[ES|QL] Do not load fields on every keystroke, when editing just the …

…source command (elastic#184423)

## Summary

Fixes elastic#184093
Closes elastic#184417

- Fixes the problem on language tools layer.
- Prevents fields loading on every keystroke, when there is only a
single source command, which does not need the fields (FROM, SHOW, ROW).
It does it in two places:
  - Validation
  - Autocompletion


### Checklist

Delete any items that are not applicable to this PR.

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or ### For maintainers
- [x] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

---------

Co-authored-by: Kibana Machine <[email protected]>

packages/kbn-esql-validation-autocomplete/src/__tests__/helpers.ts

@@ -0,0 +1,73 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { camelCase } from 'lodash';
+import { supportedFieldTypes } from '../definitions/types';
+
+export const fields = [
+  ...supportedFieldTypes.map((type) => ({ name: `${camelCase(type)}Field`, type })),
+  { name: 'any#Char$Field', type: 'number' },
+  { name: 'kubernetes.something.something', type: 'number' },
+  { name: '@timestamp', type: 'date' },
+];
+
+export const enrichFields = [
+  { name: 'otherField', type: 'string' },
+  { name: 'yetAnotherField', type: 'number' },
+];
+
+// eslint-disable-next-line @typescript-eslint/naming-convention
+export const unsupported_field = [{ name: 'unsupported_field', type: 'unsupported' }];
+
+export const indexes = [
+  'a_index',
+  'index',
+  'other_index',
+  '.secret_index',
+  'my-index',
+  'unsupported_index',
+];
+
+export const policies = [
+  {
+    name: 'policy',
+    sourceIndices: ['enrich_index'],
+    matchField: 'otherStringField',
+    enrichFields: ['otherField', 'yetAnotherField'],
+  },
+  {
+    name: 'policy$',
+    sourceIndices: ['enrich_index'],
+    matchField: 'otherStringField',
+    enrichFields: ['otherField', 'yetAnotherField'],
+  },
+];
+
+export function getCallbackMocks() {
+  return {
+    getFieldsFor: jest.fn(async ({ query }) => {
+      if (/enrich/.test(query)) {
+        return enrichFields;
+      }
+      if (/unsupported_index/.test(query)) {
+        return unsupported_field;
+      }
+      if (/dissect|grok/.test(query)) {
+        return [{ name: 'firstWord', type: 'string' }];
+      }
+      return fields;
+    }),
+    getSources: jest.fn(async () =>
+      indexes.map((name) => ({
+        name,
+        hidden: name.startsWith('.'),
+      }))
+    ),
+    getPolicies: jest.fn(async () => policies),
+  };
+}

packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.suggest.test.ts

@@ -0,0 +1,49 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { getAstAndSyntaxErrors } from '@kbn/esql-ast';
+import { ESQLCallbacks } from '../shared/types';
+import * as autocomplete from './autocomplete';
+import { getCallbackMocks } from '../__tests__/helpers';
+import { EditorContext } from './types';
+
+const setup = async (caret = '?') => {
+  if (caret.length !== 1) throw new Error('Caret must be a single character');
+  const callbacks = getCallbackMocks();
+  const suggest = async (
+    query: string,
+    ctx: EditorContext = {
+      triggerKind: 0,
+    },
+    cb: ESQLCallbacks = callbacks
+  ) => {
+    const pos = query.indexOf(caret);
+    if (pos < 0) throw new Error(`User cursor/caret "${caret}" not found in query: ${query}`);
+    const querySansCaret = query.slice(0, pos) + query.slice(pos + 1);
+    return await autocomplete.suggest(querySansCaret, pos, ctx, getAstAndSyntaxErrors, cb);
+  };
+
+  return {
+    callbacks,
+    suggest,
+  };
+};
+
+describe('autocomplete.suggest', () => {
+  test('does not load fields when suggesting within a single FROM, SHOW, ROW command', async () => {
+    const { suggest, callbacks } = await setup();
+
+    await suggest('FROM kib, ? |');
+    await suggest('FROM ?');
+    await suggest('FROM ? |');
+    await suggest('sHoW ?');
+    await suggest('row ? |');
+
+    expect(callbacks.getFieldsFor.mock.calls.length).toBe(0);
+  });
+});

packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.ts

@@ -83,6 +83,7 @@ import { ESQLCallbacks } from '../shared/types';
 import {
   getFunctionsToIgnoreForStats,
   getParamAtPosition,
+  getQueryForFields,
   isAggFunctionUsedAlready,
 } from './helper';
 import { FunctionArgSignature } from '../definitions/types';
@@ -196,7 +197,7 @@ export async function suggest(
 
   const astContext = getAstContext(innerText, ast, offset);
   // build the correct query to fetch the list of fields
-  const queryForFields = buildQueryUntilPreviousCommand(ast, finalText);
+  const queryForFields = getQueryForFields(buildQueryUntilPreviousCommand(ast, finalText), ast);
   const { getFieldsByType, getFieldsMap } = getFieldsByTypeRetriever(
     queryForFields,
     resourceRetriever

packages/kbn-esql-validation-autocomplete/src/autocomplete/helper.ts

@@ -55,3 +55,11 @@ export function getParamAtPosition(
 ) {
   return params.length > position ? params[position] : minParams ? params[params.length - 1] : null;
 }
+
+export function getQueryForFields(queryString: string, commands: ESQLCommand[]) {
+  // If there is only one source command and it does not require fields, do not
+  // fetch fields, hence return an empty string.
+  return commands.length === 1 && ['from', 'row', 'show'].includes(commands[0].name)
+    ? ''
+    : queryString;
+}

packages/kbn-esql-validation-autocomplete/src/shared/resources_helpers.ts

@@ -18,7 +18,7 @@ export function buildQueryUntilPreviousCommand(ast: ESQLAst, queryString: string
 export function getFieldsByTypeHelper(queryText: string, resourceRetriever?: ESQLCallbacks) {
   const cacheFields = new Map<string, ESQLRealField>();
   const getFields = async () => {
-    if (!cacheFields.size) {
+    if (!cacheFields.size && queryText) {
       const fieldsOfType = await resourceRetriever?.getFieldsFor?.({ query: queryText });
       for (const field of fieldsOfType || []) {
         cacheFields.set(field.name, field);

packages/kbn-esql-validation-autocomplete/src/validation/resources.ts

@@ -29,6 +29,17 @@ export async function retrieveFields(
   if (!callbacks || commands.length < 1) {
     return new Map();
   }
+  // Do not fetch fields, if query has only one source command and that command
+  // does not require fields.
+  if (commands.length === 1) {
+    switch (commands[0].name) {
+      case 'from':
+      case 'show':
+      case 'row': {
+        return new Map();
+      }
+    }
+  }
   if (commands[0].name === 'row') {
     return new Map();
   }

packages/kbn-esql-validation-autocomplete/src/validation/validation.from.test.ts

@@ -0,0 +1,49 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { getAstAndSyntaxErrors } from '@kbn/esql-ast';
+import { ESQLCallbacks } from '../shared/types';
+import { ValidationOptions } from './types';
+import { validateQuery } from './validation';
+import { getCallbackMocks } from '../__tests__/helpers';
+
+const setup = async () => {
+  const callbacks = getCallbackMocks();
+  const validate = async (
+    query: string,
+    opts: ValidationOptions = {},
+    cb: ESQLCallbacks = callbacks
+  ) => {
+    return await validateQuery(query, getAstAndSyntaxErrors, opts, cb);
+  };
+
+  return {
+    callbacks,
+    validate,
+  };
+};
+
+test('does not load fields when validating only a single FROM, SHOW, ROW command', async () => {
+  const { validate, callbacks } = await setup();
+
+  await validate('FROM kib');
+  await validate('FROM kibana_ecommerce METADATA _i');
+  await validate('FROM kibana_ecommerce METADATA _id | ');
+  await validate('SHOW');
+  await validate('ROW \t');
+
+  expect(callbacks.getFieldsFor.mock.calls.length).toBe(0);
+});
+
+test('loads fields with FROM source when commands after pipe present', async () => {
+  const { validate, callbacks } = await setup();
+
+  await validate('FROM kibana_ecommerce METADATA _id | eval');
+
+  expect(callbacks.getFieldsFor.mock.calls.length).toBe(1);
+});

packages/kbn-esql-validation-autocomplete/src/validation/validation.test.ts

@@ -20,71 +20,20 @@ import { getAstAndSyntaxErrors } from '@kbn/esql-ast';
 import { nonNullable } from '../shared/helpers';
 import { METADATA_FIELDS } from '../shared/constants';
 import { FUNCTION_DESCRIBE_BLOCK_NAME } from './function_describe_block_name';
-
-const fields = [
-  ...supportedFieldTypes.map((type) => ({ name: `${camelCase(type)}Field`, type })),
-  { name: 'any#Char$Field', type: 'number' },
-  { name: 'kubernetes.something.something', type: 'number' },
-  { name: '@timestamp', type: 'date' },
-];
-const enrichFields = [
-  { name: 'otherField', type: 'string' },
-  { name: 'yetAnotherField', type: 'number' },
-];
-// eslint-disable-next-line @typescript-eslint/naming-convention
-const unsupported_field = [{ name: 'unsupported_field', type: 'unsupported' }];
-const indexes = [
-  'a_index',
-  'index',
-  'other_index',
-  '.secret_index',
-  'my-index',
-  'unsupported_index',
-];
-const policies = [
-  {
-    name: 'policy',
-    sourceIndices: ['enrich_index'],
-    matchField: 'otherStringField',
-    enrichFields: ['otherField', 'yetAnotherField'],
-  },
-  {
-    name: 'policy$',
-    sourceIndices: ['enrich_index'],
-    matchField: 'otherStringField',
-    enrichFields: ['otherField', 'yetAnotherField'],
-  },
-];
+import {
+  fields,
+  enrichFields,
+  getCallbackMocks,
+  indexes,
+  policies,
+  unsupported_field,
+} from '../__tests__/helpers';
 
 const NESTING_LEVELS = 4;
 const NESTED_DEPTHS = Array(NESTING_LEVELS)
   .fill(0)
   .map((_, i) => i + 1);
 
-function getCallbackMocks() {
-  return {
-    getFieldsFor: jest.fn(async ({ query }) => {
-      if (/enrich/.test(query)) {
-        return enrichFields;
-      }
-      if (/unsupported_index/.test(query)) {
-        return unsupported_field;
-      }
-      if (/dissect|grok/.test(query)) {
-        return [{ name: 'firstWord', type: 'string' }];
-      }
-      return fields;
-    }),
-    getSources: jest.fn(async () =>
-      indexes.map((name) => ({
-        name,
-        hidden: name.startsWith('.'),
-      }))
-    ),
-    getPolicies: jest.fn(async () => policies),
-  };
-}
-
 const toInteger = evalFunctionDefinitions.find(({ name }) => name === 'to_integer')!;
 const toStringSignature = evalFunctionDefinitions.find(({ name }) => name === 'to_string')!;
 const toDateSignature = evalFunctionDefinitions.find(({ name }) => name === 'to_datetime')!;