Added CURRENT_USER, 'USER and SESSION_USER` system functions.

CHANGES.txt

@@ -15,6 +15,12 @@ the appropriate section of the docs.
 Breaking Changes
 ================
 
+ - ``CURRENT_USER``, ``USER`` and ``SESSION_USER`` are now reserved words as we 
+   introduced them as system functions. These terms will not be available to 
+   be used as table, and column names and for already existing entities they 
+   will have to be quoted when referenced (otherwise the terms will be treated 
+   as function calls).
+
  - ``SELECT`` statements without any ``FROM`` items are no longer executed
    against the ``sys.cluster`` table, but against a virtual table with no
    columns. Queries including ``sys.cluster`` columns but no explicit ``FROM``

blackbox/docs/best_practice/data_import.txt

@@ -23,10 +23,10 @@ Defining the Data Structure
 Before starting the import you'll have to consider how your table structure
 will look. Decisions made at this point will influence the import process later.
 
-For this example we have a simple single ``user`` table with 6 columns of
+For this example we have a simple single ``users`` table with 6 columns of
 various types::
 
-  cr> CREATE TABLE user (
+  cr> CREATE TABLE users (
   ...   id INT primary key,
   ...   name STRING,
   ...   day_joined TIMESTAMP,
@@ -40,7 +40,7 @@ various types::
 
 .. hide:
 
-  cr> DROP TABLE user;
+  cr> DROP TABLE users;
   DROP OK, 1 row affected (... sec)
 
 There's nothing wrong with this method and it does the job, but it's not very
@@ -80,7 +80,7 @@ according to your availability requirements.
 
 The ``CREATE TABLE`` statement now looks like::
 
-  cr> CREATE TABLE user (
+  cr> CREATE TABLE users(
   ...   id INT primary key,
   ...   name STRING,
   ...   day_joined TIMESTAMP,
@@ -107,17 +107,17 @@ therefore also minimise the overhead during import.
 
 ::
 
-  cr> ALTER TABLE user SET (refresh_interval = 0);
+  cr> ALTER TABLE users SET (refresh_interval = 0);
   ALTER OK, -1 rows affected (... sec)
 
 .. hide:
 
-  cr> DROP TABLE user;
+  cr> DROP TABLE users;
   DROP OK, 1 row affected (... sec)
 
 It's possible to set the refresh interval in the ``CREATE TABLE`` statement::
 
-  cr> CREATE TABLE user (
+  cr> CREATE TABLE users (
   ...   id INT primary key,
   ...   name STRING,
   ...   day_joined TIMESTAMP,
@@ -136,7 +136,7 @@ It's possible to set the refresh interval in the ``CREATE TABLE`` statement::
 Once the import is finished you can set the refresh interval to a reasonable
 value (time in ms)::
 
-  cr> ALTER TABLE user SET (refresh_interval = 1000);
+  cr> ALTER TABLE users SET (refresh_interval = 1000);
   ALTER OK, -1 rows affected (... sec)
 
 .. seealso::
@@ -212,18 +212,18 @@ will return successfully, reporting ``COPY OK, 0 rows affected (... sec)``.
 
 ::
 
-  cr> COPY user FROM '/tmp/best_practice_data/users.json';
+  cr> COPY users FROM '/tmp/best_practice_data/users.json';
   COPY OK, 150 rows affected (... sec)
 
 .. hide:
 
-  cr> REFRESH TABLE user;
+  cr> REFRESH TABLE users;
   REFRESH OK, 1 row affected (... sec)
 
-  cr> delete from user;
+  cr> delete from users;
   DELETE OK, 150 rows affected (... sec)
 
-  cr> REFRESH TABLE user;
+  cr> REFRESH TABLE users;
   REFRESH OK, 1 row affected (... sec)
 
 .. note::
@@ -242,19 +242,19 @@ defaults to 10 000 if not specified.
 
 For example::
 
-  cr> COPY user FROM '/tmp/best_practice_data/users.json'
+  cr> COPY users FROM '/tmp/best_practice_data/users.json'
   ... WITH (bulk_size = 2000);
   COPY OK, 150 rows affected (... sec)
 
 .. hide:
 
-  cr> REFRESH TABLE user;
+  cr> REFRESH TABLE users;
   REFRESH OK, 1 row affected (... sec)
 
-  cr> delete from user;
+  cr> delete from users;
   DELETE OK, 150 rows affected (... sec)
 
-  cr> REFRESH TABLE user;
+  cr> REFRESH TABLE users;
   REFRESH OK, 1 row affected (... sec)
 
 In our example it will not make a difference, but if you have a more complex
@@ -274,13 +274,13 @@ CrateDB does not automatically detect compression, so you'll need to specify
 
 For example::
 
-  cr> COPY user FROM '/tmp/best_practice_data/users.json.gz'
+  cr> COPY users FROM '/tmp/best_practice_data/users.json.gz'
   ... WITH (compression = 'gzip');
   COPY OK, 150 rows affected (... sec)
 
 .. hide:
 
-  cr> REFRESH TABLE user;
+  cr> REFRESH TABLE users;
   REFRESH OK, 1 row affected (... sec)
 
 Partitioned Tables
@@ -300,12 +300,12 @@ partition column.
 
 .. hide:
 
-  cr> DROP TABLE user;
+  cr> DROP TABLE users;
   DROP OK, 1 row affected (... sec)
 
 ::
 
-  cr> CREATE TABLE user (
+  cr> CREATE TABLE users (
   ...   id INT primary key,
   ...   name STRING,
   ...   day_joined TIMESTAMP primary key,
@@ -333,7 +333,7 @@ For example: ``users_1408312800.json``
 The value of the partition column must be defined in the ``COPY FROM``
 statement using the ``PARTITION`` clause::
 
-  cr> COPY user PARTITION (day_joined=1408312800)
+  cr> COPY users PARTITION (day_joined=1408312800)
   ... FROM '/tmp/best_practice_data/users_1408312800.json';
   COPY OK, 23 rows affected (... sec)
 

blackbox/docs/sql/scalar.txt

@@ -1621,9 +1621,11 @@ The default schema can be set when using the `JDBC
 <https://crate.io/docs/reference/protocols/http.html#default-schema>`_ such as
 `CrateDB PDO`_.
 
-The ``CURRENT_SCHEMA`` function has a special SQL syntax, meaning that it must
-be called without trailing parenthesis (``()``). However, CrateDB also supports
-the optional parenthesis.
+.. note::
+
+    The ``CURRENT_SCHEMA`` function has a special SQL syntax, meaning that it 
+    must be called without trailing parenthesis (``()``). However, CrateDB also 
+    supports the optional parenthesis.
 
 Synopsis::
 
@@ -1639,6 +1641,76 @@ Example::
     +----------------+
     SELECT 1 row in set (... sec)
 
+``CURRENT_USER``
+----------------
+
+The ``CURRENT_USER`` system information function returns the name of the 
+current connected user.
+
+Returns: ``string``
+
+Synopsis::
+
+    CURRENT_USER 
+
+Example::
+
+    cr> select current_user;
+    +--------------+
+    | current_user |
+    +--------------+
+    | crate        |
+    +--------------+
+    SELECT 1 row in set (... sec)
+
+``USER``
+--------
+
+Equivalent to ``CURRENT_USER``.
+
+Returns: ``string``
+
+Synopsis::
+
+    USER 
+
+Example::
+
+    cr> select user;
+    +--------------+
+    | current_user |
+    +--------------+
+    | crate        |
+    +--------------+
+    SELECT 1 row in set (... sec)
+
+``SESSION_USER``
+----------------
+The ``SESSION_USER`` system information function returns the name of the
+current connected user.
+
+Returns: ``string``
+
+Synopsis::
+
+    SESSION_USER
+
+Example::
+
+    cr> select session_user;
+    +--------------+
+    | session_user |
+    +--------------+
+    | crate        |
+    +--------------+
+    SELECT 1 row in set (... sec)
+
+.. note::
+
+    The ``CURRENT_USER``, ``SESSION_USER`` and ``USER`` functions have a  
+    a special SQL syntax, meaning that they must be called without trailing 
+    parenthesis (``()``).
+
 .. rubric:: Footnotes
 
 .. [#MySQL-Docs] http://dev.mysql.com/doc/refman/5.6/en/date-and-time-functions.html#function_date-format
@@ -1647,4 +1719,7 @@ Example::
 .. _Java Regular Expressions: http://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html
 .. _`MySQL date_format`: http://dev.mysql.com/doc/refman/5.6/en/date-and-time-functions.html#function_date-format
 .. _`Haversine formula`: https://en.wikipedia.org/wiki/Haversine_formula
+
+
+
 .. _`CrateDB PDO`: https://crate.io/docs/reference/pdo/usage.html#dsn

sql-parser/src/main/antlr/SqlBase.g4

@@ -232,6 +232,8 @@ primaryExpression
     | name=CURRENT_TIME ('(' precision=integerLiteral')')?                           #specialDateTimeFunction
     | name=CURRENT_TIMESTAMP ('(' precision=integerLiteral')')?                      #specialDateTimeFunction
     | CURRENT_SCHEMA ('(' ')')?                                                      #currentSchema
+    | (CURRENT_USER | USER)                                                          #currentUser
+    | SESSION_USER ('(' ')')?                                                        #sessionUser
     | SUBSTRING '(' expr FROM expr (FOR expr)? ')'                                   #substring
     | EXTRACT '(' identExpr FROM expr ')'                                            #extract
     | CAST '(' expr AS dataType ')'                                                  #cast
@@ -565,7 +567,7 @@ nonReserved
     | SHARDS | SHOW | STRICT | SYSTEM | TABLES | TABLESAMPLE | TEXT | TIME
     | TIMESTAMP | TO | TOKENIZER | TOKEN_FILTERS | TYPE | VALUES | VIEW | YEAR
     | REPOSITORY | SNAPSHOT | RESTORE | GENERATED | ALWAYS | BEGIN
-    | ISOLATION | TRANSACTION | LEVEL | LANGUAGE | OPEN | CLOSE | RENAME | USER
+    | ISOLATION | TRANSACTION | LEVEL | LANGUAGE | OPEN | CLOSE | RENAME
     ;
 
 SELECT: 'SELECT';
@@ -615,6 +617,8 @@ CURRENT_DATE: 'CURRENT_DATE';
 CURRENT_TIME: 'CURRENT_TIME';
 CURRENT_TIMESTAMP: 'CURRENT_TIMESTAMP';
 CURRENT_SCHEMA: 'CURRENT_SCHEMA';
+CURRENT_USER: 'CURRENT_USER';
+SESSION_USER: 'SESSION_USER';
 EXTRACT: 'EXTRACT';
 CASE: 'CASE';
 WHEN: 'WHEN';

sql-parser/src/main/java/io/crate/sql/parser/AstBuilder.java

@@ -1006,7 +1006,16 @@ public Node visitSubstring(SqlBaseParser.SubstringContext context) {
     @Override
     public Node visitCurrentSchema(SqlBaseParser.CurrentSchemaContext context) {
         return new FunctionCall(QualifiedName.of("current_schema"), ImmutableList.of());
+    }
 
+    @Override
+    public Node visitCurrentUser(SqlBaseParser.CurrentUserContext ctx) {
+        return new FunctionCall(QualifiedName.of("current_user"), ImmutableList.of());
+    }
+
+    @Override
+    public Node visitSessionUser(SqlBaseParser.SessionUserContext ctx) {
+        return new FunctionCall(QualifiedName.of("session_user"), ImmutableList.of());
     }
 
     @Override

sql-parser/src/test/java/io/crate/sql/parser/TestSqlParser.java

@@ -271,11 +271,18 @@ public void testCurrentTimestamp()
     }
 
     @Test
-    public void testSpecialFunctions() throws Exception {
+    public void testCurrentSchemaFunction() throws Exception {
         assertInstanceOf("CURRENT_SCHEMA", FunctionCall.class);
         assertInstanceOf("CURRENT_SCHEMA()", FunctionCall.class);
     }
 
+    @Test
+    public void testUserFunctions() {
+        assertInstanceOf("CURRENT_USER", FunctionCall.class);
+        assertInstanceOf("SESSION_USER", FunctionCall.class);
+        assertInstanceOf("USER", FunctionCall.class);
+    }
+
     private void assertInstanceOf(String expr, Class<? extends Node> cls) {
         Expression expression = SqlParser.createExpression(expr);
         assertThat(expression, instanceOf(cls));

sql-parser/src/test/java/io/crate/sql/parser/TestStatementBuilder.java

@@ -490,6 +490,10 @@ public void testSystemInformationFunctionsStmtBuilder() {
         printStatement("select current_schema()");
         printStatement("select * from information_schema.tables where table_schema = current_schema");
         printStatement("select * from information_schema.tables where table_schema = current_schema()");
+
+        printStatement("select current_user");
+        printStatement("select user");
+        printStatement("select session_user");
     }
 
     @Test

sql/src/main/java/io/crate/operation/scalar/ScalarFunctionModule.java

@@ -21,20 +21,30 @@
 
 package io.crate.operation.scalar;
 
-import io.crate.metadata.FunctionResolver;
 import io.crate.metadata.FunctionIdent;
 import io.crate.metadata.FunctionImplementation;
+import io.crate.metadata.FunctionResolver;
 import io.crate.operation.scalar.arithmetic.*;
 import io.crate.operation.scalar.cast.CastFunction;
 import io.crate.operation.scalar.cast.TryCastScalarFunction;
-import io.crate.operation.scalar.conditional.*;
-import io.crate.operation.scalar.geo.*;
+import io.crate.operation.scalar.conditional.CoalesceFunction;
+import io.crate.operation.scalar.conditional.GreatestFunction;
+import io.crate.operation.scalar.conditional.IfFunction;
+import io.crate.operation.scalar.conditional.LeastFunction;
+import io.crate.operation.scalar.conditional.NullIfFunction;
+import io.crate.operation.scalar.geo.CoordinateFunction;
+import io.crate.operation.scalar.geo.DistanceFunction;
+import io.crate.operation.scalar.geo.GeoHashFunction;
+import io.crate.operation.scalar.geo.IntersectsFunction;
+import io.crate.operation.scalar.geo.WithinFunction;
 import io.crate.operation.scalar.regex.MatchesFunction;
 import io.crate.operation.scalar.regex.ReplaceFunction;
 import io.crate.operation.scalar.string.HashFunctions;
 import io.crate.operation.scalar.string.LengthFunction;
 import io.crate.operation.scalar.string.StringCaseFunction;
 import io.crate.operation.scalar.systeminformation.CurrentSchemaFunction;
+import io.crate.operation.scalar.systeminformation.CurrentUserFunction;
+import io.crate.operation.scalar.systeminformation.SessionUserFunction;
 import io.crate.operation.scalar.timestamp.CurrentTimestampFunction;
 import org.elasticsearch.common.inject.AbstractModule;
 import org.elasticsearch.common.inject.multibindings.MapBinder;
@@ -114,6 +124,8 @@ protected void configure() {
         IfFunction.register(this);
 
         CurrentSchemaFunction.register(this);
+        CurrentUserFunction.register(this);
+        SessionUserFunction.register(this);
 
         // bind all registered functions and resolver
         // by doing it here instead of the register functions, plugins can also use the