Describe Table with catalog name.

docs/user/general/identifiers.rst

@@ -176,3 +176,89 @@ Query delimited multiple indices seperated by ``,``::
     |-------|
     | 5     |
     +-------+
+
+
+
+Fully Qualified Table Names
+===========================
+
+Description
+-----------
+With the introduction of different datasource catalogs along with Opensearch, support for fully qualified table names became compulsory to resolve tables to a catalog.
+
+Format for fully qualified table name.
+``<catalogName>.<schemaName>.<tableName>``
+
+* catalogName:[Mandatory] Catalog information is mandatory when querying over tables from catalogs other than opensearch connector.
+
+* schemaName:[Optional] Schema is a logical abstraction for a group of tables. In the current state, we only support ``default`` and ``information_schema``. Any schema mentioned in the fully qualified name other than these two will be resolved to be part of tableName.
+
+* tableName:[Mandatory] tableName is mandatory.
+
+The current resolution algorithm works in such a way, the old queries on opensearch work without specifying any catalog name.
+So queries on opensearch indices doesn't need a fully qualified table name.
+
+Table Name Resolution Algorithm.
+--------------------------------
+
+Fully qualified Name is divided into parts based on ``.`` character.
+
+TableName resolution algorithm works in the following manner.
+
+1. Take the first part of the qualified name and resolve it to a catalog from the list of catalogs configured.
+If it doesn't resolve to any of the catalog names configured, catalog name will default to ``@opensearch`` catalog.
+
+2. Take the first part of the remaining qualified name after capturing the catalog name.
+If this part represents any of the supported schemas under catalog, it will resolve to the same otherwise schema name will resolve to ``default`` schema.
+Currently ``default`` and ``information_schema`` are the only schemas supported.
+
+3. Rest of the parts are combined to resolve tablename.
+
+** Only table name identifiers are supported with fully qualified names, identifiers used for columns and other attributes doesn't require prefixing with catalog and schema information.**
+
+Examples
+--------
+Assume [my_prometheus] is the only catalog configured other than default opensearch engine.
+
+1. ``my_prometheus.default.http_requests_total``
+
+catalogName = ``my_prometheus`` [Is in the list of catalogs configured].
+
+schemaName = ``default`` [Is in the list of schemas supported].
+
+tableName = ``http_requests_total``.
+
+2. ``logs.12.13.1``
+
+
+catalogName = ``@opensearch`` [Resolves to default @opensearch connector since [my_prometheus] is the only catalog configured name.]
+
+schemaName = ``default`` [No supported schema found, so default to `default`].
+
+tableName = ``logs.12.13.1``.
+
+
+3. ``my_prometheus.http_requests_total``
+
+
+catalogName = ```my_prometheus`` [Is in the list of catalogs configured].
+
+schemaName = ``default`` [No supported schema found, so default to `default`].
+
+tableName =  ``http_requests_total``.
+
+4. ``prometheus.http_requests_total``
+
+catalogName = ``@opensearch`` [Resolves to default @opensearch connector since [my_prometheus] is the only catalog configured name.]
+
+schemaName = ``default`` [No supported schema found, so default to `default`].
+
+tableName = ``prometheus.http_requests_total``.
+
+5. ``prometheus.default.http_requests_total.1.2.3``
+
+catalogName = ``@opensearch`` [Resolves to default @opensearch connector since [my_prometheus] is the only catalog configured name.]
+
+schemaName = ``default`` [No supported schema found, so default to `default`].
+
+tableName = ``prometheus.default.http_requests_total.1.2.3``.

docs/user/ppl/cmd/describe.rst

@@ -16,9 +16,12 @@ Description
 
 Syntax
 ============
-describe <index>
+describe <catalog>.<schema>.<tablename>
+
+* catalog: optional. If catalog is not provided, it resolves to opensearch catalog.
+* schema: optional.  If schema is not provided, it resolves to  default schema.
+* tablename: mandatory. describe command must specify which tablename to query from.
 
-* index: mandatory. describe command must specify which index to query from.
 
 
 Example 1: Fetch all the metadata
@@ -63,3 +66,24 @@ PPL query::
     | age            |
     +----------------+
 
+
+Example 3: Fetch metadata for table in prometheus catalog
+=========================================================
+
+The example retrieves table info for ``prometheus_http_requests_total`` metric in prometheus catalog.
+
+PPL query::
+
+    os> describe my_prometheus.prometheus_http_requests_total;
+    fetched rows / total rows = 7/7
+    +-----------------+----------------+--------------------------------+---------------+-------------+
+    | TABLE_CATALOG   | TABLE_SCHEMA   | TABLE_NAME                     | COLUMN_NAME   | DATA_TYPE   |
+    |-----------------+----------------+--------------------------------+---------------+-------------|
+    | my_prometheus   | default        | prometheus_http_requests_total | @labels       | keyword     |
+    | my_prometheus   | default        | prometheus_http_requests_total | handler       | keyword     |
+    | my_prometheus   | default        | prometheus_http_requests_total | code          | keyword     |
+    | my_prometheus   | default        | prometheus_http_requests_total | instance      | keyword     |
+    | my_prometheus   | default        | prometheus_http_requests_total | @timestamp    | timestamp   |
+    | my_prometheus   | default        | prometheus_http_requests_total | @value        | double      |
+    | my_prometheus   | default        | prometheus_http_requests_total | job           | keyword     |
+    +-----------------+----------------+--------------------------------+---------------+-------------+

integ-test/src/test/java/org/opensearch/sql/ppl/DescribeCommandIT.java

@@ -15,6 +15,7 @@
 
 import static org.opensearch.sql.legacy.TestsConstants.TEST_INDEX_DOG;
 import static org.opensearch.sql.util.MatcherUtils.columnName;
+import static org.opensearch.sql.util.MatcherUtils.rows;
 import static org.opensearch.sql.util.MatcherUtils.verifyColumn;
 import static org.opensearch.sql.util.MatcherUtils.verifyDataRows;
 
@@ -87,4 +88,26 @@ public void describeCommandWithoutIndexShouldFailToParse() throws IOException {
       assertTrue(e.getMessage().contains("Failed to parse query due to offending symbol"));
     }
   }
+
+  @Test
+  public void testDescribeCommandWithPrometheusCatalog() throws IOException {
+    JSONObject result = executeQuery("describe  my_prometheus.prometheus_http_requests_total");
+    verifyColumn(
+        result,
+        columnName("TABLE_CATALOG"),
+        columnName("TABLE_SCHEMA"),
+        columnName("TABLE_NAME"),
+        columnName("COLUMN_NAME"),
+        columnName("DATA_TYPE")
+    );
+    verifyDataRows(result,
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "@labels", "keyword"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "handler", "keyword"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "code", "keyword"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "instance", "keyword"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "@value", "double"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "@timestamp",
+            "timestamp"),
+        rows("my_prometheus", "default", "prometheus_http_requests_total", "job", "keyword"));
+  }
 }

ppl/src/main/java/org/opensearch/sql/ppl/parser/AstBuilder.java

@@ -29,6 +29,7 @@
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
@@ -44,6 +45,7 @@
 import org.opensearch.sql.ast.expression.Literal;
 import org.opensearch.sql.ast.expression.Map;
 import org.opensearch.sql.ast.expression.ParseMethod;
+import org.opensearch.sql.ast.expression.QualifiedName;
 import org.opensearch.sql.ast.expression.UnresolvedArgument;
 import org.opensearch.sql.ast.expression.UnresolvedExpression;
 import org.opensearch.sql.ast.tree.AD;
@@ -117,11 +119,19 @@ public UnresolvedPlan visitSearchFilterFrom(SearchFilterFromContext ctx) {
 
   /**
    * Describe command.
+   * Current logic separates table and metadata info about table by adding
+   * MAPPING_ODFE_SYS_TABLE as suffix.
+   * Even with the introduction of catalog and schema name in fully qualified table name,
+   * we do the same thing by appending MAPPING_ODFE_SYS_TABLE as syffix to the last part
+   * of qualified name.
    */
   @Override
   public UnresolvedPlan visitDescribeCommand(DescribeCommandContext ctx) {
     final Relation table = (Relation) visitTableSourceClause(ctx.tableSourceClause());
-    return new Relation(qualifiedName(mappingTable(table.getTableName())));
+    QualifiedName tableQualifiedName = table.getTableQualifiedName();
+    ArrayList<String> parts = new ArrayList<>(tableQualifiedName.getParts());
+    parts.set(parts.size() - 1, mappingTable(parts.get(parts.size() - 1)));
+    return new Relation(new QualifiedName(parts));
   }
 
   /**

ppl/src/test/java/org/opensearch/sql/ppl/parser/AstBuilderTest.java

@@ -724,6 +724,14 @@ public void testDescribeCommandWithMultipleIndices() {
         relation(mappingTable("t,u")));
   }
 
+  @Test
+  public void testDescribeCommandWithFullyQualifiedTableName() {
+    assertEqual("describe prometheus.http_metric",
+        relation(qualifiedName("prometheus", mappingTable("http_metric"))));
+    assertEqual("describe prometheus.schema.http_metric",
+        relation(qualifiedName("prometheus", "schema", mappingTable("http_metric"))));
+  }
+
   @Test
   public void test_fitRCFADCommand_withoutDataFormat() {
     assertEqual("source=t | AD shingle_size=10 time_decay=0.0001 time_field='timestamp' "

prometheus/src/main/java/org/opensearch/sql/prometheus/client/PrometheusClientImpl.java

@@ -14,7 +14,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import okhttp3.HttpUrl;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
 import okhttp3.Response;
@@ -82,7 +81,11 @@ public Map<String, List<MetricMetadata>> getAllMetrics() throws IOException {
   private List<String> toListOfStrings(JSONArray array) {
     List<String> result = new ArrayList<>();
     for (int i = 0; i < array.length(); i++) {
-      result.add(array.optString(i));
+      //__name__ is internal label in prometheus representing the metric name.
+      //Exempting this from labels list as it is not required in any of the operations.
+      if (!"__name__".equals(array.optString(i))) {
+        result.add(array.optString(i));
+      }
     }
     return result;
   }

prometheus/src/test/java/org/opensearch/sql/prometheus/client/PrometheusClientImplTest.java

@@ -106,7 +106,6 @@ void testGetLabel() {
     mockWebServer.enqueue(mockResponse);
     List<String> response = prometheusClient.getLabels(METRIC_NAME);
     assertEquals(new ArrayList<String>() {{
-        add("__name__");
         add("call");
         add("code");
       }