[8.x] ESQL: Entirely remove META FUNCTIONS (#113967)

build-tools-internal/src/main/resources/changelog-schema.json

@@ -284,6 +284,7 @@
         "Cluster and node setting",
         "Command line tool",
         "CRUD",
+        "ES|QL",
         "Index setting",
         "Ingest",
         "JVM option",

docs/changelog/113967.yaml

@@ -0,0 +1,13 @@
+pr: 113967
+summary: "ESQL: Entirely remove META FUNCTIONS"
+area: ES|QL
+type: breaking
+issues: []
+breaking:
+  title: "ESQL: Entirely remove META FUNCTIONS"
+  area: ES|QL
+  details: |
+    Removes an undocumented syntax from ESQL: META FUNCTION. This was never
+    reliable or really useful. Consult the documentation instead.
+  impact: "Removes an undocumented syntax from ESQL: META FUNCTION"
+  notable: false

docs/reference/rest-api/usage.asciidoc

@@ -239,8 +239,7 @@ GET /_xpack/usage
       "keep" : 0,
       "enrich" : 0,
       "from" : 0,
-      "row" : 0,
-      "meta" : 0
+      "row" : 0
     },
     "queries" : {
       "rest" : {

x-pack/plugin/build.gradle

@@ -202,5 +202,6 @@ tasks.named("precommit").configure {
 tasks.named("yamlRestTestV7CompatTransform").configure({ task ->
   task.skipTest("security/10_forbidden/Test bulk response with invalid credentials", "warning does not exist for compatibility")
   task.skipTest("inference/inference_crud/Test get all", "Assertions on number of inference models break due to default configs")
+  task.skipTest("esql/60_usage/Basic ESQL usage output (telemetry)", "The telemetry output changed. We dropped a column. That's safe.")
 })
 

x-pack/plugin/esql/qa/server/mixed-cluster/src/javaRestTest/java/org/elasticsearch/xpack/esql/qa/mixed/MixedClusterEsqlSpecIT.java

@@ -72,10 +72,6 @@ public MixedClusterEsqlSpecIT(
     protected void shouldSkipTest(String testName) throws IOException {
         super.shouldSkipTest(testName);
         assumeTrue("Test " + testName + " is skipped on " + bwcVersion, isEnabled(testName, instructions, bwcVersion));
-        assumeFalse(
-            "Skip META tests on mixed version clusters because we change it too quickly",
-            testCase.requiredCapabilities.contains("meta")
-        );
         if (mode == ASYNC) {
             assumeTrue("Async is not supported on " + bwcVersion, supportsAsync());
         }

x-pack/plugin/esql/qa/server/multi-clusters/src/javaRestTest/java/org/elasticsearch/xpack/esql/ccq/MultiClusterSpecIT.java

@@ -112,10 +112,6 @@ protected void shouldSkipTest(String testName) throws IOException {
         );
         assumeFalse("INLINESTATS not yet supported in CCS", testCase.requiredCapabilities.contains("inlinestats"));
         assumeFalse("INLINESTATS not yet supported in CCS", testCase.requiredCapabilities.contains("inlinestats_v2"));
-        assumeFalse(
-            "Skip META tests on mixed version clusters because we change it too quickly",
-            testCase.requiredCapabilities.contains("meta")
-        );
     }
 
     private TestFeatureService remoteFeaturesService() throws IOException {

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionIT.java

@@ -34,7 +34,6 @@
 import org.elasticsearch.xpack.core.esql.action.ColumnInfo;
 import org.elasticsearch.xpack.esql.VerificationException;
 import org.elasticsearch.xpack.esql.core.type.DataType;
-import org.elasticsearch.xpack.esql.expression.function.EsqlFunctionRegistry;
 import org.elasticsearch.xpack.esql.parser.ParsingException;
 import org.elasticsearch.xpack.esql.plugin.EsqlPlugin;
 import org.junit.Before;
@@ -1038,29 +1037,6 @@ public void testShowInfo() {
         }
     }
 
-    public void testMetaFunctions() {
-        try (EsqlQueryResponse results = run("meta functions")) {
-            assertThat(
-                results.columns(),
-                equalTo(
-                    List.of(
-                        new ColumnInfoImpl("name", "keyword"),
-                        new ColumnInfoImpl("synopsis", "keyword"),
-                        new ColumnInfoImpl("argNames", "keyword"),
-                        new ColumnInfoImpl("argTypes", "keyword"),
-                        new ColumnInfoImpl("argDescriptions", "keyword"),
-                        new ColumnInfoImpl("returnType", "keyword"),
-                        new ColumnInfoImpl("description", "keyword"),
-                        new ColumnInfoImpl("optionalArgs", "boolean"),
-                        new ColumnInfoImpl("variadic", "boolean"),
-                        new ColumnInfoImpl("isAggregation", "boolean")
-                    )
-                )
-            );
-            assertThat(getValuesList(results).size(), equalTo(new EsqlFunctionRegistry().listFunctions().size()));
-        }
-    }
-
     public void testInWithNullValue() {
         try (EsqlQueryResponse results = run("from test | where null in (data, 2) | keep data")) {
             assertThat(results.columns(), equalTo(List.of(new ColumnInfoImpl("data", "long"))));

x-pack/plugin/esql/src/main/antlr/EsqlBaseLexer.g4

@@ -66,7 +66,6 @@ FROM : 'from'                 -> pushMode(FROM_MODE);
 GROK : 'grok'                 -> pushMode(EXPRESSION_MODE);
 KEEP : 'keep'                 -> pushMode(PROJECT_MODE);
 LIMIT : 'limit'               -> pushMode(EXPRESSION_MODE);
-META : 'meta'                 -> pushMode(META_MODE);
 MV_EXPAND : 'mv_expand'       -> pushMode(MVEXPAND_MODE);
 RENAME : 'rename'             -> pushMode(RENAME_MODE);
 ROW : 'row'                   -> pushMode(EXPRESSION_MODE);
@@ -467,26 +466,6 @@ SHOW_WS
     : WS -> channel(HIDDEN)
     ;
 
-//
-// META commands
-//
-mode META_MODE;
-META_PIPE : PIPE -> type(PIPE), popMode;
-
-FUNCTIONS : 'functions';
-
-META_LINE_COMMENT
-    : LINE_COMMENT -> channel(HIDDEN)
-    ;
-
-META_MULTILINE_COMMENT
-    : MULTILINE_COMMENT -> channel(HIDDEN)
-    ;
-
-META_WS
-    : WS -> channel(HIDDEN)
-    ;
-
 mode SETTING_MODE;
 SETTING_CLOSING_BRACKET : CLOSING_BRACKET -> type(CLOSING_BRACKET), popMode;