[1.3]: Add observibility changes

Signed-off-by: Naarcha-AWS <naarcha@amazon.com>

_observability-plugin/ppl/commands.md

@@ -151,6 +151,10 @@ search source=accounts | dedup gender consecutive=true | fields account_number,
 13 | F
 18 | M
 
+### Limitations
+
+The `dedup` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## eval
 
 The `eval` command evaluates an expression and appends its result to the search result.
@@ -211,6 +215,11 @@ search source=accounts | eval doubleAge = age * 2, ddAge = doubleAge * 2 | field
 | 28    | 56   | 112
 | 33    | 66   | 132
 
+
+### Limitation
+
+The ``eval`` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## fields
 
 Use the `fields` command to keep or remove fields from a search result.
@@ -256,6 +265,80 @@ search source=accounts | fields account_number, firstname, lastname | fields - a
 | Nanette | Bates
 | Dale    | Adams
 
+
+## parse
+
+Use the `parse` command to parse a text field using regular expression and append the result to the search result. 
+
+### Syntax
+
+```sql
+parse <field> <regular-expression>
+```
+
+Field | Description | Required
+:--- | :--- |:---
+field | A text field. | Yes
+regular-expression | The regular expression used to extract new fields from the given test field. If a new field name exists, it will replace the original field. | Yes
+
+The regular expression is used to match the whole text field of each document with Java regex engine. Each named capture group in the expression will become a new ``STRING`` field.
+
+*Example 1*: Create new field
+
+The example shows how to create new field `host` for each document. `host` will be the host name after `@` in `email` field. Parsing a null field will return an empty string.
+
+```sql
+os> source=accounts | parse email '.+@(?<host>.+)' | fields email, host ;
+fetched rows / total rows = 4/4
+```
+
+| email | host  
+:--- | :--- |
+| amberduke@pyrami.com  | pyrami.com 
+| hattiebond@netagy.com | netagy.com 
+| null                  | null          
+| daleadams@boink.com   | boink.com  
+
+*Example 2*: Override the existing field
+
+The example shows how to override the existing address field with street number removed.
+
+```sql
+os> source=accounts | parse address '\d+ (?<address>.+)' | fields address ;
+fetched rows / total rows = 4/4
+```
+
+| address
+:--- |
+| Holmes Lane      
+| Bristol Street   
+| Madison Street   
+| Hutchinson Court
+
+*Example 3*: Filter and sort be casted parsed field
+
+The example shows how to sort street numbers that are higher than 500 in address field.
+
+```sql
+os> source=accounts | parse address '(?<streetNumber>\d+) (?<street>.+)' | where cast(streetNumber as int) > 500 | sort num(streetNumber) | fields streetNumber, street ;
+fetched rows / total rows = 3/3
+```
+
+| streetNumber | street  
+:--- | :--- |
+| 671 | Bristol Street 
+| 789 | Madison Street 
+| 880 | Holmes Lane  
+
+### Limitations
+
+A few limitations exist when using the parse command:
+
+- Fields defined by parse cannot be parsed again. For example, `source=accounts | parse address '\d+ (?<street>.+)' | parse street '\w+ (?<road>\w+)' ;` will fail to return any expressions.
+- Fields defined by parse cannot be overridden with other commands. For example, when entering `source=accounts | parse address '\d+ (?<street>.+)' | eval street='1' | where street='1' ;` `where` will not match any documents since `street` cannot be overridden.
+- The text field used by parse cannot be overridden. For example, when entering `source=accounts | parse address '\d+ (?<street>.+)' | eval address='1' ;` `street` will not be parse since address is overridden. 
+- Fields defined by parse cannot be filtered/sorted after using them in stats command. For example, `source=accounts | parse email '.+@(?<host>.+)' | stats avg(age) by host | where host=pyrami.com ;` `where` will not parse the domain listed.
+
 ## rename
 
 Use the `rename` command to rename one or more fields in the search result.
@@ -301,6 +384,10 @@ search source=accounts | rename account_number as an, employer as emp | fields a
 | 13   | Quility
 | 18   | null
 
+### Limitations
+
+The `rename` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## sort
 
 Use the `sort` command to sort search results by a specified field.
@@ -547,6 +634,10 @@ search source=accounts | fields firstname, age | head 2;
 | Amber  | 32
 | Hattie | 36
 
+### Limitations
+
+The `head` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## rare
 
 Use the `rare` command to find the least common values of all fields in a field list.
@@ -590,6 +681,10 @@ search source=accounts | rare age by gender;
 | M  | 32
 | M  | 33
 
+### Limitations
+
+The `rare` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## top {#top-command}
 
 Use the `top` command to find the most common values of all fields in the field list.
@@ -644,6 +739,10 @@ search source=accounts | top 1 age by gender;
 | F  | 28
 | M  | 32
 
+### Limitations
+
+The `top` command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
+
 ## match
 
 Use the `match` command to search documents that match a `string`, `number`, `date`, or `boolean` value for a given field.

_search-plugins/sql/datatypes.md

@@ -23,6 +23,7 @@ double | double | DOUBLE
 keyword |	string | VARCHAR
 text | text | VARCHAR
 date | timestamp | TIMESTAMP
+date_nanos | timestamp | TIMESTAMP
 ip | ip | VARCHAR
 date | timestamp | TIMESTAMP
 binary | binary | VARBINARY
@@ -54,7 +55,7 @@ The `time` type represents the time of a clock regardless of its timezone. The `
 
 | Type | Syntax | Range
 :--- | :--- | :---
-time | `hh:mm:ss[.fraction]` | `00:00:00.000000` to `23:59:59.999999`
+time | `hh:mm:ss[.fraction]` | `00:00:00.0000000000` to `23:59:59.9999999999`
 
 ### Datetime
 
@@ -62,7 +63,7 @@ The `datetime` type is a combination of date and time. It doesn't contain timezo
 
 | Type | Syntax | Range
 :--- | :--- | :---
-datetime | `yyyy-MM-dd hh:mm:ss[.fraction]` | `0001-01-01 00:00:00.000000` to `9999-12-31 23:59:59.999999`
+datetime | `yyyy-MM-dd hh:mm:ss[.fraction]` | `0001-01-01 00:00:00.0000000000` to `9999-12-31 23:59:59.9999999999`
 
 ### Timestamp
 
@@ -72,7 +73,7 @@ The `timestamp` type is stored differently from the other types. It's converted
 
 | Type | Syntax | Range
 :--- | :--- | :---
-timestamp | `yyyy-MM-dd hh:mm:ss[.fraction]` | `0001-01-01 00:00:01.000000` UTC to `9999-12-31 23:59:59.999999`
+timestamp | `yyyy-MM-dd hh:mm:ss[.fraction]` | `0001-01-01 00:00:01.9999999999` UTC to `9999-12-31 23:59:59.9999999999`
 
 ### Interval