), logical operators (AND, OR) and so on. See [Operators](../query_additional/operators.html#operators) for a complete list.
+- **Literals**. For example, boolean, date, time and so on. See [Supported Literals](../query_additional/literals.html#literals) for a complete list.
+- **Query bind parameters**. For example, in the query `SELECT DISTINCT * FROM $1 p WHERE p.status = $2`, $1 and $2 are parameters that can be passed to the query during runtime. See [Using Query Bind Parameters](../query_additional/using_query_bind_parameters.html#concept_173E775FE46B47DF9D7D1E40680D34DF) for more details.
+- **Preset query functions**. For example, ELEMENT(expr) and IS\_DEFINED(expr). See [SELECT Statement](../query_select/the_select_statement.html#concept_85AE7D6B1E2941ED8BD2A8310A81753E) for other available functions.
+- **SELECT statements**. For example, in the example queries above `SELECT *` or `SELECT DISTINCT *`. See [SELECT Statement](../query_select/the_select_statement.html#concept_85AE7D6B1E2941ED8BD2A8310A81753E) for other available functions.
+- **Comments**. OQL permits extra characters to accompany the query string without changing the string's definition. Form a multi-line comment by enclosing the comment body within `/*` and `*/` delimiters; OQL does not permit nested comments. A single line comment body is all the characters to the right of `--` (two hyphens) up to the end of the line.
+
+The components listed above can all be part of the query string, but none of the components are required. At a minimum, a query string contains an expression that can be evaluated against specified data.
+
+The following sections provide guidelines for the query language building blocks that are used when writing typical Geode queries.
+
+- **[IMPORT Statement](../../developing/query_select/the_import_statement.html)**
+
+- **[FROM Clause](../../developing/query_select/the_from_clause.html)**
+
+- **[WHERE Clause](../../developing/query_select/the_where_clause.html)**
+
+- **[SELECT Statement](../../developing/query_select/the_select_statement.html)**
+
+
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+---
+title: Region Data Storage and Distribution
+---
+
+The Apache Geode data storage and distribution models put your data in the right place at the right time. You should understand all the options for data storage in Geode before you configure your data regions.
+
+- **[Storage and Distribution Options](../../developing/region_options/storage_distribution_options.html)**
+
+ Geode provides several models for data storage and distribution, including partitioned or replicated regions as well as distributed or non-distributed regions (local cache storage).
+
+- **[Region Types](../../developing/region_options/region_types.html)**
+
+ Region types define region behavior within a single distributed system. You have various options for region data storage and distribution.
+
+- **[Region Data Stores and Data Accessors](../../developing/region_options/data_hosts_and_accessors.html)**
+
+ Understand the difference between members that store data for a region and members that act only as data accessors to the region.
+
+- **[Creating Regions Dynamically](../../developing/region_options/dynamic_region_creation.html)**
+
+ You can dynamically create regions in your application code and automatically instantiate them on members of a distributed system.
+
+
http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/ccc2fbda/geode-docs/developing/region_options/data_hosts_and_accessors.html.md.erb
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+---
+title: Region Data Stores and Data Accessors
+---
+
+Understand the difference between members that store data for a region and members that act only as data accessors to the region.
+
+<a id="data_hosts_and_accessors__section_0EF33633F97B4C63AC34F523259AD310"></a>
+In most cases, when you define a data region in a member\u2019s cache, you also specify whether the member is a data store. Members that store data for a region are referred to as data stores or data hosts. Members that do not store data are referred to as accessor members, or empty members. Any member, store or accessor, that defines a region can access it, put data into it, and receive events from other members. To configure a region so the member is a data accessor, you use configurations that specify no local data storage for the region. Otherwise, the member is a data store for the region.
+
+For server regions, suppress local data storage at region creation by specifying a region shortcut that contains the term
+"PROXY" in its name, such as `PARTITION_PROXY` or `REPLICATE_PROXY`.
+
+For client regions, suppress local data storage at region creation by specifying the `PROXY` region
+shortcut. Do not use the `CACHING_PROXY` shortcut for this purpose, as it allows local data storage.
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+---
+title: Creating Regions Dynamically
+---
+
+You can dynamically create regions in your application code and automatically instantiate them on members of a distributed system.
+
+If your application does not require partitioned regions, you can use the <span class="keyword apiname">org.apache.geode.cache.DynamicRegionFactory</span> class to dynamically create regions, or you can create them using the `<dynamic-region-factory>` element in the cache.xml file that defines the region. See [<dynamic-region-factory>](../../reference/topics/cache_xml.html#dynamic-region-factory).
+
+Due to the number of options involved, most developers use functions to create regions dynamically in their applications, as described in this topic. Dynamic regions can also be created from the `gfsh` command line.
+
+For a complete discussion of using Geode functions, see [Function Execution](../function_exec/chapter_overview.html). Functions use the <span class="keyword apiname">org.apache.geode.cache.execute.FunctionService</span> class.
+
+For example, the following Java classes define and use a function for dynamic region creation:
+
+The <span class="keyword apiname">CreateRegionFunction</span> class defines a function invoked on a server by a client using the <span class="keyword apiname">onServer()</span> method of the <span class="keyword apiname">FunctionService</span> class. This function call initiates region creation by putting an entry into the region attributes metadata region. The entry key is the region name and the value is the set of region attributes used to create the region.
+
+``` pre
+#CreateRegionFunction.java
+
+import org.apache.geode.cache.Cache;
+import org.apache.geode.cache.CacheFactory;
+import org.apache.geode.cache.DataPolicy;
+import org.apache.geode.cache.Declarable;
+import org.apache.geode.cache.Region;
+import org.apache.geode.cache.RegionAttributes;
+import org.apache.geode.cache.RegionFactory;
+import org.apache.geode.cache.Scope;
+
+import org.apache.geode.cache.execute.Function;
+import org.apache.geode.cache.execute.FunctionContext;
+
+import java.util.Properties;
+
+public class CreateRegionFunction implements Function, Declarable {
+
+ private final Cache cache;
+
+ private final Region<String,RegionAttributes> regionAttributesMetadataRegion;
+
+ private static final String REGION_ATTRIBUTES_METADATA_REGION =
+ "_regionAttributesMetadata";
+
+ public enum Status {SUCCESSFUL, UNSUCCESSFUL, ALREADY_EXISTS};
+
+ public CreateRegionFunction() {
+ this.cache = CacheFactory.getAnyInstance();
+ this.regionAttributesMetadataRegion = createRegionAttributesMetadataRegion();
+ }
+
+ public void execute(FunctionContext context) {
+ Object[] arguments = (Object[]) context.getArguments();
+ String regionName = (String) arguments[0];
+ RegionAttributes attributes = (RegionAttributes) arguments[1];
+
+ // Create or retrieve region
+ Status status = createOrRetrieveRegion(regionName, attributes);
+
+ // Return status
+ context.getResultSender().lastResult(status);
+ }
+
+ private Status createOrRetrieveRegion(String regionName,
+ RegionAttributes attributes) {
+ Status status = Status.SUCCESSFUL;
+ Region region = this.cache.getRegion(regionName);
+ if (region == null) {
+ // Put the attributes into the metadata region. The afterCreate call will
+ // actually create the region.
+ this.regionAttributesMetadataRegion.put(regionName, attributes);
+
+ // Retrieve the region after creating it
+ region = this.cache.getRegion(regionName);
+ if (region == null) {
+ status = Status.UNSUCCESSFUL;
+ }
+ } else {
+ status = Status.ALREADY_EXISTS;
+ }
+ return status;
+ }
+
+ private Region<String,RegionAttributes>
+ createRegionAttributesMetadataRegion() {
+ Region<String, RegionAttributes> metaRegion =
+ this.cache.getRegion(REGION_ATTRIBUTES_METADATA_REGION);
+ if (metaRegion == null) {
+ RegionFactory<String, RegionAttributes> factory =
+ this.cache.createRegionFactory();
+ factory.setDataPolicy(DataPolicy.REPLICATE);
+ factory.setScope(Scope.DISTRIBUTED_ACK);
+ factory.addCacheListener(new CreateRegionCacheListener());
+ metaRegion = factory.create(REGION_ATTRIBUTES_METADATA_REGION);
+ }
+ return metaRegion;
+ }
+
+ public String getId() {
+ return getClass().getSimpleName();
+ }
+
+ public boolean optimizeForWrite() {
+ return false;
+ }
+
+ public boolean isHA() {
+ return true;
+ }
+
+ public boolean hasResult() {
+ return true;
+ }
+
+ public void init(Properties properties) {
+ }
+}
+```
+
+The <span class="keyword apiname">CreateRegionCacheListener</span> class is a cache listener that implements two methods, <span class="keyword apiname">afterCreate()</span> and <span class="keyword apiname">afterRegionCreate()</span>. The <span class="keyword apiname">afterCreate()</span> method creates the region. The <span class="keyword apiname">afterRegionCreate()</span> method causes each new server to create all the regions defined in the metadata region.
+
+``` pre
+#CreateRegionCacheListener.java
+
+import org.apache.geode.cache.Cache;
+import org.apache.geode.cache.CacheFactory;
+import org.apache.geode.cache.Declarable;
+import org.apache.geode.cache.EntryEvent;
+import org.apache.geode.cache.Region;
+import org.apache.geode.cache.RegionAttributes;
+import org.apache.geode.cache.RegionEvent;
+import org.apache.geode.cache.RegionExistsException;
+
+import org.apache.geode.cache.util.CacheListenerAdapter;
+
+import java.util.Map;
+import java.util.Properties;
+
+public class CreateRegionCacheListener
+ extends CacheListenerAdapter<String,RegionAttributes>
+ implements Declarable {
+
+ private Cache cache;
+
+ public CreateRegionCacheListener() {
+ this.cache = CacheFactory.getAnyInstance();
+ }
+
+ public void afterCreate(EntryEvent<String,RegionAttributes> event) {
+ createRegion(event.getKey(), event.getNewValue());
+ }
+
+ public void afterRegionCreate(RegionEvent<String,RegionAttributes> event) {
+ Region<String,RegionAttributes> region = event.getRegion();
+ for (Map.Entry<String,RegionAttributes> entry : region.entrySet()) {
+ createRegion(entry.getKey(), entry.getValue());
+ }
+ }
+
+ private void createRegion(String regionName, RegionAttributes attributes) {
+ if (this.cache.getLogger().fineEnabled()) {
+ this.cache.getLogger().fine(
+ "CreateRegionCacheListener creating region named: "
+ + regionName + " with attributes: " + attributes);
+ }
+ try {
+ Region region = this.cache.createRegionFactory(attributes)
+ .create(regionName);
+ if (this.cache.getLogger().fineEnabled()) {
+ this.cache.getLogger().fine("CreateRegionCacheListener created: "
+ + region);
+ }
+ System.out.println("CreateRegionCacheListener created: " + region);
+ } catch (RegionExistsException e) {/* ignore */}
+ }
+
+ public void init(Properties p) {
+ }
+}
+```
+
+