Hussain Towaileb has uploaded a new change for review.
https://asterix-gerrit.ics.uci.edu/3095
Change subject: [ASTERIXDB-2498][DOC] List slice documentation for SQL++
......................................................................
[ASTERIXDB-2498][DOC] List slice documentation for SQL++
- user model changes: no
- storage format changes: no
- interface changes: no
Details:
- Added list slice syntax documentation.
Change-Id: Iff9bb0e82f31cefcdd19ace0d02fc07e7d00025f
---
M asterixdb/asterix-doc/src/main/markdown/sqlpp/2_expr.md
1 file changed, 20 insertions(+), 13 deletions(-)
git pull ssh://asterix-gerrit.ics.uci.edu:29418/asterixdb
refs/changes/95/3095/1
diff --git a/asterixdb/asterix-doc/src/main/markdown/sqlpp/2_expr.md
b/asterixdb/asterix-doc/src/main/markdown/sqlpp/2_expr.md
index 41cf1d8..8422531 100644
--- a/asterixdb/asterix-doc/src/main/markdown/sqlpp/2_expr.md
+++ b/asterixdb/asterix-doc/src/main/markdown/sqlpp/2_expr.md
@@ -208,21 +208,24 @@
PathExpression ::= PrimaryExpression ( Field | Index )*
Field ::= "." Identifier
- Index ::= "[" Expression "]"
+ Index ::= "[" Expression (":" ( Expression )? )? "]"
-Components of complex types in the data model are accessed via path
expressions.
-Path access can be applied to the result of a query expression that yields an
instance of a complex type, for example, a
-object or array instance.
-For objects, path access is based on field names.
-For arrays, path access is based on (zero-based) array-style indexing.
-Attempts to access non-existent fields or out-of-bound array elements produce
the special value `MISSING`.
-For multisets path access is also zero-based and returns an arbitrary multiset
element if the index is within the size
-of the multiset or `MISSING` otherwise.
-Type errors will be raised for inappropriate use of a path expression, such as
applying a field accessor to a numeric
-value.
+Components of complex types in the data model are accessed via path
expressions. Path access can be applied to the
+result of a query expression that yields an instance of a complex type, for
example, an object or an array instance.
-The following examples illustrate field access for a object, index-based
element access for an array, and also a
-composition thereof.
+For objects, path access is based on field names, and it accesses the field
whose name was specified.\
+For arrays, path access is based on (zero-based) array-style indexing. Array
indexes can be used to retrieve either a
+single element from an array, or a whole subset of an array. Accessing a
single element is achieved by
+providing a single index argument (zero-based element position), while
obtaining a subset of an array is achieved by
+providing the `start` and `end` (zero-based) index positions; the returned
subset is from position `start` to position
+`end - 1`; the `end` position argument is optional. Multisets have similar
behavior to arrays, except for retrieving
+arbitrary items as order of items is not fixed in multisets.
+
+Attempts to access non-existent fields or out-of-bound array elements produce
the special value `MISSING`. Type errors
+will be raised for inappropriate use of a path expression, such as applying a
field accessor to a numeric value.
+
+The following examples illustrate field access for an object, index-based
element access or subset retrieval of an array,
+and also a composition thereof.
##### Examples
@@ -231,6 +234,10 @@
(["a", "b", "c"])[2]
({"name": "MyABCs", "array": [ "a", "b", "c"]}).array[2]
+
+ (["a", "b", "c"])[0:2]
+
+ (["a", "b", "c"])[0:]
## <a id="Primary_expressions">Primary Expressions</a>
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Iff9bb0e82f31cefcdd19ace0d02fc07e7d00025f
Gerrit-PatchSet: 1
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: Hussain Towaileb <[email protected]>
